JPH03213621A - Controller of engine with supercharger - Google Patents

Abstract

PURPOSE:To prevent overrun of a main turbocharger by partial-open controlling an exhaust switching valve by means of exhaust pressure on the upper course from a turbocharger turbine, and full-open controlling the exhaust change valve by means of supercharging pressure on the lower cource from a compressor, in an engine of a two-stage turbo system. CONSTITUTION:An intake switching valve 84 and an exhaust switching valve 85 are respectively arranged in intake/exhaust systems connected to an auxiliary turbocharger 83 out of main and auxiliary turbochargers 82, 83 mutually arranged parallelly. A full open means 86 which fully opens the exhaust switching valve 85 at the switching time from supercharging operation for only a main turbocharger 82 to the supercharging operation for both main and auxiliary turbochargers, and a partial-open means 97 for opening the exhaust switching valve 85 before switching action and for forcing the auxiliary turbocharger 83 to make approach run by means of a part of exhaust gas, are provided. Exhaust gas pressure 88 on the upper course from the turbine of one side turbocharger is introduced to the partial-open means 87, so as to partially open the exhaust change valve 85 and also to fully open the exhaust-switching valve 85 by introducing intake pipe pressure 89 on the lower course from the compressor into the full open means 86.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a turbocharger in which a main turbocharger and a sub-turbocharger are arranged in parallel,
The present invention relates to a control device for a supercharged engine that switches the number of activated turbochargers depending on engine operating conditions.

[Prior art] Two turbochargers, a main turbocharger and a sub-turbocharger, are arranged in parallel to the engine body. In the low-speed range, the supercharging operation of the sub-turbocharger is stopped and supercharging is performed only by the main turbocharger, and in the high-speed range, both turbochargers are supercharged. 2. Description of the Related Art A supercharged engine of a so-called two-stage turbo system in which a turbocharger is operated is known (Japanese Patent Application Laid-open No. 112734/1982, Japanese Patent Application Laid-open No. 5968521, etc.). The configuration of this type of supercharged engine is shown in FIG. 6, for example. For the engine body 91, the main turbocharger (T/'C
-1>92 and an auxiliary turbocharger (T, "C2>93" are provided in parallel. The intake and exhaust systems connected to the auxiliary turbocharger 93 have an intake switching valve 94 and an exhaust switching valve 95, respectively. An intake switching valve 94 and an exhaust switching valve 9 are provided.
5 are both closed, only the main turbocharger 92 is operated for supercharging, and by fully opening both, the auxiliary turbocharger 93 is also operated for supercharging, making it possible to operate two turbochargers. can.

In order to smoothly switch from one turbocharger to two turbochargers, a system is known in which a part of the exhaust gas is flowed to the auxiliary turbocharger and the auxiliary turbocharger is rotated before the changeover. JP-A-61-112734 discloses that the exhaust switching valve is controlled to be opened slightly at a boost pressure lower than that at the time of switching the turbocharger, and a part of the exhaust gas is allowed to flow to the sub-turbocharger. A two-stage turbo system is disclosed in which a run-up rotation is performed.

On the other hand, Japanese Patent Laid-Open No. 59-68521 discloses a system in which the exhaust switching valve is controlled to open and close based on the exhaust pressure, although there is no small opening control of the exhaust switching valve before switching.

[Problems to be Solved by the Invention] However, in a system that controls the exhaust switching valve to open slightly using boost pressure, it is difficult to respond to changes in the air requirement of the engine that suddenly starts up, such as during no-load racing. Since the boost pressure cannot keep up with the increase, the exhaust switching valve does not operate, and exhaust gas is not properly released to the auxiliary turbocharger, causing the problem of the main turbocharger's rotational speed increasing too much (overrun).

