JPH0467566B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a boost pressure control device for a turbocharger.

(Conventional technology) Turbochargers use the high temperature and high pressure energy of exhaust gas to rotate an exhaust turbine at high speed and drive a compressor on the same axis, allowing for high-speed, high-load operation with increased exhaust gas flow rate. In this region, the flow rate introduced into the exhaust turbine does not decrease, and the intake pipe pressure (supercharging pressure) pressurized by the compressor exceeds the upper limit of the allowable supercharging pressure, so the flow that passes through the exhaust turbine does not decrease. By opening and closing an exhaust bypass valve that bypasses a portion of the exhaust gas from upstream to downstream, the supercharging pressure is prevented from exceeding a preset pressure.

However, with such a system that prevents the boost pressure from exceeding the set pressure, the desired boost pressure cannot be obtained, especially during acceleration where output is required. By installing a solenoid valve that leaks a portion of the pipe pressure to the atmosphere and delaying the opening of the exhaust bypass valve, a boost pressure higher than the pressure set by the actuator operating pressure is obtained (for example, (Refer to ``Theory and Practice of Turbocharger'' published by Railway Japan Co., Ltd. in June 1981, JP-A-58-217723, JP-A-58-158337, JP-A-57-193720).

In this case, an on-off type solenoid valve that opens and closes at a predetermined frequency is used, and the target boost pressure set according to the operating condition is compared with the actual boost pressure detected by the intake pipe pressure sensor. However, by changing the duty representing the valve opening time ratio according to this deviation, feedback control is performed so that the actual boost pressure matches the target boost pressure.

For example, when the duty is 100%, the solenoid valve is fully open, and in this case, the exhaust bypass valve is kept fully closed via the actuator to quickly increase the turbine speed, and conversely, when the duty is 0%, the solenoid valve is fully open. is fully closed, and in this case the exhaust bypass valve opens to suppress the turbine rotation speed and prevent the boost pressure from exceeding the target value.

On the other hand, since most of the blowby gas discharged from the engine is unburned gas, there is a blowby gas reduction device that prevents the adverse effects of the blowby gas by guiding it to the combustion chamber again and reburning it.

This is because, as shown in Fig. 6, the PCV valve 5 opens in the engine low-medium load range when the negative pressure in the intake manifold 4A downstream of the throttle valve 3 increases to a certain extent, and the blow-by gas in the crank chamber 2 is released. Intake manifold 4A via first blow-by hose 6
The fresh air that flows in through the air cleaner 10 and air flow meter 11 is introduced into the rock cover chamber 7 through the second blow-by hose 9.
From there, it flows into the crank chamber 2 via a communication path, and the blow-by gas in the crank chamber 2 is exhausted.

On the other hand, in a high load range where the supercharging pressure generated by the compressor 8A increases and the intake manifold 4A becomes positive pressure, the PCV valve 5 closes, so the blow-by gas in the crank chamber 2 that has become positive pressure is released from the rocker cover. The air flows back into the chamber 7, the second blow-by hose 9, and is introduced into the intake duct 4B upstream of the compressor 8A.

In this way, the blow-by gas is returned to the intake system and is re-combusted and processed in the engine body 1.

(Problem to be Solved by the Invention) By the way, when the intake pipe pressure in the intake manifold 4A becomes positive pressure due to boost pressure feedback control, the PCV valve 5 closes as described above, so blow-by gas flows into the intake manifold 4A. Air intake duct 4 upstream of compressor 8A
As mentioned above, the intake pipe pressure downstream of the compressor 8A is introduced to the actuator via the pressure pipe, and a solenoid valve is installed in the pressure pipe branched from this pressure pipe. ,
Blow-by gas enters the inside of the solenoid valve via this pressure piping.

Blowby gas is extracted from the crank chamber where engine oil is scattered, so it contains atomized engine oil and moisture from the atmosphere, so if the temperature of the solenoid valve is below the freezing point,
These oils and moisture are cooled inside the solenoid valve.

As a result, the viscosity of the engine oil in the blow-by gas increases at the part where the valve body of the solenoid valve slides, increasing sliding resistance, and the condensed water further freezes, causing the valve body of the solenoid valve to The body's movements become slow and the valve may stick or freeze when it is open, making it impossible to return.

