JPH04183929A - Control device of engine with supercharger for vehicle - Google Patents

Abstract

PURPOSE:To prevent generation of abnormal behavior of a vehicle caused by rapid torque change by inhibiting switching from one turbocharger to two turbochargers, when it is judged that aggravation of running condition is generated. CONSTITUTION:In the low intake air amount range of an engine, a first electromagnetic valve 25 and a force electromagnetic valve 28 are controlled to close an intake switching valve 18 and an exhaust switching valve 17 simultaneously, thereby, only a main turbocharger is supercharging-operated. On the other hand, in a high intake air amount range, both main and auxiliary turbochargers are supercharging-operated. In such a control device, running condition in which generation of abnormal behavior of a vehicle is apprehended, is detected by a means 60. It is judged by a means 61 on the basis of detected running condition whether aggravation of running condition is generated or not. It is inhibited by a means 63 on the basis of a running condition aggravation generation signal that switching to supercharging operation is carried out by both turbochargers. It is thus possible to prevent the vehicle from behaving abnormally by rapid torque change in association with switching into both turbochargers even in case of bad running condition caused by frozen road, surface, raining, and the like.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention has a main turbocharger and a sub-turbocharger, and only the main turbocharger performs supercharging in a low intake air amount region, and supercharges only in a high intake air amount region. A supercharged engine that operates both turbochargers and supercharges them.
This relates to a so-called two-stage twin-turbo engine.

[Conventional technology]

The main and side turbochargers are arranged in parallel to the engine body, and in the low intake air amount range, only the main turbocharger is activated, forming a single turbocharger, and in the high intake air amount area, both turbochargers are activated. I made it to
A supercharged engine employing a so-called two-stage turbo system is known.

The configuration of this type of supercharged engine is shown in FIG. 9, for example. A main turbocharger (T/C-1) 92 and a sub-turbocharger (T/C-2) 93 are provided in parallel to the engine body 91. The intake and exhaust systems connected to the auxiliary turbocharger 93 are provided with an intake switching valve 94 and an exhaust switching valve 95, respectively, and an intake bypass passage 97 that bypasses the compressor of the auxiliary turbocharger 93 is provided with an intake bypass valve 96. is provided. In a low intake air amount range, both the intake switching valve 94 and the exhaust switching valve 95 are fully closed, so that only the main turbocharger 92 is supercharged, and in a high intake air amount range, both switching valves 94 and 95 are fully opened. and intake bypass valve 96
By closing the auxiliary turbocharger 93, the supercharging operation is also performed, and two turbochargers can be operated.

The supercharging pressure setting value when using two turbochargers is set higher than the supercharging pressure when using a single turbocharger, where only the main turbocharger operates, and this allows high torque to be obtained. ing. Note that the technology related to a turbocharger with two-stage boost pressure control in which the boost pressure is set higher when two turbochargers are used than when one turbocharger is used is disclosed in Japanese Patent Application Laid-Open No. 60-216030.
It is known from Japanese Utility Model Application No. 60-145232.

[Problem to be solved by the invention]

However, in vehicles equipped with engines that have a two-stage turbocharger with two-stage supercharging control, switching from one turbocharger to two turbochargers occurs when driving conditions (external environmental conditions) are bad, such as frozen roads or rain. If this is done, there is a risk that the steering stability will deteriorate due to sudden torque changes that are not intended by the driver of the vehicle, resulting in abnormal behavior of the vehicle. Driving performance may deteriorate due to the occurrence of tire clogging, tire slipping, etc.

The present invention has focused on the above-mentioned problem, and has developed a vehicle that is capable of preventing abnormal vehicle behavior caused by rapid changes in engine torque due to turbocharger switching even under bad driving conditions such as frozen roads or rain. The object of the present invention is to provide a control device for a supercharged engine.

(Means for Solving the Problem) A control device for a supercharged engine for a vehicle according to the present invention in accordance with this object includes a main turbocharger and a sub-turbocharger, and has an air intake downstream of a compressor of the sub-turbocharger. In addition to providing an intake switching valve to open and close the passage,
An exhaust switching valve that opens and closes the exhaust passage is provided downstream or upstream of the turbine of the auxiliary turbocharger, and in a low intake air amount region, both the intake switching valve and the exhaust switching valve are closed, thereby supercharging only the main turbocharger. , in the high intake air amount region, both the main turbocharger and the sub-turbocharger are operated for supercharging, and the supercharging pressure during supercharging by both turbochargers is higher than the supercharging pressure during supercharging by the main turbocharger alone. A control device for a vehicle supercharger (Q engine) that is set at a high temperature is equipped with the following means.