On the other hand, in a system that simply controls the opening and closing of the exhaust switching valve using exhaust pressure, immediately after the exhaust switching valve is opened by exhaust pressure, exhaust gas suddenly flows to the sub-turbocharger side, causing the exhaust pressure to increase. This may cause the exhaust switching valve to close again, causing a hunting phenomenon. Therefore, it becomes difficult to cause the exhaust switching valve to accurately open and close as desired, resulting in a problem that the controllability of the exhaust switching valve is poor.

In view of the above-mentioned problems, the present invention improves the responsiveness of the small opening control of the exhaust switching valve, ensures stability of the exhaust switching valve control when switching the turbocharger, and improves the stability during no-load racing, etc. The purpose of this invention is to prevent overrun of the main turbocharger in the system and to more smoothly switch the number of turbochargers in operation.

[Means for Solving the Problems] A control device for a supercharged engine according to the present invention, which meets this objective, as shown in FIG. (82) and the sub-turbocharger (83), and the sub-turbocharger (8
3) an intake switching valve (84) provided in each of the intake and exhaust systems of the engine connected to the engine, which causes the auxiliary turbocharger to perform supercharging operation when both are fully open, and stops the supercharging operation when both are fully open; an exhaust switching valve (85); an exhaust switching valve fully opening means (86) for fully opening the exhaust switching valve when switching from supercharging operation of only the main turbocharger to supercharging operation of both the main and auxiliary turbochargers; control for a supercharged engine [I
In the apparatus, exhaust pressure (88) upstream of the turbine of one of the turbochargers is introduced into the exhaust switching valve small opening means (87) in order to slightly open the exhaust switching valve with the exhaust pressure, and the exhaust switching valve is opened slightly with the boost pressure. In order to fully open the exhaust switching valve, the intake pipe pressure (89) downstream of the compressor of one of the turbochargers is introduced into the exhaust switching valve fully opening means (86).

[Function] In such a control device, the exhaust pressure, which always increases almost simultaneously when the rotation speed of the turbocharger increases, is introduced into the exhaust switching valve small opening means, so the exhaust switching is performed immediately as the exhaust pressure increases. The valve is controlled to be opened slightly, a part of the exhaust gas is flowed to the sub-turbocharger, the sub-turbocharger is rotated during run-up, and overrun of the main turbocharger is reliably prevented. When switching the number of turbochargers to operate, that is, switching from operating only the main turbocharger to operating both the main and auxiliary turbochargers, the exhaust switching valve is operated by boost pressure, and when the boost pressure reaches a predetermined value, the exhaust switching valve is activated. The valve is fully opened and both the main and auxiliary turbochargers operate. Since the operation of the exhaust switching valve is controlled by boost pressure, the hunting phenomenon that occurs when the operation is controlled by exhaust pressure does not occur, resulting in stable control. l characteristics can be obtained.

[Embodiments] Preferred embodiments of the present invention will be described below with reference to the drawings.

FIG. 2 shows a control device for a supercharged engine according to an embodiment of the present invention, and shows the case of a six-cylinder engine.

In Figure 2, 1 is the engine, 2 is the surge tank, and 3 is the engine.
indicates the exhaust manifold. The exhaust manifold 3 is assembled into two groups, a #1 to #3 cylinder group and a #4 to #6 cylinder group, which do not cause exhaust interference, and the assembled portions are communicated with each other by a communication path 3a. 7.8 is a main turbocharger and a sub-turbocharger arranged in parallel with each other. Each of the turbines 7a and 8a of the turbocharger 7.8 is connected to a collection part of the exhaust manifold 3, and each of the compressors 7b and 8b is connected to the surge tank 2 via an intercooler 6 and a throttle valve 4.

The main turbocharger 7 is operated from a low engine speed range to a high engine speed range, and the auxiliary turbocharger 8 is stopped in a low engine speed range.

In order to enable operation and stop of both turbochargers 7.8, an exhaust switching valve 17 is provided downstream of the turbine 8a of the auxiliary turbocharger 8, and an intake switching valve 18 is provided downstream of the compressor 8b. Suction/exhaust switching valve 18.17
When both turbochargers are fully open, both turbochargers 7.
8 is activated.

