CN111065801A

CN111065801A - Control system and control method

Info

Publication number: CN111065801A
Application number: CN201880056180.1A
Authority: CN
Inventors: 金子真一郎; 高野二郎; 冈崎敦
Original assignee: Isuzu Motors Ltd
Current assignee: Isuzu Motors Ltd
Priority date: 2017-08-31
Filing date: 2018-08-27
Publication date: 2020-04-24
Anticipated expiration: 2038-08-27
Also published as: JP6939272B2; CN111065801B; JP2019044653A; WO2019044740A1

Abstract

A control system for a turbocharged internal combustion engine, comprising: a discharge passage communicating with an intake passage portion on the upstream side of a throttle valve on the downstream side of a compressor of a turbocharger and on the downstream side of the compressor; a valve for adjusting an opening state of the discharge passage; and a control unit for controlling the operation of the valve. The control unit controls the operation of the valve so that the valve is closed when the compressor is in an operating state in a non-surge region other than the surge region and the pressure in the intake passage portion on the downstream side of the compressor when the throttle valve is closed is lower than a predetermined pressure, and the valve is opened when the pressure is equal to or higher than the predetermined pressure.

Description

Control system and control method

Technical Field

The present disclosure relates to a control system and a control method, and more particularly to a control system for an internal combustion engine with a turbocharger having a throttle valve on a downstream side of a compressor of the turbocharger, and a control method for a valve provided in a passage communicating with an upstream side of the throttle valve and a downstream side of the compressor.

Background

As an internal combustion engine (engine) for a vehicle, an internal combustion engine using a turbocharger for improving the fluidity of intake air is known. Such a turbocharger equipped engine may cause a so-called surge phenomenon in which intake air intermittently flows back from the outlet side to the inlet side of the compressor due to the improved fluidity of intake air.

It is known that such a surge phenomenon has a large relationship with the balance between the pressure ratio and the intake air flow rate in the compressor, and the intake air flow rate is smaller, and the ratio (pressure ratio) of the outlet pressure to the inlet pressure of the compressor is larger, and the surge phenomenon is more likely to occur. The surge region in which such a surge phenomenon occurs is represented, for example, in a compressor performance graph having an intake air flow rate on the horizontal axis and a pressure ratio on the vertical axis.

In order to prevent such a problem caused by the surge phenomenon, a control system is known in which a bypass passage connecting an upstream portion and a downstream portion of a compressor of a turbocharger and an air bypass valve for opening and closing the bypass passage are provided, and the air bypass valve is opened and controlled when a predetermined condition is satisfied. For example, patent document 1 discloses that when the internal pressure of the surge tank downstream of the throttle valve downstream of the compressor of the turbocharger is equal to or lower than a predetermined value, the air bypass valve is opened. According to the description of patent document 1, the predetermined value is a limit value of the pressure in the surge tank which may cause a surge phenomenon in the compressor.

On the other hand, when the compressor is operated in a region other than the surge region, abnormal sounds may be generated from the intake system. It is known that abnormal sounds from the intake system occur particularly in an engine in which the size of the turbocharger is large and the compressor is operated in an operating region of about half or so of the main performance limit of the turbocharger.

Prior art documents

Patent document

Patent document 1: japanese laid-open patent publication No. 62-78430

Disclosure of Invention

[ problems to be solved by the invention ]

When abnormal sounds generated when the compressor operates in a region other than the surge region (hereinafter, non-surge region) are generated in a large amount, the throttle valve is closed suddenly in a state where the pressure in the intake passage portion downstream of the compressor is high. Such abnormal sounds may cause the driver to feel uncomfortable.

An object of the present disclosure is to provide a control system and a control method that can more favorably prevent abnormal sounds that may be generated when a compressor of a turbocharger operates in a non-surge region in an internal combustion engine with a turbocharger.

