JPS5933844Y2 - Catalytic converter for exhaust purification - Google Patents

Description

[Detailed description of the invention] This invention relates to an engine-directly connected catalytic converter for exhaust purification.

Nowadays, catalytic converters are very often used to purify the exhaust gas emitted from engines, but the catalytic converter does not purify the exhaust gas until the catalyst reaches its activation temperature where the redox chemical reaction takes place. Does not perform its functions adequately.

This tendency is particularly noticeable when the engine is started or when it is cold, and under such conditions, the exhaust gas is released into the atmosphere without being sufficiently purified.

In order to solve these problems, conventionally the catalyst was configured in two or three stages, and the first stage aimed to raise the temperature of the exhaust gas through reaction with the catalyst rather than purifying the exhaust gas. , the exhaust gas heated to high temperature in the first stage reaction is passed through the second and third catalysts, where the exhaust gas is purified, or a reactor is installed in the exhaust passage upstream of the catalyst. There is a method in which a reactor is provided to cause a re-combustion reaction to raise the exhaust gas to a high temperature, and the gas is guided to a catalyst to purify the exhaust gas.

However, with these devices, the exhaust pressure increases and the engine output decreases, and the device becomes bulky, causing problems when installed in a vehicle.

This idea was provided to solve the above problem, and in order to introduce the exhaust gas flowing out from the engine's exhaust port into the catalyst device while maintaining its high temperature state, the catalyst device is installed in the engine. It is installed in the exhaust manifold and supplies secondary air into the exhaust manifold upstream of this catalyst device, and actively mixes the high temperature exhaust gas and secondary air in the iron part to cause re-combustion. This allows the heated exhaust gas to pass through the catalyst to perform a sufficient purification action.

An example of the configuration of this invention shown in the drawings will be described below.

Figure 1 was created based on the above-mentioned idea of the present invention.
This is a longitudinal side view of a catalytic converter for direct connection to a two-cylinder two-stroke engine. In the figure, 1 is a pot-shaped converter container with a double wall structure, inside and outside, and a heat insulating material 2 is filled between the inside and outside walls, and the entire converter container is has a structure divided into upper and lower parts, and 7 flange 3, 4 is attached to the divided surface, and these 7 langes 3, 4 are connected to coupling tools 6, 6 such as bolt nands with gasket 5 interposed. are connected by.

In the upper half of the converter container 1, an exhaust gas introduction pipe 7°7 for direct connection to the exhaust port of each cylinder of the engine is located approximately at the center of the distribution plate 13 (to be described later), that is, in the axial direction of the catalyst device. For this purpose, seven flanges 8, 8 are attached to each tube end, and this tube 7.7 is of double tube construction and has a heat insulating material 9.9. is filled to form an insulating structure.

Further, one exhaust gas outlet pipe 10 is attached to the exhaust gas outflow part at the center of the bottom on the lower half side of the converter container 1, and this pipe 10 also has a double pipe structure and is filled with a heat insulating material 11. At the same time, a flange 12 is attached to the tube end.

A dish-shaped distribution plate 13 is installed in the center of the converter container 1 to divide the inside of the converter container 1 into upper and lower chambers, and a retention chamber 25 is formed on the upstream side of the distribution plate 13.

Further, this distribution plate 13 has a bypass hole 14 in the center thereof, and a plurality of through holes 15 are provided around the bypass hole 14 .

A valve 16 is attached to this bypass hole 14, and this valve 16
The valve stem 17 passes through a guide cylinder 19 provided at the center of the upper part of the converter container 1 and projects outward from the upper part, and is configured so that the valve 16 can be opened and closed in the vertical direction from the outside of the upper part at a predetermined time. has been done.

A secondary air supply pipe 23 23 is connected to the exhaust gas introduction pipes 7 and 7, and secondary air is further supplied from the surroundings into a retention chamber 25 formed on the upstream side of the catalyst device in the converter container 1. The pipes 24, 24, and 24 are connected to each other.

Further, a catalyst device having a central chamber inside is installed in the lower chamber of the converter container 1 so as to further divide the lower chamber into an inner and outer chamber of a central chamber and an outer annular chamber.

This catalyst device is formed by filling a catalyst 20 between an inner cylinder 19a and an outer cylinder 19b of a catalyst container 19, which is made of a metal plate having ventilation holes such as punched metal and has a double-layered cylindrical container shape. ing.

The catalyst device is seated and fixed at its lower end in an upright state on an annular pedestal member 21 provided at the center of the bottom of the converter container 1, and its upper end is fixed to a sealing member 22 on the lower surface of the distribution plate 13.
are brought into contact via the

The pedestal member 21 is an exhaust gas outflow portion and is joined to the exhaust outlet pipe 10, and also allows the interior of the inner cylinder 19r of the catalyst container 19 and the interior of the exhaust outlet pipe 10 to communicate with each other.

Further, the inside of the inner cylinder 19a of the catalyst container 19 and the central bypass hole 14 of the distribution plate 13 are communicated with each other.

A through hole 15 provided around the distribution plate 13 allows constant communication between the outer annular chamber of the catalyst device and the retention chamber.

The distribution plate 13 is inclined in a funnel shape toward the central bypass hole 14, and the two exhaust gas introduction pipes 7°7 are inclined so as to introduce exhaust gas toward the central bypass hole 14 of the distribution plate 13. It's a shame.

Further, the outer contour of the lower surface of the valve 16 is approximately in the shape of an inverted hanging peg, and the upper surface thereof is a gently conical surface.

