JP7268569B2 - Control device for internal combustion engine - Google Patents

Description

The present invention relates to a control device for an internal combustion engine.

Conventionally, in order to reduce intake pulsation noise of an internal combustion engine, there is known a technique of changing the frequency band in which a resonator functions according to the operating state of the internal combustion engine (for example, Patent Documents 1 and 2).

JP 2017-106415 A Japanese Patent No. 3588525

The frequency band in which the resonator functions to reduce the intake pulsating noise is restricted according to the dimensions of parts such as the resonator and the intake passage. Therefore, if an additional component is provided in order to make the frequency band in which the resonator functions variable as in the prior art, there is a risk of an increase in mounting space and cost.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a control device for an internal combustion engine capable of reducing intake pulsating noise while suppressing an increase in the mounting space and cost of parts for reducing intake pulsating noise.

A control device for an internal combustion engine according to one aspect of the present invention is a control device for an internal combustion engine having a turbocharger in an intake passage, comprising: a rotation speed detection unit for detecting the rotation speed of the internal combustion engine; , the pressure amplitude ratio of the pressure amplitude downstream of the compressor of the turbocharger divided by the pressure amplitude upstream of the compressor is greater when the speed satisfies a predetermined resonance condition than when the speed does not satisfy the resonance condition. and a controller for controlling the turbocharger.

In the control device for an internal combustion engine according to one aspect of the present invention, when the rotational speed satisfies the predetermined resonance condition, the pressure amplitude downstream of the compressor of the turbocharger is increased compared to when the rotational speed does not satisfy the resonance condition. The turbocharger is controlled to increase the pressure amplitude ratio divided by the upstream pressure amplitude. As a result, for example, if the pressure amplitude (the magnitude of the intake pulsating noise) downstream of the compressor of the turbocharger, which is the source of the intake pulsating noise, is kept substantially constant as a reference, the compressor when the rotational speed satisfies the resonance condition. is less than the pressure amplitude upstream of the compressor if the speed does not satisfy the resonance condition. In this way, the pressure amplitude propagating upstream of the compressor is reduced by controlling the turbocharger, so that the energy of the intake pulsating noise upstream of the compressor is attenuated without adding a separate component for reducing intake pulsating noise, for example. can be made Therefore, according to the control device for an internal combustion engine according to one aspect of the present invention, it is possible to reduce intake pulsating noise while suppressing an increase in mounting space and cost of parts for reducing intake pulsating noise. .

In one embodiment, the turbocharger is a variable displacement turbocharger including a variable diffuser vane provided on the compressor side, and the controller controls prestored vane opening data when the rotational speed satisfies the resonance condition. Based on, the variable diffuser vane may be controlled so that the resonance suppression vane opening, which is the vane opening on the closing side, is obtained as compared with the efficiency-prioritized vane opening, which is the vane opening with priority given to compressor efficiency. . In this case, by controlling the vane opening of the variable diffuser vane, the energy of the intake pulsating noise upstream of the compressor can be attenuated.

In one embodiment, the vane opening data includes reference vane opening data that is preset such that the vane opening is an efficiency-prioritizing vane opening, and vane opening that is preset such that the vane opening is a resonance suppression vane opening. and the resonance suppression vane opening data obtained by the control unit, when it is determined that the rotation speed does not satisfy the resonance condition, the control unit controls the variable diffuser vane using the reference vane opening data, and the rotation speed does not resonate. If it is determined that the condition is met, the resonance suppression vane opening data may be used to control the variable diffuser vanes. In this case, the variable diffuser vanes can be controlled by properly using the reference vane opening data and the resonance suppression vane opening data according to the determination result of whether or not the rotational speed satisfies the resonance condition.

In one embodiment, a control device for an internal combustion engine includes a compressor state quantity detector that detects a compressor state quantity including at least a downstream pressure of the compressor, and the variable displacement turbocharger includes a variable nozzle provided on the turbine side. , the control unit controls the variable nozzle so that the compressor state quantity approaches the reference compressor state quantity, which is the compressor state quantity when the vane opening is the efficiency-prioritizing vane opening, when the rotational speed satisfies the resonance condition. You may In this case, since the compressor state quantity is brought close to the reference compressor state quantity while the energy of the intake pulsating noise upstream of the compressor is attenuated, both the reduction of the intake pulsating noise and the maintenance of the output and fuel consumption performance of the internal combustion engine are achieved. can be achieved.

