JPH09137754A - Exhaust gas recirculation device of internal combustion engine furnished with supercharger - Google Patents

Abstract

PROBLEM TO BE SOLVED: To change a lead valve over to an ineffective state at the time of a low load by providing the lead valve to enable EGR at the time of an intermediate high load by using exhaust pulsation in an exhaust gas recirculating pipe. SOLUTION: This exhaust gas recirculation device of an internal combustion engine furnished with a supercharger is provided with an EGR control valve 10 to open and close exhaust gas recirculating pipes 7, 8 on the exhaust gas recirculating pipes 7, 8 to communicate an exhaust manifold 2 of an engine 1 and an air intake pipe 6 to each other and a lead valve 13 free to open and close on the downstream side rather than the EGR control valve 10. The exhaust gas recirculating pipes 7, 8 are changed over to an open state by driving the lead valve 13 by an actuator 19 at the time of a low load of the engine. Exhaust gas is recirculated to the air intake pipe 6 scarcely causing channel resistance at the time of a low load of the engine.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust gas recirculation system for an internal combustion engine such as a diesel engine equipped with a supercharger.

[0002]

Since the internal combustion engines such as a diesel engine of the high-temperature combustion, the exhaust gas discharged from the internal combustion engine are contained in NO _X, as a means of reducing NO _X, conventionally An exhaust gas recirculation (that is, EGR) method, that is, a method of extracting a part of the exhaust gas from the exhaust system and returning it to the intake system of the internal combustion engine again is adopted.
By adopting EGR as the combustion method, the proportion of the inert gas (N ₂ , CO ₂ , H ₂ O, etc.) in the combustion mixture is increased, and the combustion temperature is lowered, so that the generation of NO _X is suppressed. .

As a conventional technique related to EGR, there is an exhaust gas recirculation device as shown in FIG. An exhaust manifold 2 is attached to the engine 1, and a turbine 40 of a supercharger 4 is provided on an exhaust pipe 3 connected to the exhaust manifold 2. An intake manifold 5 is attached to the engine 1, and an intake pipe 6 connected to the intake manifold 5 is provided with a compressor 41 of the supercharger 4. The exhaust gas recirculation device is an exhaust gas recirculation pipe 7, 8 that connects the exhaust manifold 2 and the intake manifold 5 of the engine 1.
And the EGR installed in the middle of the exhaust gas recirculation pipes 7 and 8.
Control valve 10 and intake pipe 6 of exhaust gas recirculation pipes 7 and 8
And a intake manifold 5 are connected to each other by a reed valve 37 and a controller (not shown) that controls opening and closing of the EGR control valve 10. The controller controls the rotation speed and load of the engine 1 to be constant. The EGR control valve 10 is configured to open when it is within the range, and the reed valve 37 is configured to open when the exhaust pulsation pressure during rotation of the engine 1 exceeds the boost pressure (intake pressure). .

In the exhaust gas recirculation system, when the engine speed and load reach a predetermined range, the EG
The R control valve 10 is opened, and the exhaust gas is introduced from the exhaust manifold 2 side into the exhaust gas recirculation pipes 7 and 8. When the exhaust pulsation pressure of the exhaust gas is higher than the boost pressure and the bending rigidity of the reed valve 37 is overcome, the reed valve 37 is opened and EGR is performed. Therefore,
Particularly at low and medium speed rotation, the EGR is effectively performed because the reed valve 37 is opened on the peak side of the exhaust pulsation pressure even when the average exhaust gas pressure is lower than the boost pressure.
As a result, NO _X can be reduced with little fuel consumption loss. Further, when the boost pressure is higher than the exhaust pulsation pressure, the reed valve 37 is pressed in the closing direction, so that the reverse flow of intake air from the intake system to the exhaust system is prevented. As described above, in the exhaust gas recirculation device for the internal combustion engine having the conventional supercharger, by providing the reed valve 37 in the exhaust gas recirculation pipes 7 and 8, the exhaust pulsation pressure is boosted while preventing the reverse flow of the intake air. It is designed to allow exhaust gas recirculation only above pressure. As the exhaust gas recirculation device as described above, for example, those disclosed in Japanese Utility Model Publication No. 6-40343 and Japanese Utility Model Publication No. 7-8554 are known.