When the valve 16 is opened, the position of the valve 16 is such that it is evacuated from the flow path of the exhaust gas introduced from the two exhaust gas introduction pipes 7, 7, and the reverse hanging peg-shaped surface on the lower surface thereof is in the flow path of the exhaust gas. It is designed to serve as a guide surface for the outer wall of the road.

That is, when the valve 16 is opened, the exhaust gas passage in the container 1 forms a Y-shape between the two exhaust inlet pipes 7.7 and the inner cylinder 19a of the catalyst container 19 toward the exhaust outlet pipe 10. It is configured as follows.

The converter container 1 substantially also serves as an exhaust manifold.

A diffuser, a front muffler, etc. are connected to the above-mentioned exhaust outlet pipe 10.

Since the present invention is constructed as described above, the exhaust gas discharged from the engine is distributed in multiple directions approximately in the axial direction of the catalyst device in the retention chamber 25 of the converter container 1 while maintaining a high temperature state in the exhaust port. The exhaust gas and the exhaust gas collide with each other within the retention chamber 25.

At this time, the retention char/bar 25 of the converter container 1
Since secondary air is supplied inside, the high-temperature exhaust gas and the secondary air, which have been made uniform in composition and temperature by colliding with each other, are stored in the retention chamber/bar 25 upstream of the catalyst device in the converter container 1. Vigorous mixing causes re-combustion to take place in the chamber, after which the through holes 15,1 around the distribution plate 13
5, flows into the outer annular chamber, passes inward from the outer periphery of the catalyst container 19, during which time it comes into contact with the catalyst 20, undergoes a combustion reaction, and is purified. From the exhaust outlet pipe 10, it passes through the diffuser and front muffler, and then flows into the rear. It passes through the muffler and is released into the outside air from the tailpipe.

In this embodiment, the secondary air is supplied through the exhaust introduction pipe 7.
70 part and the retention chamber 25 of the converter vessel 1
The secondary air is blown in approximately tangentially from the pipe 24 from around the inside of the pipe.
If the secondary air is supplied, the exhaust gas and the secondary air are simultaneously supplied and mixed into the retention chamber 25, and if the secondary air is blown in substantially tangentially from the pipe 24, the exhaust gas is swirled in the retention chamber 25. gives the secondary air and exhaust gas mixture and activates re-combustion.

Note that the supply of this secondary air does not necessarily have to be from two places as in this embodiment, but may be supplied from one place if necessary, and the supply position may also be different from the main one. Needless to say, the present invention is not limited to the embodiment, and may be provided upstream of the catalyst device in the converter container.

Further, the catalyst device may be one in which a granular catalyst is placed in the catalyst container 19 as in this embodiment, or a honeycomb catalyst.

Further, the valve 16 opens the bypass hole 14 when the catalyst 20 is overheated or during high load operation, and its opening/closing drive means detects the overheat temperature and high load state with appropriate detection means, and Based on this, the driving means is configured to be driven to open.

When the valve 16 opens the bypass hole 14 as described above, most of the exhaust gas flows out from the exhaust outlet pipe 10 through the bypass hole 14 without contacting the catalyst in the catalyst container 19, causing the catalyst 20 to become overheated. can suppress the excitement of

In addition, even in high-load operating conditions, the exhaust gas passage inside the container 1 is Y-shaped, so there is little passage resistance, and a sufficient diffuser effect can be expected, improving intake efficiency. A decrease in engine output can be prevented.

Note that when the valve 16 is opened, not all of the exhaust gas comes into contact with the catalyst, but some of it comes into contact with the catalyst and is purified, and a sufficient combustion reaction can also be expected in the diffuser and front muffler, so the result is Specifically, the exhaust gas discharged from the tailpipe is sufficiently purified.

Although the above embodiment describes a catalytic converter for direct connection to a two-cylinder two-stroke engine, similar effects can be expected even when applied to a two-cylinder four-stroke engine, and it can also be applied to an engine with two or more cylinders. It can also be applied to

As explained above, this invention provides a retention chamber in the catalytic converter container on the upstream side of the catalytic converter in a catalytic converter that is directly connected to the engine, and directs the exhaust gas outlet in the direction in which the entire amount of exhaust gas is cross-mixed within the chamber. Since the arrangement is such that the mixed exhaust gas is introduced into the catalyst device and secondary air is supplied circumferentially into the retention chamber, the exhaust gas is sufficiently mixed within the retention chamber by the secondary air. can be swirled to promote mixing of secondary air and exhaust gas, thereby promoting secondary combustion.

Further, in the overall configuration, the retention chamber can be made compact by devising the secondary air supply method and the exhaust gas introduction method as described above.

Furthermore, by using the secondary air supply method described above, even when the same total amount of exhaust gas is mixed, it is possible to efficiently mix and cause secondary combustion, and the retention chamber itself can be made compact, allowing purification at low temperatures and when starting the engine. It is possible to provide a small and efficient purification device with excellent performance.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional side view showing an embodiment of the exhaust gas purifying catalytic converter of the present invention, and FIG. 2 is a schematic plan view thereof. 1...Converter container, 10...Exhaust gas outlet, 23.24...Secondary air supply pipe, 25...Retention chamber.

Claims (1)

[Scope of utility model registration request] In a catalytic converter that is directly connected to the engine, a retention chamber is provided in the catalytic converter container on the upstream side of the catalytic device, and an exhaust outlet is arranged in the direction in which the entire amount of exhaust gas is cross-mixed within the chamber, and the mixed exhaust gas is A catalytic converter for exhaust gas purification, characterized in that secondary air is introduced into the catalytic device and supplied into the retention chamber in a circumferential direction.