JPH09264125A - Exhaust bypass system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the deterioration of pre-catalyst elements or the like by collecting exhaust gas in the small number of pre-catalyst elements or the like, shortening the time of the pre-catalyst elements or the like for reaching ignition temperatures, causing high-temperature exhaust gas through a main flow passage by using a valve and preventing the long-time exposure of the pre-catalyst elements or the like to the high-temperature exhaust gas. SOLUTION: A bypass flow passage 16 is connected to a plurality of main flow passages 12a and 12b and a pre-catalyst element, an adsorbing element or a honeycomb heater 24 is disposed in the bypass flow passage. The flow of exhaust gas is changed by valves 22a and 22b such as butterfly valves or the like. Low-temperature exhaust gas is passed into the bypass flow passage and high-temperature exhaust gas is passed into the main flow passage.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an exhaust bypass system for discharging exhaust gas from an internal combustion engine such as an automobile engine.

[0002]

2. Description of the Related Art Exhaust systems for automobile engines include
Carbon monoxide (CO) and hydrocarbons (H) contained in exhaust gas
A three-way catalyst for purifying contaminants such as C) and nitrogen oxides (NO _x ) is used as a main catalyst element.
The three-way catalyst efficiently purifies pollutants when the exhaust gas is heated to a constant temperature, that is, the so-called ignition temperature or higher. Therefore, after the engine is warmed up, the main catalytic element purifies pollutants in the exhaust gas, but before the engine is warmed up, for example, for low temperature exhaust gas immediately after the engine is started. , Purification performance is limited.
Therefore, in order to purify pollutants in low-temperature exhaust gas, immediately after the engine exhaust manifold,
It has been proposed to arrange a precatalyst element (Japanese Patent Laid-Open No. 7-766). The pre-catalyst element is obtained by supporting the catalyst composition on a carrier such as a honeycomb structure having a small volume and a small heat capacity. Since the honeycomb structure has a small heat capacity, it is heated in a short time and reaches the ignition temperature earlier than the main catalyst element.

On the other hand, the exhaust manifold is
The exhaust gas from a plurality of cylinders of the engine is collected. In the process, the cylinders may interfere with each other so that the exhaust gas flows backward or the flow of the exhaust gas becomes poor. When such exhaust interference occurs,
The pressure on the exhaust side of the cylinder, that is, the back pressure, increases, the resistance to the flow of exhaust gas increases, and the engine output decreases. So, in the exhaust manifold,
Instead of collecting exhaust gas from all cylinders in one flow path in one stage, a dual type exhaust manifold is used that collects in two flow paths.

[0004]

FIG. 9 shows the engine 3
1 shows a conventional exhaust system connected to zero. A pair of exhaust manifolds 40a, 40b are used. That is, the pair of outer cylinders 32a and 32d are connected to the exhaust manifold 40a, and the pair of inner cylinders 32b and 32c are connected to the exhaust manifold 40b. And the exhaust
The manifolds 40a and 40b are connected to the main channels 12a and 12b, respectively, and are connected to the respective main channels 12a and 1b.
2a had precatalyst elements 24a, 24b arranged.
However, in this arrangement, each main flow path 12a, 12
Since the pre-catalyst element is required for b, the heat capacity of the whole pre-catalyst element becomes large, and it took time to reach the ignition temperature. Further, the pre-catalyst element is always exposed to the exhaust gas, and when the output of the engine increases, such as during high-speed operation or high-load operation, the pre-catalyst element 24a, 2
Due to the flow resistance of 4b, the back pressure increased and the engine output decreased. Furthermore, when the output of the engine rises,
The pre-catalyst elements 24a, 24b are exposed to the hot exhaust gas and may deteriorate.

[0005]

Therefore, in the present invention,
A pre-catalyst element or the like is arranged in the bypass flow passage, and preferably, the flow of exhaust gas is switched between the main flow passage and the bypass flow passage by a valve. That is, according to the present invention, a plurality of main channels, a bypass channel connected to at least two of the main channels, and a pre-catalyst element, an adsorption element or a honeycomb heater arranged in the bypass channel. An exhaust bypass system for an internal combustion engine is provided, which comprises: the pre-catalyst element, the adsorption element, or a main catalyst element disposed downstream of the honeycomb heater. In the present invention, it is preferable that the pre-catalyst element is arranged in the bypass channel. Further, it is preferable that the main catalyst element is arranged in the main flow path. Further, it is preferable that a valve for switching the flow of the exhaust gas to the bypass flow passage is arranged. Further, it is preferable that the valve is arranged in each of the main flow paths. Furthermore, the exhaust bypass system has a central processing unit for controlling opening and closing of the valve, and a sensor for outputting a signal to the central processing unit, and the sensor is the main flow path. Are preferably arranged in

Furthermore, it is preferable that the valve is a butterfly valve. Further, it is preferable that the butterfly valve has a flap portion that can be rotated in order to block the flow of exhaust gas, and the flap portion is made of ceramics such as silicon nitride, silicon carbide, and sialon. Furthermore, the butterfly valve includes a duct, a flap member, and a pair of sleeves, and the duct includes a wall portion that forms an internal space and a pair of bearing portions that are continuous with the wall portion. A bearing hole communicating with the internal space is formed in each of the bearing portions, and the flap member includes a flap portion and a pair of shaft portions extending in a rotation axis direction of the flap portion. , The pair of shaft portions of the flap member are inserted into and fixed to the pair of bearing holes of the duct, respectively, so that the flap portion can rotate in the internal space of the duct. The member is substantially composed of ceramics such as silicon nitride, silicon carbide, and sialon, the flap portion and the pair of shaft portions are integrally formed, and the pair of sleeves are
It is preferable that they are respectively arranged between the bearing portion of the duct and the pair of shaft portions of the flap member.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION In FIG. 1, a four-cylinder engine 30 is provided.
The exhaust bypass system 10 of the present invention is connected to the exhaust manifolds 40a and 40b. However, the exhaust bypass system of the present invention may include an exhaust manifold. A pair of outer cylinders 32
a and 32d are connected to the exhaust manifold 40a, and a pair of inner cylinders 32b and 32c are connected to the exhaust manifold 40b.