[0005]

By the way, in FIG.
A characteristic diagram showing the relationship between engine speed and torque is shown. When the operating state of the engine is in the area A shown in FIG. 6, the exhaust pulsation pressure P _ex of the exhaust gas and the boost pressure P
relationship _in is a relationship such as that shown in Figure 7. As is clear from FIG. 7, in the region A which is the high load region of the engine, the exhaust pulsation pressure P _ex of the exhaust gas is the boost pressure P _in
A lower portion (see the hatched portion in FIG. 7), that is, a large backflow region of intake air appears. Therefore, the reed valve 37 has an effect of increasing the EGR rate by preventing exhaust gas from flowing backward when the engine is operating in the A region and performing exhaust gas recirculation when the exhaust pulsation pressure is higher than the boost pressure. That is,
EGR rate = exhaust gas recirculation amount / (intake air amount + exhaust gas recirculation amount).

On the other hand, in the region B shown in FIG. 6 in which the engine is in the low load region, the supercharging rate decreases, so the average intake pressure decreases, and the exhaust pulsation pressure P _ex of the exhaust gas and the boost pressure P _in The relationship becomes as shown in FIG. 8, and a reverse flow region of intake air hardly occurs. Therefore, when the exhaust gas is recirculated, the reed valve 37 increases the plate thickness of the reed valve body in order to improve the durability of the reed valve body. EG
The R rate will decrease.

[0007]

SUMMARY OF THE INVENTION The object of the present invention is to utilize the exhaust pulsation of the exhaust gas even when the engine is under medium and high load.
The reed valve in the exhaust gas recirculation pipe to enable the GR is provided, at the time of low load of the engine can be switched to state or invalid state does not exist reed valve, NO _X perform EGR in the entire region of engine operation An exhaust gas recirculation device for an internal combustion engine having a supercharger that suppresses the generation of

According to the present invention, an exhaust gas recirculation passage that connects an exhaust passage and an intake passage, an EGR control valve that opens and closes the exhaust gas recirculation passage, and an EGR control valve that is provided downstream of the EGR control valve and on the exhaust side. A check valve that opens when the pressure exceeds the pressure on the intake side, and the exhaust gas recirculation passage can be switched between a first state in which the check valve functions and a second state in which the check valve does not function. The switching means and the EGR control valve are opened in response to the engine speed and the load being within a preset predetermined range, and the switching means is switched to the second state in response to the low load. The present invention relates to an exhaust gas recirculation device for an internal combustion engine that includes a supercharger that is configured by a controller that performs control.

In the exhaust gas recirculation system for an internal combustion engine, the check valve is a reed valve including a valve seat having an opening and a reed valve body for opening and closing the opening, and the switching means has an end portion. The exhaust gas recirculation passage has a valve seat pivotally mounted in the exhaust gas recirculation passage and a drive device for driving the valve seat to open and close the exhaust gas recirculation passage.

In this exhaust gas recirculation system for an internal combustion engine, the check valve is a reed valve having a valve seat having an opening and a reed valve body for opening and closing the opening, and the switching means is the valve seat. A butterfly valve pivotally mounted in the exhaust gas recirculation passage at its central portion and a drive device for driving the butterfly valve to open and close the exhaust gas recirculation passage.

In the exhaust gas recirculation system for an internal combustion engine, the controller controls the switching means to switch to the second state in response to the closed state of the EGR control valve.

Further, in this exhaust gas recirculation system for an internal combustion engine, the switching means includes a bypass passage provided so as to bypass the check valve portion of the exhaust gas exhaust gas recirculation passage, and the check valve. And a two-way valve provided at an upstream branch point between the portion and the bypass passage. Further, the controller controls the two-way valve so as to connect the check valve portion and the bypass passage in response to the closed state of the EGR control valve.

