JPS63111276A - Exhaust gas recirculation device for internal combustion engine with supercharger - Google Patents

Abstract

PURPOSE:To prevent an engine from worsening its drivability when the engine is in a low temperature, by switching a temperature selector valve and cutting off the supply of supercharge pressure to one of the pressure chambers in a differential pressure operating mechanism when the engine is in a temperature lower than the predetermined value. CONSTITUTION:An exhaust gas recirculation (EGR) device 14 is constituted of each EGR passage 15, 16, connecting an intake manifold 2 with an exhaust passage 12 or an exhaust pipe 13, and an EGR valve 17 which is provided in each EGR passage 15, 16 and equipped with a differential pressure operating mechanism 18. Here an internal combustion engine provides in its cooling water passage or the like a temperature selector valve 29 which has three ports 30-32 responsively sensing a temperature of the engine. And when the engine is placed in a condition that its temperature reaches not a predetermined value, the temperature selector valve 29, which permits each port 31, 32 to communicate and pressure of a sensing port 27 to simultaneously act respectively on both pressure chambers 20, 21 in the differential pressure operating mechanism 18, eliminates a pressure difference between both the pressure chambers 20, 21. In this way, a valve unit 19 of the EGR valve 17 is adapted to a valve seat 26 by a spring 24.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is an internal combustion engine equipped with a supercharger such as an exhaust turbo supercharger in the intake system, in which the exhaust gas is removed for the purpose of reducing NOx in the exhaust gas. This invention relates to a device for circulating a portion of gas back into the intake system.

[Conventional technology]

Modern internal combustion engines are equipped with a supercharger such as an exhaust turbo supercharger in the intake system in order to improve output and reduce fuel consumption. Furthermore, in order to reduce NOx in exhaust gas, it is effective to recirculate a part of the exhaust gas to the intake system, and even in the internal combustion engine with a supercharger, part of the exhaust gas is recirculated to the intake system. things are being done.

Japanese Utility Model Application No. 55-25686 as a prior art discloses a valve body biased in the closing direction by a spring in an exhaust gas recirculation passage connecting an intake system and an exhaust system in an internal combustion engine with a supercharger. A reflux control valve is provided, the valve body of the reflux control valve is connected to an actuating body of a differential pressure operating mechanism, and one pressure chamber of the differential pressure operating mechanism is provided with a reflux control valve having a position slightly lower than the closed position of the throttle valve in the intake system. The pressure at the upstream sensing port is transferred to the other pressure chamber of the differential pressure operating mechanism, and the boost pressure upstream from the throttle valve is transferred to the pressure at the sensing port and the boost pressure upstream from the throttle valve. When the pressure difference is large, the valve body in the recirculation control valve opens, and when the pressure difference becomes small, the valve body closes, thereby recirculating the exhaust gas to the intake system in the partial load region of the engine. proposed that the amount of exhaust gas recirculated to the intake system be restricted to a small amount in high load ranges.

[Problem that the invention seeks to solve]

However, the exhaust gas recirculation device described in this prior art performs exhaust gas recirculation control only according to the load on the engine, regardless of the engine temperature, and the engine temperature still remains at a predetermined temperature. J7 flow of exhaust gas is carried out even in the unwarmed state.

On the other hand, when the engine temperature has not warmed up to a predetermined temperature, combustion of the intake air-fuel mixture is in an unstable state.Despite this, when exhaust gas is recirculated as in the prior art, combustion is further accelerated. There is a problem in that the drivability of the engine is significantly deteriorated due to the unstable state.

The present invention aims to solve this problem.

[Means for solving problems]

In order to achieve this object, the present invention provides a structure in which a spring is used to bias the exhaust gas recirculation passageway between the intake system and the exhaust system in a supercharged internal combustion engine in the closing direction, as in the prior art described above. A reflux control valve is provided, the valve element of the reflux control valve is connected to an actuating element of a differential pressure actuating mechanism, and one pressure chamber of the differential pressure actuating mechanism is connected to a closing valve of a throttle valve in the intake system. The pressure at the sensing port slightly upstream of the position is introduced into the other pressure chamber, and the boost pressure upstream from the throttle valve is introduced into the other pressure chamber. when the temperature of the engine is lower than a predetermined temperature, the transmission of the boost pressure to the other pressure chamber through the boost pressure transmission passage is cut off, and the sensing port is switched to communicate with the other pressure chamber. The structure is equipped with a temperature switching valve.