In the present invention, the bypass channel 16 is provided for disposing the pre-catalyst element, the adsorption element or the honeycomb heater 24, and the pre-catalyst element is provided downstream of the confluence 15 of the bypass channel 16. An adsorption element or honeycomb heater 24 is arranged. Bypass channel 16
It is preferable that the pre-catalyst element 24 is arranged in the first place. In this case, a honeycomb heater acting as a preheater, an adsorption element, etc. may be further arranged. Hereinafter, the case where the pre-catalyst element 24 is arranged in the bypass channel 16 will be mainly described. Each main channel 1
2a, 12b, the flow of exhaust gas to the main flow path 12
Valves 22a and 22b for switching between a and 12b and the bypass channel 16 are arranged. Valve 22
Butterfly valves are preferably used as a and 22b.

As shown in FIG. 1, the valves 22a and 22b are preferably arranged in the main flow passages 12a and 12b downstream of the branch points 14a and 14b, and the flow of exhaust gas in the case of this arrangement will be described below. explain. When the valves 22a and 22b are closed, the exhaust gas that has passed through the exhaust manifold 40a is discharged at the branch point 14a.
The exhaust gas flowing from the bypass passage 16 to the bypass manifold 16 passes through the branch point 14b.
It flows into the bypass flow path 16 more. These exhaust gases are
The bypass passage 16 joins at the joining point 15 and passes through the pre-catalyst element 24 arranged in the bypass passage 16. on the other hand,
When the valves 22a and 22b are opened, the exhaust gas mainly flows into the main flow passages 12a and 12b, and some exhaust gas also flows into the bypass flow passage 16. The flow of the fluid at the branch points 14a and 14b depends on the structure of the piping at the branch points 14a and 14b, but this piping structure is generally formed so that the fluid flows smoothly along the main flow paths 12a and 12b. Has been done.

In the present invention, the main flow paths 12a, 12b
There is no limitation on the manner in which the bypass flow paths 16 merge. In FIG. 1, the main flow paths 12a and 12b and the bypass flow path 16 join together at a meeting point 18, and the main flow path 13 extends further downstream. However, the main flow path 12
It is also possible that a and 12b first merge and then the bypass flow channel further merges downstream thereof. Further, the main catalyst element 26 may be arranged downstream of the pre-catalyst element 24, and as shown in FIG. 1, it is preferable that the main flow path 13 and the main catalyst element 26 are arranged. However, the main catalyst element 2
6 may be provided in each of the main flow paths 12a and 12b. The exhaust gas that has passed through the main catalyst element 26 is
Generally, the exhaust gas passes through a muffler (not shown) for silencing the exhaust gas, and is released to the atmosphere through a tail pipe.

In the present invention, when the exhaust gas has a low temperature, and when the exhaust gas contains hydrocarbons, nitrogen oxides, etc. having a certain value or more, the valves 22a and 22b are closed,
The exhaust gas that has passed through the exhaust manifolds 40 a and 40 b flows into the bypass passage 16, passes through the pre-catalyst element 24, and then passes through the main catalyst element 26. On the other hand, when the exhaust gas has a high temperature, and when the exhaust gas contains hydrocarbons, nitrogen oxides, etc. below a certain value, the valves 22a and 22b are opened to pass through the exhaust manifolds 40a and 40b. The exhaust gas
They flow into the main channels 12a and 12b, respectively, and then pass through the main catalyst element 26. However, as described above, some exhaust gas also flows into the bypass passage 16.

Therefore, immediately after the engine is started,
Since the number of pre-catalyst elements is smaller than in the conventional case, the heat capacity of the whole pre-catalyst element is reduced, and the time for the pre-catalyst element to reach the ignition temperature is shortened. Further, since the exhaust gas is concentrated on a small number of precatalyst elements, the time required for the precatalyst elements to reach the ignition temperature is shortened. On the other hand, since the high temperature exhaust gas can flow through the main flow path instead of the bypass flow path, the pre-catalyst element is not exposed to the high temperature exhaust gas for a long time, and thus deterioration can be prevented.

The precatalyst element 24 is preferably located inside the engine room, where space is limited, rather than under the floor of the vehicle. Pre-catalyst element 2
The reason for No. 4 is to prevent the increase of the heat capacity of the exhaust pipe to the pre-catalyst element due to the lengthening of the exhaust pipe as much as possible because the temperature is required to be raised quickly. Therefore, it can be said that the reduction of the volume of the entire precatalyst element itself has a technical effect. The main catalyst element 26, the honeycomb heater, which will be described later, the adsorption element, and the like need not necessarily be arranged in the engine room.