Since the exhaust gas recirculation system for the internal combustion engine is constructed as described above, the EGR control valve is opened by the control signal from the controller when the engine speed and load are within a certain range. It When the engine is operating in the medium-high load state in the A region (see FIGS. 6 and 7), the check valve opens when the exhaust pulsation pressure exceeds the boost pressure, and exhaust gas re-enters the intake passage. Circulated. However, when the exhaust pulsation pressure is lower than the boost pressure, the check valve remains closed, preventing intake air from flowing back into the exhaust gas recirculation passage. Further, in the low load state (see FIGS. 6 and 8) in which the operating state of the engine is in the B region, the boost pressure almost never exceeds the exhaust pulsation pressure, so that the intake passage changes from the exhaust passage to the exhaust gas recirculation passage. There is no concern that the intake air will flow backwards. Therefore, in this case, the control signal is issued from the controller to the switching means, and the exhaust gas recirculation passage is switched to the second state having no check valve. As a result, this exhaust gas recirculation device can perform EGR in which the exhaust gas is recirculated to the intake passage with almost no flow path resistance when the load is low.

Further, the EG is instructed by a command from the controller.
When the R control valve is closed, the check valve is fully opened to allow the exhaust gas remaining in the exhaust gas recirculation passage to be sucked into the intake passage and to be sucked into the exhaust gas recirculation passage. The residual exhaust gas can be discharged and diluted while the residual exhaust gas in the exhaust gas recirculation passage can be reduced or eliminated. It is possible to prevent substances such as curates from condensing and adhering to the wall surface of the exhaust gas recirculation passage and each wall surface of the check valve and the EGR control valve, and to prevent the exhaust gas recirculation passage, the check valve and the It is possible to improve the corrosion resistance and durability of the EGR control valve.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an exhaust gas recirculation system for an internal combustion engine equipped with a supercharger according to the present invention will be described below with reference to the drawings. FIG. 1 is an overall configuration diagram showing an embodiment of an exhaust gas recirculation device according to the present invention, and FIG.
FIG. 7 is an enlarged explanatory view of a check valve and a switching means in a portion of reference numeral C in the exhaust gas recirculation device of FIG. An exhaust manifold 2 is attached to the engine 1, and a turbine 40 of a supercharger 4 is provided on an exhaust pipe 3 connected to the exhaust manifold 2. An intake manifold 5 is attached to the engine 1, and an intake pipe 6 connected to the intake manifold 5 is provided with a compressor 41 of the supercharger 4.

This exhaust gas recirculation device has two exhaust gas recirculation pipes 7 and 8 as exhaust gas recirculation passages. One end of each of the exhaust gas recirculation pipes 7 and 8 is connected to the exhaust manifold 2 that is an exhaust passage, and the other end is connected to a connection portion of the intake pipe 6 that is an intake passage with the intake manifold 5. In addition, EGR coolers 9 and 9 and EGR control valves 10 and 10 for controlling the exhaust gas recirculation amount are provided in the middle of the exhaust gas recirculation pipes 7 and 8, respectively.
The EGR control valves 10 and 10 are controlled by the controller 20. The controller 20 has a map that stores the optimum exhaust gas recirculation amount according to the operating state of the engine 1 (that is, the relationship between the engine speed and the torque), such as the engine rotation sensor 11 and the rack sensor 12. The operating states of the engine detected by various sensors, that is, the engine speed and torque are input, and the duty ratio for energizing the solenoid (not shown) is controlled based on the map, whereby the EGR control valves 10 and 10 are controlled. It controls the opening. EGR control valve 10, 1
0 is controlled by the controller 20 to open when the rotation speed and load of the engine 1 are within a certain range and close when the number of rotations and the load of the engine 1 are outside the certain range.

A check valve 13 is attached near the connection between the exhaust gas recirculation pipes 7 and 8 and the intake pipe 6. The specific structure of the check valve 13 is as shown in FIG. In FIG. 2, the upper side is the intake side and the lower side is the exhaust side. The check valve 13 includes a valve seat 15 having an opening 14 and a reed valve body 16 having a thin plate-like rigidity for opening and closing the opening 14.
And a stopper 38 that regulates the opening degree of the reed valve body 16. The reed valve body 16 can be composed of not only a single piece but also a plurality of pieces. Valve seat 1
The shaft 5 is pivotally mounted by a shaft 18 in a recess 17 formed in the exhaust gas recirculation pipes 7 and 8, and is rotatable between a closed position shown by a solid line and an open position shown by a chain line. Valve seat 1
The rotation of 5 is performed by an actuator 19 which constitutes a switching means. The controller 19 controls the actuator 19 that constitutes the switching means. Further, the exhaust manifold 2 is provided with a wastegate control valve 39 so that exhaust gas can be discharged by bypassing the supercharger 4.