[ means for solving the problems ]

The control system of the present disclosure is a control system for a turbocharger-equipped internal combustion engine having a throttle valve on a downstream side of a compressor of a turbocharger, the control system including:

a discharge passage communicating with an intake passage portion on an upstream side of the throttle valve and on a downstream side of the compressor,

a valve for regulating the opening state of the discharge passage, an

A control unit for controlling the operation of the valve;

the control unit controls the operation of the valve so that the valve is closed when the compressor is in an operating state in a non-surge region other than a surge region and the pressure of the portion of the intake passage on the downstream side of the compressor when the throttle valve is closed is less than a predetermined pressure, and so that the valve is opened when the compressor is in an operating state in the non-surge region and the pressure of the portion of the intake passage on the downstream side of the compressor when the throttle valve is closed is equal to or greater than the predetermined pressure.

Preferably, a downstream end of the discharge passage communicates with an intake passage portion on an upstream side of the compressor.

Preferably, the control unit controls the operation of the valve such that the valve is opened when the pressure in the intake passage portion on the downstream side of the compressor is equal to or higher than a first predetermined pressure when the compressor is in an operating state in the non-surge region and the throttle valve is closed, and thereafter, the valve is closed when the pressure on the downstream side of the compressor and on the upstream side of the throttle valve is smaller than a second predetermined pressure.

The control method of the present disclosure is a control method of a valve in an internal combustion engine with a turbocharger, the internal combustion engine having a throttle valve on a downstream side of a compressor of the turbocharger, and further having a discharge passage partially communicating with an intake passage on an upstream side of the throttle valve and on a downstream side of the compressor, and a valve for adjusting an open state of the discharge passage, the control method including:

a determination step of determining whether or not a pressure of the intake passage portion on a downstream side of the compressor when the throttle valve is closed is equal to or higher than a predetermined pressure when the compressor is in an operating state in a non-surge region other than a surge region, and

and a control step of controlling the valve so as to open the closed state when it is determined by the determination step that the pressure in the intake passage portion on the downstream side of the compressor when the throttle valve is closed is equal to or higher than the predetermined pressure.

[ Effect of the invention ]

According to the control system and control method in the internal combustion engine with a turbocharger of the present disclosure, when the compressor is in an operating state in a non-surge region and the pressure of the intake passage portion on the downstream side of the compressor when the throttle valve is closed is less than a predetermined pressure, the valve related to the discharge passage is closed, and when the pressure is equal to or more than the predetermined pressure, the valve is opened. Therefore, it is possible to more favorably prevent abnormal sounds that may be generated when the compressor of the turbocharger operates in the non-surge region in the engine with the turbocharger.

Drawings

Fig. 1 is a schematic configuration diagram of a turbocharger-equipped internal combustion engine to which a control system according to an embodiment of the present disclosure is applied.

Fig. 2 is a flow chart of an embodiment of the present disclosure.

Fig. 3 is a diagram for explaining a modification of the embodiment of fig. 1.

Detailed Description

An embodiment of the present disclosure is described below with reference to the drawings.

The present embodiment is an example in which the present disclosure is applied to an internal combustion engine mounted on a vehicle. Fig. 1 is a schematic overall configuration diagram showing an internal combustion engine 10 according to the present embodiment. Here, the internal combustion engine 10 is a diesel engine, hereinafter simply referred to as an engine, but may be a gasoline engine, a CNG engine, or the like, and the present disclosure is not intended to specifically limit the type of the engine to be applied.

An intake port 11A for introducing intake air into the cylinder C and an exhaust port 11B for discharging exhaust gas from the cylinder C are provided in the cylinder head 11 of the engine 10. The cylinder head 11 is provided with an intake valve 12 and an exhaust valve 14 that are opened and closed by a valve mechanism, not shown. The cylinder head 11 is provided with an injector 15 for directly injecting fuel into the cylinder C. The fuel injection amount or the injection timing of the injector 15 is controlled in accordance with a signal input from an electronic control unit (hereinafter referred to as ECU) 100.

A cylinder block 16 is provided below the cylinder head 11, and an oil pan 17 for storing engine oil is provided below a crankcase portion 16A of the cylinder block 16. A piston P is housed in a cylinder C of the cylinder block 16 so as to be capable of reciprocating.

