JP2002256983A - Exhaust gas recirculating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To continuously control recirculating amount of exhaust gas and to reduce hunting of an EGR valve, in an exhaust gas recirculating device. SOLUTION: In this exhaust gas recirculating device for recirculating exhaust gas from an engine from an exhaust system to an intake system, a multistage type valve mechanism 4 capable of stepwisely changing opening and a continuously opening/closing type valve mechanism 5 capable of continuously changing opening are provided, and changed amount of recirculating amount of exhaust gas from full-close to full-open of the continuously opening/closing type valve mechanism 5 is set to be more than changed amount of recirculating amount of exhaust gas at an arbitrary stage of the multistage type valve mechanism 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to an exhaust gas recirculation apparatus suitable for use in a large engine.

[0002]

2. Description of the Related Art Heretofore, in order to reduce NOx (nitrogen oxide) contained in exhaust gas of an internal combustion engine (engine), a part of the exhaust gas of the engine is recirculated to an intake system according to the operating state of the engine. Exhaust gas recirculation devices (EGR devices) have been developed and put into practical use. Exhaust gas (EGR gas) taken in from the exhaust system (mainly the exhaust passage) of the engine
Is mixed into the intake air, the combustion in the combustion chamber is slowed down, the combustion temperature is lowered, and the generation of NOx is suppressed.

In such an EGR system, an exhaust system of an engine and an intake system (intake passage) are connected by an EGR passage, and exhaust gas recirculation for controlling the amount (or ratio) of exhaust gas recirculation in the EGR passage. On-off valve for equipment (E
GR valve). Here, the configuration and control of an EGR valve conventionally used for a large diesel engine will be briefly described with reference to FIGS.
In the figure, 101 is an intake passage, 102 is an intake valve, 1
03 is an exhaust valve, 104 is an exhaust passage, 105 is a turbocharger, 106 is an intercooler, 107 is a piston,
Is an EGR device. As shown in FIGS. 6 and 7A to 7D, the EGR device 1 includes an EGR valve 4. The EGR valve 4 includes an umbrella portion 4a and a shaft portion (stem).
4b, and is configured to be movable in the axial direction of the stem 4b. Further, the effective opening area of the EGR valve 4 increases with the valve lift, and the amount of EGR gas can be increased by increasing the valve lift.

Here, the illustrated EGR valve 4 is a positive pressure multi-stage type EGR valve, and the lift amount is changed by switching the air (positive pressure) introduction pattern to the two pistons 41 and 42 shown in FIG. It can be changed in four stages. That is, as shown in FIG. 6, a positive pressure tank (hereinafter, simply referred to as a tank) 10 storing high-pressure working air is connected to the EGR valve 4 via an air supply path 11. The air supply path 11 is branched in two directions on the downstream side, and the first and second electromagnetic valves 12a, 12b are provided on the branched air supply paths (first and second air supply paths) 11a, 11b, respectively. 12b is provided. Each solenoid valve 12
Reference numerals a and 12b denote solenoid valves that turn the air supply path fully open when on and turn off the air supply path fully when off.

[0005] Further, as shown in FIGS.
The valve body has a cylindrical first piston 41 and a second piston 42 provided in the first piston 41. The second piston 42 is fixed to the stem 4b, and the first piston 41 and the second piston 42 are connected to the stem 4b.
It is provided slidably in the axial direction of b. Also,
The second piston 42 is configured to be movable in the first piston 41 by a stroke amount S2, and the first piston 41 is configured to be movable by a stroke amount S1 smaller than the stroke amount S2 of the second piston 42.

Further, the first air supply path 11a is connected to the first air supply path 11a.
The second air supply passage 11 b is connected to a pressure chamber 43 of the second piston 42. On the other hand, an ECU (electronic control unit) 3 is electrically connected to each of the two solenoid valves 12a and 12b. Information such as the engine speed and the engine load is input to the ECU 3, and the required amount of exhaust gas recirculation is calculated based on the information. Then, from the relationship between the exhaust gas recirculation amount and the lift amount of the EGR valve 4 as shown in FIG.
A drive signal for each of the solenoid valves 12a and 12b is set.

Here, when the target exhaust gas recirculation amount calculated by the ECU 3 is 0, that is, when the EGR device 1 is not operated, both the solenoid valves 12a and 12b are turned off. As a result, as shown in FIG.
The air pressure does not act on the second pistons 12a and 12b, and the EGR valve 4 is fully closed by the urging force of the return spring 45.