The controller 20 includes a rotation sensor 11
The engine speed detected in (1) and the torque (engine load) detected in the rack sensor 12 are input. The rack sensor 12 detects the position of a control rack for adjusting the fuel injection amount of a fuel injection pump (not shown). In addition, the controller 20 controls the exhaust pulsation pressure P _ex and the boost pressure (intake pressure) P _{in in} the relationship A shown in FIG. _A map _in which the relation between _ex and the boost pressure P _in is divided into the region B which is the low load region of the engine having the relation shown in FIG. 8 is stored in advance. Then, based on the detected engine speed and torque, the controller 20 determines whether the current operating state of the engine 1 is in the region A or in the region B, and sends a control signal to the control valve 21. .

When the rotation speed and torque of the engine 1 are in the A range, the relationship between the exhaust pulsation pressure P _ex and the boost pressure P _in is as shown in FIG. 7, and therefore the first check valve 13 is provided. Need to be in a state. Therefore, when the operating state of the engine (engine operating state) is in the A region, the control valve 21 receiving the control signal from the controller 20 acts to bleed air from the actuator 19, and as a result,
The valve seat 15 rotates to the position shown by the solid line in FIG. 2, and the valve seat 15 closes the exhaust gas recirculation pipes 7 and 8. On the other hand, when the operating state of the engine is in the low load range of the B range, the supercharging rate is decreased and the average intake pressure is decreased, and the relationship between the exhaust pulsation pressure P _ex and the boost pressure P _in is shown in FIG. Since the relationship shown in FIG. 2 is created and the reverse flow region of the intake air hardly occurs, the control valve 21 acts to supply the air to the actuator 19, and as a result, the valve seat 1
The exhaust gas recirculation pipes 7 and 8 are opened by rotating 5 to the position shown by the alternate long and short dash line in FIG.

The operation of this exhaust gas recirculation device is as follows. First, the controller 20 determines whether or not the detected rotation speed and torque of the engine 1 are within a predetermined range set in advance.
The control valve 10 is controlled to open. At that time, E
The opening degree of the GR control valve 10 is controlled based on the map according to the operating state of the engine 1. Then, in this state, the exhaust gas discharged from the engine 1 enters the exhaust gas recirculation pipes 7 and 8 from the exhaust manifold 2 and the EGR
It is sent to the intake side through the control valve 10,
The exhaust gas recirculation pipes 7 and 8 reach the connection part with the intake pipe 6. Then, the flow of the exhaust gas is the exhaust gas recirculation pipe 7,
8 depends on whether it is closed or open at the connection site.

Exhaust gas recirculation pipes 7 and 8 closed (A
In the case of the region), if the exhaust pulsation pressure P _ex is lower than the boost pressure P _{in, the} check valve 13 remains closed, and the exhaust gas is not recirculated from the exhaust side to the intake side. There is no backflow of intake air to the exhaust side.
On the contrary, when the exhaust pulsation pressure P _ex is higher than the boost pressure P _in , the rigidity of the reed valve body 16 is overcome and the check valve 13 is opened by an amount corresponding to the differential pressure, and the opening degree of the check valve 13 is increased. An amount of exhaust gas according to the above is recirculated from the exhaust side to the intake side. The state where the exhaust gas recirculation pipes 7 and 8 are closed is
The state (state shown by the solid line in FIG. 2).

Further, when the exhaust gas recirculation pipes 7 and 8 are opened (in the case of region B), the flow passage resistance when the exhaust gas is recirculated from the exhaust side to the intake side is passed through the check valve 13. Compared to the time of recirculation, the pressure is greatly reduced, the pressure loss is naturally reduced, and the EGR rate is increased. The state in which the exhaust gas recirculation pipes 7 and 8 are opened is referred to as a second state (a state indicated by a chain line in FIG. 2). First state and second
The state is switched by a switching means 22, that is, a valve seat 15 pivotally mounted on the exhaust gas recirculation pipes 7 and 8, an actuator 19 as a drive device for driving the valve seat 15,
This is performed by a control valve 21 or the like that controls the actuator 19.