A piston ring PR that slides in contact with the inner wall of the cylinder C is attached to the outer periphery of the piston P. Further, a crankshaft CS is connected to the piston P via a connecting rod CR. In the illustrated relationship, fig. 1 shows only one of the cylinders of the engine 10, and the other cylinders are not shown. The engine 10 may be either one of a plurality of cylinders or a single cylinder.

An intake manifold 20 communicating with the intake port 11A is provided on the side of the cylinder head 11 on the intake side. An intake passage 21 through which intake air is introduced is connected to the intake manifold 20. In the intake passage 21, an air cleaner 22, an intake air flow sensor (MAF sensor) 92, the compressor 32 of the turbocharger 30, an intercooler 23, an intake air temperature sensor 93, a throttle valve THV, a boost pressure sensor (intake pressure sensor) 94, and the like are provided in this order from the intake upstream side. Here, intake air temperature sensor 93 is provided on the upstream side of throttle valve THV, but may be provided on the downstream side of throttle valve THV.

An exhaust manifold 24 communicating with the exhaust port 11B is provided on the exhaust-side portion of the cylinder head 11. An exhaust passage 25 for introducing exhaust gas into the atmosphere is connected to the exhaust manifold 24. In the exhaust passage 25, an exhaust gas temperature sensor 95, the turbine 31 of the turbocharger 30, the exhaust gas purification device 40, and the like are provided in this order from the exhaust upstream side.

The turbocharger 30 includes the turbine 31 driven by exhaust gas, and the compressor 32 connected to the turbine 31 via a rotary shaft and configured to pressurize and feed intake air. Further, the turbocharger 30 is not limited to the conventional type illustrated in the drawing, and may be a variable capacity type having variable vanes.

Further, in the engine 10, a discharge passage RT communicating with an intake passage portion 21a on the upstream side of the throttle valve THV and on the downstream side of the compressor 32 is provided. One end (upstream end) of the discharge passage RT communicates with the intake passage portion 21a, particularly with the upstream side of the intercooler 23. However, the one end of the discharge passage RT may communicate with the downstream side of the intercooler 23 in the intake passage portion 21 a. The other end (downstream end) of the discharge passage RT communicates with the intake passage portion 21b on the upstream side of the compressor 32 (and on the downstream side of the air cleaner 22). Therefore, the discharge passage RT is a bypass passage that bypasses the compressor 32. A valve (may also be referred to as a bypass valve) EV for adjusting the open state of the discharge passage RT is provided in the discharge passage RT. The valve EV is an electromagnetic control valve, and its operation is controlled in accordance with a signal (to an actuator of the valve EV) from the ECU 100. Therefore, the ECU100 functions as a control unit for controlling the operation of the valve EV.

The ECU100 performs various controls of the engine 10 and the like, and is configured to include a known arithmetic processing device (for example, CPU), a storage device (for example, ROM or RAM), an input port, an output port, and the like. An intake air flow sensor 92, an intake air temperature sensor 93, a boost pressure sensor 94, and an exhaust gas temperature sensor 95 are electrically connected to the ECU100, and an engine speed sensor 90 and an accelerator opening degree sensor 91 are also electrically connected thereto, and output signals from these sensors and the like are input thereto. Further, an intake air pressure sensor for detecting (acquiring) the pressure of intake air in the intake passage portion on the upstream side of the compressor may be provided, and an intake air pressure sensor for detecting (acquiring) the pressure of intake air may be provided on the downstream side of the intercooler 23 and on the upstream side of the throttle valve THV. The ECU100 acquires the engine speed from the output of the engine speed sensor 90 and acquires the accelerator opening from the output of the accelerator opening sensor 91. The ECU100 also acquires the intake air flow rate introduced from the air cleaner 22 into the intake passage 21 based on the output of the intake air flow rate sensor 92, the temperature of the intake air passing through the intercooler 23 based on the output of the intake air temperature sensor 93, and the pressure (boost) of the intake air pressurized by the compressor 32 based on the output of the boost pressure sensor 94. Further, the ECU100 acquires the temperature of the exhaust gas discharged from the engine 10 and flowing through the exhaust passage on the upstream side of the turbine 31, based on the output of the exhaust gas temperature sensor 95.

