JPH0332770Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] The present invention is designed to reduce the amount of exhaust gas contained in an internal combustion engine equipped with a supercharger such as an exhaust turbocharger in the intake system.
This relates to a device for recirculating a portion of exhaust gas to the intake system for the purpose of reducing NOx.

[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. In addition, NOx in exhaust gas
In order to reduce this, it is effective to recirculate part of the exhaust gas to the intake system, and in the above-mentioned internal combustion engine with a supercharger, part of the exhaust gas is recirculated to the intake system.

Utility Model Application Publication No. 55-25686 as a prior art,
A recirculation control valve equipped with a valve body biased in the closing direction by a spring is provided in an exhaust gas recirculation passage connecting an intake system and an exhaust system in a supercharged internal combustion engine, and The valve body is connected to the actuating body of the differential pressure operating mechanism, and the pressure at the sensing port location slightly upstream of the closed position of the throttle valve in the intake system is transferred to one pressure chamber of the differential pressure operating mechanism. The boost pressure upstream of the throttle valve is applied to the other pressure chamber in the mechanism, and when the pressure difference between the pressure at the sensing port and the boost pressure upstream of the throttle valve is large, a valve body in the recirculation control valve opens; By introducing each valve body so that it closes when the pressure difference becomes smaller, exhaust gas is returned to the intake system in the partial load range of the engine, and a small amount of exhaust gas is returned to the intake system in the high load range. It is proposed to regulate the

In this way, the recirculation of exhaust gas to the intake system is mainly carried out in the partial load range of the engine, and the meaning of regulating the amount to a small amount in the high load range is that in the partial load range of the engine, the air-fuel ratio of the intake mixture is is lean and generates a large amount of NOx, so a large amount of exhaust gas is returned to the intake system, while in the high load range of the engine the air-fuel ratio of the intake mixture is rich and the amount of NOx generated is low. This is to avoid a decrease in output due to exhaust gas recirculation.

[Problem that the invention attempts to solve]

However, in this way, the control to restrict the recirculation of exhaust gas to a small amount in the high load range of the engine cannot be performed using only the pressure difference between the pressure at the sensing port and the boost pressure on the upstream side of the throttle valve, as in the prior art. In this case, the change in the sensing port pressure and the boost pressure with respect to the opening degree of the throttle valve is relatively gradual, and therefore the change in the pressure difference with respect to the opening degree of the throttle valve is also gradual, and the engine load Since the recirculation control valve closes slowly in response to an increase in the engine load, the recirculation of exhaust gas to the intake system decreases as the engine load increases, as shown by the dashed line in Figure 3 of the prior art publication. will persist up to a relatively high level.

In other words, in the prior art described above, the flow rate regulation control of recirculated exhaust gas in the high load range of the engine is gradual, so the problem is that the prevention of output decline by regulating the small amount of recirculated exhaust gas in the high load range is not sufficient. It was hot.

The purpose of the present invention is to sufficiently and effectively prevent a decrease in output by regulating a small amount of recirculated exhaust gas in a high load range.

[Means for solving problems]

Therefore, unlike the prior art described above, the present invention includes a valve body biased in the closing direction by a spring in the exhaust gas recirculation passage connecting the intake system and the exhaust system in a supercharged internal combustion engine. A recirculation control valve is provided, a valve body of the recirculation 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 recirculation control valve located slightly upstream of the closed position of the throttle valve in the intake system. The pressure at the sensing port is introduced into the other pressure chamber, and the boost pressure on the upstream side of the throttle valve is introduced into the other pressure chamber. There are two valve seat orifices on the side and downstream side whose passage area increases or decreases depending on the valve body, and when the passage area of one of the two valve seat orifices increases, the passage area of the other valve seat orifice increases. The configuration is such that the size of the image is reduced.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. In the drawings, 1 indicates an internal combustion engine having an intake manifold 2 and an exhaust manifold 3, and 4 indicates an exhaust turbo supercharger directly connected to an exhaust turbine 5 and a blower compressor 6. , A supercharging passage 7 from the discharge side of the blower compressor 6 is connected to the intake manifold 2, and a carburetor 8 with a throttle valve 9 and a surge tank 10 are connected to the supercharging passage 7. A tank 10 is provided upstream of the vaporizer 8, and 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 indicates an exhaust gas recirculation device, and the exhaust gas recirculation device 14 is provided in exhaust gas recirculation passages 15 and 16 that connect the intake manifold 2 and the exhaust pipe 13, and in both of the exhaust gas recirculation passages 15 and 16. Reflux control valve 17 with diaphragm type differential pressure operating mechanism 18
and an exhaust pressure regulating valve 19 for the recirculation control valve 17, and a valve body 20 in the recirculation control valve 17.
is the two pressure chambers 2 in the differential pressure operating mechanism 8.
The valve body 20 is connected via a rod 24 to a diaphragm 23 which is an actuating body divided into two valve bodies 1 and 22. The first valve seat orifice 27 is biased in the closing direction toward the first valve seat orifice 27 provided in the valve chamber 26 that accommodates the valve.
A second valve seat orifice 28 is provided on the downstream side of the valve seat orifice 27 with the valve body 20 interposed therebetween.
0 closes the first valve seat orifice 27, the second valve seat orifice 28 is fully open, but when the valve body 20 moves away from the first valve seat orifice 27 and its passage area increases, the valve body 20 closes. is configured so that it approaches the second valve seat orifice 28 to reduce its passage area.