Hereinafter, elements and members substantially the same as those shown in FIG. 1 are designated by the same reference numerals, and the description thereof will be omitted as appropriate. In FIG. 2, the manifold 4 of the 6-cylinder engine 30 is shown.
The exhaust bypass system 10 of the present invention is connected to 0a and 40b. The cylinders 32a, 32b, 32c are connected to the exhaust manifold 40a, and the cylinder 32
Exhaust manifold 40 d, 32e, 32f
b.

In FIG. 2, main catalyst elements 26a, 26b are arranged in each of the main flow paths 12a, 12b. The exhaust manifolds 40a and 40b are connected to the main flow paths 12a and 12b, respectively, and the main flow paths 12a and 12b are connected via branch points 14a and 14b, respectively.
Both are connected to the bypass channel 16. Bypass channel 1
6 merge at a merge point 15, and a pre-catalyst element 24 is arranged downstream of the merge point 15. The bypass channel 16 is divided into two at a branch point 17, and merge points 18a and 18b, respectively.
To rejoin the main channels 12a and 12b. The main catalyst elements 26a and 26b are arranged downstream of the confluence points 18a and 18b, respectively.

FIG. 3 shows an embodiment in which a honeycomb heater or adsorption element 25 is arranged downstream of the pre-catalyst element 24 and upstream of the main catalyst element 26. FIG.
Then, engine 30, exhaust manifold 40
a, 40b, and junctions 1 from junctions 14a and 14b
The bypass flow passage 16 from 5 to the pre-catalyst element 24 is the same as in FIG. In FIG. 3, unlike the case of FIG. 1, the main flow path 12a and the main flow path 12b have a confluence point 1
The main flow path 13 is formed by joining at 8c, and then the bypass flow path 16 is joined at a joining point 18d. Confluence point 18d
Further downstream of the honeycomb heater or adsorption element 25
Is disposed, and the main catalyst element 26 is disposed downstream of this.

The honeycomb heater is for heating a fluid such as exhaust gas, and its purpose is to heat the low-temperature exhaust gas immediately after the engine is started to the ignition temperature of the main catalyst element or higher. As the honeycomb heater, a honeycomb heater having a device for applying electric power such as electrodes fixed to a honeycomb structure having a large number of through holes is preferably used. The honeycomb heater is preferably fixed together with the main catalyst element 26 in the same housing. The adsorbing element is a hydrocarbon, nitrogen oxide (N
It adsorbs gas such as O _x ) or fine particles. Generally, it has a property of adsorbing the above-mentioned gas or the like at a low temperature such as an ignition temperature or lower and discharging the adsorbed gas or the like at a high temperature such as an ignition temperature or higher. Further, as the adsorption element, an adsorption element in which an adsorption element such as zeolite is carried on the surface of the partition wall forming the through hole of the honeycomb structure is preferably used.
Both honeycomb heaters and adsorption elements may be used in the present invention. The honeycomb heater, the adsorption element, etc. may be arranged under the floor of the automobile.

The present invention can be suitably used for a dual type exhaust manifold, but can also be applied to a non-dual type exhaust manifold. In FIG. 4, each cylinder 32a, 32
b, 32c, 32d corresponding to the main flow paths 12a, 1
2b, 12c, 12d are provided, and each main flow path 1
Main catalyst element 26 on 2a, 12b, 12c, 12d
a, 26b, 26c and 26d are arranged. Along with this, each of the main flow paths 12a, 12b, 12c, 1
2d is provided with butterfly valves 22a, 22b, 22c, 22d and sensors 23a, 23b, 23c, 23d. When the butterfly valves 22a, 22b, 22c, 22d are closed, the cylinders 32a, 32b, 32
Exhaust gas from c and 32d is divided into branch points 14a and 14b,
From 14c and 14d, it flows into the bypass passage 16, passes through the confluence point 15, passes through the pre-catalyst element 24, and further passes through the honeycomb heater or the adsorption element 25.

The bypass flow path 16 passes through a branch point 17 and then joins the main flow path 12 at confluence points 19 a, 19 b, and 19 c.
Merge into a, 12b, and 12c. In FIG. 4, the bypass flow passage 16 does not join the main flow passage 12d. This is because when the exhaust gas passes through the bypass passage, it is not necessary to connect to all the surface passages because the engine such as low-temperature exhaust gas has a low output. However, the bypass flow passage 16 may be joined to all the main flow passages. In FIG. 4, the honeycomb heater or the adsorption element 25 is arranged not in the main channel but in the bypass channel before joining the main channel. Since the honeycomb heater and the adsorption element are used for low-temperature exhaust gas and the like, such arrangement may be adopted. In addition, when there are two or more main flow paths, the exhaust gas passes through one pre-catalyst element,
It is preferable that all the main channels are connected to the bypass channels. However, there may be a main flow path that is not connected to the bypass flow path. For example, when there are three main flow paths, two main flow paths are connected to a bypass flow path in which the pre-catalyst element is arranged, and one pre-catalyst element is further arranged in one main flow path. Good. Also in this case, the volume of the entire pre-catalyst element is reduced as compared with the case where the pre-catalyst element is arranged in all the three main flow paths.