Further, in this exhaust gas recirculation device, the controller 20 is configured to operate the actuator 19 of the switching means in response to the closed state of the EGR control valve 10 to perform the control to fully open the check valve 13. can do. That is, the controller 20 controls the EGR control valve 10
The actuator 19 is operated in response to the closed state of 1 to control the check valve 13 so that it is fully opened. Controller 2
The above-described control by 0 may be configured to be performed before the engine 1 is stopped. By configuring this exhaust gas recirculation device as described above, the exhaust gas remaining in the exhaust gas recirculation pipes 7 and 8 is sucked out and exhausted or diluted, and the wall surfaces of those pipes and the check valve 13 and the EGR control valve. It is possible to prevent substances contained in the exhaust gas from adhering to the respective wall surfaces of 10 and improve their corrosion resistance and durability.

Next, another embodiment of the exhaust gas recirculation system for an internal combustion engine equipped with the supercharger according to the present invention will be described. FIG. 3 is a block diagram of a check valve and switching means in another embodiment. The exhaust gas recirculation system of this embodiment has the same structure as that of the above embodiment except for the check valve 23 and the switching means 24. The check valve 23 has two openings 25, 26.
The reed valve 23 includes a valve seat 27 having a valve seat 27, and reed valve bodies 28 and 29 attached to the valve seat 27 and opening and closing the openings 25 and 26, respectively, having a thin plate-like rigidity. The switching means 24 has a butterfly valve 31 in which the central portion of the valve seat 27 is pivotally attached to the exhaust gas recirculation pipes 7 and 8 by a shaft 30 so that the exhaust gas recirculation pipes 7 and 8 can be opened and closed by the valve seat 27. , Butterfly valve 3
It has a drive device (not shown) for opening and closing 1 and, for example, the same device as the actuator 19 and the control valve 21 shown in the first embodiment. In this embodiment, the check valve 23 has two openings 25 and 26.
The number of openings can be appropriately determined as needed.

When the engine speed and the torque are in the A range, the relationship between the exhaust pulsation pressure P _ex and the boost pressure P _in is as shown in FIG. Therefore, in this case, the butterfly valve 31 is switched to the state in which the exhaust gas recirculation pipes 7 and 8 are closed (the state shown by the solid line in FIG. 3). Then, the exhaust pulsation pressure P _ex is the boost pressure P
When it exceeds _in , the reed valve 23 is opened and the exhaust gas is recirculated to the intake side. Further, when the exhaust pulsation pressure P _ex is smaller than the boost pressure P _in (hatched area in FIG. 7),
The reed valve 23 is closed to prevent backflow of intake air.

When the engine speed and torque are in the B range, the relationship between the exhaust pulsation pressure P _ex and the boost pressure P _in is as shown in FIG. 8, and the reverse flow region of intake air hardly appears. Exhaust pulsation pressure P _ex is boost pressure P _in
It will be in a larger state than. Therefore, in this case, the butterfly valve 31 is switched to the state in which the exhaust gas recirculation pipes 7 and 8 are opened (the state shown by the chain line in FIG. 3). Then, the exhaust gas discharged from the exhaust manifold 2 is recirculated to the intake side. Therefore, the flow path resistance when the exhaust gas is recirculated is smaller than when it passes through the check valve 23, and the EGR rate can be increased.

