JPS59145329A - Control device for engine fitted with turbosuperchrager - Google Patents

Abstract

PURPOSE:To prevent any drop in a temporary supercharging effect due to a response delay in a turbosupercharger, by making it so as to be supplied with exhaust gas driving another turbosupercharger, from outside the supercharging operation range. CONSTITUTION:A low-speed turbosupercharger 11 is being driven. When reaching to a first suction air quantity, an actuator 16 is turned to ON, and thereby an exhaust selector valve 15 is moved to a virtual line position. The whole quantity of exhaust gas driving a turbine Tp of the low-speed supercharger 11 is fed to a turbine Ts of a high-speed turbosupercharger 12 via an exhaust pipe 13 and an exhaust passage 2b. On the other hand, when reaching to a second suction air quantity, each of actuators 4 and 9 is turned to ON, so that the high-speed supercharger 12 starts its supercharging operation instead of the low-speed turbosupercharger 11.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a control device for an engine equipped with a turbocharger, and more particularly to a control device for an engine having a plurality of turbochargers operated in accordance with engine operating conditions.

A turbine driven by the energy of the exhaust gas discharged from the engine rotates the blower in the intake passage, thereby prepressing the intake air or mixture, increasing the volumetric efficiency and improving the engine's output performance. Chargers are already in widespread practical use. ・Among the turbochargers mentioned above, those that operate with high efficiency in a relatively high speed range cannot sufficiently improve torque in a low speed range, and are particularly This is not particularly suitable for automobile engines that require low-speed output. On the other hand, a turbocharger that operates with high efficiency in a relatively low speed range has the disadvantage that it cannot sufficiently improve output in a high speed range.

Therefore, as described in, for example, Japanese Unexamined Patent Application Publication No. 50-118117 and Japanese Utility Model Application No. 56-159626, a plurality of turbo superchargers, each turbine, and a blower have been installed in the exhaust passage and the intake passage. arranged in parallel,
Matching the turbo supercharger and engine by changing the deposit of the turbo supercharger that activates supercharging depending on the engine operating condition, or selectively operating multiple turbo superchargers depending on the operating condition. Suggestions have been made to try '&[.

However, when multiple turbo superchargers are used with full operation control as described above, when the engine operating state reaches a predetermined state and the turbo supercharger whose supercharging operation has been completely stopped until now starts operating. Naturally, it takes some time for the turbocharger's rotational speed to rise to the predetermined rotational speed, so at that time the supercharging effect temporarily decreases, causing a problem in which the engine output drops. The above temporary decrease in engine output can be solved by completely stopping the high-order supercharger and fully operating only the low-order supercharger in the low-speed range, and operating the high-order supercharger at the same time in the high-speed range. In an engine with a combined charger, this is recognized when the above-mentioned supercharger starts operating, and the operation of the low-speed supercharger and the high-speed supercharger is selectively switched. In engines with complete turbocharger switching, this is recognized when switching operation. Particularly in the latter type of engine, the above-described problem is noticeable because the turbocharger that had been operating until then stops when the operation is switched.

The present invention has been made in view of the above circumstances, and is applicable to both the above-mentioned supercharger combination type engine and the supercharger completely switching type engine, and is suitable for temporary supercharging as described above. The object of the present invention is to provide a control system for a turbocharged engine that does not cause any decrease in effectiveness.

As described above, the control device for a turbocharged engine of the present invention installs a plurality of turbochargers in parallel, and stops the operation of a specific turbocharger depending on the engine operating state. In an engine with a turbo supercharger that is operated in combination or completely switched, there is an operating state detection means that detects all operating states of the engine, and a turbine upstream of the turbo supercharger that completely stops operating in a specific operating state of the engine. an exhaust pipe that communicates the exhaust passage on the side with the exhaust passage on the downstream side of the turbine of the remaining turbocharger, and an exhaust switching position where the entire amount of exhaust gas from the turbine of the turbocharger is flowed into the exhaust pipe. The exhaust switching valve, which can switch between all modes, receives the output of the operating state detection means, and switches the exhaust when the engine operating state approaches the supercharging operating range of the turbocharger that completely stops operating in a specific operating state of the engine. and a control circuit for driving the valve to the exhaust switching position.