In such cases, the driving range such as when accelerating,
Even if the boost pressure steadily rises and exceeds the target boost pressure, the solenoid valve cannot be closed to lower the boost pressure to the target boost pressure, and the boost pressure remains below the target boost pressure. Even when the pressure is exceeded, the pressure still rises, which causes problems such as a tendency to cause knocking.

To avoid this situation, the compressor 8
A fail-safe mechanism is installed to protect the engine by stopping fuel injection when the boost pressure rises above the upper limit based on the signal from the intake pipe pressure sensor that detects the intake pipe pressure downstream of A. If there is a cut, the engine output will change significantly before and after the cut, which will cause a shock. This shock causes discomfort to the driver, and in vehicles driving on frozen roads, this shock causes the same situation as applying sudden braking, resulting in poor drivability such as the vehicle slipping. It is desirable to avoid such inconveniences before reaching fuel cut.

Therefore, with conventional equipment, feedback control is stopped uniformly after engine cooling reaches 70°C after the engine has started, and the solenoid valves are kept closed, thereby eliminating the inconvenience caused by sticking and freezing of the solenoid valves. I'm letting you do it.

However, after this start, the engine coolant temperature was 70°C.
Although the ℃ value has a considerable margin to cover the temperature range from extremely low temperatures, it is also an insufficient temperature setting.

In other words, as soon as the temperature reaches a temperature that does not interfere with the opening/closing operation of the solenoid valve, the solenoid valve is activated for feedback control, which improves drivability by responding to operating conditions that require high boost pressure. It is desirable for the purpose of

For example, in the summer, the solenoid valve operates well at room temperature without having to wait for the cooling water temperature to reach 70°C. Waiting for the temperature to reach 70°C will, on the contrary, narrow the operating range in which feedback control can be performed.

Further, even if the electromagnetic valve is heated by the combustion heat generated by the engine after starting, the engine cooling water temperature after starting is maintained at a predetermined value, so the heating effect of this combustion heat is limited. For this reason,
Even if the cooling water temperature reaches 70℃ after startup, there is no guarantee that the solenoid valve will be able to open and close without any problems at extremely low temperatures where there is a high possibility that the solenoid valve will freeze. When starting from such an extremely low temperature state, canceling the solenoid valve's feedback control stop and driving the solenoid valve immediately when the cooling water temperature reaches 70°C will cause the solenoid valve to malfunction. It is also possible that accurate boost pressure control becomes difficult.

Therefore, this invention handles the solenoid valve drive differently depending on the engine temperature at the time of starting, and when the engine temperature at the time of starting is a predetermined low temperature, the feedback control stop is immediately canceled and the solenoid valve is driven, thereby controlling the feedback control range. When the engine water temperature at startup is at a predetermined extremely low temperature, feedback control continues to be stopped and the solenoid valve is kept closed regardless of the engine temperature after startup, so that the solenoid valve is kept open. An object of the present invention is to provide a device that can further ensure the effect of preventing adhesion or freezing.

(Means for Solving the Problems) FIG. 1 is an overall configuration diagram for clearly showing the configuration of the present invention.

In the figure, 21 is an exhaust bypass valve that bypasses a part of the exhaust gas passing through the exhaust turbine of the turbocharger from upstream to downstream, 22 is a pressure-responsive actuator that drives the exhaust bypass valve, and 23 is pressurization introduced into the actuator. It is a solenoid valve that allows some air to leak into the atmosphere.

24 is supercharging pressure detection means for detecting supercharging pressure; 25
is a feedback control means that performs feedback control on the opening degree of the solenoid valve 23 so that the supercharging pressure detected by the supercharging pressure detecting means 24 reaches a target value.

In the boost pressure control device configured as described above, the present invention includes a temperature detection means 26 for detecting the engine temperature, and a temperature detecting means 26 for detecting the engine temperature. The feedback control is stopped and the solenoid valve is kept closed until the engine temperature exceeds the second predetermined value, and if the engine temperature is extremely low at the time of startup and is below the first predetermined value, the engine temperature increases thereafter. A control means 27 is provided for stopping the feedback control and keeping the solenoid valve closed regardless of the situation.

(Function) With this configuration, feedback control is immediately performed in the normal temperature range where the engine temperature at startup exceeds the second predetermined value, so that the feedback control range is expanded. In this normal temperature range, the solenoid valve 23 operates smoothly without waiting for the engine temperature to rise, so by immediately performing feedback control, high supercharging can be achieved in response to acceleration, etc. even in the operating range that has just started. pressure can be obtained,
It is possible to improve drivability.