Next, another embodiment of the exhaust gas recirculation system for an internal combustion engine according to the present invention will be described. FIG. 4 is a block diagram of a check valve and a switching means in still another embodiment of the exhaust gas recirculation system for an internal combustion engine according to the present invention.
The exhaust gas recirculation system of this embodiment has the same structure as that of the first embodiment except for the check valve 32 and the switching means 33. The reed valve 32 as the check valve 32 is provided in the exhaust gas recirculation pipes 7 and 8 so as to close the exhaust gas recirculation pipes 7 and 8. The switching means 33 includes a bypass pipe 34 as a bypass passage provided in parallel with the exhaust gas recirculation pipes 7 and 8 so as to bypass the check valve 32, and the exhaust gas recirculation pipes 7 and 8 and the bypass pipe 34. 35 on the upstream side of
It has a two-way valve 36 provided in the. The two-way valve 36 is rotatably provided at the branch point 35. By turning the two-way valve 36, the exhaust gas discharged from the exhaust manifold 2 is sent to the exhaust gas recirculation pipes 7 and 8 having the check valve 32, or passed through the check valve 32. It is sent to the bypass pipe 34 which does not exist, or to either of the passages. Further, when the two-way valve 36 is stopped midway, the exhaust gas can flow to the exhaust gas recirculation pipes 7 and 8 and the bypass pipe 34. Two-way valve 36
Is rotated by a drive device (not shown) that receives a control signal from the controller 20.

When the engine speed and the torque are in the A range, the relationship between the exhaust pulsation pressure P _ex and the boost pressure P _in is as shown in FIG. Therefore, in this case, the two-way valve 36 is switched so that the exhaust gas is fed only to the exhaust gas recirculation pipes 7 and 8 having the reed valve 32. Then, when the exhaust pulsation pressure P _ex exceeds the boost pressure P _in , the reed valve 32 is opened and the exhaust gas is recirculated to the intake side. Also, the exhaust pulsation pressure P _ex
Is smaller than the boost pressure P _in (hatched area in FIG. 7), the reed valve 32 is closed to prevent backflow of intake air.

When the engine speed and the torque are in the B range, the relationship between the exhaust pulsation pressure P _ex and the boost pressure P _in becomes as shown in FIG. 8, and the reverse flow region of the intake hardly appears. Exhaust pulsation pressure P _ex is boost pressure P _in
It will be in a larger state than. Therefore, in this case, the two-way valve 36 is switched so that the exhaust gas can be sent only to the bypass pipe 34 that does not have the reed valve 32. Then, the exhaust gas discharged from the exhaust manifold 2 is recirculated to the intake side through the bypass pipe 34. Therefore, the flow path resistance when the exhaust gas is recirculated is determined by the check valve 3
It becomes smaller than when passing 2 and the EGR rate can be increased.

Further, in this exhaust gas recirculation device, the controller 20 may be configured to perform control to fully open the two-way valve 36 constituting the check valve in response to the closed state of the EGR control valve 10. it can. That is, the controller 20 operates an actuator (not shown) in response to the closed state of the EGR control valve 10, stops the two-way valve 36 on the way, and connects the exhaust gas recirculation pipes 7 and 8 and the bypass pipe 34. Control to communicate with. Controller 20
The above-mentioned control by the above can also be configured to be controlled prior to stopping the engine 1. By configuring this exhaust gas recirculation device as described above, the exhaust gas remaining in the exhaust gas recirculation pipes 7, 8 and the bypass pipe 34 on the upstream side of the reed valve 32 is sucked out or diluted, and the exhaust gas on the downstream side is exhausted. Exhaust gas remaining in the bypass pipe 34 is sucked out and exhausted, and the pipe wall surface and the check valve 3
2. The substances contained in the exhaust gas are prevented from adhering to the respective wall surfaces of the two-way valve 36 and the EGR control valve 10, and their corrosion resistance and durability can be improved.

[0031]

Since the exhaust gas recirculation system for an internal combustion engine equipped with the supercharger according to the present invention is constructed as described above, it has the following unique effects. That is, the exhaust gas recirculation system for an internal combustion engine equipped with this supercharger uses a check valve in the exhaust gas recirculation passage when the engine is operating in the region A (see FIGS. 6 and 7). When the engine is closed and the operating state of the engine is in the B range (see FIGS. 6 and 8),
Since the exhaust gas recirculation passage is configured to be switched to a state without a check valve, the exhaust gas can be recirculated to the intake passage while preventing the intake air from flowing back to the exhaust gas recirculation passage when the engine is under heavy load. At the same time, exhaust gas can be recirculated to the intake passage with little flow resistance when the load is low. As a result, pressure loss can be reduced and the EGR rate can be increased. Therefore, the exhaust gas recirculation device for an internal combustion engine equipped with this supercharger can more effectively reduce NO _X.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram showing an embodiment of an exhaust gas recirculation device for an internal combustion engine equipped with a supercharger according to the present invention.

