JP2881450B2 - Control device for supercharged engine - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a control device for a supercharged engine, and more particularly, to a control device for a supercharged engine having a plurality of superchargers arranged side by side. It is about.

(Prior Art) Conventionally, for example, as disclosed in Japanese Utility Model Laid-Open No. 60-178329, two turbochargers, a primary and a secondary, are arranged side by side, and a turbine inlet side and a blower outlet of a secondary turbocharger are provided. By providing an exhaust cut valve and an intake cut valve on the side, and opening and closing these cut valves, supercharging is performed only with the primary turbocharger in the low flow rate region, and not only in the high flow rate region but also in the primary turbocharger. There is known a turbocharger called a twin turbo type or a sequential turbo type in which a secondary supercharger is also operated.

Further, in the turbocharger of the above-mentioned type or the like, a wastegate valve is provided in order to limit the maximum supercharging pressure due to problems such as reliability and durability of the engine.

(Problems to be Solved by the Invention) However, when the wastegate valve is open, when the primary supercharger only operates, and in addition to the primary supercharger, the secondary supercharger operates, when switching, However, sufficient exhaust gas is not supplied to the secondary supercharger, and sufficient rotation of the secondary supercharger cannot be obtained, which may cause a problem that the supercharging pressure is reduced.

Therefore, an object of the present invention is to provide a control device for a supercharged engine that can prevent a decrease in supercharging pressure at the start of operation of a secondary supercharger without deteriorating the reliability of the engine. .

(Means for Solving the Problems) According to the present invention, a primary supercharger that operates at all times and a secondary supercharger that operates in a high intake region are arranged side by side, and the engine operating state is changed in accordance with a change to a high intake region. In the control device for the supercharged engine that switches to the operation of the secondary supercharger in addition to the operation of the primary supercharger, the exhaust gas upstream of the turbine of the secondary supercharger is used to pre-rotate the wastegate valve and the secondary supercharger. Exhaust flow valve that opens the passage, when the supercharging pressure by the primary supercharger increases, prior to switching from the operation of only the primary supercharger to the operation of the secondary supercharger in addition to the primary supercharger And supply a small amount of exhaust gas to the secondary turbocharger to pre-rotate the secondary turbocharger. The amount of exhaust gas supplied to the turbocharger is increased, and the supercharging pressure of the secondary supercharger is increased, so that supercharging by the secondary supercharger is started and at least the secondary supercharger is pre-rotated. From time to the time when the secondary turbocharger starts supercharging the engine, the supercharging pressure of the primary supercharger is changed to the supercharging pressure that the wastegate valve opens when only the primary turbocharger operates. The wastegate valve control means forcibly closing the wastegate valve so that the wastegate valve does not open even when it reaches the upper limit. Release means for releasing the closing operation, and when the supercharging pressure by the primary turbocharger rises, open the exhaust flow valve to open the secondary The charger is characterized in that it comprises an exhaust circulating valve control means for pre-rotation.

(Operation and Effect of the Invention) In the control device for a supercharged engine of the present invention, when switching from the operation of only the primary supercharger to the operation of the secondary supercharger in addition to the primary supercharger, Since the wastegate valve is closed, a sufficient amount of exhaust gas is supplied to the secondary turbocharger. Therefore, even when switching to supercharging by the operation of both the primary supercharger and the secondary supercharger, the supercharging pressure does not decrease. In this control, if the wastegate valve is opened when the supercharging pressure becomes a predetermined value or more, the reliability of the engine can be maintained.

(Embodiment) Hereinafter, a control device for a supercharged engine according to a preferred embodiment of the present invention will be described with reference to the accompanying drawings.

FIG. 1 is an overall system diagram of a supercharged engine incorporating a control device according to an embodiment of the present invention.

In this embodiment, an engine 1 is a reciprocating two-cylinder engine, and exhaust passages 2 and 3 are provided independently for each cylinder. The turbine 5 of the primary turbocharger 4 is arranged in one of the two exhaust passages 2 and 3, and the turbine 7 of the secondary turbocharger 6 is arranged in the other. The two exhaust passages 2 and 3 join together downstream of the turbines 5 and 7 and are connected to a silencer (not shown). The intake passage 9 is divided into two parts downstream of an air cleaner (not shown), and the blower 11 of the primary turbocharger 4 is provided in the middle of the first branch passage 10. The blower 13 of the secondary turbocharger 6 is arranged in the middle of the above. These branch passages 10, 12
They are formed so as to face each other at the branching portion and extend substantially straight on both sides. Also, two branch passages 10, 12
Join again downstream of the respective blowers 11 and 13. An intercooler 14 is disposed in the single intake passage 9 again, a surge tank 15 is disposed downstream thereof, and a throttle valve 16 is disposed between the intercooler 14 and the surge tank 15. ing. Further, the downstream end of the intake passage 9 is branched to form two independent intake passages corresponding to each cylinder of the engine 1.
17 and 18 are connected to each intake port (not shown). In addition, fuel injection valves 19 and 20 are disposed in these independent intake passages 17 and 18, respectively.