When the target exhaust gas recirculation amount exceeds q1, only the first solenoid valve 12a is turned on. As a result, air is supplied from the tank 10 to only the first piston 41, and
As shown in (b), the first piston 41 strokes by a predetermined amount S1. At this time, the second piston 42 is in contact with the first piston 41 by the urging force of the return spring 45, and as a result, the first piston 41
The EGR valve 4 is lifted by the stroke amount S1.

The target exhaust gas recirculation amount is q2 (> q1).
When the above is reached, the first solenoid valve 12a is turned off and the second solenoid valve 12b is turned on. As a result, FIG.
As shown in (c), the air pressure acts only on the second piston 42, and the stroke amount S2 of the second piston 42 (> S
The EGR valve 4 is lifted only by 1). Further, when the calculated target exhaust gas recirculation amount becomes q3 (> q2), both the first and second solenoid valves 12a and 12b are turned on.
As a result, as shown in FIG. 7D, air pressure acts on both the first and second pistons 41 and 42, and the total stroke amount S1 + of the first piston 41 and the second piston 42 is increased.
The EGR valve 4 is lifted by S2.

[0010]

However, in such a conventional positive pressure multistage EGR valve, as shown in FIG. 8, the exhaust gas recirculation amount can be controlled only in a stepwise manner, and a continuous opening change characteristic is obtained. There was a problem that was not obtained. In particular, during a transient operation of the engine, since the pressure inside the intake / exhaust system increases rapidly, the EGR rate may be different even with the same lift amount, and in such a case, it is difficult to perform highly accurate control.

The duty of the solenoid valve is controlled so that EG
Although it is conceivable to continuously control the stroke amount of the R valve, such a system has a problem that control stability is low. It is also conceivable to configure the EGR valve using a DC motor. For example, a male screw is formed on the stem and a female screw is formed on the stem guide, and the stem is rotated by a DC motor to move the EGR valve forward and backward. With this configuration, it is possible to obtain a continuous lift characteristic according to the rotation amount of the DC motor.

However, in order to realize a large flow rate EGR valve corresponding to a large engine, a huge motor for generating a high torque is required, which is not practical in terms of mountability and manufacturing cost. In addition, it is conceivable to construct an EGR valve by combining two small DC motors, but in this case, the load on the controller becomes extremely high, and mass production has been difficult.

Japanese Patent Application Laid-Open No. Hei 5-99081 discloses an EGR valve provided with a large flow valve which is opened and closed by a diaphragm device and a small flow valve which is opened and closed by a stepping motor. A technique is described in which the opening / closing amount of the small flow valve is controlled so that the total opening / closing amount of the large flow valve and the small flow valve becomes the optimum opening / closing amount. However, in this technique, since the large flow rate valve is a diaphragm type, the lift stability with respect to the differential pressure across the valve is low, and the lift amount tends to vary in actual control.

Therefore, by applying a positive pressure multi-stage valve as described above instead of the diaphragm type and combining a continuous opening / closing valve, the opening degree characteristic of the EGR valve can be made continuous. In addition, highly accurate control can be executed. However, in the case of such a configuration, the effective opening area between the respective stages of the positive pressure multi-stage EGR valve is continuously changed by the continuous opening / closing valve. The exhaust gas recirculation amount (target value) q is equal to a threshold value (0, q in this example).
If it fluctuates near (1, q2, q3), hunting will occur in the multi-stage EGR valve. Specifically, the target value q
Fluctuates around q2, for example, the target value q
Each time it becomes 2 or more or becomes less than q2, the on / off of the two solenoid valves is reversed, and each time the two pistons move simultaneously in the opposite direction. As a result, there is a problem in that the seating sound of the piston and the sound of the discharge of the positive pressure air accompanying the switching of the solenoid valve are continuously generated, giving a troublesome feeling to the driver. In addition, some drivers may erroneously determine that the vehicle has failed. In particular, since the EGR valve of a large engine also has a large piston, the inertia is large, and the spring force and the driving air pressure acting on the valve are also high. .

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and an exhaust gas recirculation apparatus which is capable of continuously controlling the exhaust gas recirculation amount, prevents hunting of an EGR valve, and has excellent drivability. The purpose is to provide.