(1) A driving condition detecting means capable of detecting a driving condition that may cause abnormal vehicle behavior; and a driving condition deterioration determining means determining whether a deterioration of the driving condition has occurred based on a signal from the driving condition detecting means. and a switching prohibition means for prohibiting switching to supercharging operation by both of the turbochargers based on a driving condition deterioration occurrence signal from the driving condition deterioration determining means.

(2) A driving condition detection means capable of detecting a driving condition that may cause abnormal behavior of the vehicle, and a driving condition deterioration that determines whether or not a deterioration of the driving condition has occurred based on a signal from the driving condition detection means. a determining means; and a set supercharging pressure during supercharging by both of the turbochargers, based on a driving condition deterioration occurrence signal from the driving condition deterioration determining means, to a value close to the set supercharging pressure when only the main turbocharger is supercharging. and a supercharging pressure reducing means for lowering the supercharging pressure.

[Effect]

A supercharged engine for a vehicle configured as described above.

In this control device, the driving condition detection means can detect the driving conditions of the vehicle, such as rain or snowfall. The driving condition deterioration determination means can determine whether or not the driving conditions have deteriorated based on the signal from the driving condition detection means. If the driving condition deterioration determining means determines that the driving condition has deteriorated, a driving condition deterioration occurrence signal is output to the switching prohibition means, and switching to the two turbochargers is prohibited. As a result, the state of one turbocharger is maintained, an increase in supercharging pressure is prevented, and abnormal behavior of the vehicle due to sudden torque changes is prevented.

In addition, if the driving condition deterioration determining means determines that the driving condition has deteriorated, the set supercharging pressure for two turbochargers is lowered, so the l/lux change that occurs when switching turbochargers is significantly reduced. This prevents abnormal vehicle behavior from occurring due to sudden torque changes.

〔Example〕

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a vehicle supercharger/engine control device according to the present invention will be described below with reference to the drawings.

1 to 4 show a first embodiment of the present invention, and particularly show a case where it is applied to a six-cylinder engine mounted on a vehicle.

In Figure 2, 1 is the engine, 2 is the surge tank, and 3 is the engine.
indicates exhaust eyebrow bold. 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 are main turbochargers arranged in parallel with each other,
It is a secondary turbocharger. Each of the turbines 7a and 8a of the turbocharger 7.8 is connected to a gathering part of the exhaust manifold 3, and each of the compressors 7b and 8b is connected to the surge tank 2 via an ink cooler 6 and a throttle valve 4.

The main turbocharger 7 is operated from a low intake air amount region to a high intake air amount region, and the auxiliary turbocharger 8 is stopped in a low intake air amount region. In order to enable activation and deactivation 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. Sucking,
When both exhaust switching valves 18.17 are open, both turbochargers 7.8 are operated.

The downstream side of the turbine 8 a of the auxiliary turbocharger 8 and the downstream side of the turbine 7 a of the main turbocharger 7 can communicate with each other via an exhaust bypass passage 40 . The exhaust bypass passage 40 is provided with an exhaust bypass valve 41 that opens and closes the exhaust bypass passage 40. Exhaust bypass valve 4
1 is opened and closed by a diaphragm actuator 42.

In order to smoothly switch from one turbocharger to two turbochargers, a compressor 7b is installed in the intake passage of the sub-turbocharger 8 that is stopped in a low intake air amount region.
An intake bypass passage 13 that communicates the upstream side of the compressor 8b with the downstream side of the compressor 8b, and an intake bypass valve 33 disposed in the middle of the intake bypass passage 13 are provided. The intake bypass valve 33 is opened and closed by a diaphragm type actuator 10.

