JP3466909B2 - How to control the air bypass valve - Google Patents

Description

Description: BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to a method for controlling an air bypass valve for connecting and disconnecting a downstream side and an upstream side of a turbocharger in a turbo-type internal combustion engine. 2. Description of the Related Art In a turbo-type internal combustion engine having a turbocharger, when a throttle valve is suddenly closed, the pressure on the upstream side of the throttle valve temporarily rises suddenly due to intake inertia and rotational inertia of a compressor. This pressure increase causes surging that the supercharged air flows back to the turbocharger side due to pressure reflection, and generates a surge sound (pulsation sound) from the turbocharger.
Conventionally, in order to prevent the surge noise, there is known a configuration in which a communication path that connects the downstream side and the upstream side of the turbocharger is provided, and a diaphragm-type air bypass valve is disposed on the communication path. When a surge noise occurs due to the sudden closing of the throttle valve as described above, the air bypass valve is opened for a predetermined period of time to connect the upstream side and the downstream side of the turbocharger. This prevents the boost pressure from rising. A diaphragm type air bypass valve generally has a valve body provided on a diaphragm movably disposed on a valve body, and the valve body is divided into a diaphragm chamber and a communication chamber by the diaphragm. I have. Specifically, the communication chamber is arranged on the communication passage. When the valve is closed, the valve body is held in the closed position by a spring force that urges the valve body in the closing direction, and when the valve is opened, the negative pressure on the downstream side of the throttle valve is guided to the diaphragm chamber, and the negative pressure is applied. The structure is such that the diaphragm is moved and the valve body is moved to the open position against the spring force. [0004] However, for example, when the throttle valve is slightly opened during the predetermined time during which the air bypass valve is opened after the throttle valve is rapidly closed. Then, the pressure on the downstream side of the throttle valve rises and the pressure in the diaphragm chamber rises, and the pressure on the downstream side of the turbocharger falls and the pressure in the communication chamber falls. As a result, in combination with the urging force of the spring, the forces acting on the valve body and the diaphragm are balanced, and a situation appears in which the positions of the valve body and the diaphragm become unstable. Then, a so-called chattering phenomenon in which the valve body and the diaphragm vibrate is caused, and a vibration sound may be generated. [0005] This vibration noise does not always occur in conjunction with the driver's accelerator operation, and may or may not occur depending on driving conditions and the like, and the timing of occurrence varies. There was a problem of giving. On the other hand, as shown in Japanese Patent Application Laid-Open No. 5-156957, a throttle section is provided in a connection path connecting the downstream side of the throttle valve to the diaphragm chamber of the air bypass valve, and chattering is performed at the expense of responsiveness of opening and closing the valve body. Some have tried to prevent the phenomenon. However, in such a device, it is necessary to change the configuration of the conventional air bypass valve, and it is necessary to consider a balance between responsiveness of the valve body and prevention of chattering phenomenon, and it is difficult to set the throttle opening. There was a problem. In addition, there are cases in which various operating conditions, individual differences between the internal combustion engines, aging, and the like cannot be fully dealt with, and this is hardly a radical solution. [0006] However, as described above, the generation of the surge noise is caused by a sudden increase in the pressure on the downstream side of the compressor, and the generation of vibration of the diaphragm is caused by a decrease in the pressure on the downstream side of the compressor. Things. As described above, the condition for generating the surge noise and the condition for generating the vibration of the diaphragm are contradictory. The present invention has been made by paying attention to this point, and is an air bypass which is opened when a situation where a surge sound from a turbocharger is generated and is kept open for a predetermined time thereafter. When the condition that the diaphragm vibrates even within the predetermined time is set, it is determined that no surge sound is generated, and the valve is closed, so that the vibration of the diaphragm is suppressed. The present invention is applied to a diaphragm type air bypass valve provided on a communication passage communicating between a downstream side and an upstream side of a turbocharger in a turbo-type internal combustion engine. The bypass valve is opened when a surge sound is generated from the turbocharger when the throttle valve is closed,
