JP2783035B2 - Control device for deceleration air bypass valve of supercharged engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a deceleration air bypass valve control device for preventing the occurrence of surging during deceleration in a supercharged engine.

[0002]

2. Description of the Related Art In an engine equipped with a supercharger (turbocharger), when the throttle valve is rapidly switched from an open state to a closed state due to deceleration, the throttle inertia of the throttle valve is increased by the intake inertia and the rotational inertia of the compressor. The upstream pressure rises sharply. This rapid pressure increase causes surging in which the supercharged air flows back to the compressor side due to pressure reflection, and causes a problem that pulsation noise is generated.

As an example of a technique for reducing the pulsation noise,
The devices disclosed in Japanese Utility Model Laid-Open No. 64-58723 and Japanese Utility Model Laid-Open No. 63-983 are known. In these devices, a diaphragm-type air bypass valve is provided in an air bypass passage that connects the upstream side and the downstream side of the compressor of the turbocharger. During rapid deceleration, the air bypass valve is opened by the pressure guided to the diaphragm chamber. As a result, part of the supercharged air whose pressure has increased is bypassed to the upstream side of the compressor.

However, the apparatus disclosed in the above publication has the following problems to be solved. According to Japanese Patent Laid-Open Publication No. 64-58723, the turbocharger is rotating sufficiently under partial conditions where the engine speed is high, so that the air bypass valve is opened by the negative pressure and the positive pressure, and There is a problem that the supply air repeats recirculation and the intake air temperature rises abnormally. The rise in the intake air temperature causes a problem that the durability reliability of the compressor and the durability reliability of the rubber hose related to the intake duct are reduced. (B) In the device disclosed in Japanese Utility Model Publication No. 63-983, the opening timing of the air bypass valve is controlled only by the negative pressure (differential pressure) guided to the diaphragm chamber. The occurrence of surging immediately after deceleration cannot be sufficiently reduced.

Therefore, a deceleration air bypass valve control device for a supercharged engine capable of preventing a rise in intake air temperature due to recirculation of supercharged air and capable of sufficiently reducing the occurrence of surging has been proposed. Has been proposed by the present applicant (Japanese Patent Application No. Hei 3-171863). In this deceleration air bypass valve control device, a supercharging pressure acts on the outer surface side of a diaphragm to which a valve body of the air bypass valve is attached. At the time of supercharging, the supercharging pressure guided into the diaphragm chamber causes the air bypass valve to operate. Is designed to close.

[0006]

However, in the case where the air bypass valve is closed by introducing a supercharging pressure into the diaphragm chamber, as shown in FIG. 7, the supercharged air guided to the diaphragm chamber. The opening of the air bypass valve is delayed by the time that the air bypasses through the pressure transmission passage during deceleration. Therefore, at the time of sudden deceleration, the occurrence of surging cannot be sufficiently reduced. Further, in an engine using a thermal air flow meter or a Karman vortex air flow meter, there is a problem that an erroneous determination of an intake air amount due to surging occurs and an air-fuel ratio becomes rich.

SUMMARY OF THE INVENTION The present invention is directed to a deceleration air bypass valve control device which focuses on the above problem and can quickly open an air bypass valve during sudden deceleration to prevent occurrence of surging due to valve opening delay. The purpose is to provide.

[0008]

A deceleration air bypass valve control device for a turbocharged engine according to the present invention that meets this object is capable of communicating an upstream side and a downstream side of a compressor of a turbocharger through an air bypass passage. The air bypass passage is provided with a diaphragm-type air bypass valve that guides the supercharged air downstream of the compressor to the upstream of the compressor in the air bypass passage, and the air bypass valve is closed by the supercharging pressure guided into the diaphragm chamber. In the deceleration air bypass valve control device of the turbocharged engine,
The air bypass valve is connected to a positive pressure relief valve that releases supercharged air in the diaphragm chamber to the atmosphere during rapid deceleration.

[0009]

In the deceleration air bypass valve control device for a supercharged engine having the above-described structure, a positive pressure relief valve is connected to the air bypass valve. It can be released to the atmosphere instantly. Therefore, it is possible to quickly perform the opening operation of the air bypass valve at the time of rapid deceleration, and it is possible to prevent occurrence of surging due to delay in valve opening.