[0016]

According to a first aspect of the present invention, there is provided an exhaust gas recirculation system for recirculating exhaust gas from an engine from an exhaust system to an intake system. A multi-stage valve mechanism that can be changed to
It has a continuous opening and closing valve mechanism whose opening can be continuously changed, and the amount of change of the exhaust gas recirculation amount from the fully closed to the fully open state of the continuous opening and closing valve mechanism is controlled by an exhaust gas return at an arbitrary stage of the multi-stage valve mechanism. The flow rate is set to be larger than the change amount. As a result, hysteresis can be imparted to the multi-stage valve mechanism, so that the number of times the multi-stage valve mechanism operates is reduced and hunting is prevented.

Further, in the exhaust gas recirculation apparatus according to the present invention, when the target exhaust gas recirculation amount increases, first, only the opening degree of the continuous opening / closing valve mechanism is increased to continuously increase the exhaust gas recirculation amount. When the amount of recirculation is increased and the target amount of exhaust gas recirculation is larger than the amount of exhaust gas recirculation when the continuous open / close valve mechanism is fully opened, the opening of the multi-stage valve mechanism is increased by one step, and the multi-stage valve mechanism is increased. The opening degree of the continuous opening / closing valve mechanism is rapidly reduced by a predetermined amount so that the change characteristic of the total exhaust gas recirculation amount of the two valve mechanisms, the valve mechanism and the continuous opening / closing valve mechanism, becomes continuous. Also,
When the target exhaust gas recirculation amount decreases, first, only the opening degree of the continuous opening and closing valve mechanism is reduced to continuously reduce the exhaust gas recirculation amount, and the opening degree of the continuous opening and closing valve mechanism is fully closed. When the target exhaust gas recirculation amount is smaller than the exhaust gas recirculation amount at the time of, the opening degree of the multi-stage valve mechanism is reduced by one step, and two of the multi-stage valve mechanism and the continuous opening and closing valve mechanism are used. The opening degree of the valve mechanism is rapidly increased by a predetermined amount so that the change characteristic of the total exhaust gas recirculation amount of the valve mechanism becomes continuous.

Thus, the multi-stage valve mechanism can have different operating characteristics when the target exhaust gas recirculation amount increases and decreases, and hysteresis is imparted to the multi-stage valve mechanism. Therefore, the number of operations of the multi-stage valve mechanism is reduced, and hunting is prevented.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an exhaust gas recirculation device according to an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic diagram showing the overall configuration, and FIG. 2 is a diagram showing the lift characteristics of a DC motor type EGR valve. As shown in FIG. 1, exhaust gas in the exhaust passage 104 is supplied between the intake passage 101 and the exhaust passage 104 of the engine.
Exhaust gas recirculation system (EG
R device) 1 is interposed. This EGR device 1 is an EG
The EGR valve body 2 includes an R valve body 2 and an ECU (electronic control device) 3 as control means.
Is composed of a positive pressure multi-stage EGR valve (multi-stage valve mechanism) 4 for large flow rate control and a DC motor type EGR valve (continuous opening / closing type valve mechanism) 5 for small flow rate control. Here, the positive pressure multi-stage EGR valve (hereinafter, referred to as a multi-stage valve) 4 is the same as that described in the section of the prior art, and the common members are denoted by the same reference numerals as the conventional one. And a detailed description is omitted.

Next, a DC motor type EGR valve (hereinafter referred to as "EGR valve")
The motor-operated valve 5 will be described. The motor-operated valve 5 is provided adjacent to the multi-stage valve 4 as shown in the figure, and is configured such that its opening can be continuously changed. An amount of exhaust gas corresponding to the total lift amount (total effective opening area) of these two EGR valves 4 and 5 is recirculated to the intake passage 101.

The motor-operated valve 5 has an umbrella portion 5a and a shaft portion (stem) 5b, like the multi-stage valve 4.
A male screw is formed on the stem 5b, and a female screw is formed on a guide (not shown) of the stem 5b. The DC motor 6 is connected to the stem 5b.
When the stem 5b is rotationally driven by the DC motor 6, the valve 5 is lifted according to the amount of rotation. Although not shown, the motor type valve 5 is provided with a position sensor, and the lift amount (opening) is feedback-controlled based on the position information from the position sensor.