A method for controlling an air bypass valve that is closed after a predetermined time has elapsed from the opening, wherein the air bypass valve is closed even when the diaphragm oscillates even within the predetermined time. It is characterized by doing so. Thus, according to such a method, the vibration of the diaphragm can be reliably prevented by closing the air bypass valve under conditions where the diaphragm can vibrate. Moreover, even if the communication passage is closed under conditions where the diaphragm can oscillate, no surge noise is generated from the turbocharger, so that the generation of the surge noise can be reliably prevented. In addition, only the software change does not change the configuration of the conventional air bypass valve,
This has the effect that its realization is very simple. The condition that the diaphragm vibrates, which can be easily detected by using an existing intake pressure sensor or the like, is that the pressure on the downstream side of the turbocharger is equal to or more than a predetermined value within the predetermined time, and the pressure changes with time. The case where the amount is equal to or less than a predetermined amount is exemplified. An embodiment of a method for controlling an air bypass valve according to the present invention will be described below with reference to the drawings. FIG. 1 is a schematic configuration diagram illustrating a turbo-type internal combustion engine 1 to which a control method of an air bypass valve 5 according to the present embodiment is applied. The turbo-type internal combustion engine 1 has a plurality of cylinders 7
(Only one is shown in FIG. 1), an intake system 4 for supplying intake air to each cylinder 7, an exhaust system 6 for discharging exhaust, and an exhaust system 6 on the exhaust system 6. The drive turbine 22 provided and the compressor 2 provided on the intake system 4
1 and a turbocharger 2 having the same. [0012] The intake system path 4 is used to supply outside air to the intake valve 71 of the cylinder 7.
In this embodiment, on this intake system path 4,
An air cleaner 81, a compressor 21, an intercooler 82, a throttle valve 83, and an injector 84 are arranged in this order from upstream. Specifically, the intake system path 4 includes an air cleaner 81 and a compressor 2
A first introduction path 41 connecting the first intake port 21a, a second introduction path 42 communicating the discharge port 21b of the compressor 21 and the intercooler 82, a third introduction path 43 communicating the intercooler 82 and the throttle valve 83, It comprises a surge tank 44 and an intake manifold 45 which communicate the throttle valve 83 and the intake valve 71. Thus, the injector 84 is provided in the intake manifold 45 near the intake valve 71. The exhaust passage 6 communicates the exhaust valve 72 with the outside so as to discharge the exhaust gas discharged from the exhaust valve 72 to the outside. An exhaust muffler is provided. Specifically, the exhaust passage 6 is provided with an exhaust manifold 61 that communicates the exhaust valve 72 and the introduction port 22 a of the drive turbine 22.
And an exhaust passage 62 communicating the outlet port 22b of the drive turbine 22 and the exhaust muffler. As described above, the turbocharger 2
The drive turbine 22 and the compressor 21 are provided.
Are arranged coaxially and are configured to work together. Then, the drive turbine 22 is rotated by the exhaust pressure, and the compressor 21 is operated by using the rotational force to perform a pumping operation.
Then, it is sent to the cylinder 7. In this embodiment, the communication passage 3 is provided for communicating the second introduction passage 42 downstream of the compressor 21 and the first introduction passage 41 upstream of the compressor 21. An air bypass valve 5 is provided above.
The air bypass valve 5 is a diaphragm type that is driven to open and close by an air bypass valve control valve VSV (hereinafter referred to as an ABV control valve VSV). This prevents the pressure in the upstream side of the throttle valve 83, that is, the pressure in the second and third introduction paths 42 and 43, from temporarily rising due to the inertia and the rotational inertia of the compressor 21,
As a result, it is provided to prevent the generation of surge noise from the turbocharger 2. Specifically, the air bypass valve 5 includes a valve body 52, a movable diaphragm 51 that divides a space in the valve body 52 into a diaphragm chamber 53 and a communication chamber 54, and a valve body 55 provided in the diaphragm 51. Is provided. A control port 56 is opened in the diaphragm chamber 53, and a first port 57 and a second port 58 are opened in the communication chamber 54. The valve body 55 is brought into contact with the inner opening surface 58a of the second port 58 by the movement of the diaphragm 51, and the valve closing position where the communication between the first port 57 and the second port 58 is interrupted. Separate the first port 5
It is configured to move between a valve-opening position where the valve 7 communicates with the second port 58. Furthermore, the diaphragm chamber 5