The exhaust pressure regulating valve 19 is configured to adjust the atmospheric pressure 29 and the exhaust pressure chamber 3.
0, the pressure chamber 29 communicates with the surge tank 10 or the atmosphere through an orifice 32, and a communication pipe 33 that opens and closes with the vertical movement of the diaphragm 31, and a spring 34. The communication pipe 33 is kept open at all times, and the exhaust pressure chamber 30 is connected between the exhaust gas recirculation passage 15 and the recirculation control valve 17 via a passage 35. One pressure chamber 2 in the differential pressure operating mechanism 18 via 36
A sensing port 37 is connected to the carburetor 8 and is provided at a portion slightly upstream of the closed position (idle opening) of the throttle valve 9 in the carburetor 8.
The surge tank 10 is connected to the other pressure chamber 22 in the differential pressure operating mechanism 18 through a pressure transmission passage 38 with a restrictor orifice 39.
The supercharging pressure transmission passage 40 from the

Further, 41 indicates a temperature switching valve that is attached to the cooling water passage, lubricating oil passage, cylinder block, cylinder head, etc. of the engine 1 and is related to the temperature of the engine.
The temperature switching valve 41 has three ports 42, 43,
44, and the ports 42 and 43 are communicated with each other until the engine temperature reaches a predetermined temperature.
When the engine warms up to a predetermined temperature, ports 43 and 44 are switched to communicate with each other.
is connected to the intake manifold 2 via a passage 45, the port 43 is connected to the communication passage 36 via a passage 47 with a check valve 46, and the port 44 is connected to the passage 48.
The air cleaners 11 and the like are respectively connected to the atmosphere communicating portions through the air cleaners 11 and the like.

The differential pressure operating mechanism 18 is provided with an adjustable stopper 49 for defining the minimum passage area of the second valve seat orifice 28.

In this configuration, when the engine 1 has not warmed up to a predetermined temperature, the temperature switching valve 41
2 and 43 are in communication with each other, and one pressure chamber 21 in the differential pressure operating mechanism 18 is communicated with the atmosphere, so negative pressure does not act on the one pressure chamber 21, and therefore, The valve body 20 of the recirculation control valve 17 remains in contact with the first valve seat orifice 27 by the spring 25, and the exhaust gas is not recirculated to the intake system.

When the engine 1 warms up to a predetermined temperature, the temperature switching valve 41
switches the ports 43 and 44 to communicate with each other, and cuts off communication of one pressure chamber 21 with the atmosphere. When the throttle valve 9 is closed in this state, no negative pressure is generated at the sensing port 37, so no negative pressure acts on one pressure chamber 21 in the differential pressure operating mechanism 18, and the throttle valve 9 In the closed state, due to the small amount of exhaust gas, the rotation speed of the exhaust turbo supercharger 4 is slow and the supercharging pressure on the upstream side of the carburetor 8 is also low. Since the pressure difference between
7 is closed, exhaust gas is not recirculated to the intake system.

Next, as the opening degree of the throttle valve 9 increases, the pressure in the pressure chamber 21 of the recirculation control valve 17 increases.
Pc (However, in this embodiment, this pressure Pc is a composite value of the pressure at the 37 sensing ports, the intake pressure downstream of the throttle valve 9, and the supercharging pressure upstream of the throttle valve 9. ), as shown by the dotted line in FIG. 3, has a pressure characteristic in which the pressure once becomes negative pressure below atmospheric pressure and then rises gradually. pressure
As shown by the solid line in FIG. 3, Pa has a pressure characteristic that gradually increases as the opening degree of the throttle valve 9 increases, and therefore the pressure difference between the boost pressure and the sensing port pressure is The pressure is highest in the partial load range when the valve 9 is partially opened, and gradually decreases as the opening degree of the throttle valve 9 increases, that is, the load increases. The passage area of the first valve seat orifice 27 will be increased or decreased depending on the difference.