An air flow meter 21 for detecting the amount of intake air is provided upstream of the intake passage 9 at a position upstream of the first and second branch passages 10 and 12.

The two exhaust passages 2 and 3 are provided with a primary turbocharger 4
And upstream of the secondary turbocharger 6, they are communicated with each other by a communication passage 22 having a relatively small diameter. In the exhaust passage 3 where the turbine 7 of the secondary turbocharger 6 is disposed, an exhaust cut valve 23 is provided immediately downstream of the opening position of the communication passage 22. Further, a merging exhaust device 24 extending from the middle of the communication passage 22 and downstream of the turbines 5 and 7 is provided.
A bypass passage 25 communicating with the bypass passage 25 is formed.
In 25, a waste gate valve 27 linked to a diaphragm type actuator 26 is provided. Further, a leakage passage 28 is formed for communicating the upstream portion of the waste gate valve 27 of the bypass passage 25 and the downstream of the exhaust cut valve 23 of the exhaust passage 3 connected to the turbine 7 of the secondary turbocharger 6, and the leakage passage 28 is formed in the leakage passage 28. Is provided with an exhaust leakage valve 30 linked to a diaphragm type actuator 29.

The exhaust cut valve 23 is linked to a diaphragm type actuator 31. On the other hand, in the branch passage 12 in which the blower 13 of the secondary turbocharger 6 is provided, an intake cut valve 32 is provided downstream of the blower 13. The intake cut valve 32 is constituted by a butterfly valve, and is also linked to a diaphragm type actuator 33.
A relief passage 34 is formed in the secondary branch passage 12 so as to bypass the blower 13, and a diaphragm-type intake relief valve 35 is excreted in the relief passage 34.

The pressure chamber of the diaphragm type actuator 29 for operating the exhaust leak valve 30 is connected via a conduit 36 to a branch passage 10 in which the blower 11 of the primary turbocharger 4 is discharged.
Is connected to the downstream side of the blower 11. When the pressure downstream of the blower 11 becomes equal to or higher than a predetermined value, the actuator 29 operates to open the exhaust leak valve 30, whereby when the exhaust cut valve 23 is closed, a small amount of exhaust gas flows through the bypass passage 28. It flows and is supplied to the turbine 7 of the secondary turbocharger 6. Therefore, the secondary turbocharger 7 starts rotating before the exhaust cut valve 23 opens.
During this time, the rotation of the secondary turbocharger 6 increases due to the opening of the intake relief valve as described later,
Transient response when the exhaust cut valve is opened is improved, and torque shock is reduced.

The pressure chamber of the actuator 33 that operates the intake cut valve 32 is connected to an output port of an electromagnetic solenoid type three-way valve 38 by a conduit 37. The actuator 31 for operating the exhaust cut valve 23 is connected to an output port of an electromagnetic solenoid type three-way valve 40 via a conduit 39. Further, the pressure chamber of the actuator 41 that operates the intake relief valve 35 is connected to the output port of the electromagnetic solenoid type three-way valve 43 by the conduit 42. As described later, the intake relief valve 35 opens the relief passage 34 until a predetermined time before the exhaust cut valve 23 and the intake cut valve 32 are opened. Thus, when the secondary turbocharger 6 is pre-rotated by the exhaust gas flowing through the leakage passage 28, the pressure upstream of the intake cut valve 32 is prevented from rising and entering the surging region. To increase the rotation.

Further, the actuator 26 for operating the waste gate valve 27 is connected to an electromagnetic solenoid type three-way valve 45 by a conduit 44.
Connected to the output port.

The above four solenoid three-way solenoid valves 38, 40, 43, 45
Is controlled by a control unit 46 configured using a microcomputer. The control unit 46 receives, in addition to the engine speed R and the intake air amount Q, detection signals such as a throttle opening degree VTO, a supercharging pressure P1 downstream of the blower 11 of the primary turbocharger 4, and a total supercharging pressure P3. The input is performed, and the following control is performed based on the input.