A check valve 12 is provided in a bypass passage that communicates the upstream and downstream sides of the intake switching valve 18, so that when the intake switching valve 18 is closed, the compressor outlet pressure on the sub-turbocharger 8 side changes to the main turbocharger 7 side. When it gets bigger,
This allows air to flow from the upstream side to the downstream side. In the figure, 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 via an exhaust gas catalyst 21. The intake switching valve 18 is opened and closed by an actuator 11, and the exhaust switching valve 17 is opened and closed by a diaphragm actuator 16. The wastegate valve 31 is opened and closed by an actuator 9.

The actuator 9.10.11.16.42 is actuated by the introduction of boost pressure or negative pressure.

Each actuator 9.10.11.16.42 has first and second actuators for selectively switching between supercharging pressure or negative pressure from the positive pressure tank 51 and atmospheric pressure from downstream of the air flow meter 24. , third, fourth, fifth, and sixth solenoid valves 25
．． 26.27.28.32.44 are connected. Switching of each solenoid valve 25.26.27.28.32.44 is as follows.
This is done according to instructions from the engine control computer 29. Note that a check valve 45 that allows only one flow of negative pressure is interposed in the passage for introducing negative pressure into the second electromagnetic valve 26.

When the first electromagnetic valve 25 is turned ON, the actuator 11 is actuated to fully open the intake switching valve 18, and when it is OFF, the actuator 11 is activated so that the intake switching valve 18 is fully closed. When the fourth solenoid valve 28 is turned on, the exhaust switching valve 17
The actuator 16 is operated to fully open O.
FF operates the actuator 16 to fully close the exhaust switching valve 17. When the third solenoid valve 27 is turned ON, the actuator 10 is operated to fully close the intake bypass valve 33, and when it is OFF, the actuator 10 is operated so as to fully open the intake bypass valve 33.

The fifth solenoid valve 32 that introduces atmospheric pressure into the actuator 42 that operates the exhaust bypass valve 41 is ON.

Duty control is used instead of OFF control. Similarly, an actuator 9 that operates the wastegate valve 31
The sixth solenoid valve 44 that guides atmospheric pressure to ON, 0FFII
It is controlled by duty, not by IJ.

As is well known, duty control is to control the energization time using a duty ratio, and by digitally changing the ratio of energization and non-energization, the average current is variably controlled in an analog manner. Note that the duty ratio is the ratio of the energizing time to the time of one cycle, and if the energizing time in one cycle is A and the non-energizing time is B, the duty ratio -
It is expressed as A/(A+B)×100(%). In this embodiment, by controlling the duty of the fifth solenoid valve 32 and the sixth solenoid valve 44, it is possible to vary the opening amounts of these solenoid valves.

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. The engine operating condition detection sensor includes a boost pressure detection means (intake pipe pressure sensor) 30, a throttle opening sensor 5, an air flow meter 24 as an intake air amount measurement sensor, an engine rotation speed sensor 50, and an oxygen sensor 19. It can be done.

The engine control computer 29 includes a central processor (CPU) for calculations, a read-only memory (ROM), and a read-only memory (ROM).
), -Random access memory (RAM) for time storage
), an input/output interface (I10 interface), and an A/D converter that converts analog signals from various sensors into digital quantities.

The engine control computer 29 is configured to receive a signal from a driving condition detection means 60 capable of detecting driving conditions that may cause abnormal behavior of the vehicle. Here, abnormal behavior of the vehicle means that it becomes difficult for the vehicle to drive normally due to tire slipping or the like. This is thought to be caused by deterioration in driving conditions (external environmental conditions) such as freezing of the driving road surface due to low temperatures, rain, and snowfall.

If switching from one turbocharger to two turbochargers is performed when the vehicle is under poor driving conditions, there is a risk that the vehicle will behave abnormally due to a sudden change in torque that is not intended by the driver of the vehicle. Therefore, in this embodiment, the driving conditions are detected by the driving condition detection means 60, and the following means are used to prevent abnormal behavior of the vehicle when the driving conditions deteriorate.

The engine control computer 29 includes a driving condition deterioration determining means 6 which determines the occurrence of a deterioration of the driving condition based on a signal from the driving condition detecting means 60. In addition, the engine control computer 29 has
A switching inhibiting means 63 is formed which prohibits both turbochargers 7.8 from switching to supercharging operation based on a driving condition deterioration occurrence signal from the driving condition deterioration determining means 6.