In order to smoothly switch from one turbocharger to two turbochargers, the intake passage of the auxiliary turbocharger 8 that is stopped in a low speed range is provided with an intake bypass passage 13 that communicates between the upstream and downstream of the compressor 8b. , an intake bypass valve 33 disposed midway through the intake bypass passage 13 is provided. The intake bypass valve 33 is opened and closed by the actuator 10.

Note that the air flow downstream side of the intake bypass passage may be communicated with the intake passage upstream of the compressor of the main turbocharger 7. In addition, a check valve 12 is provided in the bypass passage that communicates the upstream and downstream sides of the intake switching valve 18, so that even when the intake switching valve 18 is closed, the compressor outlet pressure on the auxiliary turbocharger 8 side is lower than that on the main turbocharger 7 side. This allows air to flow from the upstream side to the downstream side when it becomes large.

In FIG. 2, 14 indicates an intake passage on the compressor outlet side, and 15 indicates an intake passage on the compressor inlet side.

The intake passage 15 is connected to an air cleaner 23 via an air flow meter 24. A front pipe 20 forming an exhaust passage is connected to an exhaust muffler 22 via an exhaust gas catalyst 21.
connected to.

The intake switching valve 18 is opened and closed by the actuator 11. The exhaust gas switching valve 17 is controlled to be switched between fully open and fully open by a diaphragm actuator 16 serving as exhaust gas switching valve fully opening means. The supercharging pressure upstream of the compressor of the turbocharger 7 (downstream of the intake switching valve 18) is introduced into the diaphragm chamber 16a of the actuator 16 via a fourth three-way solenoid valve 28.

The fourth three-way solenoid valve 28 selectively switches between the boost pressure and atmospheric pressure. The exhaust switching valve 17 is also connected to another diaphragm actuator 32 that serves as exhaust switching valve small opening means, and can be controlled to be switched between a small opening and a full opening according to the stroke of the actuator 32.

In the diaphragm chamber 32a of this actuator 32,
Exhaust pressure on the upstream side of the turbine of the main turbocharger 7 is introduced via the exhaust gas cooler 34 .

In this embodiment, the exhaust gas pressure is taken directly from the high-temperature exhaust manifold 3, so an exhaust gas cooler 34 is provided for cooling, but if the exhaust gas is taken out from a cooled part, the exhaust gas cooler can be omitted. For example, in recent years, many engines have been equipped with EGR systems as a measure against exhaust gases, but the vacuum modulator in the EGR system always maintains the same exhaust pressure as upstream of the turbocharger and extracts the pressure from a part where the exhaust gases are cooled. If so, an exhaust gas cooler is not required. Note that 9 indicates an actuator that opens and closes the waste gate valve 31.

The first, second, third,
A fourth three-way solenoid valve 25, 26, 27, 28 is provided. Switching of the three-way solenoid valves 25, 26, 27, and 28 is performed according to commands from the engine control computer 29. When the three-way solenoid valve 25.28 is turned on, the actuator 11.1 is turned on to fully open the intake and exhaust switching valve 18.17.
6 is activated, and when it is OFF, the actuator 11.16 is activated so that the intake/exhaust switching valve 18.17 is closed. 16a is a diaphragm chamber of the actuator 16;
a is the diaphragm chamber of the actuator 10, 11a11
1b indicates a diaphragm chamber of the actuator 11, respectively.

The engine control computer 29 is electrically connected to sensors for detecting various operating conditions of the engine, and receives signals from the various sensors. Engine operating condition detection sensors include an intake pipe pressure sensor 30°, a throttle opening sensor 5, and an air flow meter 2 as an intake air amount measurement sensor.
4.02 sensor 19 etc. are included.