The above-mentioned electromagnetic solenoid type three-way valve for controlling the intake cut valve 32
One input port of 38 is connected to a vacuum tank 48 via conduit 47.
The other input port is connected via a conduit 49 to an output port 70 of a differential pressure detecting valve 50 described later. An intake negative pressure downstream of the throttle valve 16 is introduced into the negative pressure tank 48 via a check valve 51. One input port of the electromagnetic solenoid type three-way valve 40 for controlling the exhaust cut valve 23 is open to the atmosphere, and the other input port is connected to a conduit.
The conduit 47 connected to the negative pressure tank 48 via 52
It is connected to the. On the other hand, one input port of an electromagnetic solenoid type three-way valve 43 for controlling the intake relief valve 35 is connected to a conduit 53.
And the other input port is open to the atmosphere. Also, one input port of the electromagnetic solenoid type three-way valve 45 for controlling the waste gate valve 27 is open to the atmosphere, and the other input port is
The conduit 54 is connected to the conduit 36 communicating with the downstream side of the primary side blower 11.

The inside of the casing 61 of the differential pressure detecting valve 150 is divided into three chambers 64, 65, 66 by first and second two diaphragms 62, 63, as shown in FIG. . A first input port 67 is opened in the first chamber 64 on one end side, and a compression spring 68 is disposed between the inner surface of the end of the casing 61 and the first diaphragm 62. . A second input port 69 is opened in the second chamber 65 at the center, an output port 70 is provided at the center of the end wall of the casing 61, and a third port 66 is provided at the other end of the third chamber 66. The air opening port 71 is opened. The above diaphragm
A valve body 72 penetrating through the second diaphragm 63 and extending toward the output port 70 of the third chamber 66 is fixed to 62.

As shown in FIG. 3, the first input port 67 is connected to the downstream side of the intake cut valve 32 by a conduit 73, and the supercharging pressure P1 downstream of the blower 11 of the primary turbocharger 4 is provided. Is introduced into the first chamber 64. Further, the second input port 69 is connected to the upstream of the intake cut valve 32 by a conduit 74, so that the pressure P2 upstream of the intake cut valve 32 when the intake cut valve 32 is closed is introduced. ing. The pressure P1, which is introduced from these two input ports 67, 69,
When the difference of P2 is equal to or larger than the predetermined value, the valve body 72
open. The output port 70 is connected via a conduit 49 to one of the input ports of an electromagnetic solenoid type three-way valve 38 for controlling the intake cut valve 32. Therefore, in a state where the three-way valve 38 connects the conduit 37 connected to the pressure chamber of the actuator 33 for operating the intake cut valve 32 to the conduit 49 connected to the output port of the differential pressure detection valve 50, the differential pressure P2-P1 Is larger than a predetermined value, air is introduced into the actuator 33, and the intake cut valve 32 is opened. Also, the three-way valve 38
However, when the conduit 37 on the actuator 33 side is communicated with the conduit 47 connected to the negative pressure tank 48, a negative pressure is supplied to the actuator 33, and the intake cut valve 32 is closed.

On the other hand, the exhaust cut valve 23 is provided with a three-way valve 40 for controlling the exhaust cut valve 23 and an actuator 31 for operating the exhaust cut valve 23.
To the pressure chamber of the negative pressure tank 48
When connected to 52, the actuator is closed by supplying a negative pressure to the actuator. Further, when the three-way valve 40 opens the output side conduit 39 to the atmosphere, the exhaust cut valve 23 is opened, and supercharging by the secondary turbocharger 6 is performed.

FIG. 3 is a control map showing the open / close state of the intake cut valve 32, the exhaust cut valve 23, the intake relief valve 35, and the wastegate valve 27 together with the open / close state of the exhaust leak valve 30. This map is stored in the control unit 46 in advance, and the four electromagnetic solenoid type three-way valves 38, 40, 43, and 45 are controlled based on the map.

In a region where the engine speed R is low or the intake air amount Q is small, the intake relief valve 35 is open, and the secondary turbocharger 6 is pre-rotated by opening the exhaust leakage valve 30. When the engine speed reaches R2 or the intake air amount reaches the line of Q2, the intake relief valve 35 is closed, and thereafter, until the exhaust cut valve 23 is opened, the downstream side of the blower 13 downstream of the secondary turbocharger 6 is opened. Pressure rises. When the exhaust gas reaches the Q4-R4 line, the exhaust cut valve 23 opens, and then, when the exhaust cut valve 23 reaches the Q6-R6 line and the intake cut valve 32 opens, supercharging by the secondary turbocharger 6 starts. Primary turbocharger 4 and secondary turbocharger 6 at R6 line
Into the supercharging region by both superchargers.