When the exhaust switching valve is set to the exhaust switching position, the turbine of the turbocharger that is not yet in supercharging operation will be supplied with the exhaust gas that drove the other turbocharger, and the turbocharging will start. A turbocharger whose operation is completely stopped is pre-rotated from outside its supercharging operation area. In other words, rotational inertia is already given to this turbo supercharger at the time it starts supercharging operation, and this turbo supercharger instantly starts supercharging rotation after starting supercharging operation. Therefore, there is no temporary reduction in supercharging effect due to the response delay of this turbo supercharger.

Embodiments of the present invention will be described in detail below with reference to all the drawings.

FIG. 1 schematically shows a control system for a turbocharged engine according to a first embodiment of the present invention. engine 1
The exhaust passage 2 that discharges the exhaust gas is the exhaust passage 2 a I
The exhaust gas is branched into two systems, 2 and 2b, and an exhaust switching valve 3 is provided at this branch. This exhaust switching valve 3 is connected to the two exhaust passages 2 a + 2 by an actuator 4.
A switching operation is performed so that exhaust gas is selectively made to flow through only one of the two channels.

On the other hand, the intake passage 5 through which the intake air of the engine l flows,
Air 7 that detects the amount of intake air that indicates the operating status of the engine
0-On the downstream side of the sensor 6, the intake passage 5 a r 5
The system is branched into two systems b, which are combined on the upstream side of the throttle valve 7. An intake switching valve 8 is provided at this junction, and the intake switching valve 8 is switched by an actuator 9 so that only one of the two intake passages 5aν5b is selectively communicated with the engine 1. Be manipulated.

A fuel injection valve 10 is provided in the intake passage 5 on the downstream side of the throttle valve 7 to fully inject fuel into intake air to form a complete mixture. Although not shown in the figure, this fuel injection valve 1o is controlled, as has been conventionally done, to fully inject fuel with an injection amount and injection timing depending on the engine operating state.

A turbine Tp rotationally driven by exhaust gas is disposed in one exhaust passage 2a of the two exhaust passages 2a12b described above, and the turbine Tp is disposed in the intake passage 5a via a rotating shaft Lpi. It is connected to the installed blower Cp. In other words, these turbine Tp, rotating shaft Lp
A low-speed turbo supercharger 11 is configured as a main element of the blower Cp. Similarly, the other exhaust passage 2b is provided with a turbine Ts driven by exhaust gas, and the other intake passage 5b is provided with a blower Cs, and these turbines Ts and blower Cs are connected to the rotation axis Ls. A high-speed turbo supercharger 12 is constructed by connecting the two.

The low-speed turbo supercharger 11 is selected to efficiently improve engine output in a relatively low-speed range, and the -blade high-speed turbo supercharger 12 efficiently improves engine output in a relatively high-speed range. Those that serve are selectively used.

On the downstream side of the turbine Tp of the low-speed turbocharger 11, an upstream end of an exhaust pipe 13 is opened in the exhaust passage 2a, and a downstream end of the exhaust pipe 13 is connected to the turbine Ts of the high-speed turbocharger 12. The exhaust conduit 13 is opened to the exhaust passage 2b on the upstream side of the exhaust passage 13.This exhaust conduit 13 is equipped with a non-return check that allows exhaust gas to flow only from the exhaust passage 2a side to the exhaust passage 2b side, and prevents the exhaust gas from flowing in the opposite direction. A valve 14 is provided. At the opening of the exhaust conduit 13 to the exhaust passage 2a, the exhaust passage 2af is normally open and the exhaust conduit 3 is fully closed (the position indicated by the solid line in the figure), and the exhaust conduit 13 is opened by being driven by the actuator 16. Exhaust passage 2a
f An exhaust switching valve 15 is provided which assumes a fully closed exhaust switching position (the position indicated by the imaginary line in the figure).

Further, a relief passage 17 that bypasses the proa Csi is connected to the intake passage 5b, and the IJ IJ-F passage 1
7 is an IJ of the type that opens when energized, consisting of a solenoid valve, etc.
An IJ-F valve 18 is provided.

An upstream end of an exhaust bypass passage 19 is opened in the exhaust passage 2 on the upstream side of the exhaust switching valve 3, and its downstream end communicates with the exhaust passage 2a on the downstream side of the turbine Tp.

A wastegate valve 20 is interposed in the exhaust bypass passage 19, and the wastegate valve 20 is operated by a diaphragm actuator 21 having a control pressure conduit 21a opened to the intake passage 5 on the upstream side of the throttle valve 7. It has become so.

The intake air amount signal S1, which is the output of the air flow sensor 6 mentioned above, is input to the control circuit 22, and the control circuit 22 generates actuator drive signals 82, 83 +IJ, IJ-F valve drive signal according to this intake air amount signal 81. 84 f
Output.