The engine control computer 29 includes a central processor unit (CPU) for performing calculations, and a read-only memory (ROM) that is a read-only memory.
, -Random access memory (RAM) for time storage
, input/output interface (I/D interface)
, is equipped with an A/D converter that converts analog signals from various sensors into digital quantities. Figure 3 shows a control program for opening and closing the switching valve, which is stored in the ROM and
This is a program that is read out by U and executes calculations for opening and closing valves.

The control method in this embodiment will be explained with reference to the control flow shown in FIG. In addition, in Fig. 3, the first to fourth
VSVN for each three-way solenoid valve.

1 to VSVN0.4, the turbocharger is expressed as T/C.

First, in FIG. 3, the valve control routine is entered at step 100, and the engine intake air IQ is determined at step 101.
Load. The intake air amount is a signal from the air flow meter 24. Next, in step 102, whether it is a high speed range or a low speed range,
That is, it is determined whether it is a two-turbocharger operating range or a single turbocharger operating range. In the illustrated example, for example, if Q is greater than 5500Q/min, it is determined that two turbochargers should be operated;
When it is below min, it is determined that one turbocharger is in operation range. However, as will be explained later, there is a time delay before the two turbochargers actually operate.
It will switch around 0001/min.

If it is determined in step 102 that it is necessary to switch to two-turbocharger operation, the process proceeds to step 103, in which the intake switching valve 18 is opened during the one-turbocharger operation (
(partial loading), the second three-way solenoid valve 26 is turned OFF and the intake switching valve 18 is closed. Next, in step 104, the third three-way solenoid valve 27 is turned on,
The intake pipe pressure (supercharging pressure) downstream of the compressor is introduced into the diaphragm chamber 10a of the actuator 10, and the intake bypass valve 33 is closed. However, in this case, as described later, 1
In the individual turbocharger operating range, the exhaust switching valve 17 has already been controlled to be slightly opened by the actuator 32 serving as the exhaust switching valve small opening means, and the auxiliary turbocharger 8 is in the run-up rotation.

Next, after the third three-way solenoid valve 270N, a predetermined time delay, for example, 1 second, necessary to increase the run-up rotation speed of the turbocharger on the inactive side, that is, the auxiliary turbocharger 8, is provided. After seconds have elapsed, the fourth three-way solenoid valve 28 is turned ON in step 105, and the intake pipe pressure (supercharging pressure) downstream of the compressor is guided to the diaphragm chamber 16a of the actuator 16, which serves as a means for fully opening the exhaust switching valve, and the exhaust switching valve 17 is opened. Fully open. If sub-turbocharger 8
When the compressor pressure of the main turbocharger 7 becomes greater than the compressor pressure of the main turbocharger 7, the supercharged air of the auxiliary turbocharger 8 is supplied to the engine via the check valve 12. Subsequently, after turning on the fourth three-way solenoid valve 280N, for a predetermined period of time,
For example, after 0.5 seconds have elapsed, the first three-way solenoid valve 25 is turned ON in step 106, the intake pipe pressure (supercharging pressure) downstream of the compressor is guided to the diaphragm chamber 11a of the actuator 11, and the intake switching valve 18 is fully opened. . In this state, two turbochargers operate (note that when switching to two turbochargers after the above-mentioned predetermined time has elapsed, the intake air amount is approximately 600%, which is the target for good turbine efficiency).
0fl,'m! n). The process then proceeds to step 114 and returns.

If it is determined in step 102 that one turbocharger is in the operating range, the process proceeds to step 107, and the first three-way solenoid valve 2
5 is turned OFF to close the intake switching valve 18, and then in step 108, the fourth three-way solenoid valve 28 is turned OFF to close the exhaust switching valve 17. Subsequently, in step 109, the third three-way solenoid valve 27 is turned off, the intake bypass valve 33 is opened, and the process proceeds to step 110, where the intake pipe pressure PM is read. In step 111, it is determined whether the load is light or high.