[0010]

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

First Embodiment FIGS. 1 to 4 show a first embodiment of the present invention.
Particularly, a case where the present invention is applied to a six-cylinder engine mounted on a vehicle is shown. In FIG. 2, 1 indicates an engine, 2 indicates a surge tank, and 3 indicates an exhaust manifold. The exhaust manifold 3 has # 1 to # 3 cylinder groups and # 4 to
Are assembled into two of the # 6 cylinder group, and the assembly part is a communication passage 3a.
Is communicated by Reference numerals 7 and 8 are a main turbocharger and a sub turbocharger arranged in parallel with each other.
Turbines 7a, 8 of turbochargers 7, 8 respectively
a is connected to the collecting portion of the exhaust manifold 3, and each of the compressors 7 b and 8 b is connected to the surge tank 2 via the intercooler 6 and the 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 sub turbocharger 8 is stopped in the low intake air amount region. In order to enable the operation and stoppage of both turbochargers 7, 8, an exhaust switching valve 1 is provided downstream of the turbine 8a of the sub-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 of the turbine 8a of the sub turbocharger 8 and the downstream 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
Is opened and closed by a diaphragm type actuator 42.

In the intake passage of the auxiliary turbocharger 8 stopped in the low intake air amount range, one turbocharger
In order to smoothly switch to the individual turbocharger, an intake bypass passage 13 that communicates between the upstream of the compressor 7b and the downstream of the compressor 8b, and an intake bypass valve 33 provided in the middle of the intake bypass passage 13 are provided. . The intake bypass valve 33 is a diaphragm type actuator 1
Opened and closed by 0. A check valve 12 is provided in a bypass passage communicating the upstream and downstream of the intake switching valve 18, and when the intake switching valve 18 is closed, the compressor outlet pressure on the sub turbocharger 8 side reduces the main turbocharger 7.
The air is allowed to flow from the upstream side to the downstream side when it becomes larger than the side. In the drawing, reference numeral 14 denotes an intake passage on the compressor outlet side, and reference numeral 15 denotes 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 an exhaust muffler (not shown) via an 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 type actuator 16. The waste gate valve 31 is opened and closed by the actuator 9.

Actuators 9, 10, 11, 16, 4
2 is activated by the introduction of a supercharging pressure or a negative pressure. Each actuator 9, 10, 11, 16,
In order to selectively switch between the supercharging pressure or the negative pressure from the positive pressure tank 51 and the atmospheric pressure from the downstream of the air flow meter 24, first, second, third, fourth, fifth, and Sixth
Of the electromagnetic valves 25, 26, 27, 28, 32, 44 are connected. Each solenoid valve 25, 26, 27, 28, 32, 4
The switching of No. 4 is performed according to a command from the engine control computer 29. The second solenoid valve 26
A check valve 45 that allows only one flow of the negative pressure is interposed in the passage for introducing the negative pressure into the passage.

The first solenoid valve 25 is turned on when the intake switching valve 1
Actuator 11 is operated so that 8 is fully opened,
When OFF, the actuator 11 is operated so that the intake switching valve 18 is fully closed. Turning on the fourth solenoid valve 28 activates the actuator 16 to fully open the exhaust switching valve 17, and turning off the fourth solenoid valve 28 activates the actuator 10 to fully close the exhaust switching valve 17. O of the third solenoid valve 27
N activates the actuator 10 so that the intake bypass valve 33 is fully closed, and OFF activates the actuator 10 so that the intake bypass valve 33 is fully opened.

A fifth solenoid valve 32 for introducing atmospheric pressure to an actuator 42 for operating an exhaust bypass valve 41
N, not duty control but duty control. Similarly, the sixth solenoid valve 44 that guides the supercharging pressure to the actuator 9 that operates the wastegate valve 31 is also ON, OF
Duty control is performed instead of F control. As is well known, the duty control is to control the energization time by the duty ratio, and the average current is variably controlled in an analog manner by digitally changing the ratio of energization and non-energization. The duty ratio is the ratio of the energizing time to the time of one cycle, and the energizing time in one cycle is A,
Assuming that the non-energization time is B, the duty ratio = A / (A +
B) × 100 (%). In the present embodiment, the fifth
By controlling the duty of the electromagnetic valve 32 and the sixth electromagnetic valve 44, the opening amounts of these electromagnetic valves can be varied.

The opening degree of the exhaust bypass valve 41 is variable by varying the amount of bleed (leakage) of the supercharging pressure introduced into the diaphragm chamber of the actuator 42 into the atmosphere by duty control of the fifth solenoid valve 32. It is possible. The opening degree of the wastegate valve 31 can be varied by varying the amount of bleed (leakage) of supercharging pressure introduced into the diaphragm chamber of the actuator 9 into the atmosphere by duty control of the sixth solenoid valve 44. ing.