Hereinafter, the operation of the apparatus of this embodiment will be described while fully explaining the control circuit 22 in detail. Figure 2 shows the control circuit 2 above.
2 configuration? It is shown in detail. As shown in this FIG. It is input to a second comparator 30.32. As mentioned above, the two turbo superchargers 11 and 12 are selectively used in the low speed region and the high speed region, respectively, so they are set at the predetermined engine speed B, 2f as the boundary, and the rotation speed R2.
In the following supercharging regions, the low-speed turbo supercharger 11 operates,
In the region exceeding the rotation speed tag 2, the high-speed turbo supercharger 12
It is desirable to switch the operation so that the Therefore, the second comparator 32 has an intake air amount Q2 corresponding to the engine speed R2 (as is well known, in an operating range where supercharging is generally performed, the engine speed corresponds to the intake air amount). A reference voltage e2 carrying the amount of air is applied, and the magnitude of the reference voltage e2 and the intake air amount signal S1 is compared and determined.

When the intake air amount signal S1 completely exceeds the reference voltage e2, that is, when the intake air amount completely exceeds the predetermined intake air amount Q2 (this is considered to be when the engine speed at full-open high speed exceeds the predetermined speed Rzi). ), an output S6 is issued from the second comparator 32. This output S6 is input to a drive circuit 33, and the drive circuit 33 outputs an actuator drive signal S2 to turn on the actuators 4 and 9.

Here, when the actuators 4 and 9 are in the OFF state, that is, when the intake air amount is below Q2, the exhaust switching valve 3 and the intake switching valve 8 are in the position shown by the solid line in FIG. is a two-system exhaust passage 2a
.

2b, and the intake air is supplied to the engine 1 through only one of the two intake passages 5a+5b. Therefore, if the engine speed reaches the supercharging region in a region of about 2 or less revolutions corresponding to the intake air amount Q2, the low-speed turbo supercharger 11 operates to supercharge the intake air flowing through the intake passage 5a. is pressurized to improve engine output in the low speed range.

When the actuators 4 and 9 are turned on as described above, the exhaust switching valve 3 and the intake switching valve 8 move to the positions shown by the imaginary lines in FIG. 2b, and the intake passage 5a is closed, so that the intake air flows through the intake passage 5b. Therefore, in the engine rotation speed region exceeding the rotation speed R2i (which is naturally a supercharging region), the high-speed turbo supercharger 12 performs supercharging operation,
Engine output in the high-speed range is improved.

The following is a turbo supercharger 12ff, which is a characteristic part of the present invention.
i The point of rotating in advance before supercharging operation will be explained. The intake air amount signal S1 is based on the engine rotation speed R2 mentioned above.
A reference voltage e4 carrying an intake air amount Q1 corresponding to a predetermined engine rotational speed R1 lower than 1 is input to a first comparator 30 to which the reference voltage e4 is applied.
1 and the intake air amount signal Sl. When the intake air amount signal Sl completely exceeds the reference voltage e1, that is, when the intake air amount exceeds the above-mentioned Qlffi (this is considered to be when the engine speed exceeds the above-mentioned predetermined speed R,1), the corresponding 1 comparator 30 issues an output S5. When this output S5 is input to the drive circuit 31, the actuator drive signal S3 is output from the drive circuit 31, and the actuator 16 is turned on.

As mentioned above, when this actuator 16 is turned ON, the exhaust switching valve 15 moves to the exhaust switching position shown by the virtual line in the figure, and therefore the exhaust gas driven to the turbine Tp' of the low-speed turbo supercharger 11 is switched on. The entire amount is passed through the exhaust pipe 13 and the exhaust passage 2b to the turbine T of the high-speed turbo supercharger 12.
s (note that since Ql (Q2), the exhaust switching valve 3 is still closing the upstream end of the exhaust passage 2b at this time, and therefore the turbine T of the low-speed turbo supercharger 11 is
p'r-driven exhaust gas is not returned to the upstream side of the turbine Tp). By supplying the exhaust gas to the turbine Ts in this way, the high-speed turbo supercharger 1
2 rotates. Therefore, when the intake air amount reaches Q2 (that is, the engine speed reaches R2), the actuators 4 and 9 are turned on, and the high-speed turbo supercharger 12 is activated in place of the low-speed turbo supercharger 11. When starting,
This means that the high speed turbocharger 12 is already rotating. Of course, this rotation is obtained by the exhaust gas whose energy has been reduced by driving the low-speed turbo supercharger 11, so the supercharging rotation speed is not a high rotation speed, but anyway, in this way, the high-speed turbo supercharger 11 is driven. Since rotational inertia is given to the supercharger 12, the actuator 4 is
When the exhaust gas is supplied to the turbine TS after being turned to N, the rotational speed of the high-speed turbo supercharger 12 instantly increases to supercharging rotational speed 1. Therefore, immediately after the low-speed turbocharger 11 is stopped, the high-speed turbocharger 12 starts to perform a supercharging operation, and when the operation of these turbochargers 11 and 12 is switched, the supercharging effect is reduced over time and the engine 1 The output never drops.