A spring 59 is disposed on the valve 3 to elastically urge the valve body 55 in the valve closing position direction. Thus, the first port 57 of the air bypass valve 5 communicates with the second introduction passage 42, and the second port 58 communicates with the first introduction passage 41. Further, the control port 56 is configured to be able to selectively communicate with either the third introduction path 43 or the surge tank 44 via the ABV control valve VSV. The ABV control valve VSV is a three-way valve that can be driven electromagnetically, and moves the control port 56 at the same pressure as the surge tank 44 that generates a negative pressure or the second introduction passage 42 by moving a control valve body (not shown). The third
The air bypass valve 5 is selectively opened and closed to communicate with any one of the introduction paths 43. In particular,
By making the control port 56 communicate with the surge tank 44, the diaphragm chamber 53 is made to have a negative pressure, and the pressure difference between the diaphragm chamber 53 and the communication chamber 54 moves the diaphragm 51 and the valve body 55 to the open position. Third
By communicating with the introduction path 43, the diaphragm chamber 5
3 and the communication chamber 54 have the same pressure, and have a function of moving the diaphragm 51 and the valve body 55 to the closed position by the force of the spring 59. In this embodiment, the ABV control valve VSV is driven and controlled by a valve control signal a from the controller 9 described below. The controller 9 includes at least an input interface 91, an output interface 92, a CPU 93,
It has a built-in memory 94. Thus, the input interface 91 receives the intake pressure signal b output from the intake pressure sensor SR disposed in the surge tank 44, and the output interface 92 controls at least the ABV control valve 5A. To output a valve control signal a. The intake pressure signal b has a voltage or current value corresponding to the intake pressure, and the value is C
When fetched into the PU 93, it is converted into a digital value via an A / D conversion circuit (not shown). In this embodiment, the second or third introduction path 42 estimated from this value,
The pressure of 43 is used. The valve control signal a is a binary signal, and the ABV control valve V
The SV is driven in any direction. And
In this embodiment, the memory 94 stores at least a valve control program for appropriately controlling the ABV control valve VSV and driving the air bypass valve 5 in accordance with the state of the intake pressure. The control method of the air bypass valve 5 according to the present embodiment follows this valve control program, which will be described with reference to the flowchart shown in FIG. This valve control program comprises a step S
It is composed of a plurality of steps from 1 to step S7, and these series of steps are repeated periodically. First, in step S1, it is determined whether or not a situation in which a surge sound is generated. Specifically, the situation in which a surge noise occurs is that the pressure in the second or third introduction path 42, 43 indirectly obtained from the intake pressure detected by the intake pressure sensor SR is 760 mmHg or more, and
This is the case where the amount of change in the pressure per unit time exceeds -30 mmHg. The detection of the intake pressure is periodically performed by another routine, for example, and is updated and stored in the memory 94. Further, the unit time here refers to a certain time appropriately set by a timer or the like. If it is determined that the situation is such that a surge noise is generated, step S2 is performed.
If not, the process proceeds to step S7. In step S2, the value (ON) of the valve control signal a for driving the ABV control valve VSV is set to output the control port 56 of the air bypass valve 5 and the surge tank 44 to communicate with each other, and this is output. As a result,
The air bypass valve 5 is opened. Then, the process proceeds to step S3. In step S3, the standby time is set to a predetermined time. Specifically, the predetermined time is set to, for example, 1.28 seconds. And step S4
Proceed to. In step S4, it is determined whether a predetermined time has elapsed. If the predetermined time has elapsed, the process proceeds to step S6; otherwise, the process proceeds to step S5. In step S5, it is determined whether or not the diaphragm 51 is in a state where vibration occurs. Specifically, the vibration generation state is, for example, that the pressure of the third introduction path 43 is 760 m
mHg or more and the pressure change per unit time is −
It is the case of 30 mmHg or less. When it is determined that the vibration is generated, the process proceeds to step S6. Otherwise, the process returns to step S4. In step S6, the value (OF) of the valve control signal a for driving the ABV control valve to communicate the control port 56 of the air bypass valve 5 with the third introduction path 43 is established.
F) is set and output. As a result, the air bypass valve 5 is closed. In step S7,
The valve control program in this cycle ends, and the process returns to step S1. The air bypass valve 5 operates as follows according to the control method of the air bypass valve 5 of the present embodiment configured as described above. First, when the accelerator (not shown) is depressed and the turbocharger 2 is operating, the accelerator is returned and the throttle valve 83 is released.
