JPS6343381Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a secondary air supply device for supplying secondary air to the exhaust system of an engine to promote the oxidation reaction of exhaust gas.

As a means of purifying exhaust gas by promoting the oxidation of CO and HC in engine exhaust gas, a device is used that supplies secondary air from an air cleaner in the intake system to the exhaust system via a reed valve. This system connects the air cleaner, which is the intake system, with the engine's exhaust system through a conduit, and a reed valve is placed in the middle of the conduit to allow flow only to the exhaust side. When the pressure on the exhaust side is negative, fresh air is sent to the exhaust side, and when the pressure on the exhaust side is positive, the reed plate of the reed valve is pressed to prevent exhaust from flowing into the air cleaner side.

However, if the reed plate of the reed valve is damaged, for example, the high heat of the exhaust gas flows back into the air cleaner, causing a problem in that it burns out the reed valve's filter member and the air cleaner's filter element (not shown).

As a countermeasure to this problem, as shown in Japanese Utility Model Publication No. 57-12162, a reed valve is fixed facing the chamber provided in the passage communicating the exhaust port and the air cleaner, and a bimetal is installed inside the chamber. Some are equipped with a shutter that is moved, and the passage is opened and closed by the expansion and contraction of the bimetal due to the heat of the exhaust gas. However, in this case, when the lead plate is damaged, the shutter, which is rotated by a bimetal, opens due to the pressure of the exhaust gas, and the high-temperature exhaust gas continues to flow toward the air cleaner, and there is a risk of burning out the filter components, etc. be.

The present invention provides a secondary air supply device that solves this problem.The valve box installed on the retainer is heat-treated so that the valve is open at normal temperatures and closed at high temperatures. A cut-off valve made of a shape-memory alloy is installed to prevent burnout of the filter member due to backflow of high-temperature exhaust gas.

The shutoff valve 1 shown in FIG. 1 is made of a reversible shape memory alloy and has a thin conical shape. Several linear cuts 4 are provided on the inclined surface from the apex 2 of the conical shutoff valve 1 toward the base 3, each forming a triangular displacement piece 5, and the base 3 has a plurality of mounting holes 6. is drilled. As shown in the perspective view of FIG. 2, in the above-mentioned shutoff valve 1, at normal temperature, the displacement piece 5 formed by the linear cut 4 curves outward from the base 3 to form a passage 7, and at high temperature, the displacement piece 5 forms a passage 7. The displacement piece 5 is uncurved and returns to its planar shape, the sides and apexes of the adjacent triangular displacement pieces 5 come into contact, and the cut 4 becomes a sealed conical shape, blocking the passage 7. 1st
The valve is heat-treated to the closed state shown in the figure. Third
The figure is an explanatory sectional view of a main part of the above-mentioned shutoff valve 1 installed in an air cleaner A.

A passage 15 formed by the body B and the section wall 14 communicates with the expansion chamber 13 formed by the retainer 11 through a through hole 16 . A filter member 17 is disposed at the boundary between the through hole 25 of the reed valve 20 and the expansion chamber 13 communicating with the window hole 12 provided in the retainer 11. The reed valve 20 is housed in the valve box 10 and pressed against the retainer 11, so that the peripheral wall 24 other than the through hole 25 is kept airtight, and the reed plate 21 is freely displaced between the stopper 22 and the valve seat 23 due to pressure fluctuations. .

The valve box 10 is connected to the housing portion 18 of the reed valve 20 and is provided with a pipe 8 consisting of a tapered portion 9 and a cylindrical portion 26. For example, a mounting hole 6 formed in the base 3 shown in FIG.
It is fixed at 9. Furthermore, a connecting pipe 27 leading to the exhaust side is connected to the cylindrical portion 26.

The solid line diagram of the shutoff valve 1 in FIG. 3 is the reed valve 20.
The diagram shows when the is operating normally, and when the exhaust side is under negative pressure, the reed plate 21 of the reed valve 20 moves to the stopper 22 side, and the air from the air cleaner A is purified by the filter member 17 and flows into the exhaust system. do.

Also, when the exhaust system becomes positive pressure, the lead plate 21
is pressed against the valve seat 23 by exhaust pressure to block backflow of exhaust gas. The shutoff valve 1 tries to close due to the heat of the exhaust gas filling the valve box, but the vibration of the reed plate 21 due to the exhaust pulsation causes cold air to enter the valve box, suppressing the movement of the shutoff valve 1. Leave passage 7 open.

However, if the lead plate 21 is damaged and the high-temperature exhaust gas from the exhaust side flows back from the conduit 27 to the air cleaner A side, the shutoff valve 1 will be exposed to abnormally high temperatures and will be in the position shown by the two-dot chain line in FIG. Each displacement piece 5 is rapidly displaced, and the sides and apexes of adjacent triangular displacement pieces 5 come into contact, forming a conical shape that blocks the cut 4 and blocking the passage. Even when exhaust gas pressure is applied to the outer surface of the shutoff valve 1, each displacement piece 5 is supported by contacting the side of the adjacent displacement piece 5, and does not bend inward.

As described above, in the secondary air supply device of the present invention, a shutoff valve is formed using a reversible shape memory alloy so as to form a conical shape toward the exhaust side, and the conical apex of this shutoff valve is directed toward the exhaust side. Since the valve body is mounted inside the valve box, when the many displacement pieces cut into triangular shapes are exposed to high temperatures, the exhaust gas will continue to flow to the air cleaner side due to a malfunction of the lead plate. Even when the valve is in contact with the side of the adjacent displacement piece, each displacement piece of the shutoff valve is supported by being in contact with the side of the adjacent displacement piece. will not flow to the air cleaner side.

In addition, since the shutoff valve is made of a reversible reaction type shape memory alloy, it returns to its original state when the temperature returns to normal, so it can be used permanently.

[Brief explanation of the drawing]

Fig. 1 is a front view of the product of the present invention (at abnormally high temperatures), Fig. 2 is a perspective view of the product of the present invention at normal temperature, and Fig. 3 is a cross-sectional view of the main parts for explanation when the product of the present invention is installed. 1...Shutoff valve, 2...Apex, 3...Base, 4...
...Cut, 5...Displacement piece, 6...Mounting hole, 9...
...Tapered portion, 10...Valve box, 20...Reed valve, 21...Reed plate.

Claims (1)

[Scope of utility model registration request] A retainer that communicates with the air cleaner and has a filter member inside is installed on the peripheral wall of the air cleaner, and a valve box that has a built-in reed valve and a pipe connected to the exhaust side is installed on the outer wall of the retainer. Inside the pipe of the box, a plurality of triangular displacement pieces made of reversible shape memory alloy are cut from the base toward the apex to form a plurality of triangular displacement pieces, which come into contact with each side of each adjacent displacement piece. A secondary air supply device equipped with a conical shutoff valve with its apex facing the exhaust side.