[Action/effect of the invention]

With this configuration, when the engine is warmed to a predetermined temperature, one pressure chamber in the differential pressure operating mechanism contains the pressure at the sensing port, and the other pressure chamber contains the boost pressure upstream from the throttle valve. Because each acts,
The exhaust gas can be returned to the intake system mainly in a partial load region where the pressure difference between the pressure at the sensing port and the boost pressure upstream of the throttle valve becomes large.

On the other hand, when the engine temperature has not warmed up to a predetermined temperature, the pressure at the sensing port is switched to act on the other pressure chamber in the differential pressure operation mechanism by the operation of the temperature switching valve, and the pressure at the sensing port is always applied to the other pressure chamber. Since there is no pressure difference between the two pressure chambers and the one pressure chamber where the pressure of be.

Therefore, according to the present invention, in a supercharged internal combustion engine, although exhaust gas is mainly recirculated to the intake system in a partial load range, when the engine temperature is low,
Since the recirculation of exhaust gas to the intake system can be canted, it is possible to reliably prevent deterioration of drivability until the engine temperature reaches a predetermined temperature.

[Embodiment] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the drawing, reference numeral 1 indicates an internal combustion engine having an intake manifold 2 on one side and an exhaust manifold 3 on the other side, and reference numeral 4 indicates an exhaust turbine 5 and a blower. Each exhaust turbo supercharger is shown directly connected to a compressor 6, and a supercharging passage 7 from the discharge side of the blower-compressor 6 is connected to the intake manifold 2. A carburetor 8 with a throttle valve 9 and a surge tank 10 are provided such that the surge tank IO is located upstream of the carburetor 8, while an air cleaner 11 is connected to the suction side of the blower compressor 6. . Further, an inlet side of the exhaust turbine 5 is connected to the exhaust manifold 3 via an exhaust passage 12, and an exhaust pipe 13 to the atmosphere is connected to the outlet side of the exhaust turbine 5.

Reference numeral 14 in the figure indicates an exhaust gas recirculation device, and the exhaust gas recirculation device 14 includes the intake manifold 2 and the exhaust passage 1.
2 or exhaust gas recirculation passage 15.16 connecting with the exhaust pipe 13
and a recirculation control valve 17 with a diaphragm type differential pressure operating mechanism 18 provided in the re-exhaust gas recirculation passage 15.16. A rod 23 is attached to a diaphragm 22 which is an actuating body forming two pressure chambers 20 and 21.
A spring 24 provided in one pressure chamber 20 of the differential pressure actuation mechanism 18 moves the valve body 19 in the closing direction toward a valve seat 26 provided in a valve chamber 25 that accommodates the valve body 19. The negative pressure chamber 20 is energized and the throttle valve 9 is in the closed position (idle opening degree) in the carburetor 8.
It communicates via a pressure transmission passage 28 with a sensing port 27 provided at a slightly more upstream location.

On the other hand, reference numeral 29 in the figure indicates a wax-type temperature switching valve that is attached to the cooling water passage, lubricating oil passage, cylinder block, cylinder head, etc. of the internal combustion engine l and is related to the temperature of the engine. Two, three ports 30,3
1.32, and the ports 31 and 32 are communicated with each other until the temperature of the engine 1 warms to a predetermined temperature, but when the temperature reaches a predetermined temperature, the communication between the ports 31 and 32 is cut off.
The ports 30 and 31 are switched so that they communicate with each other, and the port 30 is connected to the surge tank 10 through the boost pressure transmission passage 33, and the port 31 is connected to the pressure transmission passage 34.
and the port 32 to the other pressure chamber 21 in the differential pressure operating mechanism 18 via the same supercharging pressure transmission passage 35.

In this configuration, when the engine 1 is not warmed to a predetermined temperature, the temperature switching valve 29 is in a state of communicating the ports 31 and 32 with each other, and the pressure between one pressure chamber 20 and the other pressure chamber in the differential pressure operating mechanism 18 is The pressure at each sensing port 27 is acting on both chambers 21 at the same time, and there is no pressure difference between one pressure chamber 20 and the other pressure chamber 21, and the pressure at the reflux control valve 17 is Since the valve body 19 is held in pressure contact with the valve seat 26 by the spring 24, even if the throttle valve 9 is opened or closed, the exhaust gas is not recirculated to the intake system.