In one embodiment, the controller may control the turbocharger to at least intermittently choke the compressor when the rotational speed satisfies the resonance condition. In this case, the energy of the intake pulsating noise upstream of the compressor can be attenuated by utilizing the characteristic of the compressor that causes the choke phenomenon.

ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to reduce an intake pulsating sound, suppressing the mounting space of the components for reduction of an intake pulsating sound, and the increase in cost.

1 is a schematic configuration diagram showing an engine system including a control device for an internal combustion engine according to one embodiment; FIG. 2 is an exemplary cross-sectional view of the variable displacement turbocharger of FIG. 1; FIG. It is a diagram. (a) is a figure which illustrates the open state of a diffuser vane. (b) is a diagram illustrating a closed state of diffuser vanes. (a) is a figure which illustrates the open state of a nozzle vane. (b) is a diagram illustrating a closed state of the nozzle vanes. FIG. 2 is a block diagram showing the configuration of an ECU in FIG. 1; FIG. FIG. 4 is a schematic diagram illustrating compressor characteristics; FIG. 3 is a schematic diagram for explaining compressor efficiency; FIG. 2 is a schematic diagram for explaining vane opening degree control of the ECU in FIG. 1 ; FIG. 2 is a flowchart illustrating processing of an ECU in FIG. 1; FIG. FIG. 2 is another flowchart illustrating the processing of the ECU of FIG. 1; FIG.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or equivalent elements are denoted by the same reference numerals, and overlapping descriptions are omitted.

FIG. 1 is a schematic configuration diagram showing an engine system including a control device for an internal combustion engine according to one embodiment. An engine (internal combustion engine) 1 is, for example, a common rail four-cylinder in-line diesel engine.

The engine 1 has an engine body 2 . The engine body 2 is provided with four cylinders 3 . Each cylinder 3 is provided with an injector 5 for injecting fuel into the combustion chamber 4 . Each injector 5 is connected to a common rail 6 . High-pressure fuel stored in a common rail 6 is supplied to the injectors 5 . The engine 1 has a turbocharger 21 in the intake passage 7 . The turbocharger 21 has a turbine 22 arranged on the exhaust passage 12 side and a compressor 23 arranged on the intake passage 7 side. The engine 1 is mounted, for example, on a vehicle or the like.

An intake passage 7 for drawing air into the combustion chamber 4 is connected to the engine body 2 via an intake manifold 8 . The intake passage 7 is provided with an air cleaner 9, a compressor 23 of a turbocharger 21, an intercooler 10, and a throttle valve 11 in this order from the upstream side in the flow direction of the intake air. An exhaust passage 12 for discharging exhaust gas after combustion is connected to the engine body 2 via an exhaust manifold 13 . The exhaust passage 12 is provided with a catalyst 14 including, for example, a DOC [Diesel Oxidation Catalyst] and a DPF [Diesel Particulate Filter].

The engine 1 includes an EGR unit 15 that recirculates part of exhaust gas after combustion into the combustion chamber 4 as exhaust gas recirculation (EGR) gas. The EGR unit 15 is provided so as to connect the intake passage 7 and the exhaust manifold 13 . The EGR unit 15 includes an EGR passage 16 for circulating EGR gas, an EGR valve 17 for adjusting the recirculation amount of EGR gas, an EGR cooler 18 for cooling the EGR gas, a bypass passage 19 for bypassing the EGR cooler 18, an EGR It has a switching valve 20 for switching the gas flow path to the EGR cooler 18 side or the bypass passage 19 side.

As shown in FIG. 2 , the turbine 22 has a turbine wheel 24 and a turbine housing 25 that houses the turbine wheel 24 . The turbine housing 25 is formed with a scroll passage 25a and an exhaust passage 25b. The scroll passage 25 a and the discharge passage 25 b communicate with the exhaust passage 12 . The scroll passage 25a is a passage for swirling the exhaust gas from the exhaust manifold 13. As shown in FIG. The discharge passage 25b is located downstream of the scroll passage 25a and is a passage for discharging the exhaust gas in the scroll passage 25a through the turbine wheel 24. As shown in FIG.