The intake cut valve 32, the exhaust cut valve 23, and the intake relief valve 35 have some hysteresis from the high flow side to the low flow side, that is, Q5-R5, Q3-- shown by broken lines in FIG.
It switches on each line of R3 and Q1-R1.

The broken portions of these lines are on a so-called no-load line or low-load line.

The wastegate valve 27 is opened when the engine speed R and the throttle opening TVO are equal to or higher than a predetermined value, and when the supercharging pressure P1 downstream of the blower 11 of the primary turbocharger 4 is equal to or higher than a predetermined value. The wastegate valve 27 is also outside the control of the map in FIG. 3 described above. However, when the supercharger is switched to the supercharging by both the primary turbocharger 4 and the secondary turbocharger 6, Even if the condition is satisfied, it is closed.
The closing control of the wastegate valve 27 at the time of switching the operation of the supercharger is released when the overall supercharging pressure P3 exceeds a predetermined value larger than the predetermined value in the supercharging pressure P1. This prevents a decrease in the supercharging pressure when switching the operation of the supercharger.

In addition, during acceleration, as shown in FIG. 4, the timing of opening the exhaust cut valve 23 and the intake cut valve 32 is shifted to a high flow rate and a high rotation side with respect to a steady state, so that the secondary turbocharger 6 operates. Switching to the supercharging region is delayed. As a result, a decrease in the supercharging pressure which may occur when the timing is not changed is prevented. However, the closing timing of the intake relief valve 35 is not changed.

Next, referring to the flowcharts of FIGS. 5 and 6, the intake cut valve by the control unit 46 will be described.
A specific example of the above control for the exhaust cut valve 23, the intake relief valve 35, and the wastegate valve 27 will be described. In the flowcharts of FIGS. 5 and 6, S represents each step. Further, F is a flag, and the state of this flag (F = 1 to 6) means as shown in FIG. 3, and the previous transition is performed on the high flow rate side of the Q1-R1 line, respectively. From the low flow side of the Q2-R2 line to the high flow side (F = 2), from the high flow side to the low flow side of the Q3-R3 line. (F = 3), the transition from the low flow side to the high flow side of the Q4-R4 line (F = 4), Q5
-The transition from the high flow side to the low flow side of the R5 line (F
= 5) and the transition from the low flow rate side to the high flow rate side of the Q6-R6 line (F = 6). Hereinafter, description will be made step by step.

First, in FIG. 5, the process is started, and initialization (initialization) is performed in S1. At this time, the flag F is set to 1.

Next, at S2, the intake air amount Q and the engine speed R are input. Then, map values Q1 to Q6 and R1 to R6 are read in S3.

Next, in S4, the change rate dQ / dt of the intake air amount Q is set to a predetermined value A.
Acceleration determination is performed depending on whether the value is greater than the value.

If dQ / dt is greater than A and it is accelerating, then in S5,
Q4, Q6, R4, R6 corresponding to the opening timing of the exhaust cut valve 23 and the intake cut valve 32 are respectively set to predetermined values ΔQ4, ΔQ6,
The increase correction is performed by ΔR4 and ΔR6. If it is not during acceleration, the process proceeds to S6.

In S6, it is determined whether or not the flag F is 1, that is, whether or not the previous transition was from the high flow side to the low flow side of the Q1-R1 line. Note that initially F = 1, so this determination is YES.

If F = 1, then in S7, it is determined whether the current intake air amount Q is larger than Q2. If NO, then in S8
Then, it is determined whether the current engine speed R is greater than R2. If the determination in S7 is YES or the determination in S8 is YES, the flag F is set to 2 in S9, and control is performed to close the intake relief valve 35 in S10 (a positive pressure is introduced into the actuator). If the determinations in S7 and S8 are both NO, the process returns.

When the determination in S6 is NO, in S11, whether the flag F is set to an even number, that is, the transition in the previous line is from the low flow side to the high flow side, or from the high flow side to the low flow side. Is determined. When this determination is YES, S12
Then, it is determined whether or not F = 2, that is, whether or not the previous shift was from the bottom flow rate side to the high flow rate side of the Q2-R2 line, and if F = 2, the process proceeds to S13.