In the present invention, the opening and closing of the valves 22a and 22b are preferably controlled by the sensors 23a and 23b and the like and a central processing unit (not shown). In FIG. 1, the sensors 22a and 22b are connected to the main channels 12a and 12b.
In b, it is arranged slightly upstream of the branch points 14a and 14b. Preferably, it is not limited to being slightly upstream of the branch points 14a and 14b, and it is also disposed slightly downstream of the branch points 14a and 14b in the main flow paths 12a and 12b.
The sensor, temperature sensor, oxygen sensor, a hydrocarbon sensor, NO _x sensor or the like is used appropriately, the temperature sensor is preferably used. These sensors provide signals corresponding to temperature, oxygen concentration, hydrocarbon concentration, nitrogen oxide concentration, etc.
Generally, it outputs an electric signal, and a conventional sensor can be used.

As the central processing unit, for example, a central processing unit for controlling the ignition timing or the like of the engine or a central processing unit for adjusting the fuel amount for adjusting the air-fuel ratio is used at the same time as the valve. You may control opening and closing. For example, in the case of a temperature sensor, when an electric signal corresponding to the temperature of the exhaust gas is connected to the central processing unit, and an electric signal corresponding to a temperature below a certain level is input to the central processing unit. First, the central processing unit adjusts so as to output a signal for closing the valve, particularly an electric signal. On the other hand, when an electric signal corresponding to a certain temperature or more is input from the temperature sensor to the central processing unit, the central processing unit adjusts so as to output a signal for opening the valve, particularly an electric signal.

Similarly, in the case of a hydrocarbon sensor, a NO _x sensor, etc., an electric signal corresponding to the concentration of these pollutants is connected so as to be input to the central processing unit, and these concentrations are equal to or higher than a certain value. When a corresponding electric signal is input to the central processing unit when the above condition occurs, the central processing unit adjusts so as to output a signal for closing the valve, particularly an electric signal. Meanwhile, hydrocarbon sensor, N
When an electric signal corresponding to when the concentration of these pollutants falls below a certain value from the O _x sensor is input to the central processing unit, the central processing unit outputs a signal to open the valve, Adjust to output an electrical signal.

Each of the pre-catalyst element and the main catalyst element has a honeycomb structure having partition walls for forming a large number of through holes, and a catalyst composition coated on the surfaces of the partition walls of the honeycomb structure. It is preferable. The exhaust gas flows into the through hole from the inflow end surface of the honeycomb structure, passes through the through hole, and flows out from the outflow end surface of the honeycomb structure. The volume of the honeycomb structure of the pre-catalyst element is 800c.
It is preferably m ³ or less, more preferably 600 cm ³ or less, still more preferably 500 cm ³ or less. This is because space is limited in the engine room. The heat capacity of the honeycomb structure of the pre-catalyst element is 1 cm in the range of room temperature to 300 ° C.
It is preferably 0.5 J / K or less per ³ and 0.
It is more preferably 4 J / K or less. This is because if the heat capacity is small, the temperature of the precatalyst element will rise rapidly.

On the other hand, the volume of the honeycomb structure of the main catalyst element is preferably larger than the volume of the pre-catalyst element, but may be about the same as the volume of the pre-catalyst element. The volume of the honeycomb structure of the main catalyst element is, for example, preferably about 400 to 1000 cm ³ . The heat capacity of the honeycomb structure of the main catalyst element is not particularly limited. As the main catalyst element, for example, those described in Japanese Patent Application No. 8-7082 can be preferably used. The horizontal cross-sectional shape of the through-hole of the honeycomb structure is not particularly limited, but in view of thermal shock resistance, it is more flexible than hexagonal or more polygonal, corrugated, etc. The shape is preferred.

The cell density of the honeycomb structure, that is, the density of the through holes is not particularly limited, but the heat conduction efficiency,
In terms of catalyst purification efficiency, etc., 100 to 600 cells / inch ²
Is preferable, and 200 to 500 cells / inch ² is more preferable. When the number of cells exceeds 600 cells / inch ² , the pressure loss of fluid increases. As the honeycomb structure, both a foil type in which a rolled thin plate (foil) is wound with a corrugated shape and an extrusion type by a powder metallurgy extrusion method can be used, but an extrusion type is preferable in terms of durability. The material of the honeycomb structure may be ceramics or metal. In the case of ceramics, cordierite or the like is preferably used.

The catalyst composition contains an active component such as a noble metal, and thereby removes by oxidizing or reducing pollutants such as nitrogen oxides, carbon monoxide, and hydrocarbons in the exhaust gas. You can The catalyst composition contains a carrier having a large surface area and a catalytically active substance supported on the carrier. Here, as the carrier, for example, γ-Al ₂
Typical examples include O ₃ type, TiO ₂ type, SiO ₂ —Al ₂ O ₃ type and the like, and perovskite type powder and particles. Examples of the catalytically active substance include platinum (P
t), noble metals such as palladium (Pd) and rhodium (Rh), base metals such as Cu, Ni, Cr and Co. 10 to 100 g of the catalyst composition in which 10 to 100 g of platinum (Pt) and palladium (Pd) are supported on 1 cubic foot of γ-Al ₂ O ₃ -based carrier is preferable.