Here, as shown in FIG. 2, the motor-operated valve 5 is capable of extremely precise control, and has an actual lift amount (indicated by a solid line) that substantially matches an indicated lift amount (control target value) indicated by a broken line. Shown) can be obtained. In addition, the engine speed and the engine load are input to the ECU 3 in addition to the information from the position sensor, and the target exhaust gas recirculation amount is set based on the engine speed and the engine load. ing. In this embodiment, the fuel injection amount is used as the engine load.

The operation of the two EGR valves 4 and 5 is controlled so that the target exhaust gas recirculation amount set by the ECU 3 is achieved. Specifically, an on / off signal for the first and second solenoid valves 12a and 12b is output from the ECU 3 for controlling the operation of the multi-stage valve 4, and the operation of the motor-operated valve 5 is controlled. A drive signal for the DC motor 6 is output for control.

The motor-operated valve 5 has an effective opening area change amount (or a change amount of the exhaust gas recirculation amount) from the fully closed state to the fully open state which is larger than the effective opening area change amount of any one stage of the multi-stage valve 4. Is also set to be large. That is, the amount of change in flow rate (equivalent to the amount of change in the effective opening area) from fully closed to fully opened of the motor-operated valve 5 is defined as Δq, and the position number of the multi-stage valve 4 in four stages is determined. 1 to No. 4
The exhaust gas recirculation amount at q0 (= 0), q1,
If q2 and q3 are set, the opening amount of the motor-operated valve 5 is set so that the following relationship is established. Δq> q1-q0, and Δq> q2-q1, and Δ
q> q3-q2 In the exhaust gas recirculation device of the present embodiment, the operation control of the two EGR valves 4 and 5 is performed with characteristics as shown in FIGS. That is, when the target exhaust gas recirculation amount set by the ECU 3 is 0, two E
The GR valves 4 and 5 are both fully closed, and only the opening of the motor-operated valve 5 is changed in accordance with the increase in the target exhaust gas recirculation amount. Thereby, the exhaust gas recirculation amount continuously increases.

Further, even if the target exhaust gas recirculation amount reaches q1, the multi-stage valve 4 holds the current position (No. 1, here, the lift amount 0), and further increases the opening of the motor-operated valve 5. Let it. When the target exhaust gas recirculation amount is larger than the flow rate (q0 + Δq) when the motor type valve 5 is fully opened, the position of the multi-stage type valve 4 is set to No. 2 (i.e., lift by one step), and the opening of the motor-operated valve 5 is quickly increased by a predetermined opening so that the change characteristic of the total exhaust gas recirculation amount of the two EGR valves 4 and 5 becomes continuous. To reduce. At this time, the opening amount x of the motor-operated valve 5 alone is an opening amount corresponding to Δq- (q1−q0) in the exhaust gas recirculation amount, as can be seen from FIG. 3, and the predetermined amount is the exhaust gas recirculation amount. And (q1-
q0). The motor-operated valve 5
The relationship between the opening degree of the single body and the exhaust gas recirculation amount is stored in a map or the like in advance.

Thereafter, when the target exhaust gas recirculation amount increases, the opening of the motor-operated valve 5 is first increased in the same manner as described above. In addition to the one-stage lift, the opening of the motor-operated valve 5 is reduced by a predetermined amount so that the total recirculation amount change characteristic becomes continuous. On the other hand, when the target exhaust gas recirculation amount decreases, the operation control of the EGR valves 4 and 5 is performed as follows. That is, first, only the opening of the motor-operated valve 5 is reduced, and when the motor-operated valve 5 is fully closed,
The position of the multi-stage valve 4 is decreased by one, and the motor-operated valve 5 is quickly opened by a predetermined opening so that the change characteristic of the total recirculation amount of the two EGR valves 4 and 5 becomes continuous.

For example, when the multi-stage valve 4 is in the position No.
3 and the target exhaust gas recirculation amount is less than q2, the position of the multi-stage valve 4 is changed to No. 3. 3 to N
o. 2, and the opening of the motor-operated valve 5 is opened by the opening corresponding to (q2−q1) in the exhaust gas recirculation amount. And, in this way, each EGR valve 4,
By controlling the opening of 5, the operating characteristics can be different between when the flow rate is increased and when the flow rate is decreased, and a dead zone as shown in FIG. 5 can be set. In addition, by providing such a dead zone, hysteresis is given to the operation characteristics of the multi-stage valve 4, so that the number of times of operation of the multi-stage valve 4 is reduced, and hunting is prevented.

