JPS5822963Y2 - Secondary air supply control device in internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a secondary air supply control device for preventing afterburn in an internal combustion engine.

There is an exhaust gas purification method that utilizes exhaust pulsation to introduce secondary air into an exhaust passage, and then oxidizes unburned components in the exhaust gas in a thermal reactor or the like.

By the way, when the throttle valve is suddenly closed and the engine is decelerated suddenly while driving, the negative pressure in the intake passage becomes high, and the fuel remaining in various places in the pipe is sucked into the combustion chamber at once, making the air-fuel mixture richer. Unburned components increase and are discharged into the exhaust system.

When secondary air is introduced into the exhaust gas containing many unburned components in this manner, a so-called afterburn phenomenon occurs in which the unburned components are explosively combusted.

The present invention aims to provide a device that can prevent such afterburn, and includes a negative pressure actuator that is activated when the inside of the suction passage suddenly becomes high negative pressure, and a device that is activated by the negative pressure actuator. Next, install an air supply control valve,
In a device that closes the control valve and stops the supply of secondary air when the suction passage becomes high negative pressure due to sudden deceleration, the valve body is made of an elastic material, and the valve seat is shaped like an annular protrusion. It is characterized in that the member constituting the valve seat also serves as a cap for the valve chamber.

The following explanation will be given with reference to the drawings. In Fig. 1, reference numeral 1
2 is a two-cylinder engine, each cylinder 2 has an intake port 3, an exhaust port 4, and secondary air supply pipes 5 and 6 communicate with both exhaust ports, respectively.

The secondary air supply pipes 5, 6 communicate with one secondary air supply pipe 9 via a check pulp 7.8, and communicate with the atmosphere via an air cleaner 10.

A secondary air control valve 11 is provided in the middle of the secondary air supply pipe 9, and the control valve is operated by a negative pressure actuator 12.

As shown in FIG. 2, in this control valve, a disc-shaped valve body 14 made of an elastic material and having a metal core in the center is fixed by bolts 15 to the tip of a valve rod 13 supported by a sliding OT function. A cap 17 made of sheet metal or cast metal that closes the valve chamber 16 is integrally formed with an annular protrusion, and the tip of the protrusion forms a valve seat 18 to which the valve body 14 is pressed. .

The inside of this valve seat forms an inverted conical discharge port 19, to which a secondary air supply pipe 9 is connected.

On the side opposite to the valve seat 18, a valve seat 20 is formed by an annular projection on the inner wall of the valve body 2Qa, and the opposite side of the valve body 14 is brought into pressure contact with the valve seat.

The negative pressure actuator 12 has a first negative pressure chamber 22 and a second negative pressure chamber 2 separated by a diaphragm 21 fixed to the valve rod 13.
3, a valve plate 24 is fixed to the diaphragm 21,
The valve plate is provided with an orifice 25 and a check pulp 26 that flows only from the first negative pressure chamber 22 to the second negative pressure chamber.

The first negative pressure chamber 22 is connected to the negative pressure introduction pipe 2 through an orifice 27.
8 communicates with the intake passage 29 of the engine downstream of the throttle valve 30.

Next, the operation of this device will be explained.

In operating conditions other than sudden deceleration of the engine, the negative pressure actuator 12 does not operate, and the diaphragm 21
1 turn, pull up the valve rod 13 and separate the valve body 14 from the valve seat 18 to open the discharge port 19, and the valve body is in pressure contact with the valve seat 20 above.

Therefore, due to the pulsation in the exhaust passage, when the pressure is negative, the outside air passes through the air cleaner 10, through the secondary air supply pipe 9, the discharge port 19, the check valve 7, 8, the secondary air supply pipe 5, 6.
The exhaust gas is introduced into the exhaust port 4 through the exhaust gas, and unburned components in the exhaust gas are oxidized in a thermal reactor provided in the exhaust system.

In this state, since the valve body 14 is in pressure contact with the valve seat 20 on the opposite side, the negative pressure in the suction passage 29 causes the outside air to pass through the gap between the valve rod 13 and the hole in the valve body 20a, and the first
There is no leakage through the negative pressure chamber 22 to the suction pipe side.

Next, if you quickly close the throttle valve 30 and decelerate suddenly,
The negative pressure within the suction passage 29 increases rapidly.

The second negative pressure 23 is applied to the first negative pressure chamber 22 through the orifice 25.
As a result, the second negative pressure chamber cannot follow sudden pressure fluctuations, and the diaphragm 21 is deviated toward the first negative and positive chamber, pressing the valve body 14 against the valve seat 18.

As a result, the secondary air supply passage is blocked and the secondary air is stopped.

Therefore, even if unburned components in the exhaust gas increase, outer burn will not occur.

The pressure inside the second negative pressure chamber 23 gradually becomes negative through the orifice 25, and becomes equal to the pressure in the first negative pressure chamber.
The high negative pressure in the suction passage due to sudden deceleration is temporary, and the negative pressure also becomes low, eliminating the risk of afterburn.The negative pressure in the first negative pressure chamber 22 also becomes low, and both The pressure in the negative pressure chamber is the same, and the spring 31 causes the diaphragm 2 to
1 is deflected, the valve body 14 is separated from the valve seat 18, and secondary air is supplied again.

In response to fluctuations in the internal pressure of the suction passage at times other than sudden deceleration, the second negative pressure chamber follows the first negative pressure chamber and becomes negative pressure, and the diameter of the orifice 25 and other conditions are adjusted so that the valve does not open. is the standard.

As is clear from the above, according to the present invention, a control valve is provided in the secondary air supply pipe, and the control valve is closed only when the negative pressure in the suction passage becomes high due to sudden deceleration. In a device designed to stop the supply, the valve body is made of an elastic material, and the valve seat is formed in the shape of an annular protrusion, so the valve body is in airtight contact with the valve seat, and the secondary It can block air and reliably prevent afterburn.

Furthermore, since the member forming the valve seat also serves as a cap for the valve chamber, the structure is simple and assembly, repair and inspection can be easily performed.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing an embodiment of the present invention, and FIG. 2 is a sectional view of a valve mechanism section. 1...2 cylinder engine, 2...cylinder, 3...
Intake port, 4... Exhaust port, 5, 6... Secondary air supply pipe, 7, 8... Check pulp, 9... Secondary air supply pipe, 10... Air cleaner, 11...・Secondary air control valve, 12... Negative pressure actuator, 13...
Valve body, 14... Valve body, 15... Bolt, 16...
Valve chamber, 17...cap, 18...valve seat,
19...Discharge port, 20...Pulb sheet, 20a.
... Eye space, 21... Diaphragm, 22... First negative pressure chamber, 23... Second negative pressure chamber, 24... Valve plate, 25...
...Orifice, 26...Check valve, 2T...
- Orifice, 28... Negative pressure introduction pipe, 29... Suction passage, 30... Throttle valve, 31... Spring.

Claims (1)

[Scope of utility model registration request] A secondary air supply passage provided for introducing outside air into the exhaust passage, and a negative pressure actuator that has a negative pressure chamber communicating with the suction passage and is activated when the suction passage suddenly becomes high negative pressure. a control valve that is provided in the secondary air supply passage and closes when the negative pressure actuator is actuated; the valve body of the control valve is made of an elastic material; and the member that constitutes the valve seat is a cap of the valve chamber. Button 2 for an internal combustion engine, which also has a valve seat formed in the shape of an annular protrusion.
Next air supply control device.