The honeycomb heater has the above-mentioned honeycomb structure and is made of metal and has slits for adjusting resistance, and an electrode for supplying electric power to the honeycomb structure. Those are preferable.
More preferably, the honeycomb heater is fixed to the housing via a holding member that is inserted into a groove formed on the peripheral surface of the honeycomb structure. As the honeycomb heater and the holding member, for example, those described in Japanese Patent Application No. 8-70221 can be preferably used. Incidentally, such a holding member includes a pre-catalyst element, a main catalyst element,
It can also be used as an adsorption element. As the metallic honeycomb structure, any material can be used as long as it is a metal that generates heat when energized. Since it is exposed to high temperatures such as automobile exhaust gas, Fe-Cr-Al alloys are preferable from the viewpoints of heat resistance and oxidation resistance, and those containing a small amount of boron are particularly preferable. It is preferable that at least one electrode for supplying electric power is connected to the peripheral surface of the honeycomb structure, and for example, a conductive connecting member secures conduction between the honeycomb structure and the electrode. The term "electrode" as used herein means a generic term for terminals for applying a voltage to the heater, and includes terminals such as ground. Examples of the adsorption element include, for example, JP-A-7-232084 and JP-A-8-10.
Those described in Japanese Patent Laid-Open No. 566 and Japanese Patent Laid-Open No. 10613/1996 can be preferably used.

A butterfly valve can be preferably used as the valve. The butterfly valve is used for switching the flow passage of the fluid, and generally has a duct that forms the flow passage of the fluid and a flap that is rotatably fixed inside the duct. Fluid can flow through the duct when the flaps are positioned substantially parallel to the fluid flow. On the other hand, the fluid cannot pass through the duct when the flaps are arranged in a direction that intersects the fluid flow. These two states are controlled by the rotation of the flap. The butterfly valve preferably has a ceramic flap. Since ceramics has high heat resistance, thermal deformation of the flap at high temperatures can be prevented. Further, since ceramics have high abrasion resistance, abrasion of the flaps can be avoided. Further, ceramics have a lower coefficient of thermal expansion than general metals and can prevent wear, so that a good sealing function can be maintained when the flap is closed.

As a butterfly valve, Japanese Patent Application No. 6-32
As described in No. 2254, the flap portion and the pin acting as a shaft for rotating the flap portion may be separately manufactured, and the pin may be fixed to the flap portion. On the other hand, as described in Japanese Patent Application No. 7-285985, a ceramic flap and a ceramic shaft portion may be integrally formed as a flap member by injection molding, casting molding or the like. Since the flap portion and the pair of shaft portions are integrally formed, the durability of the joint portion between the flap portion and the shaft portion is improved.

5 and 6 show the latter butterfly valve 1
It is explanatory drawing of 00. The duct and sleeve may be made of ceramic or metal. 5 and 6 show the state where the flap member 120 closes the duct 110. Shaft 124 of flap member 120
a and 124b are rotatably inserted and fixed to the bearing portions 114a and 114b of the duct 110 together with the sleeves 130 and 140. Duct 110, flap member 1
20 and the pair of sleeves 130 and 140 are the housing 1
52 and 154. The flap portion 122 of the flap member 120 can rotate the internal space 11 of the duct 110, thereby closing or opening the duct 110. In FIG. 5A, the flap member 120
The phantom line indicates that the flap member 120 opens the duct 110.

7 and 8 are explanatory views of the duct 110 and the flap member 120 used in FIGS. 5 and 6, respectively. In FIG. 7, the duct 110 is the internal space 11
1 forming the wall 112 and the bearing holes 113a, 113
It has the bearing parts 114a and 114b which form b. The bearing portions 114a and 114b are continuous with the wall portion 112, and the bearing holes 113a and 113b are in communication with the internal space 111.
The pair of bearing holes 113a and 113b share an axis, and the axial direction intersects the axial direction of the wall portion 112 at a right angle.
It is preferable that the inner peripheral surface of the wall portion 112 has a substantially cylindrical shape because the substantially disk-shaped flap portion 122 of the flap member 120 rotates in the internal space 111. The inner peripheral surfaces 113a and 113b of the bearing portions 114a and 114b are respectively the outer peripheral surfaces 130s and 14 of the sleeves 130 and 140.
Corresponding to 0s, it has a substantially cylindrical shape. 5 and 6
In the above embodiment, as the flap member 120 rotates,
Inner peripheral surfaces 113a, 113 of the bearings 114a, 114b
b and the outer peripheral surfaces 130s, 14 of the sleeves 130, 140
0s slides. Further, the inner peripheral surfaces 133 and 143 of the sleeves 130 and 140 and the shaft portion 124 of the flap member 120 are included.
It is preferable that the outer peripheral surfaces of a and 124b can slide. This is because by having two pairs of sliding surfaces, friction when the flap member 120 rotates is further reduced.

The duct 110 has a pair of side surfaces 110s and 110t substantially parallel to each other. The wall portion 112 or the bearing portions 114a and 114b communicates with the bearing holes 113a and 113b from one side surface 110s of the duct 110. Grooves 116a and 116b are formed. Groove 11
6a and 116b are formed parallel to the axial direction of the wall 112. Shafts 124a of flap member 120, 1
24b pass through the grooves 116a and 116b, respectively, so that the bearing portions 114a and 114b of the duct 110 are
Can be inserted. That is, FIG. 7 (c), (d)
The width 116c of the grooves 116a and 116b is preferably greater than or equal to the outer diameter of the shaft portions 124a and 124b of the flap member 120. In FIG. 7, the width 1 of the grooves 116a and 116b
16c is formed in the diameter of the bearing holes 113a and 113b.