FIG. 2 is an enlarged explanatory view of a check valve and a switching means in a portion indicated by reference numeral C in the exhaust gas recirculation device of FIG.

FIG. 3 is an enlarged explanatory view showing another embodiment of the exhaust gas recirculation device for an internal combustion engine equipped with the supercharger according to the present invention.

FIG. 4 is an explanatory view showing yet another embodiment of the check valve and the switching means in the exhaust gas recirculation device for an internal combustion engine equipped with the supercharger according to the present invention.

FIG. 5 is an overall configuration diagram showing a conventional exhaust gas recirculation device for an internal combustion engine.

FIG. 6 is a characteristic diagram showing a relationship between engine speed and torque.

7 is a characteristic diagram showing the relationship between the exhaust pulsation pressure P _in of the exhaust gas and the boost pressure P _{ex in} the state of the area A in FIG.

8 is a characteristic diagram showing the relationship between the exhaust pulsation pressure P _in of the exhaust gas and the boost pressure P _{ex in} the state of region B in FIG.

[Explanation of symbols]

 1 engine 3 exhaust pipe (exhaust passage) 4 supercharger 6 intake pipe (intake passage) 7,8 exhaust gas recirculation pipe (exhaust gas recirculation passage) 10 EGR control valve 13, 23, 32 reed valve (check valve) ) 14, 25, 26 Opening 15, 27 Valve seat 16 Reed valve body 19 Actuator (driving device) 20 Controller 22, 24, 33 Switching means 28, 29 Reed valve body 31 Butterfly valve 34 Bypass pipe (bypass passage) 35 Branching point 36 two-way valve

Claims (6)

[Claims] 1. An exhaust gas recirculation passage that connects an exhaust passage and an intake passage, an EGR control valve that opens and closes the exhaust gas recirculation passage, and a pressure on the exhaust side that is provided downstream of the EGR control valve A check valve that opens when the pressure on the intake side is exceeded, and switching means that can switch the exhaust gas recirculation passage between a first state in which the check valve functions and a second state in which the check valve does not function. , And E in response to the engine speed and the load being within a preset predetermined range.
An exhaust gas recirculation apparatus for an internal combustion engine, comprising a supercharger configured to open a GR control valve and respond to a low load to control the switching means to switch to the second state. 2. The check valve is a reed valve comprising a valve seat having an opening and a reed valve body for opening and closing the opening, and the switching means has an end portion rotatable in the exhaust gas recirculation passage. The valve seat pivotally attached to the valve seat and a drive device for driving the valve seat so as to open and close the exhaust gas recirculation passage.
An exhaust gas recirculation apparatus for an internal combustion engine, which is provided with the supercharger according to. 3. The check valve is a reed valve having a valve seat having an opening and a reed valve body for opening and closing the opening, and the switching means has a central portion of the valve seat in the exhaust gas recirculation passage. The turbocharger according to claim 1 or 2, further comprising: a butterfly valve pivotally attached to the rotor and a drive device that drives the butterfly valve to open and close the exhaust gas recirculation passage. Exhaust gas recirculation device for internal combustion engine equipped with. 4. The controller responds to a closed state of the EGR control valve by means of the switching means.
The control for switching to the state is performed.
An exhaust gas recirculation apparatus for an internal combustion engine, comprising the supercharger according to any one of items 1 to 3. 5. A bypass passage provided so as to bypass the check valve portion of the exhaust gas exhaust gas recirculation passage, and an upstream branch point between the check valve portion and the bypass passage. An exhaust gas recirculation system for an internal combustion engine having a supercharger according to claim 1, further comprising a two-way valve provided in the. 6. The controller controls the two-way valve so as to connect the check valve portion and the bypass passage in response to a closed state of the EGR control valve. Exhaust gas recirculation system for internal combustion engine equipped with supercharger.