As shown in FIG. 1, the signal from the driving condition detection means 60 is input to the driving condition deterioration determination means 61, and the signal from the driving condition deterioration determination means 61 is input to the switching prohibition means 63.
is man-powered. The signal from the switching inhibiting means 63 is output to the fourth solenoid valve 28 that controls the opening and closing of the exhaust switching valve 17 and the first solenoid valve 25 that controls the opening and closing of the intake switching valve 18. When the driving condition deteriorates, the switching prohibition means 63 switches the driving condition deterioration determination means 61.
The first solenoid valve 25 and the fourth solenoid valve 2 are configured such that one turbocharger state is forcibly maintained by a signal from the
Control 8. The driving condition deterioration determining means 61 and the switching inhibiting means 63 that perform these controls are constructed from programs stored in the engine control computer 29.

Next, the operation of the supercharged engine control system described in "2" will be explained with reference to the flowchart of FIG.

As described above, in the high intake air amount region of the present supercharged engine, 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 →
-5QQ mm11g is controlled by the Westgehlhalp 31 which is subjected to duty control.

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. The reason why one turbocharger is used in the low intake air amount range is that the supercharging characteristics of one turbocharger are superior to the supercharging characteristics of two turbochargers in the low intake air amount range. By using one turbocharger, the boost pressure and torque will be 7.

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. Therefore, it is possible to further improve the boost pressure rise characteristics and response at the initial stage of acceleration from a low load.

When transitioning from a low intake air amount region to a high intake air amount region, that is, when switching from one turbocharger operation to two turbocharger operation, the exhaust bypass is activated when the intake switching valve 18 and the exhaust switching valve 17 are closed. By controlling the valve 41 to open slightly using duty control and further closing the intake bypass valve 33, the run-up rotation speed of the auxiliary turbocharger 8 is increased, making it possible to switch the turbocharger more smoothly (with less shock at switching). become.

If it rains while the vehicle is driving, the road surface becomes wet, making the tires more likely to slip when driving at high speeds. In such a case, if switching from one turbocharger to two turbochargers is performed, there is a risk that the vehicle will behave abnormally due to a sudden change in torque. therefore,
Under such driving conditions, one turbocharger to two
It is necessary to prohibit switching to individual turbochargers.

FIG. 4 shows a processing procedure for prohibiting switching from one turbocharger to two turbochargers when driving conditions are bad.

In FIG. 4, the process is started in step 101, and in step 102 it is determined whether the driving conditions are such that the steering stability of the vehicle deteriorates. This judgment process is performed by the driving condition deterioration judgment means 60 shown in FIG. Here, if it is determined that the running conditions are not bad, the process proceeds to step 104, and switching to two turbochargers becomes possible. Therefore, if the switching conditions are satisfied, switching to two turbochargers is performed. If the steering knob 102 determines that the running conditions are poor, the process proceeds to step 103, and switching to two turbochargers is prohibited.

That is, in this case, even if the switching conditions are satisfied, one turbocharger remains in the turbocharger state. Step 1 (1
When the processing of step 3 and 104 is completed, the process proceeds to step 105, and the switching prohibition processing is completed.

In this way, if it is determined that the driving conditions have worsened,
Since switching to a two-turbocharger is prohibited, as shown in Figure 3, even if the engine speed (N The sudden change in torque due to this will be eliminated. As a result, the torque during driving is kept almost constant, and abnormal vehicle behavior due to sudden changes in torque is reliably prevented.

Second Embodiment FIGS. 5 to 8 show a second embodiment of the present invention. The second embodiment differs from the first embodiment in the presence or absence of a switching inhibiting means and a supercharging pressure reducing means, and other parts are the same as the first embodiment. By assigning the same reference numerals, the explanation of the corresponding parts will be omitted, and only one different part will be explained.

As shown in FIG. 5, the signal from the running condition detection means 60 is input to the running condition deterioration determination means 61, and the signal from the running condition deterioration determination means 61 is manually inputted to the supercharging pressure reducing means 64. Let's do it. The supercharging pressure lowering means 64 changes the set supercharging pressure when supercharging by both turbochargers 7.8 to the supercharging pressure when only the main turbocharger 7 is supercharging, based on the driving condition deterioration occurrence signal from the driving condition deterioration determining means 61. It has a function to lower the boost pressure to near the set boost pressure. In other words, the supercharging pressure reducing means 64 changes the set supercharging pressure based on the signal from the running deterioration determining means 61, and the waste gate valve 31
Due to the duty control, the supercharging pressure when using two turbochargers is significantly reduced.