In FIG. 8, the flap member 120 includes a flap portion 122 having a substantially disc shape, a pair of shaft portions 124 a and 124 b having a substantially columnar shape, and the flap portion 12.
2 and a pair of connecting portions 127a, 128a, 127b, 128b for connecting the pair of shaft portions 124a, 124b. The rotation axis of the flap member 120 is the flap portion 12
It passes through the center of 2 and is common to the axes of the shaft portions 124a and 124b. The flap part 122 has a pair of side surfaces 122s and 122t which are parallel to each other. A peripheral surface 122u of the flap portion 122 has a cylindrical surface inclined by 20 degrees in the rotation direction with respect to the perpendicular direction of the side surfaces 122s and 122t. For example,
As shown in FIG. 5, when the flap portion 122 closes the internal space 111 of the duct 110, the flap portion 122 intersects the axial longitudinal direction of the wall portion 112 at about 20 degrees. This angle is preferably 10 to 30 degrees. Shaft 12
4a is a notch portion 12 for fixing the lever 162.
6. As the lever 162 moves, the flap portion 122 rotates.

In FIG. 8, it is preferable that the connecting portion has a shape of a rotating body that shares the rotation axis of the flap member 120, and the connecting portion extends along the rotation axis toward the center of the flap portion. The tapered portions toward the end, that is, the conical portions 127a and 127b, and the conical portion 127a,
Flange 128a, 128b continuous to the bottom surface of 127b
And Flange 128a, 128b and shaft portion 124
It is preferable that the a and 124b are connected in the vicinity of the peripheral surface 122u of the flap portion 122. Shafts 124a, 124
b and the flap part 122, the connection parts 127a, 127
Since the connection is made by b, 128a, and 128b, it is possible to reduce the stress concentration generated in the connection portion by the rotating torque of the flap member 120.

End face 1 of the flange portions 128a and 128b
29a and 129b are sleeves 130 and 140, respectively.
Airtightly contact the end faces 131, 141 of the flanges 128a, 128b so that when the flap 122 is closed, the fluid will end face 129 of the flanges 128a, 128b.
a, 129b and the end faces 131 of the sleeves 130, 140,
It is possible to prevent leakage from the gap with 141. Peripheral surfaces 129c, 1 of the flange portions 128a, 128b
29d is preferably flush with the outer peripheral surfaces 130s and 140s of the sleeves 130 and 140, respectively. However, the peripheral surfaces 129c and 1c of the flange portions 128a and 128b are
29d may be larger or smaller than the outer peripheral surfaces 130s and 140s of the sleeves 130 and 140 in the radial direction of the rotating shaft.

The pair of sleeves 130 and 140 have a shape of a rotating body that shares the rotation axis of the flap member 120, and the pair of shaft portions 124 a and 12 of the flap member 120.
It is preferable to rotate as 4b rotates.
The sleeve 130 has a cylindrical shape, and has a through hole 133 penetrating from one end surface 131 to the other end surface 132. The shaft portion 124 a of the flap member 120 is fitted into the through hole 133 of the sleeve 130, and the shaft portion 124 a
The notch 126 of a projects from the end surface 132 of the sleeve 130.

The sleeve 140 includes a pair of end surfaces 141,
The end surface 141 has a shape having 142, and the recess 1 for fitting the shaft portion 124b of the flap member 120 into the end surface 141.
43 are formed. A gap may be formed between the end surface 124c of the shaft portion 124b and the recess 143. The end surface 142 of the sleeve 140 is tapered to form the apex 144. The end surface 142 is a curved surface that is chamfered around the apex 144, and the sleeve 140
However, it is easy to rotate together with the flap member 120 at the apex 144.

In FIG. 5, the flap portion 122 has the duct 11
It is preferable to provide a stopper 151 for restraining the rotation of the flap portion 122 when the 0 is opened. When the butterfly valve vibrates, the flap portion 12
2 to prevent the vibration of the shaft member 124 of the flap member 120.
It is possible to prevent wear of the notch 126 of a and the lever 162. 5 and 6, the duct 110 and the flap member 1 are shown.
20, the sleeve 130, and the sleeve 140 are housed in the internal space formed by the housings 152 and 154. However, the end of the shaft portion 124a of the flap member 120 projects to the outside of the housings 152 and 154. Each of the housings 152 and 154 has wall portions 153 and 155 that form a fluid passage, and the passage is formed by the duct 110.
Communicates with the internal space 111. Housings 152, 15
4 has a wall portion that forms a fluid flow path,
This fluid flow path communicates with the internal space 111 of the duct 110. The housing 152 has a bottom portion 15 that supports the sleeve 140, the end surface of the bearing portion 114b of the duct 110, and the like.
2a.

An airtight member 172 such as an o-ring is sandwiched and fixed between the housing 152 and the side surface 110 t of the duct 110, and an airtight member 174 such as an o-ring is sandwiched between the housing 154 and the side surface 110 s of the duct 110. It is fixed, which prevents fluid from leaking. The airtight member 172 is arranged outside the internal space 111 on the side surface 110t of the duct 110, and is preferably slightly larger than the diameter of the internal space 111 on the side surface 110t. The airtight member 174 is arranged outside the grooves 116a and 116b in the side surface 110s of the duct 110, and the side surface 1
It is preferably arranged outside the grooves 116a and 116b in 10s.

The lever 162 includes a flap member 120.
A recess 162a for fitting the notch 126 of the shaft portion 124a is formed. The lever 162 has a recess 162b for fixing the seat 158 flush with the outer surface of the lever. The recess 162b is formed by the lever 1
It is formed on the side opposite to the recess 162 a with respect to 62.
The lever 162 has a handle 163, and the handle 1
63 is connected to the connecting rod 185 of the actuator 184. A through hole for penetrating the joint pin 178 is formed in the handle 163. Joint pin 17
8 penetrates the through hole of the handle 163 and the joint 176 to fix the handle 163 and the connecting rod 185.