Then, when the internal combustion engine 1 warms up to a predetermined temperature, the temperature switching valve 29 switches the ports 30 and 31 to communicate with each other, and the other pressure chamber 21 in the differential pressure operating mechanism 18
The boost pressure on the upstream side of the throttle valve 9 is applied to the throttle valve 9. When the throttle valve 9 is closed in this state, no negative pressure is generated at the 32 sensing ports, so the differential pressure operating mechanism 1
Negative pressure does not act on one of the pressure chambers 20 in 8, and when the throttle valve 9 is closed, there is less exhaust gas, so the rotation speed of the exhaust turbocharger 4 is slow and the rotation speed on the upstream side of the carburetor 8 is low. The supercharging pressure is also low, so differential pressure operation (the pressure difference between the pressure chambers 20 and 21 in the shallow groove 18 is small, so the valve element 19 in the reflux control valve 17 closes the valve seat 26 with the spring 24). Therefore, the exhaust gas is not returned to the intake system.

Next, as the opening degree of the throttle valve 9 increases, the negative pressure at the sensing port 27 increases toward the vacuum side (on the other hand, as the supercharging pressure increases, the differential pressure operating mechanism 1
Since the pressure between the pressure chambers 20 and 21 at 8 increases, the valve body 19 of the recirculation control valve 17 opens against the spring 24 due to the pressure difference, and exhaust gas flows into the intake system. flow is performed, and the throttle valve 9
As the opening degree of
Since the pressure difference between the intake and exhaust gases becomes smaller, the valve body 19 of the flow control valve 17 is closed more than before, and the amount of exhaust gas recirculated to the intake system is controlled to be reduced.

In the above embodiment, a wax-type temperature switching valve 29 was used, but the present invention is not limited to this. , an electromagnetic type operated by a temperature sensor, etc. may be used, and it goes without saying that the present invention is equally applicable to supercharged internal combustion engines other than exhaust turbocharged internal combustion engines.

[Brief explanation of the drawing]

The drawings are diagrams showing embodiments of the invention. 1...Internal combustion engine, 2...Intake manifold, 3
...exhaust manifold, 4...exhaust turbo supercharger, 7...supercharging passage, 8...carburizer, 9...
・Throttle valve, 12...Exhaust passage, 13...
Exhaust pipe, 14...Exhaust gas recirculation device, 15.16.
... Exhaust gas recirculation passage, 17 ... Reflux control valve, 1
8...Diaphragm type differential pressure operating mechanism, 19...
Valve element, 20.21...Pressure chamber, 22...Diaphragm as operating body, 27...Sensing port, 29...Temperature switching valve, 28.34...Pressure transmission Passage, 33, 34...Supercharging pressure transmission passage.

Claims (1)

[Claims] (1) A recirculation control valve equipped with a valve body biased in the closing direction by a spring is provided in the exhaust gas recirculation passage connecting the intake system and the exhaust system in a supercharged internal combustion engine, and The valve body of the recirculation control valve is connected to the actuating body of the differential pressure operating mechanism, and pressure is transmitted to one pressure chamber of the differential pressure operating mechanism from a sensing port location slightly upstream of the closed position of the throttle valve in the intake system. A passage is connected to the other pressure chamber, a supercharging pressure transmission passage from the upstream side of the throttle valve is connected to the other pressure chamber, and a valve body in the recirculation control valve transmits the pressure difference between the pressure at the sensing port and the supercharging pressure upstream of the throttle valve. In the exhaust gas recirculation device for an internal combustion engine with a supercharger, which are connected to each other so as to operate according to the above, the supercharging pressure transmission passage includes:
When the temperature of the engine is lower than a predetermined temperature in relation to the engine temperature, the transmission of the boost pressure to the other pressure chamber through the boost pressure transmission passage is cut off, and the sensing port is communicated with the other pressure chamber. An exhaust gas recirculation device for an internal combustion engine equipped with a supercharger, characterized in that it is provided with a temperature switching valve for switching the temperature.