In S13, it is determined whether the current intake air amount Q is larger than Q4. If NO, then in S14, it is determined whether the current engine speed R is larger than R4. And S13 or S
If any one of the determinations in 14 is YES, the flag F is set to 4 in S15, and control is performed to open the exhaust cut valve 23 in S16 (negative pressure is introduced into the actuator).

If the determinations in S13 and S14 are both NO, it is determined in S17 whether the current intake air amount Q is smaller than Q1.

If the determination in S17 is YES, it is determined in S18 whether the current engine speed R is smaller than R1. If the determination is YES, the flag F is set to 1 in S19, and control is performed to open the intake relief valve 35 in S20 (a negative pressure is introduced into the actuator). If the determinations in S17 and S18 are both NO, the process returns.

If the determination in S12 is NO, the flag F is set to 4 in S21.
That is, it is determined whether the previous transition was a transition from the low flow rate side to the high flow rate side of Q4-R4. If this determination is YES, it is determined in S22 whether the current intake air amount Q is greater than Q6, and if this determination is NO, then in S23, it is determined whether the current engine speed R is greater than R6. I do. Then, if either S22 or S23 is YES, the flag F is set to 6 in S24, and control to open the intake cut valve 32 is performed in S25 (the actuator is communicated with the differential pressure detection valve side). When the determination in S23 is NO, it is determined in S26 whether the intake air amount Q is smaller than Q3.
Is smaller than R3. And the determination of S27 is YES
If so, the flag F is set to 3 in S28, and control is performed to close the exhaust cut valve 23 in S29 (atmosphere is introduced into the actuator).

When the determination in S21 is NO, the flag F = 6, that is, the previous transition is a transition from the low flow rate side to the high flow rate side of the Q6-R6 line, and in this case, in S30, the current intake air It is determined whether the quantity Q is smaller than Q5. If YES, then in S31, it is determined whether the current R is smaller than R5. Then, if YES, the flag F is set to 5 in S32, and S33
Control to close the intake cut valve 32 (introduce negative pressure to the actuator). If the determination in S30 or S31 is NO, the process returns.

Subsequent to S25, it is determined in S34 whether the previous flag F was not 6, and if the determination is YES, the supercharging pressure P3 for performing the opening operation of the wastegate valve 27 is set in S35. . This supercharging pressure P3 has, for example, a characteristic as shown in FIG. 7 and is used when switching from supercharging of only the primary turbocharger 4 to supercharging with the addition of the secondary turbocharger 6. This is set only to a value higher than the supercharging pressure P1 used in normal control. The supercharging pressure P1 and the supercharging pressure P3 are indicated by Pset. After the setting of the wastegate valve opening operation supercharging pressure in S35, or when the determination in S34 is NO, it is determined in S36 whether the current supercharging pressure is equal to or higher than the set supercharging pressure Pset, and this determination is made. If NO is determined, the wastegate valve 27 is closed in step S37, and if this determination is YES, the operation of opening the wastegate valve 27 is performed in step S38, and the process returns. This prevents a decrease in the supercharging pressure at the time of switching of supercharging from supercharging of only the primary turbocharger 4 to addition of the secondary turbocharger 6.

Next, control when the determination in S11 is NO will be described with reference to the flowchart of FIG.

When the determination in S11 is NO, in S41, it is determined whether or not the flag is F3, that is, whether or not the previous transition was from the high flow side to the low flow side of the Q3-R3 line. And YE
If S, then it is determined in S42 whether this time Q is greater than Q1, and if YES, it is determined in S43 whether this time R is less than R1. If YES, the flag F is set to 1 in S44, and then control is performed to open the exhaust cut valve 23 in S45.

If any of the determination of S42 or S43 is NO,
It is determined whether Q is larger than Q4. If NO, R is set to R in S47.
Determine if it is greater than 7. And S46 or
If any of the determinations in S47 is YES, the flag F is set to 4 in S48, and if NO in S49, the process returns as it is.

If the determination in S41 is NO, it means that the flag F = 5, so in this case, it is determined in S50 whether Q is smaller than Q3, and if YES, it is determined in S51 whether R is smaller than R3. If the determination in S51 is YES, the flag F is set to 3 in S52, and then control is performed to close the exhaust cut valve 23 in S53.