Even when the high-speed turbo supercharger 12 starts to perform supercharging operation, the exhaust switching valve 15 opens the upstream end of the exhaust pipe 13, but the exhaust pipe 13 is provided with a check valve 14. Therefore, the exhaust gas flowing into the exhaust passage 2b does not pass through the entire exhaust conduit 13 and escape to the exhaust passage 2a.

As explained above, the high-speed turbo supercharger 12 is rotated in advance from outside its supercharging operation area, and this rotation causes the air flow from the blower Cs of the high-speed turbo supercharger 12 to the intake passage 5.
bi IJ IJ-fu passage 17, so that the pressure in the intake passage 5b between the closed intake switching valve 8 and the
A relief valve 18 is provided. That is, as shown in FIG. 2, the output S6 of the second comparator 32 mentioned above is input to the AND gate 35 through the entire inverting amplifier 34. At the same time, the output S5 of the first comparator 30 is input to this AND gate 35, and when this output S5 and the output S7 of the inverting amplifier 34 are both input, That is, when the intake air amount takes a value between Q] and Q2, the gate output Ss f is generated. When the drive circuit 36 receives this gate output Ssf, the IJ IJ-F valve 18
I) Send the leaf valve drive signal S4 f and open the +7 leaf valve 18. Therefore, the amount of intake air is Q
The relief passage 17 is kept open until the high-speed turbo supercharger 12 performs supercharging operation beyond 2, and even if the high-speed turbo supercharger 12 is rotated by exhaust gas at this time, the supercharger The air that has passed through the blower Csi of No. 12 is returned to the atmosphere side through this relief passage 17i, so that the air that has passed through the air intake passage 5
The pressure inside b does not increase, and the rotational resistance of the supercharger 12 does not increase.

Therefore, the supercharger 12 can rotate up extremely rapidly. If the amount of intake air exceeds Ql, IJ from the drive circuit 36
- The output of the valve drive signal S4 is stopped, and the IJ valve 18 is closed. Thereby, the intake air is pressurized by the blower Cs of the high-speed turbo supercharger 12, which has started its supercharging operation, and is supplied to the engine l.

Actuators 4, 9 and actuator 1 explained above
6 and the operation timing of the relief valve 18 are summarized in the table below.

During supercharging operation using the low-speed turbocharger 11 or the high-speed turbocharger 12, when the supercharging pressure rises above the set value, the high supercharging pressure is introduced to the actuator 21 via the control pressure conduit 21a. Then, the diaphragm 21b of the actuator 21 is moved to the right in FIG. As a result, the wastegate valve 20 is opened, and part of the exhaust gas discharged from the engine 1 bypasses the turbocharger 11 or 12i and is discharged through the exhaust bypass passage 19i. The rotational speed of the engine 12 decreases and an abnormal increase in supercharging pressure is prevented. The engine installed in the engine is operated at high speed while receiving supercharging from the high speed turbo supercharger 12, and when the car approaches an uphill slope, the high speed turbo supercharger 12 is activated to the low speed turbo supercharger 11. In such cases, when the low-speed turbo supercharger 11 starts its supercharging operation, the speed increase of the supercharger 11 may be delayed, causing a temporary decrease in the supercharging effect. In order to prevent this delay in increasing the rotation of the low-speed turbocharger 11, the exhaust gas driven by the turbine Tsi of the high-speed turbocharger 12 is guided to the upstream side of the turbine Tp of the low-speed turbocharger 11. A conduit is provided, and before the operation is switched from the high-speed turbocharger 12 to the low-speed turbocharger 11, exhaust gas is supplied to the turbine Tp of the low-speed turbocharger 11 through this exhaust conduit to perform supercharging. All you need to do is pre-rotate machine 1.