The compressor 23 has a compressor impeller 26 and a compressor housing 27 that accommodates the compressor impeller 26 . The compressor housing 27 is formed with an introduction passage 27a and a delivery passage 27b. The introduction passage 27 a and the delivery passage 27 b communicate with the intake passage 7 . The introduction passage 27 a is a passage for introducing the intake air from the air cleaner 9 . The delivery passage 27b is located on the downstream side of the introduction passage 27a and is a passage for delivering the intake air compressed by the compressor impeller 26. As shown in FIG.

Turbine wheel 24 and compressor impeller 26 are connected by turbine shaft 28 . The turbine shaft 28 is rotatably supported by the intermediate housing 29 via bearings (not shown).

The turbocharger 21 includes a variable diffuser vane 21a provided on the compressor 23 side and a variable nozzle 21b provided on the turbine 22 side. That is, the engine 1 has a turbocharger 21 configured as a variable displacement turbocharger.

FIG. 3A is a diagram illustrating an open state of diffuser vanes. FIG.3(b) is a figure which illustrates the closed state of a diffuser vane. As shown in FIGS. 2 and 3 , the variable diffuser vane 21 a has an annular diffuser plate 30 and a plurality of diffuser vanes 32 rotatably attached to the diffuser plate 30 via a rotating shaft 31 . are doing. Each diffuser vane 32 adjusts the direction and flow velocity of intake air flowing from the introduction passage 27a of the compressor housing 27 to the delivery passage 27b. Each diffuser vane 32 is arranged at regular intervals in the circumferential direction of the diffuser plate 30 . Each rotating shaft 31 is connected to a unison ring 33 via an arm (not shown) and rotates in synchronization with the rotation of the unison ring 33 . The unison ring 33 is configured to be driven by a drive section 34 (see FIG. 1) via a drive mechanism (not shown). A known structure can be used for the structure around the unison ring 33 including the rotating shaft 31 and the drive mechanism. The drive unit 34 is electrically connected to an ECU 60, which will be described later, and the operation of the drive unit 34 is controlled by the ECU 60 (details will be described later).

FIG. 4(a) is a diagram illustrating an open state of the nozzle vanes. FIG.4(b) is a figure which illustrates the closed state of a nozzle vane. As shown in FIGS. 2 and 4, the variable nozzle 21b has an annular nozzle plate 40 and a plurality of nozzle vanes 42 rotatably attached to the nozzle plate 40 via a rotating shaft 41. there is Each nozzle vane 42 adjusts the direction and flow velocity of the exhaust gas flowing from the scroll passage 25a of the turbine housing 25 to the discharge passage 25b. Each nozzle vane 42 is arranged at regular intervals in the circumferential direction of the nozzle plate 40 . Each rotating shaft 41 is connected to a unison ring 43 via an arm (not shown) and rotates in synchronization with the rotation of the unison ring 43 . The unison ring 43 is configured to be driven by a drive section 44 (see FIG. 1) via a drive mechanism (not shown). A known structure can be used for the structure around the unison ring 43 including the rotating shaft 41 and the drive mechanism. The drive unit 44 is electrically connected to an ECU 60, which will be described later, and the operation of the drive unit 44 is controlled by the ECU 60 (details will be described later).

The internal combustion engine control device 100 controls the turbocharger 21 in order to reduce intake pulsation noise of the engine 1 . More specifically, the control device 100 for the internal combustion engine controls the variable diffuser vanes 21a and the variable nozzles 21b so as to suppress resonance of intake pulsation.

5 is a block diagram showing the configuration of the ECU in FIG. 1. FIG. As shown in FIGS. 1 and 5, the control device 100 for an internal combustion engine includes an engine speed sensor (rotation speed detector) 51, an accelerator sensor 52, an air flow sensor (compressor state quantity detector) 53, and a downstream sensor. It includes a pressure sensor 54 (compressor state quantity detection section), an upstream pressure sensor (compressor state quantity detection section) 55 , a turbine speed sensor 56 , and an ECU [Electronic Control Unit] (control section) 60 . The ECU 60 is connected to the sensors 51 to 56, the variable diffuser vane 21a, and the variable nozzle 21b.

The engine rotation speed sensor 51 is a detector that detects, for example, the rotation speed of the crankshaft of the engine 1 as the rotation speed of the engine 1 (hereinafter referred to as engine rotation speed). The engine speed sensor 51 transmits a detection signal of the detected engine speed to the ECU 60 .