When the engine temperature at startup is low, exceeding the first predetermined value and below the second predetermined value, the solenoid valve 23 is sufficiently heated by the combustion heat generated by the engine to a temperature that does not interfere with driving. This is a temperature range in which the temperature can be increased, and as soon as the temperature exceeds the second predetermined value, the feedback control stop is canceled.

In this case, the second predetermined value does not need to take into account the extremely low temperature below the first predetermined value, so the engine temperature at which this feedback control stop is canceled can be set lower than in the conventional example. , the feedback control range in this temperature range is expanded.

In this case as well, acceleration performance can be improved in the operating range immediately after starting.

Next, when the engine water temperature at the time of startup is extremely low, below the first predetermined value, it is a temperature range in which it is difficult to heat the solenoid valve 23 to a temperature that does not hinder operation due to combustion heat. The solenoid valve 23 continues to be kept closed regardless of the engine temperature after starting.

As a result, it is possible to reliably prevent the supercharging pressure from increasing beyond the pressure set by the operating pressure of the actuator 22, and to avoid problems such as knocking. Further, since fuel cut-off does not occur, it is possible to eliminate the discomfort caused to the driver due to a shock and poor drivability such as slipping on frozen roads.

(Embodiment) FIG. 2 is a schematic diagram showing the mechanical configuration of an embodiment of the present invention. First, the blow-by gas reduction device will be explained. This is the same as the conventional example.

That is, the intake manifold 4A downstream of the crank chamber of the engine body 1 and the intake throttle valve (the intake throttle valve is interposed in the throttle chamber 3A)
A rocker cover chamber 7 is connected to the crank chamber through a first blow-by hose 6 through a PVC valve 5, and is further connected to the crank chamber through a communication passage (not shown).
A second blow-by hose 9 communicates with the intake duct 4B upstream of the compressor 8A of the turbocharger 8.

The PVC valve 5 responds to the pressure difference before and after the valve and controls the amount of blow-by gas sucked in according to the load state of the engine.

Therefore, in the engine low and medium load range where the negative pressure in the intake manifold 4A downstream of the throttle valve increases to a certain extent, the PVC valve 5 opens, and the blow-by gas in the crank chamber flows through the first blow-by hose 6 to the intake manifold 4A. will be introduced in

Along with this, the fresh air that has flowed through the air cleaner 10 and air flow meter 11 is supplied to the rocker cover chamber 7 via the second blow-by hose 9.
The gas flows from here to the crank chamber via a communication path (not shown), and scavenges the blow-by gas in the crank chamber.

On the other hand, when the engine is in a high load range and the supercharging pressure by the turbocharger 8 increases and the intake manifold 4A downstream of the throttle valve becomes positive pressure, the PCV valve 5 closes, so blow-by gas no longer flows to the intake manifold 4A. On the other hand, the blow-by gas in the crank chamber that has become under positive pressure flows back through the rocker cover chamber 7 and the second blow-by hose 9, and is introduced into the intake duct 4B upstream of the compressor 8A.

In this way, the blow-by gas is returned to the intake system and is re-combusted and processed in the engine body 1.

In the figure, 12A is an exhaust manifold upstream of the exhaust turbine 8B of the turbocharger 8, 12B is an exhaust passage downstream of the exhaust turbine 8B, 13 is a catalytic converter, and 14 is a muffler.

Next, talking about the boost pressure control device, the third
The figure is a main mechanical configuration diagram of the part that performs supercharging pressure control in this embodiment, and FIG. 4 is an enlarged view of the inside of the solenoid valve.

31 is an exhaust bypass valve that bypasses a part of the exhaust gas passing through the exhaust turbine 8B from upstream to downstream via the bypass passage 30; 34 is a pressure-responsive diaphragm actuator that drives this exhaust bypass valve 31; The exhaust bypass valve 31 opens when the intake pipe pressure (supercharging pressure) acting on the diaphragm chamber 35 of the actuator 34 increases,
Exhaust turbine 8 increases the amount of exhaust gas bypass.
The rotation of the compressor B is lowered to lower the supercharging pressure generated by the compressor 8A.