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 detecting sensors include 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 performing calculations, a read-only memory (ROM) as 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.

The compressor 7b of the main turbocharger 7
And an intake passage 14a located downstream of the compressor 8b of the sub-turbocharger 8.
An air bypass passage 61 that guides the supercharged air downstream of the compressors 7b and 8b to the upstream of the compressors 7b and 8b is connected to the vicinity of the merging portion 14c where the air flows through the compressors 7b and 8b. When the valve is opened, the compressors 7b, 8b
An air bypass valve 62 is provided for flowing downstream supercharged air upstream of the compressors 7b, 8b.

The air bypass valve 62 can be opened by a differential pressure between a supercharging pressure acting on a diaphragm 62b provided with a valve body 62a and a supercharging pressure acting on a diaphragm chamber 62c. In the diaphragm chamber 62c,
A compression coil spring 62d for urging the diaphragm 62b in the valve closing direction is provided. Diaphragm chamber 62
In a state where the negative pressure is guided to the position c, the diaphragm 62b is displaced toward the compression coil spring 62d, and the air bypass valve 62 is opened.

The diaphragm chamber 62c of the air bypass valve 62 is connected to the intake passage 1 through a first pressure introducing passage 63.
4 can be communicated with the vicinity of the junction 14c. The first pressure introduction passage 63 is provided with a positive pressure delay valve 64 for delaying and introducing the supercharging pressure into the diaphragm chamber 62c of the air bypass valve 62. In the positive pressure delay valve 64, a check valve 64a as a passage and a throttle portion 64b are arranged in parallel. The check valve 64a is connected to the merging portion 14 from the side of the diaphragm chamber 62c of the air bypass valve 62.
It has a function to allow only the flow of intake air to the c side. Aperture part 6
4b restricts the flow rate of the intake air flowing into the diaphragm chamber 62c from the merging portion 14c side to a certain amount, and
It has a function of preventing the pressure in 2c from sharply rising due to the introduction of supercharged air.

The air bypass valve 62 is connected to a positive pressure relief valve 81 for releasing supercharged air in the diaphragm chamber 62c to the atmosphere at the time of rapid deceleration from a supercharging state. The positive pressure relief valve 81 includes a seventh solenoid valve (DSV7), which is a two-way solenoid valve in this embodiment. Positive pressure relief valve 81
Are opened at the time of sudden deceleration by an output signal from the engine control computer 29. At the time of supercharging, the diaphragm chamber 62c of the air bypass valve 62
The supercharged air guided to the inside is used to release the positive pressure relief valve 81 during sudden deceleration.
Is discharged into the intake passage 15 located downstream of the air flow meter 24. In the present embodiment, the supercharged air in the diaphragm chamber 62c is discharged into the intake passage 15, but may be directly discharged to the atmosphere via an air filter or the like.

Next, the operation of the first embodiment will be described. In the high intake air amount range, both the intake switching valve 18 and the exhaust switching valve 17 are opened, and the intake bypass valve 33 is closed. As a result, the two turbochargers 7, 8 are driven, a sufficient amount of supercharged air is obtained, and the output is improved. At low speed and 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 one turbocharger supercharging characteristic is superior to two turbocharger supercharging characteristics in the low intake air amount region. By using one turbocharger, the boost pressure and the rise of torque are quickened, and the response is quick. When shifting from the low intake air amount region to the high intake air amount region, that is, when switching from one turbocharger 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 and switch the turbocharger. It is possible to perform more smoothly (shock at the time of switching is small).

Immediately after deceleration, the pressure upstream of the throttle valve rises sharply due to the closing of the throttle valve 4, and this sudden rise acts on the diaphragm 62 b of the air bypass valve 62. The diaphragm 62b is displaced toward the compression coil spring 62d by this pressure, and the diaphragm 62b
The air bypass valve 62 is opened by the movement of the valve body 62a accompanying the displacement of b. Here, the diaphragm chamber 6
Although the pressure which has risen rapidly to 2c is guided through the first pressure introduction passage 63, the positive pressure delay valve 64 is interposed in the first pressure introduction passage 63, so that the pressure in the diaphragm chamber 62c is reduced. A surge is prevented by the supercharging introduced. Therefore, immediately after deceleration, the diaphragm 62b can be easily changed by the supercharging pressure that has risen sharply, and the air bypass valve 62 is quickly opened. Therefore, the intake air having a high pressure is bypassed to the upstream side of the compressors 7b and 8b via the air bypass valve 62.