FIG. 7 shows a processing procedure for reducing the boost pressure when running conditions are poor.

In FIG. 7, the process is started in step 201, and in step 202 it is determined whether the driving conditions are such that abnormal behavior of the vehicle is likely to occur. Here, if it is determined that the running conditions are not bad, the process proceeds to step 204, where the supercharging pressure when two turbochargers are used is significantly increased as compared to when one turbocharger is used. Step 202
If it is determined that the running conditions are poor, the process proceeds to step 203, where the set supercharging pressure for two turbochargers is lowered to near the set supercharging pressure for one turbocharger. Therefore, the torque characteristic when switching from one turbocharger to two turbochargers becomes almost flat as shown in FIG. 6, and abnormal behavior of the vehicle due to sudden changes in torque is prevented.

FIG. 8 shows more specific processing of the supercharging pressure reduction processing in FIG. 7.

As shown in FIG. 8, the process starts at step 300, and based on the signal from the outside temperature sensor (shown in the diagram), the process starts at step 300.
01, it is determined whether the outside temperature is low. Here, if it is determined that the outside temperature is high, proceed to step 308,
As usual, the supercharging pressure when using two turbochargers is higher than the supercharging pressure when using one turbocharger. Step 30
If it is determined in step 1 that the outside temperature is low, step 302
Then, it is determined whether the road surface on which the vehicle is traveling is unpaved or not based on the signal from the road surface sensor (road shown). If it is determined that the driving road surface is paved, step 30
If it is determined that the road is not paved, the process advances to step 303. In step 303, it is determined whether the vehicle is turning based on the signal from the steering wheel angle sensor (the road shown).

In step 303, if it is determined that the vehicle is traveling straight, the process proceeds to step 308, and if it is determined that the vehicle is turning, the process proceeds to step 304. In step 304, it is determined whether the tires are slipping based on signals from speed sensors that detect the rotational speed of each wheel. That is, it is determined whether there is a significant difference in the rotational speed of each wheel.

Here, if it is determined that the tire is not slipping, the process proceeds to step 308; on the other hand, if it is determined that the tire is slipping, the process proceeds to step 305.

In step 305, it is determined whether or not the wiper is operating based on oN and oFF (8-6) of the wiper switch (as shown in the diagram).In the case of snowfall, the wiper is used. It is indirectly determined that it is snowing.If it is determined in step 305 that the wiper is not operating, the process proceeds to step 308, and if it is determined that the wiper is being used, the process proceeds to step 306.

In step 306, it is determined whether or not it is raining based on the signal from the water droplet sensor (the path shown). Here, if it is determined that it is not raining, step 30
The process proceeds to step 8, and if it is determined that it is raining, the process proceeds to step 307.

In step 307, in order to prevent abnormal behavior of the vehicle due to deterioration of driving conditions, the set supercharging pressure for two turbochargers is reduced to near the set supercharging pressure for one turbocharger. When the processes in steps 307 and 308 are completed, the process proceeds to step 309, and the process for reducing the boost pressure is completed.

In this way, the factors that worsen the driving conditions (step 301
-306), and when switching to two turbochargers under such deteriorating running conditions, the set and running boost pressures are reduced to the set boost pressure of one turbocharger.

In each of the embodiments, the exhaust switching valve 17 and the exhaust bypass valve 41 are provided in the exhaust passage downstream of the turbine of the sub-turbocharger 8, but these are installed in the exhaust passage 1 m upstream of the turbine of the sub-turbocharger 8. It is also possible to provide such a configuration.

〔Effect of the invention〕

As explained above, in the control device for a supercharged engine for a vehicle according to the present invention, the driving condition deterioration determining means determines the occurrence of a deterioration of the driving condition based on the signal from the driving condition detecting means. However, the switching means prohibits switching from one turbocharger to two turbochargers based on the signal from the driving condition deterioration determining means.
Even when the vehicle is accelerating, the single turbocharger state is maintained and the supercharging pressure is kept constant. Therefore, abnormal behavior of the vehicle due to sudden torque changes is prevented, and driving performance is improved.