The exhaust gas recirculation apparatus according to one embodiment of the present invention is configured as described above.
The control of each of the EGR valves 4 and 5 is executed based on the control logic as shown in FIG. First, in the ECU 3,
A target exhaust gas recirculation amount is set from a map 31 stored in advance based on the engine rotation speed and the fuel injection amount.

Next, the position (lift amount) of the multi-stage valve 4 corresponding to the target exhaust gas recirculation amount is determined from each of the exhaust gas recirculation amount increasing map 32 and the exhaust gas recirculation amount decreasing map 33 also stored in the ECU 3 in advance. Is set. Then, the determination means 34 determines the multi-stage valve 4 based on the information obtained from these two maps 32 and 33.
And outputs a signal to each of the solenoid valves 12a and 12b.

At this time, if the valve positions set in the two maps 32 and 33 are the same, the judgment means 34
Then, a signal is output to each of the solenoid valves 12a and 12b so that the multi-stage valve 4 is at this position. On the other hand, if the valve positions set in the two maps 32 and 33 are different, the determination means 34 refers to the valve position set in the previous control cycle, and determines that the same valve position as the previously set valve position exists. If this is the case, this is output as the current valve position.

For example, as shown in FIG. 4, if the target exhaust gas recirculation amount is qa, the valve positions set in the respective maps 32 and 33 are different. As shown in FIG. 4, the position of the multi-stage valve 4 is No. qa. No. 2 is No. This is a target exhaust gas recirculation amount that can be handled even by 3. In this case, the position set in the previous control cycle is No. No. 2 this time, Two positions apply. Thus, the operation of the multi-stage valve 4 is suppressed as much as possible.

On the other hand, if the valve positions set from the increase / decrease maps 32 and 33 are different from each other, and if both are different from the previously set valve positions, the previously set target exhaust gas recirculation amount is referred to. If the exhaust gas recirculation amount is in the increasing direction, the valve position set on the increasing map 32 is selected, and if it is decreasing, the valve position set on the decreasing map 33 is selected.

Then, as described above, the judgment means 34
When the position of the multi-stage valve is set in the above, a control signal is output to each of the solenoid valves 12a and 12b so as to be in this position. At this time, the flow rate according to the position is read from the map 35 shown in FIG.
6 is input. The target exhaust gas recirculation amount set on the map 31 is also input to the adder 36, and the recirculation amount of the motor-operated valve 5 is set by subtracting the recirculation amount of the multi-stage valve 4 from the target exhaust gas recirculation amount. Then, the lift amount of the motor-operated valve 5 is set by the map 37 storing the relationship between the lift amount of the motor-operated valve 5 and the flow rate, and is output to the DC motor 6. Although not shown, feedback control based on information from the position sensor is performed thereafter, and the drive current to the DC motor 6 is controlled.

As described above, the EGR device of this embodiment is
A positive-pressure multi-stage EGR valve 4 is provided with a positive-pressure multi-stage EGR valve 4 and a DC motor-type EGR valve 5.
Continuous exhaust gas recirculation control can be performed with a simple configuration that is set to be larger than the change amount of the exhaust gas recirculation in an arbitrary stage of the valve 4. In addition, as shown in FIG. 5, a dead zone can be set in the positive pressure multi-stage EGR valve 4, so that the number of times of operation of the positive pressure multi-stage EGR valve 4 can be reduced and hunting can be prevented. Thereby, the seating noise of the pistons 41 and 42 can be reduced, and the EGR device 1 excellent in drivability can be provided.

Further, since the conventional positive pressure multistage EGR valve 4 only needs to be provided with the DC motor type EGR valve 5 for small flow, there is an advantage that the present apparatus can be manufactured at a relatively low cost. Note that the exhaust gas recirculation device of the present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention. For example, the turbocharger 105 and the intercooler 106 shown in FIG. 1 are not essential components of the present invention and may be omitted.