The ECU100 acquires various values based on the outputs from the sensors and the like, performs calculation based on a program and data stored in advance, and outputs an operation signal to each of the injector 15, the (actuator of the) throttle valve THV, the (actuator of the) valve EV, and the like. This controls the operations of the injector 15, the throttle valve THV, the valve EV, and the like. Therefore, the ECU100 assumes a function as a control unit of each of these.

In a vehicle equipped with the engine 10 having the above-described configuration, the engine 10 is normally operated such that the compressor of the turbocharger operates (operates) in a region other than the surge region (non-surge region). For example, the engine 10 is of a type with a large displacement, and the compressor is of a large size. As described above, the surge region is a predetermined region where a surge phenomenon is likely to occur, and the region other than the predetermined region is referred to as a "non-surge region".

On the other hand, when the compressor is in an operating state in the non-surge region (when the engine operating state is in an operating region in the non-surge region), the throttle THV is closed, and therefore there is a time during which the pressure on the downstream side of the compressor 32, that is, the intake air pressure, increases. At this time, although the operation region of the compressor does not enter the surge region, an abnormal sound may be generated from the intake system of the engine 10. As one of the causes of the abnormal sound, the pressure fluctuation generated in the intake passage (particularly, the intake passage portion 21a on the upstream side of the throttle valve THV and on the downstream side of the compressor 32) can be increased based on the high pressure on the downstream side of the compressor. Therefore, the present inventors have conducted intensive studies and finally found that: by providing the above-described discharge passage RT and the valve EV and controlling the opening degree of the discharge passage RT, that is, the opening degree of the valve EV when such an abnormal sound is likely to occur, the abnormal sound can be prevented or suppressed.

Hereinafter, control for preventing or suppressing the above-described abnormal sound when the compressor is in an operating state in the non-surge region will be described based on the flowchart of fig. 2. Wherein the routine of fig. 2 is repeated at regular time intervals. The control of the valve EV described below is premised on: the compressor is in an operating state in the non-surge region, and even the closed driving of the throttle valve THV does not cause the operating state of the compressor to enter the surge region.

The ECU100 determines in step S201 whether the valve EV is in the closed state. The valve EV is normally in a closed state. When the valve EV is in the closed state, an affirmative determination is made in step S201. When the valve EV is in the open state, a negative determination is made in step S201.

When an affirmative determination is made in step S201 because the valve EV is in the closed state, it is determined in step S203 whether or not the throttle valve THV is driven closed. Basically, the ECU100 controls the opening degree of the throttle valve THV to the depression amount of the accelerator pedal operated by the driver, that is, to an opening degree corresponding to the accelerator opening degree detected (acquired) from the output of the accelerator opening degree sensor 91. In addition, ECU100 controls the opening degree of throttle valve THV to an opening degree calculated from the acquired accelerator opening degree or the like, according to a program or the like predetermined in consideration of fuel consumption or the like. When the ECU100 determines to close (close-drive) the throttle valve in the open state to the full close by the operation of the opening degree control of the throttle valve THV, the ECU100 makes an affirmative determination in step S203. When the throttle valve THV is not driven to close (i.e., is controlled to be opened to an opening degree larger than the full close), the ECU100 makes a negative determination in step S203.

If an affirmative determination is made in step S203 by closing and driving the throttle valve THV, it is determined in step S205 whether or not the intake pressure is equal to or higher than a predetermined pressure. The intake pressure here is a pressure detected (obtained) from the output of the boost pressure sensor 94, and is a boost pressure. The intake pressure to be determined in step S205 is the intake pressure on the downstream side of the throttle valve THV, but may be the intake pressure on the upstream side of the throttle valve THV if the intake pressure is the intake pressure on the downstream side of the compressor 32. When the ECU100 estimates the intake air pressure on the downstream side of the compressor 32 in the calculation of the engine control, the estimated intake air pressure may be used in step S205. The predetermined pressure is determined in advance based on experiments, and is set to be equal to or less than a limit value of a pressure at which the abnormal sound is likely to be generated. When the intake air pressure is equal to or higher than the predetermined pressure, an affirmative determination is made in step S205. When the intake air pressure is less than the predetermined pressure, a negative determination is made in step S205.