Airtight member 160 having a thin annular shape
Is the end surface 162c around the recess 162a of the lever 162.
And the end surface 132 of the sleeve 130 are sandwiched and fixed. The airtight member 160 can further prevent leakage of fluid from between the inner peripheral surface 133 of the sleeve 130 and the outer peripheral surface of the shaft portion 124a. Further, it is preferable that the airtight member 160 covers the outer peripheral surface 130s of the sleeve 130 and the inner peripheral surface 113a of the bearing portion 114a of the duct 110, that is, the sliding surface, so that the fluid leaks from the sliding surface. Can be further prevented.
The lever holding member 164 may be a fastener such as a bolt or a screw, and penetrates the nut 166 and the cap 156 so that the apex 164 a of the lever holding member 164 is the lever 1.
The seat 162 is fixed to the seat 158, and the lever 162
Is rotatably fixed to the notch 126 of the shaft portion 124a of the flap member 120. The lever holding member 164 shares the rotation axis of the flap member 120.

The connecting rod 185 of the actuator 184 is capable of translational movement, and the lever 162 converts the translational movement into rotational movement. Bracket 182 secures actuator 184 and housing 152. Cap 1
56 covers the lever 162 so that the handle 163 of the lever 162 can move. The flange portion 157 of the cap 156 and the flange portion 153 of the housing 152 are
It is fixed with fasteners such as bolts.

As a method of manufacturing the butterfly valve, the pair of shaft portions 124a and 124b of the flap member 120 are sequentially passed through the grooves 116a and 116b of the duct 110 and inserted into the bearing portions 114a and 114b of the duct 110. When the pair of shaft portions of the flap member 120 have different lengths,
After passing the long shaft portion 124a through the groove 116a, the bearing portion 1
14a, and then the short shank 124b is inserted into the groove 116.
After passing through b, the bearing portion 114b is inserted. afterwards,
Bearing holes 113a and 113b from both end surfaces of the duct 110
Insert the sleeves 130 and 140 into the
The shaft portions 124a and 124b of the flap member 120 are fitted into the sleeves 130 and 140, respectively. Then, the duct 110, the flap member 120, the sleeves 130, 140
Is housed in the housings 152 and 154, the lever 162 is attached, and the actuator 162 is connected.

The flap portion 122 of the flap member 120
And the pair of shaft portions 124a and 124b are integrally formed, and preferably, the flap portion 122 and the pair of shaft portions 1 are formed.
24a, 124b and a pair of bearings 127a, 127
b, 128a, 128b are integrally formed. That is, preferably, the entire flap member 120 is integrally formed. The term “integrally formed” includes a case obtained by sintering a ceramic molded body having a desired shape. For example, a ceramic molded body having a flap portion, a pair of shaft portions, and a pair of connecting portions is molded from a raw material containing ceramic powder, and the molded body is white-processed and sintered. As the ceramic powder, for example, silicon nitride or silicon carbide is used.

In the molding step, injection molding, cast molding or press molding and machining are performed. In injection molding, a molding material containing a ceramic powder and an organic binder such as resin or wax is molded by a molding machine such as an in-line screw type, and then degreased under pressure or atmospheric pressure to remove the organic binder. , A molded body is obtained. In the cast molding, a slurry containing a ceramic powder, a small amount of an organic binder, a peptizer and a solvent is solid-cast, molded by pressure casting, etc., then dried and the organic binder is removed to obtain a molded product.

In the press molding and machining, a granular powder containing a ceramic powder and a small amount of an organic binder is press molded at low pressure, the organic binder is removed by heating, and a ceramic stationary blade is shaving with a machining center or the like, and molded. Get the body. The mechanical processing using a machining center may be either wet or dry. In the case of wet processing, calcination is preferable in order to impart strength to the molded product. In the case of the dry type, the organic binder may be removed after machining using a machining center. For sintering, the atmosphere and temperature may be selected according to the ceramic powder. Usually, for silicon nitride, it may be maintained at about 1700 ° C. in a nitrogen atmosphere, and for silicon carbide, it may be maintained at about 2700 in an argon atmosphere.
It may be maintained at 000 ° C. In addition, finishing may be performed after sintering.

[0047]

EFFECTS OF THE INVENTION In the present invention, the number of pre-catalyst elements, adsorption elements, and honeycomb heaters is sufficient, so the total heat capacity of the pre-catalyst elements and the like becomes small, and the time for the pre-catalyst elements and the like to reach the ignition temperature is It gets shorter. In addition, since the exhaust gas concentrates on a small number of pre-catalyst elements and the like when the engine is started, the time for the pre-catalyst elements and the like to reach the ignition temperature is shortened. Also, by using a valve,
Since the high-temperature exhaust gas can flow through the main flow path instead of the bypass flow path, the pre-catalyst element and the like are not exposed to the high-temperature exhaust gas for a long time, and deterioration can be prevented.

[Brief description of drawings]

FIG. 1 is an illustration of an embodiment of an engine and an exhaust bypass system of the present invention.

FIG. 2 is an illustration of another embodiment of the engine and exhaust bypass system of the present invention.

FIG. 3 is an illustration of an engine and another embodiment of the exhaust bypass system of the present invention.

FIG. 4 is an illustration of an engine and another embodiment of the exhaust bypass system of the present invention.