When the opening of the throttle valve 4 is located between the idling state and the fully opened state, that is, in the partial state, the supercharged air is guided to the diaphragm chamber 62c of the air bypass valve 62. The valve body 62a is closed by the movement of the valve body 62a accompanying the displacement of the diaphragm 62b. Therefore, recirculation of the supercharged air by the air bypass passage 61 is reliably prevented, and a rise in the intake air temperature is prevented.

FIG. 4 shows a control processing procedure of the positive pressure relief valve 81 in the first embodiment. As shown in FIG.
In step 101, a control routine is started, and the routine proceeds to step 102, where the supercharging pressure PM is taken. Next, the routine proceeds to step 103, where the supercharging pressure PM is 360 mmH
A determination is made whether gabs is exceeded. That is, in step 103, it is determined whether the load is light or high.

In step 103, the supercharging pressure PM becomes 3
If it is determined that it exceeds 60 mmHgabs,
Proceeding to step 104, the throttle opening TA is captured. Next, the routine proceeds to step 105, where the throttle opening T
It is determined whether or not A exceeds 20 ° (deg). Here, if it is determined that the opening degree TA of the throttle valve 4 exceeds 20 °, the routine proceeds to step 106, where the positive pressure relief valve 81 composed of the seventh solenoid valve (VSV7) is turned off.
FF is set, and the positive pressure relief valve 81 is closed.

If it is determined in step 105 that the throttle opening degree TA is smaller than 20 °, the routine proceeds to step 107, where the closing speed ΔTA of the throttle valve 4 is acquired. Next, the routine proceeds to step 108, where it is determined whether or not the valve closing speed ΔTA exceeds -0.7 deg / 8 ms. Here, ΔTA> −0.7 deg / 8 ms
If it is determined, the process proceeds to step 106.

In step 103, PM> 360 mm
If it is determined that the load is not Hgabs, that is, if it is determined in step 103 that the load is light, step 1
Go to 09. Similarly, in step 108, ΔTA <−
If it is determined to be 0.7 deg / 8 ms, that is, if it is determined in step 108 that rapid deceleration has occurred,
Proceed to step 109. In step 109, the positive pressure relief valve 81 including the seventh solenoid valve (VSV7) is opened by a command from the engine control computer 29. When the processing of Steps 106 and 109 is completed, the routine proceeds to Step 110, where the processing is returned.

As described above, when the air bypass valve 62 is opened due to rapid deceleration, the positive pressure relief valve 81 is also opened, so that the supercharged air in the diaphragm chamber 62c can be quickly released to the atmosphere. . Therefore, as shown in FIG. 7, the valve opening operation of the air bypass valve 62 at the time of rapid deceleration becomes quick, and the occurrence of surging (intake pulsation) due to valve opening delay is prevented. As a result, even in the case of an engine using a thermal air flow meter or a Karman vortex air flow meter, erroneous determination of the intake air amount due to occurrence of surging is prevented, and the problem that the air-fuel ratio becomes over-rich is eliminated.

Second Embodiment FIGS. 5 and 6 show a second embodiment of the present invention.
This embodiment is different from the first embodiment only in the operation configuration of the air bypass valve, and the other parts are the same as those of the first embodiment. The description of the corresponding parts will be omitted, and different parts will be described.

In the first embodiment, the supercharging pressure downstream of the compressors 7b and 8b is led to the diaphragm chamber 62c through the positive pressure delay valve 64, but the present embodiment does not use the positive pressure delay valve 64. It has a configuration. In FIG.
The diaphragm chamber 62c can communicate with a port 72 arranged near the throttle valve 4 via a second pressure introduction passage 71. The port 72 is disposed at a position where the pressure becomes negative when the throttle valve 4 is fully closed. When a negative pressure is introduced into the diaphragm chamber 62c through the second pressure introduction passage 71, the diaphragm 62b is displaced toward the compression coil spring 62d, and the air bypass valve 62 is opened.

The air bypass valve 62 is connected to a positive pressure relief valve 81 for releasing supercharged air in the diaphragm chamber 62c to the atmosphere at the time of rapid deceleration from a supercharging state. The positive pressure relief valve 81 includes a seventh solenoid valve (VSV7) which is a two-way solenoid valve in the present embodiment. Positive pressure relief valve 81
Are opened at the time of deceleration by an output signal from the engine control computer 29. The supercharged air in the diaphragm chamber 62c of the air bypass valve 62 is supplied to the air flow meter 24 through the positive pressure relief valve 81.
Is discharged into the intake passage 15 located downstream of the air passage.