If a negative determination is made in step S203 because throttle valve THV is not being closed or if a negative determination is made in step S205 because the intake pressure is less than the predetermined pressure, the routine proceeds to step S207 to close valve EV. That is, the ECU100 outputs an operation signal to the actuator of the valve EV so as to close the valve EV. As a result, when a negative determination is made in step S203 or step S205, the valve EV is maintained in the closed state. Further, the routine ends through step S207.

On the other hand, if an affirmative determination is made in step S203 by closing and driving the throttle valve THV and an affirmative determination is made in step S205 by setting the intake air pressure to a predetermined pressure or higher, the routine proceeds to step S209 to open the valve EV. That is, the ECU100 outputs an operation signal to the actuator of the valve EV so as to open the valve EV. The opening degree of the valve EV that is opened at this time is fully opened. However, when the valve EV can be opened to an arbitrary opening degree other than the full opening degree, a target opening degree of the valve EV may be determined in accordance with data or a program preliminarily determined by experiments based on the acquired intake air pressure or the like, and the valve EV may be controlled so as to be the target opening degree. Further, the routine ends through step S209.

The closed discharge passage RT is opened by opening the valve EV after the step S209, and as a result, the intake air (pressure) of the intake passage portion 21a on the downstream side of the compressor can be discharged to the intake passage portion 21b on the upstream side of the compressor. Therefore, the occurrence of the abnormal sound as described above can be prevented or suppressed.

In step S201 of the routine after the passage of step S209, the valve EV is opened, and therefore a negative determination is made. Thereby proceeding to step S211. In step S211, it is determined whether or not a predetermined time has elapsed. The time to be determined is the time from when the valve EV is controlled to be opened in step S209, and is measured by timer means (time measuring means) of the ECU 100. The predetermined time is a time until the possibility of occurrence of an abnormal sound decreases or becomes zero, and is determined in advance based on experiments and is set to be equal to or longer than a time required until the intake pressure on the downstream side of the compressor 32 and the upstream side of the throttle valve THV becomes lower than the second predetermined pressure. For example, the predetermined time is 2 to 3 seconds. Here, the second predetermined pressure is the same as the predetermined pressure in step S205, but may be different from the predetermined pressure. For example, the second prescribed pressure is determined as a pressure lower than the prescribed pressure in step S205.

When a negative determination is made in step S211 because the predetermined time has not elapsed, the routine ends. On the other hand, when an affirmative determination is made in step S211 because the predetermined time has elapsed, step S207 described above is performed. Thereby, the valve EV is closed as described above.

As described above, according to the above-described control (in the control system including the discharge passage RT, the valve EV, and the control means thereof (the functional portion corresponding thereto of the ECU 100)), when the compressor 32 is in the operating state in the region other than the surge region and the intake pressure of the intake passage portion 21c on the downstream side of the compressor 32 when the throttle valve THV is closed is equal to or higher than the predetermined pressure, the valve EV is opened. This can prevent or suppress the abnormal sound.

Further, when the compressor 32 is in an operating state in a region other than the surge region, and the intake pressure of the intake passage portion 21c on the downstream side of the compressor 32 when the throttle valve THV is closed is less than a prescribed pressure, the valve EV maintains the closed state. Therefore, the opening control of the valve EV can be performed in a limited manner. Therefore, even when the engine is mounted on a vehicle that is driven for a long time, such as a commercial vehicle, the valve EV is operated in a limited manner, and the life of the valve EV can be further increased.

Further, since the valve EV is closed when the possibility of occurrence of an abnormal sound is reduced or zero after the valve EV is opened, the subsequent supercharging by the turbocharger can be prevented from being affected by the open control of the valve EV.