[0036]

As described above in detail, according to the exhaust gas recirculation system of the first aspect of the present invention, a multi-stage valve mechanism whose opening can be changed stepwise, and the opening can be continuously changed With a possible continuous opening and closing valve mechanism, the change amount of the exhaust gas recirculation amount from fully closed to full open of the continuous opening and closing valve mechanism is smaller than the change amount of the exhaust gas recirculation amount at any stage of the multi-stage valve mechanism. The configuration that is set to be large has an advantage that the exhaust gas recirculation amount can be continuously controlled. Also,
The number of actuations of the multi-stage valve mechanism can be reduced, and hunting can be prevented. As a result, the operating noise of the multi-stage valve mechanism can be reduced, and an exhaust gas recirculation device excellent in drivability can be provided. Also,
With the simple configuration as described above, there is an advantage that the present apparatus can be manufactured at relatively low cost.

According to the exhaust gas recirculation apparatus of the present invention, the multi-stage valve mechanism can have different operating characteristics when the target exhaust gas recirculation amount increases and decreases. Hysteresis can be imparted to the mechanism. Therefore, there is an advantage that the number of operations of the multi-stage valve mechanism can be reduced and hunting can be prevented.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing an overall configuration of an exhaust gas recirculation device according to one embodiment of the present invention.

FIG. 2 is a view showing a lift characteristic of a DC motor type EGR bub applied to an exhaust gas recirculation device according to one embodiment of the present invention.

FIG. 3 is a diagram for explaining operation characteristics of the exhaust gas recirculation device according to one embodiment of the present invention.

FIG. 4 is a diagram for explaining control logic of the exhaust gas recirculation device according to one embodiment of the present invention.

FIG. 5 is a diagram for explaining the operation characteristics of the exhaust gas recirculation device according to one embodiment of the present invention.

FIG. 6 is a schematic diagram showing a configuration of a conventional exhaust gas recirculation device.

FIGS. 7A to 7D are schematic cross-sectional views illustrating the operation of a conventional exhaust gas recirculation device.

FIG. 8 is a diagram for explaining the operation characteristics of a conventional exhaust gas recirculation device.

[Explanation of symbols]

Reference Signs List 1 Exhaust gas recirculation device (EGR device) 2 EGR valve main body 3 ECU (electronic control device) as control means 4 Positive pressure multistage EGR valve (multistage valve) as multistage valve mechanism 5 Continuous opening and closing valve mechanism DC motor type EGR
Valve (motor type valve) 101 Intake passage (intake system) 104 Exhaust passage (exhaust system)

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3G062 AA01 AA05 CA04 CA05 DA01 DA02 DA08 EA11 EA12 EB15 ED10 ED12 FA05 FA06 FA09 FA24 GA06 GA15 GA21

Claims (2)

[Claims] 1. An exhaust gas recirculation system for recirculating exhaust gas from an engine from an exhaust system to an intake system, comprising: a multi-stage valve mechanism capable of changing an opening in a stepwise manner; A variable amount of exhaust gas recirculation from fully closed to fully open of the continuous opening and closing type valve mechanism is set to be larger than an amount of change of exhaust gas recirculation amount at an arbitrary stage of the multi-stage valve mechanism. An exhaust gas recirculation device, characterized in that: 2. When the target exhaust gas recirculation amount increases, the exhaust gas recirculation device first increases the opening of only the continuous opening / closing valve mechanism, and reduces the exhaust gas when the continuous opening / closing valve mechanism is fully opened. When the target exhaust gas recirculation amount is larger than the recirculation amount, the opening degree of the multi-stage valve mechanism increases by one step, and the total exhaust gas of the two valve mechanisms of the multi-stage valve mechanism and the continuous opening / closing valve mechanism is increased. The opening degree of the continuous open / close valve mechanism is configured to decrease quickly by a predetermined amount so that the change characteristic of the recirculation amount is continuous. When the target exhaust gas recirculation amount decreases, the continuous When the opening degree of only the opening / closing valve mechanism is reduced and the target exhaust gas recirculation amount is smaller than the exhaust gas recirculation amount when the continuous opening / closing valve mechanism is fully closed, the opening degree of the multi-stage valve mechanism is increased by one step. As it decreases The opening degree of the continuous opening and closing valve mechanism is quickly increased by a predetermined amount so that the change characteristic of the total exhaust gas recirculation amount of the two valve mechanisms of the multi-stage valve mechanism and the continuous opening and closing valve mechanism becomes continuous. The exhaust gas recirculation device according to claim 1, wherein the exhaust gas recirculation device is configured to perform the following.