Air bypass valve 62 and positive pressure relief valve 8
A check valve 82 is interposed in the passage between the check valve 82 and the check valve 82. The check valve 82 has a function of allowing a flow only in a direction in which the supercharged air guided to the diaphragm chamber 62c is released to the atmosphere side.

In the second embodiment constructed as described above, immediately after the deceleration, the pressure of the supercharged air upstream of the throttle valve 4 sharply increases, and the diaphragm 62b of the air bypass valve 62 is opened by the suddenly increased supercharging pressure. Displaced in the valve direction. Further, in this state, the negative pressure from the port 72, which becomes a negative pressure when the throttle valve 4 is fully closed, is applied to the second pressure introduction passage 7
1 through the diaphragm chamber 62c. Therefore, the air bypass valve 62 is quickly opened by the supercharging pressure (positive pressure) acting on the diaphragm 62b side and the negative pressure guided to the diaphragm chamber 62c. That is, the displacement of the diaphragm 62b is faster by using the negative pressure than in the valve-opening operation using only the supercharging pressure, and the responsiveness of the valve-opening operation is significantly improved. Therefore, the opening operation of the air bypass valve 62 is further advanced than in the first embodiment, and the supercharging pressure increased by the rapid closing of the throttle valve 4 is instantaneously bypassed to the upstream side of the compressors 7b and 8b, and the pulsation noise due to surging. Is reliably prevented.

In each of the embodiments described above, a two-stage twin turbo engine in which two turbochargers are provided for one engine has been described. However, one turbocharger is provided for one engine. Of course, it can be applied to an engine.

[0037]

According to the present invention, the following effects can be obtained. The air bypass valve, which is closed by the supercharging pressure guided to the diaphragm chamber, is connected to a positive pressure relief valve that releases supercharged air in the diaphragm chamber to the atmosphere during sudden deceleration. The valve can be opened, and the occurrence of surging due to a delay in valve opening can be prevented. As a result, even in the case of an engine using a thermal air flow meter or a Karman vortex air flow meter, erroneous determination of the intake air amount due to surging can be prevented, and the problem that the air-fuel ratio becomes over-rich can be solved.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a deceleration air bypass valve control device of a supercharged engine according to a first embodiment of the present invention.

FIG. 2 is a system diagram of a supercharged engine equipped with the device of FIG. 1;

FIG. 3 is an enlarged cross-sectional view showing a flow of intake air when the air bypass valve in the apparatus of FIG. 1 operates.

FIG. 4 is a flowchart showing a control processing procedure of a positive pressure relief valve in the apparatus of FIG. 1;

FIG. 5 is a schematic configuration diagram of a deceleration air bypass valve control device for a supercharged engine according to a second embodiment of the present invention.

6 is a system diagram of a supercharged engine provided with the device of FIG. 5;

FIG. 7 is a characteristic diagram showing valve opening characteristics of an air bypass valve during rapid deceleration of a conventional engine with a supercharger.

[Explanation of symbols]

 Reference Signs List 4 throttle valve 7 main turbocharger 7b compressor 8 sub turbocharger 8b compressor 61 air bypass passage 62 air bypass valve 62a valve body 62c diaphragm chamber 64 positive pressure delay valve 72 port which becomes negative pressure when throttle valve is fully closed 81 positive pressure relief valve

Continuation of the front page (56) References JP-A-4-370324 (JP, A) JP-A-3-23319 (JP, A) JP-A-3-78530 (JP, A) JP-A-63-90033 (JP) , U) JP-A 61-66625 (JP, U) JP-A 1-58723 (JP, U) JP-A 63-983 (JP, Y2) (58) Fields surveyed (Int. Cl. ⁶ , DB Name) F02B 37/00-37/24

Claims (1)

(57) [Claims] 1. A diaphragm-type air bypass that connects an upstream side and a downstream side of a compressor of a turbocharger through an air bypass passage so as to be able to communicate with each other, and guides supercharged air downstream of the compressor upstream of the compressor to the air bypass passage. A deceleration air bypass valve control device for an engine with a supercharger, wherein a valve is provided, and the air bypass valve is closed by a supercharging pressure guided into a diaphragm chamber. A deceleration air bypass valve control device for an engine with a supercharger, wherein a positive pressure relief valve for releasing a supercharged air in a room to the atmosphere is connected.