Above, an embodiment in which the present invention is applied to a completely switched supercharger type engine has been described. Next, a second embodiment in which the present invention is fully applied to a supercharger combined type engine will be described.

In the second embodiment of the present invention shown in FIG. 3, elements that are equivalent to the respective elements of the first embodiment shown in FIG. As shown in FIG. 3, a turbo supercharger 11' includes an exhaust passage 2a, a turbine T'p arranged in an intake passage 5a, a blower CIp, and a rotating shaft Up connecting these, and an exhaust passage 2b. , Turby T's arranged in the intake passage 5b
, blower C1, , and a rotating shaft US that connects these
As will be described later, only the turbocharger 11' is operated in a relatively low speed range, and both turbochargers 11° and 12' are operated in a relatively high speed range. , generally each primary turbocharger 11',
It is called a secondary turbocharger 121. In other words, the primary turbocharger 11' is selected to be one that efficiently improves engine output in a relatively low speed range, while the secondary turbocharger 12' is the same as the primary turbocharger 1 described above.
1' as well as those that efficiently improve engine output when operated in a relatively high speed range are selected and used.

In order to control the operation of the two turbochargers 11' and 12' as described above, the turbine T's of the secondary turbocharger 12' is disposed in the exhaust passage 2b.
An on-off valve 53 is provided on the upstream side of s. The on-off valve 53 normally closes the exhaust passage 2b, but is driven by the actuator 54 to fully open the exhaust passage 2b. Further, an on-off valve 58 is provided in the intake passage 5b on the upstream side of the confluence of the intake passages 5a and 5b and on the downstream side of the blower C's of the secondary turbocharger 12'.

This on-off valve 58 also normally closes the intake passage 5b, but is driven by the actuator 59 to close the intake passage 5b.
fully open.

Hereinafter, the structure of the control circuit 55 to which the intake air amount signal S; which is the output of the air flow sensor 6 is inputted will be explained in detail with reference to FIG. . The intake air amount signal S1 of the air flow sensor 6 is input to a first comparator 60 of the control circuit 55. As described above, the first comparator 60 has a predetermined amount of intake air corresponding to the engine rotation speed R2 when starting the operation of the secondary turbocharger 12''i in addition to the primary turbocharger 11°. A reference voltage e2 carrying Q2 is applied, and this first comparator 60 compares the reference voltage e2 and the intake air amount signal S
Compare and determine the size with 1. And intake air amount signal S1
When it completely exceeds the reference voltage e2, that is, when the intake air amount exceeds the intake air amount Q2', the first comparator 60 generates an output S]5. This output 815 is input to the drive circuit 61, which drives the output S
In response to I5, the actuator drive signal S12 is output, and the actuator 54.59'k is turned on.

As described above, when the actuators 54, 59 are turned on, the on-off valves 53, 58, which were previously closed for the exhaust passage 2b and the intake passage 5bi, are opened. Climb up on it and
The exhaust gas discharged from the engine 1 is also supplied to the turbine T's of the secondary turbo supercharger 12', and the air pressurized by the blower C's is supplied to the engine 1. The secondary turbo supercharger [2°] performs supercharging operation together with the primary turbo supercharger 11°, and the engine output in the high speed range is efficiently improved.

When the amount of intake air becomes equal to or less than Q2, the output S15 is no longer generated from the first comparator 60, the on-off valve 53 is closed, and the exhaust gas is allowed to flow only into the exhaust passage 2a. Under such conditions, the engine l is still the primary turbo supercharger] 1'
If the engine is operated in the supercharging operation range, the primary turbocharger IJ' will naturally operate, and the engine output in the low speed range will be improved. At this time, the on-off valve 58 of the intake passage 5b is
Since it is closed together with the on-off valve 53, the intake air that has completely passed through the blower Cb of the turbo supercharger 111 flows into the intake passage 5b.
It is normally pressurized and supplied to the engine 1 without escaping to the side.

Next, the point of pre-rotating the secondary turbocharger 12'' before the supercharging operation of the secondary turbocharger 12'' is performed will be explained. The intake air amount signal Sl of the air flow sensor 6 is input to the first comparator 60 and the second comparator 62 as described above. This second comparator 62 has a predetermined intake air amount Qlk corresponding to an engine rotational speed R1 lower than the engine rotational speed R2 at which the secondary turbocharger 121 starts its supercharging operation. is added, and when the intake air amount exceeds the above QJffi and the intake air amount signal S1 exceeds the above reference voltage e1, the second comparator 62 generates an output S17f. This output SI7 is input to an AND gate 64, and at the same time, the output 815 of the first comparator 60 is input to the AND gate 64 through the entire inverting amplifier 63. This AND gate 64 connects the output 816 of the inverting amplifier 63 and the second comparator 62.
When the outputs 817 of
．． 66.