FIG. 5 is an explanatory diagram of a butterfly valve that can be used in the present invention. (A) It is the front view which notched one part. (B) A-
It is sectional drawing cut | disconnected along the A'line.

FIG. 6 is a cross-sectional view of the left side surface of the butterfly valve.

FIG. 7 is an explanatory diagram of a duct used for a butterfly valve. (A) It is sectional drawing cut | disconnected along the BB 'line. (B) It is a front view. (C) It is sectional drawing cut | disconnected along CC 'line. (D) It is sectional drawing cut | disconnected along the DD 'line.

FIG. 8 is an explanatory diagram of a flap member used in a butterfly valve. (A) It is explanatory drawing seen from the E direction.
(B) It is a top view. (C) It is a side view. (D) It is a front view.

FIG. 9 is an illustration of an embodiment of an engine and a conventional exhaust bypass system.

[Explanation of symbols]

10 ... Exhaust gas bypass system, 12a, 12b, 12
c, 12d ... Main flow path, 13 ... Main flow path, 14
a, 14b, 14c, 14d ... Branching point, 15 ... Confluence point, 16 ... Bypass flow path, 17 ... Branching point, 18,18
a, 18b, 18c, 18d ... Confluence point, 19a, 19
b, 19c ... Confluence point, 22a, 22b, 22c, 22
d ... Butterfly valve, 23a, 23b, 23c, 23d
..Sensor, 24, 24a, 24b ... Pre-catalyst element, adsorption element or honeycomb heater, 25 ... Honeycomb heater or adsorption element, 26, 26a, 26b, 26c, 26
d ... Main catalyst element, 30 ... Engine, 32a, 32
b, 32c, 32d, 32e, 32f ... Cylinder, 4
0a, 40b ... Exhaust manifold, 100.
..Butterfly valves, 110 ... Ducts, 110s, 110
t ... Side surface of duct, 111 ... Internal space, 112 ... Wall portion, 113a, 113b ... Bearing holes, 114a, 11
4b ... Bearing portion, 116a, 116b ... Groove, 116c
... Width of groove, 120 ... Flap member, 122 ... Flap part, 124a, 124b ... Shaft part, 126 ... Notch part 127a, 127b ... Conical shape part, 128a, 1
28b ... Flange portion, 129a, 129b ... Flange portion end surface, 129c, 129d ... Flange portion peripheral surface,
130 ... Sleeve, 131, 132 ... End face, 140 ...
-Sleeve, 141, 142 ... End face, 143 ... Recessed portion,
144 ... Apex, 151 ... Stopper, 152, 154
... Housing, 156 ... Cap, 158 ... Sheet, 160 ... Airtight member, 162 ... Lever, 164 ...
Lever holder, 166 ... Nut, 172, 174 ... Airtight member, 176 ... Joint, 178 ... Joint pin, 180 ... Joint ring, 182 ... Bracket, 184 ... Actuator 185 ... Connecting rod, 18
6 ... Regulator

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location B01D 53/87 F01N 9/00 A F01N 3/08 F02D 9/04 E 3/24 F16K 1/22 AC 7/08 E 9/00 B01D 53/34 A F02D 9/04 116H F16K 1/22 53/36 B

Claims (9)

[Claims] 1. A plurality of main flow paths, a bypass flow path connected to at least two of the main flow paths, a pre-catalyst element, an adsorption element or a honeycomb heater disposed in the bypass flow path, An exhaust gas bypass system for an internal combustion engine, comprising: a catalyst element, the adsorption element, or a main catalyst element disposed downstream of the honeycomb heater. 2. The exhaust bypass system according to claim 1, wherein the pre-catalyst element is arranged in the bypass flow passage. 3. The exhaust bypass system according to claim 1, wherein the main catalyst element is arranged in the main flow path. 4. The exhaust bypass system according to claim 1, wherein a valve for switching the flow of exhaust gas to the bypass flow passage is arranged. 5. The exhaust bypass system according to claim 4, wherein the valve is disposed in each of the main flow paths. 6. The exhaust bypass system includes a central processing unit for controlling opening and closing of the valve, and a sensor for outputting a signal to the central processing unit, the sensor being the main unit. The exhaust bypass system according to claim 4 or 5, wherein the exhaust bypass system is arranged in a flow path. 7. The exhaust bypass system according to claim 4, 5 or 6, wherein the valve is a butterfly valve. 8. The butterfly valve has a flap part that can rotate to block the flow of exhaust gas, and the flap part is made of ceramics such as silicon nitride, silicon carbide, and sialon. The exhaust bypass system of claim 7, wherein the exhaust bypass system comprises: 9. The butterfly valve includes a duct, a flap member, and a pair of sleeves, and the duct includes a wall portion for forming an internal space, and a pair of bearing portions continuous with the wall portion. And a bearing hole communicating with the internal space is formed in each of the bearing portions, and the flap member includes a flap portion and a pair of shaft portions extending in a rotation axis direction of the flap portion. And a pair of the shaft portions of the flap member are respectively provided so that the flap portion can rotate in the internal space of the duct.
The flap member is inserted into and fixed to the pair of bearing holes of the duct, and the flap member is substantially made of ceramics such as silicon nitride, silicon carbide, and sialon, and the flap portion and the pair of shaft portions are integrally formed. The exhaust bypass system according to claim 7, wherein the pair of sleeves are arranged between the bearing portion of the duct and the pair of shaft portions of the flap member, respectively. .