If the determination of either S50 or S51 is NO,
At S54, it is determined whether Q is greater than Q6. If this determination is NO, then, at S55, it is determined whether R is greater than R6.
If the determination at S54 or S55 is YES, the flag F is set to 6 at S56, and then control is performed to open the intake cut valve 32 at S57. On the other hand, when the determination of NO is made in S55, the process returns as it is.

Further, following S57, the waste gate valve 27 is controlled in the same manner as in S34 to S38. That is, S58
Then, it is determined whether the previous flag F was 6 or not. When the determination is YES, a supercharging pressure P3 for performing the opening operation of the wastegate valve 27 is set in S59. This boost pressure P3
Has a characteristic as shown in FIG. 7 similarly to the above case, and is used only when switching from supercharging with only the primary turbocharger 4 to supercharging with the addition of the secondary turbocharger 6. Is set to a value higher than the supercharging pressure P1 used in normal control. The supercharging pressure P1 and the supercharging pressure P3 are indicated by Pset. After setting the wastegate valve opening operation supercharging pressure in S59, or when the determination in S58 is NO, it is determined in S60 whether the current supercharging pressure is equal to or higher than the set supercharging pressure Pset, and this determination is made. If NO is determined, the wastegate valve 27 is closed in step S61, and if this determination is YES, an operation of opening the wastegate valve 27 is performed in step S62, and the process returns. This prevents a decrease in the supercharging pressure at the time of switching of supercharging from supercharging of only the primary turbocharger 4 to addition of the secondary turbocharger 6.

[Brief description of the drawings]

FIG. 1 is an overall system diagram of a supercharged engine incorporating a control device according to an embodiment of the present invention, FIG. 2 is a cross-sectional view of a differential pressure detecting valve in the above embodiment, FIG. 3 and FIG. FIGS. 5 and 6 are flow charts for executing the control of the above embodiment, and FIG. 7 is a control characteristic diagram for the control of the waste gate valve in the above embodiment. FIG. 4 is a characteristic diagram illustrating an example of a set supercharging pressure. 1 ... Engine 4 ... Primary turbocharger 6 ... Secondary turbocharger 23 ... Exhaust cut valve 27 ... Wastegate valve 31,33,41 ... Actuator 32 ... Intake cut 34 ... Relief valve 35… Intake relief valve 38, 40, 43 …… Electromagnetic solenoid three-way valve 46 …… Control unit

────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Seiji Tajima 3-1, Shinchi, Fuchu-cho, Aki-gun, Hiroshima Prefecture Inside Mazda Co., Ltd. (56) References JP-A-59-145328 (JP, A) JP-A-2 -256828 (JP, A) JP-A-64-60718 (JP, A) JP-A-3-88917 (JP, A) JP-A-61-198529 (JP, U) JP-A-63-36628 (JP, U) (58) Fields surveyed (Int. Cl. ⁶ , DB name) F02B 37/007 F02B 37/12 302

Claims (1)

(57) [Claims] 1. A primary supercharger that operates at all times and a secondary supercharger that operates in a high intake region are provided side by side, and when the engine operation state changes to a high intake region, the primary supercharger is added to the primary supercharger. In a control device for a supercharged engine that switches to operation of a secondary supercharger, a wastegate valve, an exhaust flow valve that opens an exhaust passage upstream of a turbine of the secondary supercharger to pre-rotate the secondary supercharger When the supercharging pressure of the primary turbocharger increases, a small amount is supplied to the secondary turbocharger before switching from the operation of the primary turbocharger to the operation of the secondary turbocharger in addition to the operation of the primary turbocharger. Supply of exhaust gas to pre-rotate the secondary turbocharger, and further, the engine operating state shifts to a high intake region to supply exhaust gas to the secondary turbocharger. In addition to increasing the amount, further increasing the supercharging pressure by the secondary supercharger, starting supercharging by the secondary supercharger, and starting the engine by the secondary supercharger at least from when the secondary supercharger is pre-rotated. Until the start of supercharging, the wastegate valve opens even if the supercharging pressure of the primary turbocharger reaches the supercharging pressure that the wastegate valve opens when only the primary turbocharger operates. Wastegate valve control means for forcibly closing the wastegate valve so that the supercharging pressure by the secondary supercharger acts on the engine so as to cancel the wastegate valve closing operation, and When the supercharging pressure of the primary turbocharger increases, the exhaust flow valve that opens the exhaust flow valve and pre-rotates the secondary turbocharger Control device for an engine with a supercharger, characterized in that it comprises a valve control means.