The drive circuit 65 receives this gate output S+s2, outputs an actuator drive signal 513f, and drives the actuator 16.
Turn all on. When this actuator 16 is turned on, the exhaust switching valve 15 moves to the exhaust switching position indicated by the imaginary line in the figure. Gas is supplied to the secondary turbocharger 12° turbine T'sK via the exhaust conduit 13 and the exhaust passage 2bi. By supplying the exhaust gas to the turbine T's in this way, the secondary turbo supercharger 12'' performs preliminary rotation before its supercharging operation, and then, as described above, the intake air amount reaches Q2 and supercharges. When starting the charging operation, the rotational speed is rapidly increased to the supercharging speed, so that the supercharging effect does not deteriorate further.

At the same time that the actuator drive signal 813 is output from the drive circuit 65, the IJ-F valve drive signal S14 is output from the drive circuit 66, and the IJ-F valve 18 is opened by the relief valve drive signal SI4. Therefore, this 2
Next, the turbocharger 12' is rotated by preliminary rotation of the turbocharger 12'.
The pressure inside the intake passage 5b on the downstream side of the blower Cs of ' increases, and the rotational resistance of the supercharger 12'' does not increase, so that the rotation of the supercharger ]2'' increases extremely rapidly.

When the amount of intake air exceeds Q2, the output S16 is no longer generated from the inverting amplifier 63, and the gate output 818 is stopped. As a result, the actuator 16 is turned off, the exhaust switching valve 15 is returned to the position indicated by the solid line in the figure, and the primary and secondary turbochargers 11° t12'' begin to operate together as described above. At the same time, the relief valve 18 is closed, and the intake air flowing through the intake passage 5b is normally pressurized by the blower C's of the secondary turbocharger 12' and supplied to the engine l.

The operation timings of the actuators 54 and 59, the actuator 16, and the relief valve 18 explained above are summarized in the table below.3 In the two embodiments explained above, two turbo superchargers are used. However, the present invention is of course applicable to an engine in which three or more turbochargers are arranged in parallel.

As explained in detail above, the control device for a turbocharged engine according to the present invention improves the responsiveness of the turbocharger to start supercharging operation in a completely switched supercharger type or a combined supercharger type engine. Therefore, this turbocharger prevents a temporary decrease in engine output when starting supercharging operation, and is highly effective in improving the drivability of an engine equipped with a plurality of turbochargers.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram showing a first embodiment of the present invention, Fig. 2 is a system diagram showing the configuration of the control circuit of the first embodiment, and Fig. 3 is a schematic diagram showing a second embodiment of the invention. , FIG. 4 is a system diagram showing the configuration of the control circuit of the second embodiment. ■... Engine 2+2a+2b... Exhaust passage 3... Exhaust switching valve 4.16.54... Actuator 515a1
5b...Intake passage 6...Air flow sensor 11...
・Low speed turbo supercharger 11'...Primary turbo supercharger 12...High speed turbo supercharger 12-...Secondary turbo supercharger 13... ...Exhaust pipe 15...River/exhaust switching valve 2
2.55...Control circuit

Claims (1)

[Claims] A plurality of turbo superchargers each consisting of a turbine arranged in the exhaust passage of the engine and driven by exhaust gas, and a blower arranged in the intake passage and connected to the turbine via a rotating shaft are connected to each turbine and blower. Operating state detection means for detecting the operating state of the engine in a turbocharged engine installed in parallel in each passage and configured to stop the operation of a specific turbocharger depending on the engine operating state. an exhaust conduit that communicates an exhaust passage on the upstream side of the turbine of the turbocharger whose operation is to be stopped in a specific operating state of the engine with an exhaust passage on the downstream side of the turbine of the remaining turbocharger; an exhaust switching valve capable of assuming an exhaust switching position for causing the entire amount of exhaust gas that has driven the turbine of the feeder to flow into the exhaust conduit; and an exhaust switching valve that receives the output of the operating state detection means and is activated when the engine operating state is a specific operating state of the engine. A control device for a turbocharged engine, comprising: a control circuit for driving an exhaust switching valve to the exhaust switching position when the turbosupercharger approaches a supercharging operation region where the turbocharging is stopped.