Although the figure shows an example in which the intake pipe pressure is used as the load signal, the intake pipe pressure may be replaced by the throttle opening or the intake air amount/'engine speed. For example, if the intake pipe pressure PM is less than -1100 mHg, it is determined to be a light load, and if it is -1001 nInHg or more, it is determined to be a high load.

If it is determined that the load is high in step 111, step 1
Step 13, the second three-way solenoid valve 26 is turned off. That is, by turning off the second three-way solenoid valve 26, atmospheric pressure is introduced into both the diaphragm chambers 11a and 11b of the actuator 11, and the intake switching valve 18 is closed. In this state, the intake switching valve 18 is fully open, the exhaust switching valve 17 is closed, and the intake bypass valve 33 is fully open, so one turbocharger is activated when the amount of intake air is small, and boost pressure and torque response are good. Become.

If it is determined in step 111 that the load is light, the process proceeds to step 112, where the second three-way solenoid valve 26 is turned on, the negative pressure in the surge tank 2 is guided to the diaphragm 11b of the actuator 11, and the intake switching valve 18 is opened. In this state,
Since the exhaust switching valve 17 is open, the auxiliary turbocharger 8 does not operate, and only the main turbocharger 7 operates. However, since the intake passage 14 has the intake switching valve 18 open, the intake passages for two turbochargers are open. In other words, compressor 7b of both turbochargers
, 8b. As a result, a large amount of supercharging air can be supplied to the engine 1, and acceleration characteristics from low loads are improved. Subsequently, the process advances to step 114 and returns.

In the above control, in the high speed range, both the intake switching valve 18 and the exhaust switching valve 17 are opened, and the intake bypass valve 33 is closed. As a result, the two turbochargers 7.8 operate for supercharging, a sufficient amount of supercharging air is obtained, and the output is improved. At this time, the boost pressure is the set pressure, for example +500 m
It is controlled by a waste gate valve 31 so as not to exceed Hg.

In a low speed range and under high load, both the intake switching valve 18 and the exhaust switching valve 17 are closed, and the intake bypass valve 33 is opened. As a result, only one turbocharger 7 is driven. By using one turbocharger, boost pressure and torque rise quickly, and response is quick.

In a low speed range and under light load, the intake switching valve 18 is opened while the exhaust switching valve 17 is closed. As a result, the intake passages for two turbochargers are opened while one turbocharger remains driven, and an increase in intake resistance caused by one turbocharger can be eliminated. This makes it possible to further improve the boost pressure rise characteristics and response at the beginning of acceleration from a low load.

When shifting from a low speed range to a high speed range, that is, when switching from one turbocharger operation to two turbocharger operation, small opening control of the exhaust switching valve 17 is started before switching. Before switching the turbocharger, the rotational speed of the main turbocharger 7 increases as the amount of intake air increases, and as the rotational speed of the turbocharger 7 increases, the exhaust pressure also increases almost simultaneously.

Since the exhaust pressure is introduced into the actuator 32 as the exhaust switching valve face means, the actuator 32 is actuated immediately as the exhaust pressure increases, and the exhaust switching valve 17 is slightly opened. This small opening of the exhaust switching valve 17 is carried out by the exhaust pressure rising almost simultaneously with the increase in the rotational speed of the main turbocharger 7, so that part of the exhaust gas is quickly transferred to the auxiliary turbocharger 8 by the small opening of the exhaust switching valve 17. As a result, the sub-turbocharger 8 is appropriately rotated during the run-up, and overrun of the main turbocharger 7 is reliably prevented.

After the auxiliary turbocharger 8 makes a run-up rotation and reaches a predetermined supercharging pressure, the actuator 16 fully opens the exhaust switching valve 17 and operates as a normal twin turbo. The exhaust switching valve 17 is fully opened by the actuator 1 due to supercharging pressure.
6, stable control is ensured without being affected by a drop in exhaust pressure due to valve opening.