In this case, if the valve seat orifice for the valve body 20 in the recirculation control valve 17 is only the first valve seat orifice 27 as in the prior art described above, the characteristics of the recirculation amount of exhaust gas to the intake system are as follows. As shown by the dotted line A in FIG. 4, the pressure difference is at its maximum in the partial load region where it is greatest, and as the load increases beyond this point, the pressure difference gradually decreases. Even in a high load range, a considerable amount of exhaust gas is recirculated to the intake system near the partial load range where the amount of exhaust gas recirculated is maximum, resulting in a decrease in output in this load range.

In contrast, in the present invention, a second valve seat orifice 28 is provided in the valve chamber 26 of the reflux control valve 17 on the downstream side with the valve body 20 sandwiched between the first valve seat orifice 27. Due to the pressure difference, the valve body 20 in the reflux control valve 17 moves away from the first valve seat orifice 27 and its passage area increases, and when the passage area exceeds a certain value, the valve body 20 becomes By approaching the second valve seat orifice 28 and reducing its passage area, the recirculation of exhaust gas to the intake system is reduced, so the amount of recirculation of exhaust gas against the load reaches the maximum value Q1 in the partial load region. Later, this will reduce the stopper 49 in the high load range.
This results in a rapid decline to the minimum regulation value Q0. In other words, the recirculation characteristics of the exhaust gas to the intake system are mountain-shaped as shown by the solid line B in FIG. 4, and the amount of exhaust gas recirculation in the high load range can be rapidly reduced.

In addition, in the above embodiment, the minimum regulation value Q0 of the exhaust gas recirculation amount in the high load range was set by the stopper 49, but instead of this stopper 49, it was provided in the second valve seat orifice 28. The minimum regulation value Q0 of the exhaust gas recirculation amount may be set by a through hole or a through hole provided in the valve body 20, and the present invention is also applicable to the exhaust pressure regulating valve 19 as in the above embodiment. Needless to say, the present invention can also be applied to exhaust gas recirculation devices that are not equipped with such equipment.

[Operations and effects of the invention] As described above, the present invention has two valve seat orifices in the valve chamber of the reflux control valve, on the upstream side and the downstream side with the valve element in between, whose passage area can be increased or decreased by the valve element. By arranging the two valve seat orifices so that when the passage area of one of the valve seat orifices increases, the passage area of the other valve seat orifice decreases, so that a sufficient amount of exhaust gas can be recirculated in the partial load range. While ensuring this, it also rapidly controls the reduction of the amount of exhaust gas recirculation in the high load range, which reduces the amount of recirculation of exhaust gas in the high load range, which is the problem with the prior art described above. This has the effect of reliably avoiding a decrease in engine output due to insufficient control.

[Brief explanation of drawings]

Fig. 1 is a diagram showing an embodiment of the present invention, Fig. 2 is an enlarged sectional view of the main part of the recirculation control valve in Fig. 1, Fig. 3 is a diagram showing pressure characteristics with respect to the opening degree of the throttle valve, and Fig. 4 is a diagram showing an example of the present invention. The figure is a diagram showing the recirculation amount characteristics of exhaust gas. 1... Internal combustion engine, 2... Intake manifold, 3... Exhaust manifold, 4... Exhaust turbo supercharger, 7... Supercharging passage, 8... Carburetor, 9... Throttle valve, 12...
Exhaust passage, 13...Exhaust pipe, 14...Exhaust gas recirculation device, 15, 16...Exhaust gas recirculation passage, 17...Recirculation control valve, 18...Diaphragm type differential pressure operating mechanism, 2
0... Valve body, 21, 22... Pressure chamber, 23... Diaphragm as an operating body, 26... Valve chamber, 27... First valve seat orifice, 28... Second valve seat orifice, 37
...Sensing port, 38...Pressure transmission passage, 40
...Supercharging pressure transmission passage.

Claims (1)

[Scope of utility model registration request] A recirculation control valve equipped with a valve body biased in a closing direction by a spring is provided in an exhaust gas recirculation passage connecting an intake system and an exhaust system in a supercharged internal combustion engine,
The valve body of the recirculation control valve is connected to the actuating body of the differential pressure operating mechanism, and one pressure chamber of the differential pressure operating mechanism receives pressure from a sensing port location slightly upstream of the closed position of the throttle valve in the intake system. A transmission passage is connected to the other pressure chamber, and a boost pressure transmission passage from the upstream side of the throttle valve is connected to the other pressure chamber. In an exhaust gas recirculation system for an internal combustion engine with a supercharger that is connected to each other so as to operate according to the difference, a valve chamber housing a valve body of the recirculation control valve includes:
Two valve seat orifices whose passage area increases or decreases depending on the valve body are installed on the upstream and downstream sides of the valve body, and when the passage area of one of the valve seat orifices increases, the passage area of the other valve seat orifice increases. An exhaust gas recirculation device for an internal combustion engine with a supercharger, characterized in that the passage area of the seat orifice is reduced.