Is rapidly closed, the pressure on the downstream side of the compressor 21, that is, the pressure on the second and third introduction paths 42 and 43 temporarily rises sharply due to the inertia of the intake air and the rotational inertia of the compressor 21. The pressure is 760 mmHg or more, and the amount of change in the pressure per unit time is -30 mmHg.
If the pressure exceeds Hg, it is determined that a surge sound (pulsation sound) is generated from the turbocharger 2 due to a surging in which the supercharged air flows backward to the turbocharger 2 due to the pressure reflection due to the rapid rise of the pressure. Then, the ABV control valve VSV is driven so that the control port 56 of the air bypass valve 5 communicates with the surge tank 44, and the air bypass valve 5 is opened. As a result,
The supercharged air in the third introduction paths 42 and 43 is guided into the first introduction path 41, and surging is avoided. This open state lasts for 1.28 seconds,
During this time, for example, when an operation for slightly opening the throttle valve is performed, the supercharged air in the second or third introduction passages 42 and 43 flows into the surge tank side, and
Alternatively, the pressure rising speed in the third introduction paths 42 and 43 decreases. This is recognized by the fact that the amount of change per unit time in the second or third introduction paths 42, 43 has become equal to or less than -30 mmHg, and at the same time, it is determined that the diaphragm 51 vibrates. Then, the ABV control valve VSV is driven to make the control port 56 of the air bypass valve 5 communicate with the third introduction path 43, and the air bypass valve 5 is closed. In this state, since the positions of the diaphragm 51 and the valve body 55 are fixed at the closed positions, the generation of vibration is reliably prevented, and no surge noise is generated. As described above, according to the method of controlling the air bypass valve 5 according to the present embodiment, the vibration of the diaphragm 51 can be reliably prevented by closing the air bypass valve 5 under conditions where the diaphragm 51 can vibrate. . In addition, under the condition that the diaphragm 51 can vibrate, the surge sound from the turbocharger 2 is hardly generated, so that the generation of the surge sound can be surely prevented. In addition, the condition under which the diaphragm 51 vibrates is determined by the existing intake pressure sensor S.
Since the detection is performed by using R or the like, the realization of the present embodiment can be realized simply by changing only the software, and is simple without changing the hardware configuration. The present invention is not limited to the above-described embodiment. For example, detection of a condition under which the diaphragm can vibrate may be performed by a method other than the embodiment. In addition, the configuration of each unit can be variously modified without departing from the spirit of the present invention. As described in detail above, the present invention focuses on the point that surge noise is unlikely to occur under conditions where the diaphragm vibrates. Conventionally, surge noise from a turbocharger is generated. The air bypass valve that was opened when the situation became open and kept open for a predetermined time after that, when the diaphragm vibrated even within the predetermined time, no surge sound was generated. Judgment is made to close. Therefore, according to such a method, by closing the air bypass valve under conditions where the diaphragm can vibrate, vibration of the diaphragm can be reliably suppressed, and vibration noise caused by this vibration can be prevented. In addition, under conditions where the diaphragm can vibrate, even if the communication passage is closed, surge noise from the turbocharger is unlikely to be generated, so that generation of the surge noise can be reliably prevented. Further, it can be realized only by changing the software, and also has an effect that it is not necessary to change the configuration of the conventional air bypass valve.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic overall configuration diagram of an internal combustion engine showing one embodiment of the present invention. FIG. 2 is a flowchart showing a control program of the embodiment. [Description of Signs] 1 ... Turbo-type internal combustion engine 2 ... Turbocharger 21 ... Compressor 3 ... Communication path 41 ... Downstream side (first introduction path) 42 ... Upstream side (second introduction path) 5 ... Air bypass valve 51 ... Diaphragm 83 ... Throttle valve

Claims (1)

(57) Claims: In a turbo-type internal combustion engine, the invention is applied to a diaphragm-type air bypass valve provided on a communication path that connects a downstream side and an upstream side of a compressor of a turbocharger, A method for controlling an air bypass valve, wherein the air bypass valve is opened when a surge sound is generated from a turbocharger, and is closed after a predetermined time has elapsed from the opening, wherein the air bypass valve is closed within the predetermined time. The method of controlling an air bypass valve, wherein the air bypass valve is closed when the diaphragm oscillates.