The characteristics before and during turbocharger switching are as shown in FIG. 4, for example. In Figure 4, 201
202 is the boost pressure, 202 is the exhaust pressure upstream of the turbocharger, 203 is the rotational speed of the turbocharger, 204 is the engine rotational speed, 205 is the opening degree of the exhaust switching valve 17, and 206 is the opening degree of the throttle valve 4. The characteristics of the solid line are when the exhaust switching valve is controlled to open and close using only the boost pressure (
Conventional), the characteristic indicated by the dashed-dotted line indicates the characteristic when the exhaust switching valve 17 is controlled to be opened slightly by the exhaust pressure and the exhaust switching valve 11 is fully opened by the boost pressure, according to the present invention.

In the example shown in FIG. 4, the actuator 32 for small opening control for the exhaust gas switching valve 17 is set to start operating earlier than the actuator 9 for the wastegate pulp 31, and the exhaust gas is discharged at point A in the diagram. The switching valve 17 starts to open slightly. Then, when the exhaust pressure upstream of the turbocharger turbine exceeds the above set value and the exhaust gas switching valve 17 is slightly opened, a part of the exhaust gas flows to the auxiliary turbocharger 8 side, and the auxiliary turbocharger 8 on the stop side is run-up. The number of revolutions can be increased.

When the amount of intake air reaches the point where the operation is switched from one turbocharger to two turbochargers (point B in the figure), the exhaust switching valve 17 is activated via the actuator 16 due to boost pressure.
is fully opened. At this time, the run-up rotation speed of the auxiliary turbocharger 8 has already been increased, so the switching shock is small and the drop in boost pressure can be suppressed to a small level. Furthermore, since a portion of the exhaust gas is already flowing to the auxiliary turbocharger side, the shock of switching the exhaust pressure can be suppressed to a small level. moreover,
Since the exhaust switching valve 17 is opened by the boost pressure that has reached a sufficiently high set pressure, even if the boost pressure temporarily decreases slightly due to switching, the exhaust switching valve 17 opening control itself will not be affected. has no effect.

Therefore, unlike when the exhaust gas switching valve is fully opened with exhaust pressure, the hunting phenomenon does not occur.

In this way, in the present invention, even when the engine speed suddenly increases as in no-load racing, the exhaust pressure always increases almost simultaneously as the turbocharger speed increases, and the exhaust pressure is transferred to the actuator 32. Since the exhaust gas switching valve 17 is opened slightly by the introduction, the small opening control is started with extremely good responsiveness, and overrun of the main turbocharger 7 is prevented.

At the time of switching, the exhaust switching valve 17 can be fully opened with the sub-turbocharger 8 fully rotated while reducing both the boost pressure and exhaust pressure to a small level, so the transition at the time of switching is smooth. At the same time, stable full-open control operation of the exhaust gas switching valve 17 is ensured. As a result, it is possible to quickly switch to the specified two turbochargers,
It is also possible to quickly increase the engine speed (D in Figure 4).

Note that region C in FIG. 4 corresponds to the operating amount of the actuator 32, in which the exhaust switching valve 17 is slightly opened by the actuator 32 before the exhaust switching valve 17 is fully opened, and the small opening amount gradually increases. Therefore, the capacity and size of the actuator 16 for full opening can be small.

FIG. 5 shows a control device for a supercharged engine according to another embodiment of the present invention. In this embodiment, the exhaust switching valve 1
The small opening means and the full opening means of No. 7 are performed by one actuator 41 consisting of a two-stage diaphragm type actuator. That is, pressure from the fourth three-way solenoid valve 28 is introduced into the diaphragm chamber 41a of the actuator 41, and exhaust pressure is introduced from the exhaust manifold 3 into the diaphragm chamber 41b via the exhaust gas cooler 34. Other configurations and operations are similar to those of the previous embodiment. Further, the control flow of each valve may also be substantially the same as in the previous embodiment.