The determination in step S211 is not limited to be performed in time. For example, in the case where the intake passage portion on the downstream side of the compressor 32 and on the upstream side of the throttle valve THV includes an intake pressure sensor, it is also possible to determine whether or not the intake pressure detected (acquired) from the output of the intake pressure sensor is smaller than the second predetermined pressure. In the case where the intake pressure of the engine is estimated from the operating state thereof, such determination may be performed using the estimated (acquired) intake pressure.

As described above, the control of the valve EV described with reference to fig. 2 assumes: the operating state of the compressor is in the non-surge region, and even if the throttle valve THV is driven closed, the operating state of the compressor does not enter the surge region. However, in the case of an engine in which the compressor may enter the surge region due to the closed driving of the throttle valve THV, a determination step may be further provided to determine whether or not the compressor does not enter the surge region even if the throttle valve THV is driven closed. In fig. 2, when the affirmative determination is made in step S201, the determination step may be incorporated in any stage toward step S209 before step S209, and preferably, after step S201 and before step S203. In this determination step, it is possible to determine whether the engine operating state, more specifically, the operating state determined based on the intake air flow rate obtained based on the output of the intake air flow rate sensor 92 and the intake air pressure (supercharging pressure) obtained based on the output of the supercharging pressure sensor 94 is in a non-surge region or a partially predetermined region (region separated from the surge region and not likely to enter the surge region) of the non-surge region. If the determination step is affirmative, the ECU100 may proceed to the step S209. In the case where it is considered that the compressor may enter the surge region due to the closed driving of the throttle valve THV in this determination step and a negative determination is made, the valve EV may be opened to prevent the occurrence of the surge phenomenon as is generally known.

While the present disclosure has been described with reference to the exemplary embodiments, various modifications can be made to the present disclosure. Various substitutions and alterations can be made without departing from the spirit and scope of the present disclosure as defined by the claims of the present application.

For example, in the above embodiment, one discharge passage RT and one valve EV are provided. However, this does not limit the number of discharge passages and the number of valves EV. For example, as shown in fig. 3, two discharge passages RT1, RT2 connecting the

intake passage portions

21a, 21b may be provided, and valves EV1, EV2 may be provided. This makes it possible to flexibly apply a commercially available valve or the like according to the size of the engine or the turbocharger.

The present application is based on the japanese patent application filed on 2017, 8/31 (japanese application 2017-166705), the contents of which are incorporated herein by reference.

[ Industrial Applicability ]

The control system and the control method of the present disclosure are useful in more favorably preventing abnormal sounds that may be generated when a compressor of a turbocharger operates in a non-surge region in an engine with a turbocharger.

[ description of reference numerals ]

10 internal combustion engine (Engine)

30 turbo charger

32 compressor

100 Electronic Control Unit (ECU) (control unit)

THV throttle valve

RT discharge path

EV valve

Claims

1. A control system for a turbocharger-equipped internal combustion engine having a throttle valve on a downstream side of a compressor of a turbocharger, characterized by comprising:

a valve for regulating the opening state of the discharge passage, an

A control unit for controlling the operation of the valve;

2. The control system as set forth in claim 1,

the downstream end of the discharge passage communicates with an intake passage portion on the upstream side of the compressor.

3. The control system according to claim 1 or 2,

the control unit controls the operation of the valve so that the valve is opened when the pressure in the intake passage portion on the downstream side of the compressor is equal to or higher than a first predetermined pressure when the compressor is in an operating state in the non-surge region and the throttle valve is closed, and thereafter, the valve is closed when the pressure on the downstream side of the compressor and on the upstream side of the throttle valve is smaller than a second predetermined pressure.

4. A control method of a valve in a turbocharger-equipped internal combustion engine having a throttle valve on a downstream side of a compressor of the turbocharger, and further having a discharge passage communicating with an intake passage portion on an upstream side of the throttle valve and on a downstream side of the compressor, and a valve for adjusting an open state of the discharge passage, the control method comprising: