JPH05214945A - Control device for engine with supercharger - Google Patents

Abstract

PURPOSE:To prevent unreliable operations of both intake and exhaust selector valves by switching the operation to the supercharged operation by only a main turbo-charger when the pressure in an accumulating tank becomes lower than a preset value even if the supercharged operation conditions of both the main and auxiliary turbo-chargers are met. CONSTITUTION:In the low intake air quantity area, both an intake selector valve 18 and an exhaust selector valve 17 are closed, and the supercharged operation by only a main turbo-charger is performed. In the high intake air quantity area, actuators 11, 16 are driven by the pressure feed from an accumulating tank, both the intake selector valve 18 and exhaust selector valve 17 are closed, and the supercharged operation by both the main and auxiliary turbo-chargers is performed. The pressure in the accumulating tank is detected by a pressure detecting means 7. When the pressure in the accumulating tank becomes lower than a preset value, a switching judging means 72 commands to switch the operation to the supercharged operation by only the main turbo- charger even if the operating conditions of both the main and auxiliary turbo- chargers are met.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has a main turbocharger and a sub-turbocharger, supercharges only the main turbocharger in a low intake air amount range, and operates both turbochargers in a high intake air amount range. The present invention relates to a supercharged engine that supercharges with both turbochargers, a so-called two-stage twin turbo engine.

[0002]

2. Description of the Related Art An engine main body is provided with two main and sub turbochargers in parallel, and in the low intake air amount range, only the main turbocharger is operated to make one turbocharger. In the high intake air amount range, both turbochargers are operated. There is known a supercharged engine that employs a so-called two-stage turbo system that operates a charger.

The structure of this type of supercharged engine is shown in FIG. 10, for example. Engine body 39
1, a main turbocharger (T / C-1) 392 and a sub turbocharger (T / C-2) 393 are provided in parallel. The intake and exhaust systems connected to the sub turbocharger 393 are respectively provided with an intake switching valve 394 and an exhaust switching valve 395, and an intake bypass passage 397 that bypasses the compressor of the sub turbocharger 393,
An intake bypass valve 396 is provided. In the low intake air amount region, both the intake switching valve 394 and the exhaust switching valve 395 are fully closed to supercharge only the main turbocharger 392, and in the high intake air amount region, both switching valves 394, 3
By fully opening both 95 and closing the intake bypass valve 396, the auxiliary turbocharger 393 can also be supercharged and two turbochargers can be operated.

When shifting from the low intake air amount region to the high intake air amount region, the intake switching valve 394 and the exhaust switching valve 39.
5 is closed, the exhaust bypass valve 398 is controlled to a small opening, and the intake bypass valve 396 is closed to increase the running speed of the auxiliary turbocharger 393, so that the turbocharger can be switched more smoothly (at the time of switching). It is possible to perform small shocks.

In the supercharged engine, the intake switching valve, the exhaust switching valve, the intake bypass valve, and the exhaust bypass valve are each opened and closed by a diaphragm type actuator. The supercharged air stored in the pressure storage tank is supplied to the diaphragm chamber of each actuator via an electromagnetic valve. The supercharging pressure is accumulated in the accumulator tank when the supercharging pressure is sufficiently increased, and the supercharging pressure accumulated in the accumulator tank is transferred to the above-mentioned actuators via the solenoid valve when switching the turbocharger. guided by,
Each valve is opened and closed.

[0006] Japanese Patent Application No. 2-564 previously proposed by the applicant
In No. 94, the switching condition from one turbocharger to two turbochargers is performed based on the intake air amount, and the switching condition from two turbochargers to one turbocharger is performed based on the engine speed. In this case, when switching to the two turbochargers, each solenoid valve is turned on and the intake switching valve actuator and the exhaust switching valve actuator are supercharged from the accumulator tank at a predetermined rotation speed (for example, 3000 rpm) or more. Pressure is applied to hold two turbochargers.

[0007]

However, since there is a slight air leak in the solenoid valve for the actuator, if the light load operation with the low boost pressure continues for a long time, as shown in FIG. In addition, the pressure accumulated in the accumulator tank gradually decreases, and it becomes difficult to sufficiently control the movement of the actuator, and it becomes impossible to maintain the two-turbocharger state. In other words, each switching valve cannot maintain the normal switching position even though the opening / closing signal to the solenoid valve is normally output. Therefore, there is a problem that rattling occurs at the time of acceleration, or the intake switching valve and the exhaust switching valve that have been closed once due to the pressure drop suddenly open due to acceleration, causing a torque shock.

In view of the above problems, the present invention prevents uncertain operation of the intake switching valve and the exhaust switching valve due to the pressure drop in the pressure accumulator tank, and reduces the drivability during acceleration and the occurrence of torque shock. It is an object of the present invention to provide a control device for an engine with a supercharger, which can be prevented.

[0009]

According to the present invention, there is provided a control device for a supercharged engine according to the present invention, comprising a main turbocharger and a sub turbocharger, and an intake passage is provided downstream of a compressor of the sub turbocharger. By providing an intake switching valve that opens and closes, and an exhaust switching valve that opens and closes the exhaust passage downstream or upstream of the turbine of the auxiliary turbocharger, by closing both the intake switching valve and the exhaust switching valve in the low intake air amount range. Only the main turbocharger is supercharged, and in the high intake air amount range, the actuators are driven by the pressure supply from the accumulator tank to open both the intake switching valve and the exhaust switching valve, and both turbochargers are overloaded. In a control device for an engine with a supercharger configured to perform a supply operation, a pressure detection means for detecting a pressure in the accumulator tank When the pressure in the accumulator tank detected by the pressure detecting means is lower than a predetermined value, even if the supercharging operation condition by both the main turbocharger and the sub-turbocharger is satisfied, the supercharger by the main turbocharger alone is used. Switching determination means for instructing switching to the feeding operation.

[0010]

In the control device for an engine with a supercharger configured as described above, the pressure in the accumulator tank is detected by the pressure detecting means, and the pressure in the accumulator tank detected by the pressure detecting means is lower than a predetermined value. If it is low, the switching determination means switches to one turbocharger even in the two turbocharger state. In the single turbocharger state, the pressure for holding the intake switching valve and the exhaust switching valve in the closed position is unnecessary, so that the intake switching valve and the exhaust switching valve are prevented from operating uncertainly. Therefore, deterioration of drivability at the time of acceleration is prevented, and the occurrence of torque shock is eliminated.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of a control device for an engine with a supercharger according to the present invention will be described below with reference to the drawings.

First Embodiment FIGS. 1 to 7 show a first embodiment of the present invention.
Especially, the case where the present invention is applied to a 6-cylinder engine mounted on a vehicle is shown. In FIG. 2, 1 is an engine, 2 is a surge tank, and 3 is an exhaust manifold. The exhaust manifold 3 includes # 1 to # 3 cylinder groups and # 4 to
It is assembled into two of the # 6 cylinder groups, and the assembly portion is the communication passage 3a.
Is communicated by. Reference numerals 7 and 8 denote a main turbocharger and a sub turbocharger arranged in parallel with each other.
Turbine 7a, 8 of turbocharger 7, 8 respectively
The a is connected to the collecting portion of the exhaust manifold 3, and the compressors 7b and 8b are connected to the surge tank 2 via the intercooler 6 and the throttle valve 4.

The main turbocharger 7 is operated from the low intake air amount region to the high intake air amount region, and the sub turbocharger 8 is stopped in the low intake air amount region. In order to enable both the turbochargers 7 and 8 to operate and stop, the exhaust switching valve 1 is provided downstream of the turbine 8a of the auxiliary turbocharger 8.
7, an intake switching valve 18 is provided downstream of the compressor 8b. When both the intake and exhaust switching valves 18 and 17 are open, both turbochargers 7 and 8 are operated. The downstream side of the turbine 8a of the sub turbocharger 8 and the downstream side of the turbine 7a 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 41
Are opened and closed by a diaphragm type actuator 42.

In the intake passage of the auxiliary turbocharger 8 that is stopped in the low intake air amount range, one turbocharger to two
In order to facilitate the switching to the individual turbocharger, an intake bypass passage 13 that connects the upstream side of the compressor 7b and 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 a diaphragm type actuator 1.
It is opened and closed by 0. A check valve 12 is provided in a bypass passage that connects upstream and downstream of the intake switching valve 18, and when the intake switching valve 18 is closed, the compressor outlet pressure on the side of the auxiliary turbocharger 8 is the main turbocharger 7.
When larger than the side, air is allowed 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. The front pipe 20 forming the exhaust passage is connected to the exhaust muffler via the exhaust gas catalyst 21. The intake switching valve 18 is opened and closed by the actuator 11, and the exhaust switching valve 17 is opened and closed by the diaphragm actuator 16. The waste gate valve 31 is adapted to be opened and closed by the actuator 9.

A pressure accumulating tank (positive pressure tank) 51 is connected to an intake passage between the compressor downstream of both turbochargers 7 and 8 and the intercooler 6. Accumulation tank 5
1 is provided with a check valve 51a for storing only positive pressure. The volume of the accumulator tank 51 is, for example, 30
It is 0 cc.

Actuators 9, 10, 11, 16, 4
2 is activated by the introduction of supercharging pressure. The actuators 9, 10, 11, 16 and 42 are provided with first, third and fourth actuators for selectively switching the boost pressure from the accumulator tank 51 and the atmospheric pressure from the downstream of the air flow meter 24, for example. , Fifth and sixth solenoid valves 25,
26, 27, 28, 32, 44 are connected. Switching of each solenoid valve 25, 27, 28, 32, 44 is performed according to a command from the engine control computer 29. The first solenoid valve 25, the third solenoid valve 27,
The air filter 2 is attached to the atmospheric side port of the fourth solenoid valve 28.
6 are attached respectively.

When the first solenoid valve 25 is turned ON, the intake switching valve 1
Actuating the actuator 11 so that 8 is fully opened,
When OFF, the actuator 11 is operated so that the intake switching valve 18 is fully closed. When the fourth solenoid valve 28 is turned on, the actuator 16 is operated so as to fully open the exhaust gas switching valve 17, and when it is turned off, the actuator 16 is operated so as to fully close the exhaust gas switching valve 17. O of the second solenoid valve 27
N operates the actuator 10 so as to fully close the intake bypass valve 33, and OFF operates the actuator 10 so as to fully open the intake bypass valve 33.

The fifth solenoid valve 32, which introduces atmospheric pressure into the actuator 42 that operates the exhaust bypass valve 41, is
Duty control is performed instead of N and OFF control. Similarly, the sixth solenoid valve 44, which guides the negative pressure to the actuator 9 that operates the wastegate valve 31, is turned on and off.
The duty is controlled instead of the control. As is well known, the duty control is to control the energization time by the duty value, and the average current is variably controlled in an analog manner by digitally changing the ratio of energization and non-energization. The duty value is the ratio of the energization time to the time of one cycle, and the energization time in one cycle is A,
When the non-energization time is B, it is represented by the following: Duty value = A / (A + B) × 100 (%).

The opening degree of the exhaust bypass valve 41 is changed by changing the bleed amount (leak amount) of the supercharged air introduced into the diaphragm chamber of the actuator 42 to the atmosphere by the duty control of the fifth solenoid valve 32. It is possible. The opening degree of the waste gate valve 31 can be changed by changing the bleed amount (leak amount) of supercharged air introduced into the diaphragm chamber of the actuator 9 to the atmosphere by duty control of the sixth solenoid valve 44. ing.

The compressor 7b of the main turbocharger 7
Of the intake passage 14a located downstream of the compressor 8b of the auxiliary turbocharger 8
An air bypass passage 61 that guides the supercharged air downstream of the compressors 7b and 8b to the upstream side of the compressors 7b and 8b is connected near the confluence portion 14c where the b and the b merge. The air bypass passage 61 has the compressors 7b, 8b when the valve is opened.
An air bypass valve 62 is provided to allow the supercharged air on the downstream side to flow to the upstream side of the compressors 7b and 8b.

The diaphragm chamber of the air bypass valve 62 communicates with the downstream side of the throttle valve 4 via a sensing passage 63. In the light load region of the engine, the intake pipe negative pressure is introduced into the diaphragm chamber of the air bypass valve 62 via the sensing passage 63, and the air bypass valve 62 is opened. In the high load region of the engine, the supercharging pressure is introduced into the diaphragm chamber of the air bypass valve 62 via the sensing passage 63, and the air bypass valve 62 is closed.

Engine control computer 29
Is electrically connected to various operating condition detection sensors of the engine and receives signals from the various sensors. The engine operating condition detection sensor includes an intake pipe pressure sensor 30, a throttle opening sensor 5, an air flow meter 24 as an intake air amount measuring sensor, an engine speed sensor 50, and an oxygen sensor 19. The engine control computer 29 includes a central processor unit (CPU) for calculation, a read only memory (ROM) which is a read-only memory, a random access memory (RAM) for temporary storage, and an input / output interface (I).
/ O interface) and an A / D converter for converting analog signals from various sensors into digital quantities.

As shown in FIG. 1, the engine control computer 29 is provided with a pressure detecting means 71 and a switching judging means 72. The pressure detection means 71 and the switching determination means 72 are the engine control computer 2
9 is stored in the program. The pressure detection means 71 has a function of detecting the pressure inside the pressure accumulation tank 51. As a method of detecting the pressure in the accumulator tank 51, there are a method of directly detecting with a pressure switch or the like and a method of indirectly detecting from the load condition of the engine or the like, but in the present embodiment, it is indirectly detected. Has been adopted. This will be described later. The signal from the pressure detection means 71 is input to the switching determination means 72.

When the pressure in the pressure accumulating tank 51 detected by the pressure detecting means 71 becomes lower than a predetermined value, the switching determining means 72 determines whether the supercharging operation conditions of both the main turbocharger 7 and the sub turbocharger 8 are high. Even if it is established, it has a function of switching to the supercharging operation by only the main turbocharger 7. In this way, when the pressure in the accumulator tank 51 decreases, the exhaust gas switching valve 17 and the intake gas switching valve 18 are opened by the pressure detection means 71, and the two turbochargers are forcibly switched to the one turbocharger. It is like this.

Next, the operation of the first embodiment will be described. In the high intake air amount region, both the intake switching valve 18 and the exhaust switching valve 17 are opened and the intake bypass valve 10 is closed. As a result, the two turbochargers 7 and 8 are driven, a sufficient amount of supercharged air is obtained, and the output is improved. Both the intake switching valve 18 and the exhaust switching valve 17 are closed and the intake bypass valve 33 is opened in the low speed range and at the time of high load. This drives only the main turbocharger 7. The reason why one turbocharger is used in the low intake air amount region is that the one turbocharger supercharging characteristic is superior to the two turbocharger supercharging characteristic in the low intake air amount region. By using one turbocharger, the boost pressure and torque rise faster, and the response becomes faster.

When shifting from the low intake air amount region to the high intake air amount region, that is, when switching from one turbocharger operation to two turbocharger operation, the intake switching valve 18
When the exhaust switching valve 17 is closed, the exhaust bypass valve 41 is controlled to be small open by duty control, and the intake bypass valve 33 is closed to increase the running speed of the auxiliary turbocharger 8 to switch the turbocharger. It becomes possible to carry out more smoothly (small shock when switching).

Immediately after deceleration, the pressure on the upstream side of the throttle valve rises sharply due to the closing of the throttle valve 4. However, in this state, the downstream side of the throttle valve 4 becomes a negative pressure, so that the diaphragm chamber 62b of the air bypass valve 62 has a negative pressure. The pressure is introduced and the air bypass valve 62 is opened. As a result, the supercharged air compressed by the compressors 7b, 8b of the turbochargers 7, 8 is returned to the upstream of the compressors 7b, 8b via the air bypass passage 61. Therefore, the occurrence of surging in which the supercharged air flows back to the compressor side due to pressure reflection is prevented.

3 to 7 show a processing procedure of supercharging pressure control in the engine control computer 29. At step 101, the supercharging pressure control routine is started, and the routine proceeds to step 102, where it is judged if the engine speed NE is higher than 3000 rpm. In step 102, the engine speed NE is 3000
When it is determined that the rotation speed is higher than rpm, the routine proceeds to step 103, where it is determined whether or not a flag for turning on the fourth solenoid valve (VSV4) 28 for driving the exhaust gas switching valve 17 is set. To be judged. Here, when it is determined that the fourth electromagnetic valve 28 is ON based on the flag, the process proceeds to step 143 of FIG. 7 and returns.

If it is determined in step 102 that the engine speed NE is lower than 3000 rpm, the process proceeds to step 104. If it is determined in step 103 that the flag for turning on the fourth electromagnetic valve 28 is not set, the process similarly proceeds to step 104.
In step 104, the intake air amount Ga is 130 g / se.
It is determined whether or not there are more than c. If it is determined that the intake air amount Ga is more than 130 g / sec, the routine proceeds to step 105, where the engine speed NE is 35.
It is determined whether the rotation speed is higher than 00 rpm.

When it is determined in step 105 that the engine speed NE is higher than 3500 rpm, the routine proceeds to step 106 in FIG. 7 and the fourth solenoid valve 2
8 is turned on. As a result, the exhaust gas switching valve 17 is opened. Next, in step 107, the first solenoid valve (VSV1) 25 is turned on, and the intake switching valve 18 is opened. When the process of step 107 is completed, the process proceeds to step 108, a flag indicating that the fourth electromagnetic valve 28 is ON is set, and the process proceeds to step 109.

At step 109, the count value of the cumulative temperature rise time T ₁ based on the operation of the fifth solenoid valve 32 is reset, and at step 110, the duty ratio of the fifth solenoid valve 32 is reset. When the processing of step 110 is completed, the routine proceeds to step 313, where the count value of the minimum running revolution time T ₂ based on the fifth solenoid valve 32 is reset, and then proceeds to step 143 and returns.

In step 104, the intake air amount Ga
Is determined to be less than 130 g / sec,
Go to step 111. Similarly, when it is determined in step 105 that the engine speed NE is lower than 3500 rpm, the process proceeds to step 111. Step 1
In 11, the fourth solenoid valve 28 that drives the exhaust switching valve 17
It is determined whether or not the flag for turning OFF is set. That is, in step 111, the flag is determined in the initial state where the two turbochargers are switched to the one turbocharger. When it is determined in step 111 that the flag for turning off the fourth solenoid valve 28 is not set, the process proceeds to step 112.

In step 112, the boost pressure PM is 125
It is determined whether it is higher than 0 mmHgabs. If it is determined that the supercharging pressure PM is higher than 1250 mmHgabs, the process proceeds to step 113,
In order to reduce the target supercharging pressure, the duty ratio of the fifth solenoid valve 32 that drives the exhaust bypass valve 41 is made small, and the bleed amount of supercharging air supplied to the actuator 42 is reduced. Next, proceeding to step 114 of FIG.
It is determined whether the duty ratio of the solenoid valve 32 is less than zero.

In step 114, the fifth solenoid valve 3
When it is determined that the duty ratio of 2 is smaller than zero, the routine proceeds to step 115, where the duty ratio is reset to zero. That is, since the duty ratio is not 0% or less, if the duty ratio becomes 0% or less by subtracting the duty ratio in step 113, step 11
In step 4 and step 115, the duty ratio is corrected. When it is determined in step 114 that the duty ratio of the fifth solenoid valve 32 is greater than zero, the process goes beyond step 115 and proceeds to step 116 of FIG.

In step 116, the intake bypass valve 18
The third solenoid valve (VSV3) 27 for driving the engine is turned on, whereby the intake bypass valve 18 is closed. When the process of step 116 is completed, the process proceeds to step 117, and counting of the time during which the fifth electromagnetic valve 32 that drives the exhaust bypass valve 41 is feedback-controlled is started. That is, here, the time taken for the auxiliary turbocharger 8 to perform the approach rotation by opening the exhaust bypass valve 41 is measured by the counter in the computer 29. By measuring this time, the heating degree of the compressor 8b of the sub turbocharger 8 can be measured. This run-up time is accumulated after the engine is started until the engine is stopped.

In step 132 of FIG. 5, when the fifth solenoid valve 32 for driving the exhaust bypass valve 41 is closed, that is, counting of the time during which the fifth solenoid valve 32 is not feedback-controlled is started. This time computer 2
By measuring with the counter in 9, the degree of cooling of the compressor 8b of the sub turbocharger 8 can be measured. This cooling time is accumulated after the initial heating of the auxiliary turbocharger 8 until the engine is stopped. In the engine control computer 29, the cumulative time of the cooling time is subtracted from the cumulative time of the run-up time of the sub turbocharger 7. As a result, the cumulative temperature rise time effective for raising the temperature of the compressor 8b of the sub turbocharger 8 is calculated.

When the cumulative temperature rise time is calculated in step 117 of FIG. 5, the routine proceeds to step 118, where the calculated cumulative temperature rise time is compared with the preset time. Here, if it is determined that the cumulative temperature increase time has reached the set time, the process proceeds to step 119. In step 119, the cumulative temperature rise time is replaced with the set time, and the process proceeds to step 120. In step 120, the intake air amount Ga is 100 g /
It is determined whether it is greater than sec.

In FIG. 5, when it is determined in step 120 that the intake air amount Ga is more than 100 g / sec, the process proceeds to step 311, and based on the operation of the fifth solenoid valve 32 that drives the exhaust bypass valve 41. The minimum running speed T ₂ is counted. That is, the minimum time for the approach rotation is counted every time the approach rotation is performed. Step 3
When the minimum run-up rotation time is counted in 11 based on the operation of the fifth solenoid valve 32, the routine proceeds to step 312, where the minimum run-up rotation time T ₂ is compared with the set value. By this comparison, it is possible to determine whether or not the auxiliary turbocharger 8 is sufficiently performing the approach rotation. Here, when it is determined that the minimum running speed T ₂ is equal to or exceeds the set value, that is, when it is determined that the running speed is sufficiently performed, Proceeding to step 106, switching from one turbocharger to two turbochargers is started as described above. Step 118
If it is determined that the cumulative temperature increase time has not reached the set time, the process proceeds to step 143 and returns.

If it is determined in step 112 of FIG. 3 that the boost pressure is lower than 1250 mmHgabs, the routine proceeds to step 121, where the throttle opening TA is 60.
It is determined whether or not it exceeds deg. Here, when it is determined that the throttle opening TA exceeds 60 deg, the routine proceeds to step 122, where the supercharging pressure PM is 1100.
It is determined whether it is higher than mmHgabs. The reason why the supercharging pressure PM is determined in step 122 is that it is delayed that the supercharging pressure rises due to the turbo lag, and when it is determined that the supercharging pressure PM is equal to or higher than a predetermined value, as shown in FIG.
To step 123.

In step 123, the exhaust bypass valve 41
It is determined whether or not the duty control of the fifth solenoid valve 32 for driving the is performed for the first time. Here, when the duty control of the exhaust bypass valve 41 is performed for the first time, the routine proceeds to step 124, where the skip control is performed. The skip control is necessary because there is a difference between the driving force at the start of opening the exhaust bypass valve 41 and the driving force at the end of opening the valve. That is, there is hysteresis in the driving force of the exhaust bypass valve 41, and in order to cope with this, skip control is performed in which the duty ratio is corrected by the integral constant value.

When the processing of step 124 is completed, the routine proceeds to step 125, where a flag indicating that the initial step of duty control of the fifth solenoid valve 32 is completed is set, and the routine proceeds to step 126. When it is determined in step 123 that the duty control of the fifth solenoid valve 32 is not performed for the first time, the routine proceeds to step 128, where the duty ratio of 2% is added, and then the routine proceeds to step 126.

At step 126, it is judged if the duty ratio of the fifth solenoid valve 32 has reached 100%. If it is determined that the duty ratio of the fifth solenoid valve 32 has reached 100%, step 1
27, the duty ratio of the fifth solenoid valve 32 is set to 100.
%, And proceeds to step 116 in FIG. Step 116
Then, as described above, the third solenoid valve 27 that drives the intake bypass valve 33 is turned on, and the routine proceeds to step 117 to open the valve by the feedback control of the fifth solenoid valve 32 that drives the exhaust bypass valve 41. Is counted.

In step 121 of FIG. 3, the throttle opening T
If it is determined that A is smaller than 60 deg, then FIG.
To step 130. When it is determined in step 122 of FIG. 3 that the supercharging pressure PM is lower than 1100 mmHgabs, the process similarly proceeds to step 130. Step 13
At 0, the duty ratio of the fifth solenoid valve 32 is 0%.
Is reset to. When this process ends, step 1
In step 31, a flag indicating that the duty ratio of the fifth solenoid valve 32 has been set to 0% is set. That is, in this state, all the positive pressure supplied to the actuator 42 that drives the exhaust bypass valve 41 is bleeded, and the exhaust bypass valve 41 is closed.

When the processing of step 131 is completed, the routine proceeds to step 132, where the fifth exhaust bypass valve 41 is driven.
The counting of the closing time of the solenoid valve 32 is started. Here, the time during which the auxiliary turbocharger 8 is cooled by heat dissipation when the exhaust bypass valve 41 is closed is determined by the computer 2
It is measured by the counter in 9. Here, the cooling time is subtracted from the cumulative temperature increase time described above. When the fifth solenoid valve 32 is counted in step 132 of FIG. 5, the process proceeds to step 314, and the fifth electromagnetic valve 32 is counted in the same manner as described above.
The count value of the minimum run-up rotation time T ₂ based on the solenoid valve 32 is reset. When this process is completed, the routine proceeds to step 133, where the calculated cumulative temperature rise times are compared, and it is determined whether the cumulative temperature rise times are less than zero. If the calculated cumulative temperature rise time is smaller than zero, the routine proceeds to step 134, where the cumulative temperature rise time is replaced with zero.

When the accumulated temperature rise time is replaced with zero in step 134, the routine proceeds to step 135, where a flag indicating that the fourth electromagnetic valve 28 for driving the exhaust gas switching valve 17 is turned on is set. Is judged. That is, it is determined whether the exhaust switching valve 17 is fully open. Here, when it is determined that the exhaust gas switching valve 17 is fully opened, the routine proceeds to step 136 in FIG. 7, where the first electromagnetic valve 25 that drives the intake gas switching valve 18 is turned off, and the intake gas switching valve 18 is closed. Be spoken.

In step 137, one second after the first electromagnetic valve 25 is turned off, the fourth electromagnetic valve 28 for driving the exhaust switching valve 17 is turned off and the exhaust switching valve 17 is closed. When the processing of step 137 is completed, the routine proceeds to step 138, where the third electromagnetic valve 27 that drives the intake bypass valve 18 is turned off. As a result, the intake bypass valve 18 is opened, and the switching from the two turbochargers to the one turbocharger is performed.

At step 138, the third solenoid valve 27 is turned off.
If it is F, the routine proceeds to step 139, where the fourth solenoid valve 2
A flag indicating that 8 is turned off is set, and step 1
Proceed to step 43 and return.

If it is determined in step 135 of FIG. 5 that the flag for turning on the fourth solenoid valve 28 is not set, that is, if it is determined that the turbocharger has two turbochargers, the step of FIG. 7 is performed. Proceeding to 140, it is determined whether or not the supercharging pressure PM is lower than 200 mmHgabs. If it is determined that the supercharging pressure PM is lower than 200 mmHgabs, the routine proceeds to step 141, where the first solenoid valve 25 is turned on and the intake switching valve 18 is opened. When this process ends, the process proceeds to step 143 of FIG. 7 and returns. When it is determined in step 140 that the supercharging pressure PM is higher than 200 mmHgabs, the routine proceeds to step 142, where the first solenoid valve 25 is turned off.
FF is set, and the intake switching valve 18 is closed. When the intake switching valve 18 is closed, the routine proceeds to step 143 and returns.

Steps 150 to 15 in FIG.
Reference numeral 5 shows a control processing procedure in the pressure detection means 71 and the switching determination means 72. If it is determined in step 103 of FIG. 1 that the flag for turning on the fourth solenoid valve 28 is set, the process proceeds to step 150 of FIG. At step 150, the atmospheric pressure PA (absolute pressure) is subtracted from the intake pipe pressure, that is, the supercharging pressure PM (absolute pressure),
The pressure difference (relative pressure) Pmt between the two is calculated. Step 1
When the differential pressure PMt is calculated at 50, step 1
In step 51, the differential pressure PMt is compared with the preset determination pressure. In this embodiment, the determination pressure of the differential pressure PMt is 2
It is set to 00 mmHg.

In step 151, the differential pressure PMt becomes 2
If it is determined that the pressure exceeds 00 mmHg, the process proceeds to step 152. In step 152, the counter CLOW indicating that the supercharging pressure is low is set to zero, and then the routine proceeds to step 143 and returns. Step 151
When it is determined that the differential pressure PMt has not reached 200 mmHg in step S1, the process proceeds to step 153. In step 153, the time during which the boost pressure is low is measured. That is, in step 153, for example, the time during which light load operation is performed is measured.

Next, the routine proceeds to step 154, where it is judged if the light load operation is continued for a predetermined time or longer. When it is determined in step 154 that the duration of the light load operation is shorter than the predetermined time, the process proceeds to step 143 and returns. When it is determined in step 154 that the duration of the light load operation is longer than the predetermined time, it is estimated that the pressure in the accumulator tank 51 is lower than the predetermined value due to a slight air leak from the solenoid valve. , Go to step 155.

At step 155, a guard process is performed by the pressure drop in the accumulator tank 51. That is, here, processing is performed to the effect that switching from the two turbocharger to the one turbocharger should be performed even if the supercharging operation condition of the two turbocharger is satisfied. As a result, the routine proceeds from step 155 to step 136, where the first solenoid valve 25 for the intake switching valve is turned off, and further proceeds to step 137, the fourth solenoid valve 28 for the exhaust switching valve is turned off.

When the solenoid valves 25 and 28 are turned off,
Each of the actuators 11 and 16 is driven by the urging force of a spring housed in the spring chamber, and the exhaust switching valve 17 and the intake switching valve 18 are closed. As a result, switching from 2 turbochargers to 1 turbocharger
The operation is performed without supplying the pressure in the accumulator tank 51 to the actuators 11 and 12, and it is not necessary to hold the intake switching valve 18 and the exhaust switching valve 17 in the closed position by the positive pressure from the accumulator tank 51. Therefore, the deterioration of drivability during acceleration is prevented, and the occurrence of torque shock is eliminated. Thus, step 1
50 to 155 are pressure detection means 71 and switching determination means 72
Make up.

Second Embodiment FIGS. 8 and 9 show a second embodiment of the present invention.
In the first embodiment, the method of indirectly detecting the pressure in the accumulator tank 51 is adopted, but in the present embodiment, the pressure detecting means 71 is used.
Is composed of a pressure switch (not shown). The pressure switch has the accumulator tank 51 attached to the side surface,
When the pressure in the accumulator tank 51 is a pressure value sufficient to drive each actuator, an ON signal is output to the switching determination means 72, as shown in FIG.

FIG. 9 shows a control processing procedure when a pressure switch is used. In step 103 of FIG. 1, if the flag indicating that the fourth solenoid valve 28 is ON is set, that is, if it is the two turbocharger, the process proceeds to step 160 of FIG. 9 and the pressure switch is turned ON.
Is determined. If it is determined that the pressure switch is N, it is not necessary to switch to one turbocharger, so the process proceeds to step 143.
Will be returned.

If it is determined in step 160 that the pressure switch is off, the process proceeds to step 136 of FIG. 7 as in the first embodiment, the intake switching valve 18 is closed, and step 137 is performed. Then, the exhaust switching valve 17 is closed. As a result, switching from the two turbocharger to the one turbocharger is performed.

In the first embodiment, the pressure in the accumulator tank 51 is estimated based on the light load operation time. However, the pressure in the accumulator tank is calculated from the boost pressure, compressor pressure, intake air amount, etc. It is also possible to ask. The process S of FIG. 5 determines whether the temperature of the sub-turbocharger 8 has risen, and if the temperature of the sub-turbocharger exceeds a predetermined value, preferentially switches to the two turbochargers. This is a process for cooling the compressor 8b of the sub turbocharger 8 by the outside air that is generated, and the present invention can be realized even if this process is not performed.

[0059]

According to the present invention, when the pressure in the pressure accumulating tank detected by the pressure detecting means is lower than a predetermined value, the supercharging operation condition by both the main turbocharger and the sub turbocharger is satisfied. However, since the switching determination means issues the command to switch to the supercharging movable state only by the main turbocharger, it is possible to prevent the uncertain operation of the intake switching valve and the exhaust switching valve. Therefore, deterioration of drivability at the time of acceleration can be prevented and the occurrence of torque shock can be prevented.

[Brief description of drawings]

FIG. 1 is a block diagram of a control device for an engine with a supercharger according to a first embodiment of the present invention.

FIG. 2 is a control system diagram of a supercharged engine equipped with the device of FIG.

3 is a flowchart showing a part of a control processing procedure in the apparatus of FIG.

FIG. 4 is a flowchart following FIG.

FIG. 5 is a flowchart following FIG.

FIG. 6 is a flowchart following FIG.

FIG. 7 is a flowchart following FIG.

FIG. 8 is an operational characteristic diagram of a pressure switch used in the control device for the engine with the supercharger according to the second embodiment of the present invention.

9 is a flowchart showing a part of a processing procedure of control when the pressure switch of FIG. 8 is used.

FIG. 10 is a schematic configuration diagram of a conventional engine with a supercharger.

FIG. 11 is a characteristic diagram of the engine with the supercharger of FIG. 10.

[Explanation of symbols]

 1 Engine 7 Main Turbocharger 8 Sub Turbocharger 17 Exhaust Switching Valve 18 Intake Switching Valve 25 First Solenoid Valve 26 Fourth Solenoid Valve 29 Engine Control Computer 51 Accumulation Tank 71 Pressure Detecting Means 72 Switching Judging Means

Claims (1)

[Claims] 1. A main turbocharger and a sub turbocharger are provided, an intake switching valve for opening and closing an intake passage is provided downstream of the compressor of the sub turbocharger, and an exhaust passage is opened and closed downstream or upstream of the turbine of the sub turbocharger. Exhaust switching valve is installed to operate only the main turbocharger by closing both the intake switching valve and the exhaust switching valve in the low intake air amount range, and pressure supply from the accumulator tank in the high intake air amount range. In the control device of the engine with a supercharger, which drives both actuators to open both the intake switching valve and the exhaust switching valve to supercharge both turbochargers, the pressure in the accumulator tank The pressure in the accumulator tank detected by the pressure detecting means and the pressure detecting means for detecting And a switching determination unit for instructing to switch to the supercharging operation by only the main turbocharger even when the supercharging operation conditions by both the main turbocharger and the sub turbocharger are satisfied. Control device for engine with supercharger.