Note that 37 is a pressure pipe that introduces the boost pressure downstream of the compressor 8A into the diaphragm chamber 35;
3 is an orifice installed in this pressure piping 37;
2 is an exhaust bypass valve 31 that controls the reciprocating movement of the rod 33.
This is a link mechanism that converts the rotational movement of the

These components are parts that mechanically control boost pressure, and operate even when electrical boost pressure control based on electromagnetic valve drive, which will be described later, is not performed. The pressure is controlled by the spring constant of.

Next, 40 is a solenoid valve that leaks a part of the boost pressure introduced into the actuator 34 to the atmosphere, and is branched from the pressure pipe 37 downstream of the orifice 38 to the pressure pipe 39A that communicates with the intake duct 4B upstream of the compressor 8A. Intervened.

The solenoid valve 40 is an on-off type solenoid valve that opens and closes at a predetermined frequency, and is controlled by duty (valve opening time ratio takes a value from 0 to 100%). For example, when the electromagnetic valve solenoid 45 is de-energized, the valve body 42 is moved toward the valve seat 43 by the return spring 46.
Since the pressure piping 39A is shut off, the supercharging pressure introduced into the diaphragm chamber 35 will not leak to the atmosphere.

However, when the current is applied, the valve body 42 is attracted by the core 44 and moves away from the valve seat 43, thereby causing a portion of the supercharging pressure introduced into the diaphragm chamber 35 to leak to the atmosphere. In this case, the supercharging pressure acting on the diaphragm chamber 35 decreases due to the throttling action of the orifice 38, so the exhaust bypass valve 31 rotates to the closing side, increasing the rotation of the exhaust turbine 8B and generating the compressor 8A. Increase the boost pressure.

Note that 39B is branched from pressure pipe 39A,
This is a pipe that guides pressure behind the valve body 42, thereby canceling out the supercharging pressure before and after the valve body 42, and improving the responsiveness of the electromagnetic valve operation.

In addition, in FIG. 4, 47 is a shim press-fitted into the core 44, 48 is a spacer, 49 is a bearing press-fitted into the spacer 48, and 50 is an air passage provided between the spacer 48 and the bearing 49. .

In addition, in FIG. 2, a control unit 60 that controls the duty of the solenoid valve 40 sets the boost pressure detected by an intake pipe pressure sensor 59 as a boost pressure detection means for the current operating state. Feedback control is performed to the target value set.

In this case, the operating state is basically determined from the signals of the crank angle sensor 55 that detects the engine speed and the throttle valve opening sensor 56 that detects the throttle valve opening as the engine load.

Next, the temperature detection means which is the main part of this invention is
In this example, it is composed of a water temperature sensor 58 that detects the engine cooling water temperature. In order to detect the temperature of the solenoid valve 40, a temperature sensor can be provided directly near the solenoid valve 40, but the temperature after the solenoid valve 40 is started can be approximately estimated by the cooling water temperature at the time of engine startup. Therefore, the existing water temperature sensor 58 is used rather than installing a new sensor and increasing costs.

Therefore, the temperature detection means is not limited to a water temperature sensor, but may be any device that detects the engine temperature.

The control unit 60 is composed of a microcomputer, and signals from the intake air temperature sensor 57 and the air flow meter 11 are also input to the control unit 60.

FIG. 5 is a flowchart illustrating the operations performed by control unit 60. The numbers in the figure indicate processing numbers.

At 61, various signals such as engine speed, throttle valve opening, intake pipe pressure, and cooling water temperature are read in, and at 62, a target boost pressure corresponding to the current operating status is searched for by table search or the like. I ask.

Let's start with the operating state in which the water temperature at startup is above a predetermined value (for example, 10℃).
Proceed to step 65. 65, the actual throttle valve opening θ is compared with a predetermined value (for example, 70°), and if θ > 70°, it is determined that the accelerator pedal is depressed greatly and the engine is accelerating, and output is required from the engine. 6～68
Performs feedback control of boost pressure.

That is, in 66, the intake pipe pressure P at that time is compared with the target boost pressure Po, and if P>Po, it exceeds the target value, so it is necessary to lower P to the target value Po, and in 68 If P≦Po, the target value has not been reached, so it is necessary to increase P.
At step 7, the duty is increased and outputted. In this case, when the duty decreases, the diaphragm chamber 3
The boost pressure acting on the exhaust bypass valve 5 increases, and the exhaust bypass valve 3
1 opens to lower the supercharging pressure, and when the duty increases, the exhaust bypass valve 31 closes and the supercharging pressure increases. Through this feedback control, the boost pressure P converges to the target value Po.

If θ≦70° at 65, it is determined that the accelerator pedal is not pressed strongly and the operating range does not require supercharging, so the duty of the solenoid valve 40 is changed to maintain the supercharging pressure. There is no need to perform this control, and in this case, the duty is set to 0% and the output is made at 69 to keep the solenoid valve 40 fully closed. This prevents the electromagnetic valve 40 from operating unnecessarily and improves the durability of the electromagnetic valve 40.

Next, to explain the main part of this invention, this is 6
It consists of parts 3, 64, 70, 71, and 72, and includes the cooling water temperature at startup (water temperature at startup), a first predetermined value (-10°C), and a second predetermined value (10°C). The temperature range was divided into three: extremely low temperature when the water temperature at startup is below -10℃, low temperature when it exceeds -10℃ and below 10℃, and normal temperature range above 10℃. The handling of the solenoid valve drive after startup is different.

In other words, if the water temperature at startup exceeds 10℃ in steps 63 and 64, the solenoid valve temperature is also at the same temperature, and malfunctions such as sticking or freezing are unlikely, so immediately proceed to step 65 and control the boost pressure. conduct.

For example, in summer, etc., the solenoid valve 40 is originally in a temperature range that is suitable for operation, so immediately after startup, the solenoid valve is driven to perform boost pressure feedback control to prepare for the operating range where high boost pressure is required. This leads to improved drivability.

However, in the conventional example, feedback control is uniformly stopped until the cooling water temperature after startup reaches a relatively high predetermined value (70 degrees Celsius) even in a temperature range where it is not necessary to consider sticking or freezing of the solenoid valve 40. Therefore, good acceleration performance cannot be obtained when accelerating immediately after starting.

On the other hand, in this example, when the water temperature at startup exceeds 10°C, normal feedback control immediately enters, so the feedback control range is expanded, and even if acceleration is performed immediately after startup, the A high boost pressure can be obtained depending on the engine speed, and good acceleration performance can be obtained even immediately after starting.

In addition, if the water temperature at startup is over -10℃ and below 10℃, it is determined that the solenoid valve temperature is heated to a temperature that does not interfere with operation due to engine combustion heat during startup, and in this case, the solenoid valve is The feedback control is stopped at step 72, the duty is set to 0%, and the solenoid valve 40 is kept closed until the valve temperature reaches a temperature that does not interfere with driving (cooling water temperature after startup is 10°C).
When the cooling water temperature reaches 10℃ after startup, it changes from 71 to 6.
Proceed to step 5 to control the boost pressure.

That is, even if the electromagnetic valve 40 is sticky or frozen during startup, the stoppage of the feedback control is canceled as soon as the electromagnetic valve 40 is subsequently heated and reaches a temperature at which it is determined that the sticking or freezing has melted.

In this case as well, the feedback control stop is released from a relatively low temperature (10°C), and the feedback control range is expanded, making it possible to improve acceleration in the operating range immediately after startup.

Next, if the water temperature at startup is -10℃ or lower at 63, it is determined that the engine combustion heat after startup will not heat the solenoid valve temperature to a temperature that does not interfere with driving, and at 70 The feedback control is stopped at , the duty is set to 0%, and the solenoid valve 40 is kept closed. Therefore, in this case, the fully closed state of the solenoid valve 40 continues even after the engine starts, regardless of the rise in the cooling water temperature after the engine starts.

In the conventional example, even at such extremely low temperatures, when the cooling water temperature after startup reaches 70°C, the feedback control stop is canceled, so the solenoid valve temperature may not have reached a temperature that does not affect the drive. This causes inconveniences such as knocking due to malfunction of the solenoid valve and shock when fuel is cut.

On the other hand, in this example, regardless of the rise in cooling water temperature after startup, the drive is completely stopped in the temperature range where the solenoid valve 40 is likely to malfunction, so it is possible to reliably prevent such inconveniences. It can be done.

However, even in this case, mechanical boost pressure control is performed in which the actuator 34 is driven based on the boost pressure downstream of the compressor, so even if the boost pressure increases during acceleration etc. Since the actuator 34 opens the exhaust bypass valve 31 due to the boost pressure, the boost pressure does not rise above the pressure set by the operating pressure of the actuator 34.

As a result, it is possible to reliably avoid inconveniences such as knocking, and it also does not lead to fuel cut-off, which eliminates driver discomfort caused by shock and poor drivability such as slipping on frozen roads. be able to.

Note that since the first predetermined value and the second predetermined value change depending on the type of engine, the optimum values may be set through experiments or the like.

(Effects of the Invention) The present invention provides an exhaust bypass valve that bypasses a portion of exhaust gas passing through an exhaust turbine of a turbocharger from upstream to downstream, a pressure-responsive actuator that is driven by the exhaust bypass valve, and a pressure-responsive actuator that is introduced into the actuator. A solenoid valve that leaks a portion of the pressurized air into the atmosphere, a boost pressure detection means that detects the boost pressure, and a feedback control that controls the opening degree of the solenoid valve so that the detected boost pressure reaches the target value. A turbocharger supercharging pressure control device comprising: a temperature detection means for detecting engine temperature; and a temperature detection means for detecting engine temperature; The feedback control is stopped and the solenoid valve is kept closed until the second predetermined value is exceeded, and when the engine temperature is extremely low at the time of starting, which is below the first predetermined value, regardless of the subsequent rise in engine temperature. Since the control means for stopping the feedback control and keeping the solenoid valve closed is provided, it is possible to expand the feedback control range, and it is possible to obtain good acceleration even in the operating range immediately after starting. .

In addition, when starting from an extremely low temperature range where it is difficult to heat the solenoid valve to a temperature that does not interfere with operation due to combustion heat, the solenoid valve will continue to be closed regardless of the rise in engine temperature after startup. As a result, it is possible to reliably prevent the boost pressure from rising above the pressure set by the actuator's operating pressure, thereby avoiding inconveniences such as knocking, and also to avoid fuel cut-off, which is caused by a shock. Discomfort for the driver and poor drivability such as slipping on frozen roads can be eliminated.

[Brief explanation of the drawing]

Fig. 1 is an overall configuration diagram clearly showing the configuration of this invention, Fig. 2 is a schematic diagram showing the mechanical configuration of an embodiment of this invention, and Fig. 3 is a part that performs supercharging pressure control of this embodiment. 4 is an enlarged view of the inside of the solenoid valve, and FIG. 5 is a flowchart explaining the operations performed by the control unit 60. FIG. 6 is a schematic diagram of a conventional blow-by gas reduction device. 1...Engine body, 3...Intake throttle valve, 4A...Intake manifold, 4B...Intake duct, 5...PCV
Valve, 6... First blow-by hose, 7... Locker cover chamber, 8... Turbo charger, 8 A... Compressor, 8 B... Exhaust turbine, 9... Second blow-by hose, 21... Exhaust bypass valve, 22... Pressure responsive actuator, 23... Electromagnetic Valve, 24...Supercharging pressure detection means, 25...Feedback control means, 2
6... Temperature detection means, 27... Control means, 30... Bypass passage, 31... Exhaust bypass valve, 34... Actuator, 35... Diaphragm chamber, 37... Pressure piping, 39A, 39B... Pressure piping, 40... Solenoid valve,
42... Valve body, 43... Valve seat, 44... Core, 45... Solenoid, 55... Crank angle sensor, 56... Throttle valve opening sensor, 58... Water temperature sensor, 59... Intake pipe pressure sensor, 60... Control unit.

Claims (1)

[Claims] 1. An exhaust bypass valve that bypasses a portion of the exhaust gas passing through the exhaust turbine of the turbocharger from upstream to downstream, a pressure-responsive actuator that drives the exhaust bypass valve, and a portion of the pressurized air that is introduced into the actuator. A turbocharger equipped with a solenoid valve that leaks to the atmosphere, a boost pressure detection means that detects boost pressure, and a feedback control means that feedback controls the opening degree of the solenoid valve so that the detected boost pressure becomes a target value. In the boost pressure control device, temperature detection means for detecting engine temperature;
When the engine temperature exceeds the first predetermined value at startup, the engine temperature exceeds the second predetermined value.
When the engine temperature is lower than the predetermined value, the engine temperature is
The feedback control is stopped and the electromagnetic valve is kept closed until the first predetermined value is exceeded, and when the engine temperature is extremely low at the time of starting, the feedback control is stopped regardless of the subsequent rise in engine temperature. A supercharging pressure control device for a turbocharger, comprising a control means for stopping the control and keeping the solenoid valve closed.