JPS6214366Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a device that controls the recirculation of exhaust gas according to the condition of the engine when part of the exhaust gas is recirculated to the intake system for the purpose of reducing exhaust gas pollution. It is.

When the carburetor of an internal combustion engine reaches a high temperature due to an increase in engine room temperature, etc., a phenomenon such as so-called percolation occurs due to boiling of the fuel, and the air-fuel ratio of the intake air mixture to the engine becomes richer. There is a tendency.

Therefore, the carburetor of recent internal combustion engines is equipped with a hot idle compensator, which sucks new air downstream from the ventilary part without passing through the ventilary part of the carburetor when the temperature exceeds a certain temperature. Efforts are being made to prevent the tendency towards richness.

On the other hand, in recent internal combustion engines, part of the exhaust gas is recirculated to the intake system for the purpose of reducing exhaust gas pollution, and in this case, the control valve for exhaust gas recirculation is related to the intake negative pressure. However, since it is configured to open when the intake negative pressure increases toward the vacuum side, the hot idle compensator and exhaust gas recirculation device operate simultaneously when the engine is started from a high temperature, or when the engine is at high temperature. There are cases.

In such a case, the intake mixture to the engine becomes too lean due to both the intake of air by the hot idle compensator and the recirculation of exhaust gas, making ignition combustion of the intake mixture unstable and causing ignition. Until combustion stabilizes, engine drivability (torque unevenness) will not only deteriorate, but CO,
This resulted in an increase in the generation of unburned harmful gases such as HC.

The present invention utilizes the hot idle compensator mechanism to cut or reduce exhaust gas recirculation to the intake system when the temperature becomes high enough to activate the hot idle compensator of the carburetor. Therefore, the above-mentioned disadvantages are prevented with a simple structure that does not impair the function of exhaust gas recirculation control, and the gist is as follows:
A pressure-operated recirculation control valve is provided in the recirculation passage that recirculates a portion of the exhaust gas to the intake system, and the pressure chamber of the recirculation control valve is located in the carburetor at a location slightly upstream from the closed position of the throttle valve. The reflux control valve is connected to the provided sensing port so that when the negative pressure at the sensing port increases to the vacuum side, the reflux control valve opens, and the intake system downstream of the throttle valve is connected to the atmosphere when the temperature is high. In the internal combustion engine, the pressure chamber of the recirculation control valve is connected to the air passage via a communication passage, and the pressure chamber of the recirculation control valve is connected to the air passage for a hot idle compensator, and the pressure chamber is connected to the air passage for a hot idle compensator, and A check valve that opens only in the direction from the air passage to the pressure chamber is provided inside.

An embodiment of the present invention will be described below with reference to the drawings. In the drawings, 1 is an engine, 2 is an intake manifold equipped with a carburetor 3 with a throttle valve 4, and 5 is an exhaust pipe. A recirculation control valve device 7 is provided in the connecting exhaust gas recirculation passage 6 and is normally biased to close by a spring 9 in a pressure chamber 8 defined by a diaphragm. The throttle valve 4 in the carburetor 3 is opened at a position slightly below the closed position (idle opening degree) through the pressure transmission passage 10 equipped with a passage opening/closing valve apparatus 24 that closes the passage at low temperatures or introduces atmospheric air. The recirculation control valve device 7 is connected to the sensing port 11 provided at the upstream side, and does not open when the throttle valve 4 is closed, but when the throttle valve 4 is opened, exhaust pressure is generated by the exhaust pressure from the exhaust pipe. The regulating valve device 22 is opened by actuation of a diaphragm to allow exhaust gas to flow back into the intake manifold 2.

Reference numeral 12 designates a hot idle compesator air passage that connects the port 13 on the downstream side of the throttle valve 4 with an air cleaner (not shown) or a vacant space in a carburetor float chamber connected to the air cleaner. It is equipped with a temperature sensing valve 14, and when the temperature reaches such a high temperature that percolation or vapor lock occurs in the vaporizer 3, a passage is opened by the temperature sensing valve 14, and the air passage is supplied from the air passage 12 to the intake system. Fresh air is being sucked in.

An orifice 15 is provided in the air passage 12 near the connection to the port 13, and the air passage 12 between the orifice 15 and the temperature sensing valve 14 is connected to the control valve device 7 through a communication passage 16. The communication passage 6 is connected to the pressure transmission passage 10 to the
A check valve 17 is provided which opens only in the direction from the air passage 12 to the pressure transmission passage 10.

In this configuration, when the temperature is low, the temperature sensing valve 14 in the air passage 12 does not operate and the passage does not open, but is closed.
There is no intake of fresh air from the air passage 12.
The check valve 17 in the communication passage 16 between the exhaust gas recirculation passage 10 and the pressure transmission passage 10 also does not open, so that the intake negative pressure downstream of the throttle valve 4 does not act on the exhaust gas recirculation control valve device 7. Sensing port 1
Since only the negative pressure of 1 acts through the exhaust pressure regulating valve device 22, the recirculation control valve device 7 opens and closes in response to changes in the negative pressure of the sensing port 11, and the recirculation of exhaust gas to the intake system is prevented. It is carried out as usual.

Note that the device configured by the port 21 slightly upstream of the sensing port 11, the exhaust pressure regulating valve device 22, and the passage 20 that communicates them is configured to reduce the recirculation of exhaust gas during light loads,
This is to prevent combustion from becoming unstable.

If the temperature becomes high enough to cause percolation or vapor lock in the vaporizer 3 while the vehicle is operating at low speed or under high load for a long period of time, or while the vehicle is stopped in the hot sun, the temperature in the air passage 12 will increase. Since the sensing valve 14 is actuated to open the passage, fresh air is sucked in from the air passage 12 downstream of the throttle valve 4 during engine operation.

On the other hand, when the throttle valve 4 is partially open, the negative pressure in the sensing port 11 is greater on the vacuum side than the negative pressure in the air passage 12, and a pressure difference is created between the sensing port 11 and the air passage 12, which causes the check valve 17 in the communication passage 16 to is opened by the pressure difference, the air in the air passage 12 enters the pressure transmission passage 10, and the negative pressure value acting on the reflux control valve device 7 becomes smaller toward the atmosphere than the negative pressure value at the sensing port 11. Then, the recirculation control valve device 7 closes and operates, so the recirculation of exhaust gas to the intake system is controlled to be cut or reduced, and by controlling the recirculation of exhaust gas to be cut or reduced, the intake air-fuel mixture to the engine is controlled. Therefore, the leanness of the intake air mixture can be kept to a certain level, and the ignition combustion of the intake air-fuel mixture can be stabilized while the temperature sensing valve 14 is operating.

As described above, according to the present invention, the air passage for the hot idle compensator and the pressure chamber in the exhaust gas recirculation control valve are connected via a communication passage, and during this communication passage, the air passage is connected in the direction from the air passage to the pressure chamber. By installing a check valve that only opens,
When the hot idle compesator is operating, the air in the air passage for the hot idle compesator is introduced into the pressure chamber of the reflux control valve through the communication passage with a check valve, thereby increasing the pressure in the reflux control valve. Since the negative pressure in the chamber can be lowered to the atmospheric pressure side, the recirculation of exhaust gas to the intake system can be cut or reduced in conjunction with the operation of the hot idle compensator. Since the check valve in the communication passage is closed by the intake negative pressure on the downstream side of the throttle valve when the engine is not in use, the exhaust gas recirculation control by the negative pressure at the sensing port is not inhibited.

Therefore, according to the present invention, it is possible to reliably prevent the air-fuel ratio adjusted by the hot idle compensator from becoming leaner due to the recirculation of exhaust gas to the intake system, thereby improving drivability in the above state. In addition, it is possible to reduce the generation of unburned harmful gases such as CO and HC. Furthermore, when the hot idle compensator is operating, the exhaust gas recirculation cut or reduction can be reduced by using the hot idle compensator. This can be done without impairing the exhaust gas recirculation control function using the negative pressure of the sensing port, and in addition, a separate temperature sensing valve can be installed to cut or reduce the exhaust gas recirculation when the temperature is high. Since there is no need to provide the same, the structure is simplified and can be provided at low cost, and the installation space can be reduced.

[Brief explanation of the drawing]

The drawings are diagrams showing embodiments of the present invention. 1... Engine, 2... Intake manifold, 3...
Carburetor, 4...Throttle valve, 5...Exhaust pipe, 6
...Exhaust gas recirculation passage, 7...Recirculation control valve device,
10... Negative pressure passage, 12... Air passage, 14...
Temperature sensing valve, 16...Communication passage, 17...Check valve.

Claims (1)

[Scope of utility model registration request] A pressure-operated recirculation control valve is provided in the recirculation passage that recirculates a portion of the exhaust gas to the intake system, and the pressure chamber of the recirculation control valve is located in the carburetor at a position slightly upstream from the closed position of the throttle valve. The reflux control valve is connected to the provided sensing port so that when the negative pressure at the sensing port increases to the vacuum side, the reflux control valve opens, and the intake system downstream of the throttle valve is connected to the atmosphere when the temperature is high. In the internal combustion engine, the pressure chamber of the recirculation control valve is connected to the air passage via a communication passage, and the pressure chamber of the recirculation control valve is connected to the air passage for a hot idle compensator, and the pressure chamber is connected to the air passage for a hot idle compensator, and 1. An exhaust gas recirculation control device for an internal combustion engine, comprising a check valve that opens only in the direction from an air passage to a pressure chamber.