[Effects of the Invention] As explained above, when the supercharged engine control device of the present invention is used, the exhaust pressure upstream of the turbocharger turbine is used to control the exhaust switching valve to open slightly, and the exhaust switching valve downstream of the turbocharger compressor is controlled to open slightly. Since the exhaust switching valve is fully opened by boost pressure, the exhaust switching valve can be opened slightly in response to the exhaust pressure, which increases almost simultaneously with the increase in turbocharger rotation speed, before switching the turbocharger, allowing some of the exhaust gas to It is possible to increase the run-up speed of the auxiliary turbocharger by appropriately flowing it to the auxiliary turbocharger side, and it is also possible to reliably prevent overrun of the main turbocharger even in cases such as during no-load racing. Sometimes, the exhaust switching valve can be fully opened when the set pressure is reached and the supercharging pressure is sufficiently increased, allowing stable operation without hunting, etc., and improving the controllability of the exhaust switching valve. can.

[Brief explanation of drawings]

FIG. 1 is a schematic system diagram showing the basic configuration of a control device for a supercharged engine according to the present invention; FIG. 2 is a system diagram of a control device for a supercharged engine according to an embodiment of the present invention; 3 is a control flow diagram of the device shown in FIG. 2, FIG. 4 is a characteristic diagram of the device shown in FIG. 2 before and during turbocharger switching, and FIG. 5 is a supercharger according to another embodiment of the present invention. Fig. 6 is a schematic system diagram of a conventional parallel turbocharged engine. 1... Engine 2... Surge tank 3... Exhaust manifold 4... Throttle valve 5... Throttle opening sensor 6... ...Intercooler 7...Main turbocharger 7a18a...Turbine 7b, 8b...Compressor 8...
Sub-turbocharger 10...Intake bypass valve actuator 11
...Intake switching valve actuator 13...
・・Intake bypass passage 14 ・・Intake passage (] Compressor upstream 15 ・
...Intake passage (upstream of compressor) 16...
...Exhaust switching valve actuator 17 as means for fully opening the exhaust switching valve...Exhaust switching valve 18...Intake switching valve 24...Air flow meter 25... First three-way solenoid valve 26...Second three-way solenoid valve 27...Third three-way solenoid valve 28...Fourth three-way solenoid valve 29... ... Engine control computer 30 ... Intake pipe pressure sensor 31 ... Waste] Gate valve 32 ...
...Exhaust switching valve actuator 33 as exhaust switching valve small opening means...Intake bypass valve 34...Exhaust gas cooler 41...Exhaust switching valve small opening means, exhaust switching Application for permission for actuator that also serves as means for fully opening the valve Person: Toyota Motor Corporation

Claims (1)

[Claims] 1. A main turbocharger and a sub-turbocharger are installed in parallel with the engine body, and each is installed in the intake and exhaust systems of the engine connected to the sub-turbocharger, and when both are fully open, the sub-turbocharger is supercharged. an intake switching valve and an exhaust switching valve that stop the supercharging operation when both are fully closed, and the exhaust switching valve when switching from supercharging operation of only the main turbocharger to supercharging operation of both the main and auxiliary turbochargers. an exhaust switching valve full opening means for fully opening the exhaust switching valve, and an exhaust switching valve small opening means for slightly opening the exhaust switching valve before switching to flow a part of the exhaust gas to the auxiliary turbocharger and causing the auxiliary turbocharger to perform a run-up rotation. In a control device for a supercharged engine, exhaust pressure upstream of the turbine of one of the turbochargers is introduced into the exhaust switching valve small opening means in order to slightly open the exhaust switching valve using exhaust pressure, and the exhaust pressure is introduced into the exhaust switching valve small opening means using the supercharging pressure. A control device for a supercharged engine, characterized in that intake pipe pressure downstream of a compressor of one of the turbochargers is introduced into the exhaust switching valve fully opening means to fully open the exhaust switching valve.