Further, the driving condition deterioration determining means determines the deterioration of the driving condition based on the signal from the driving condition detecting means, and the supercharging pressure reducing means determines whether the driving condition has deteriorated based on the signal from the driving condition deterioration determining means. Since the set supercharging pressure at the time of the turbocharger is reduced to the vicinity of the set supercharging pressure at the time of the turbocharger, the IJ
This makes it possible to reduce the l·lux change, and prevent the occurrence of abnormal vehicle behavior due to a sudden one-herk change.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a control device for a supercharged vehicle engine according to a first embodiment of the present invention, and FIG. 2 is a system diagram of a supercharged engine for a vehicle according to a first embodiment of the present invention. , Figure 3 is a characteristic diagram showing changes in J filtration supply pressure in the equipment shown in Figure 2, and Figure 4 is a characteristic diagram showing changes in J filtration supply pressure in the equipment shown in Figure 2, to prohibit switching from one turbocharger to two turbochargers. Flowcharts 1 to 5 showing the processing procedure of FIG. A characteristic diagram showing changes in pressure, Figure 7 is a flowchart showing the processing procedure for lowering the set supercharging pressure when two turbochargers are used in the device shown in Figure 5, and Figure 8 is a flowchart showing the processing procedure in Figure 7. A detailed flowchart is shown in FIG. 9, which is a schematic system diagram of a conventional supercharged engine. ■ Engine 7 Main turbocharger 8 Sub-turbocharger 13 Intake bypass passage 17 Exhaust switching valve 18 ...Intake switching valve 29...Engine control computer 3
3...Intake bypass valve 40...Exhaust bypass passage 41...Exhaust bypass valve 60...Driving condition detection means 61...Driving condition Deterioration determination means 63...
・Switching prohibition means 64...Supercharging pressure reducing means Patent Applicant Toyota Motor Corporation representative
Attorney Patent attorney Circle side Keio-shaped can 1) ζ He-shaped can Ll: (bao,

Claims (1)

[Claims] 1. A main turbocharger and a sub-turbocharger are provided, and an intake switching valve for opening and closing the intake passage is provided downstream of the compressor of the sub-turbocharger, and an exhaust gas is provided downstream or upstream of the turbine of the sub-turbocharger. An exhaust switching valve that opens and closes the passage is provided, and in a low intake air amount range, both the intake switching valve and the exhaust switching valve are closed to supercharge only the main turbocharger, and in a high intake air amount range, the main turbo A supercharged engine for vehicles in which both the charger and the auxiliary turbocharger are supercharged, and the supercharging pressure when both turbochargers are supercharging is set higher than the supercharging pressure when only the main turbocharger is supercharging. A control device comprising: a driving condition detection means capable of detecting a driving condition that may cause abnormal behavior of the vehicle; and a driving condition deterioration detecting means that determines whether or not a deterioration of the driving condition has occurred based on a signal from the driving condition detection means. A vehicle comprising: a determining means; and a switching prohibition means for prohibiting switching to supercharging operation by both of the turbochargers based on a driving condition deterioration occurrence signal from the driving condition deterioration determining means. Control device for supercharged engines. 2. Equipped with a main turbocharger and a sub-turbocharger, an intake switching valve for opening and closing the intake passage is provided downstream of the compressor of the sub-turbocharger, and an exhaust switching valve for opening and closing the exhaust passage downstream or upstream of the turbine of the sub-turbocharger. In the low intake air amount range, both the intake switching valve and the exhaust switching valve are closed to operate only the main turbocharger, and in the high intake air amount range, the main turbocharger and the auxiliary turbocharger are supercharged. In a control device for a vehicle supercharged engine that operates both turbochargers and sets the supercharging pressure during supercharging by both turbochargers to be higher than the supercharging pressure during supercharging by only the main turbocharger, a driving condition detecting means capable of detecting a driving condition that may cause abnormal behavior; a driving condition deterioration determining means determining whether a deterioration of the driving condition has occurred based on a signal from the driving condition detecting means; A supercharging pressure reduction that lowers the set supercharging pressure during supercharging by both turbochargers to the vicinity of the set supercharging pressure when supercharging only the main turbocharger, based on the driving condition deterioration occurrence signal from the condition deterioration determining means. 1. A control device for a supercharged engine for a vehicle, comprising: means;