The accelerator sensor 52 is attached to, for example, an accelerator pedal of the vehicle. The accelerator sensor 52 detects the accelerator opening of the accelerator pedal as the load on the engine 1 when the driver is driving the vehicle, for example. The accelerator sensor 52 transmits a detection signal of the detected accelerator opening to the ECU 60 .

The airflow sensor 53 is a detector that detects the intake air amount of the engine 1 . The airflow sensor 53 is provided, for example, between the air cleaner 9 and the compressor 23 in the intake passage 7 . The airflow sensor 53 transmits a detection signal of the detected amount of intake air to the ECU 60 .

The downstream pressure sensor 54 is provided, for example, between the compressor 23 and the intercooler 10 in the intake passage 7, and is a detector that detects the pressure of intake air on the downstream side of the compressor 23 as the downstream pressure. The downstream pressure sensor 54 transmits a detection signal of the detected downstream pressure to the ECU 60 .

The upstream pressure sensor 55 is provided, for example, between the air cleaner 9 and the compressor 23 in the intake passage 7, and is a detector that detects the pressure of intake air on the upstream side of the compressor 23 as the upstream pressure. The upstream pressure sensor 55 transmits a detection signal of the detected upstream pressure to the ECU 60 .

The turbine rotation speed sensor 56 is a detector that detects the rotation speed of the turbine shaft 28 (hereinafter referred to as "turbine rotation speed"). The turbine speed sensor 56 may be mounted near the turbine shaft 28 in the intermediate housing 29, for example. A turbine speed sensor 56 outputs a detected value of the turbine speed to the ECU 60 .

Based on the engine speed, the ECU 60 adjusts the pressure amplitude downstream of the compressor 23 of the turbocharger 21 when the engine speed satisfies a predetermined resonance condition compared to when the engine speed does not satisfy the resonance condition. The turbocharger 21 is controlled so that the pressure amplitude ratio divided by the upstream pressure amplitude becomes large. As an example, the ECU 60 controls the variable diffuser vanes based on the vane opening data stored in advance based on the engine speed (details will be described later).

The ECU 60 is an electronic control unit having a CPU [Central Processing Unit], a ROM [Read Only Memory], a RAM [Random Access Memory], a CAN [Controller Area Network] communication circuit, and the like. The ECU 60 implements various functions by loading programs stored in the ROM into the RAM and executing the programs loaded into the RAM by the CPU. The ECU 60 may be composed of a plurality of electronic control units.

The ECU 60 includes an engine state acquisition unit 61, a compressor state acquisition unit 62, a vane opening data storage unit 63, a nozzle opening data storage unit 64, a vane opening control unit 65, a nozzle opening control unit 65, and a nozzle opening control unit 65. and a degree control unit 66 .

The engine state acquisition unit 61 acquires the engine state based on the detection results of the sensors 51-55. The engine state acquisition unit 61 detects, for example, the engine speed detected by the engine speed sensor 51, the accelerator opening detected by the accelerator sensor 52, the intake air amount detected by the airflow sensor 53, and the downstream pressure sensor 54. The detected downstream pressure and the upstream pressure detected by the upstream pressure sensor 55 are acquired as the engine state.

Note that the engine state acquisition unit 61 may calculate the fuel injection amount and the target air-fuel ratio of the engine 1 according to the accelerator opening and the engine speed, for example, by a known method. The engine state acquisition unit 61 may calculate the target intake air amount of the engine 1 based on the calculated fuel injection amount and target air-fuel ratio.

The engine state acquisition unit 61 determines whether or not the engine speed satisfies the resonance condition based on the engine speed. The resonance condition is a condition corresponding to whether or not the intake sound of the engine 1 resonates due to the intake pulsation of the engine 1 . The intake pulsation means the pressure pulsation in the intake passage 7 generated by the up-and-down reciprocating motion of the piston in the cylinder 3 and the opening and closing operation of the intake valve. Intake pulsation occurs in the intake passage 7 downstream of the compressor 23 and propagates upstream of the compressor 23 via the compressor 23 .

The pressure amplitude downstream of the compressor 23 means the amplitude of intake pulsation downstream of the compressor 23 and corresponds to the downstream pressure detected by the downstream pressure sensor 54 here. The pressure amplitude upstream of the compressor 23 means the amplitude of intake air pulsation on the upstream side of the compressor 23 and corresponds to the upstream pressure detected by the upstream pressure sensor 55 here. The pressure amplitude ratio corresponds, as an example, to the pressure ratio across the compressor 23, which is the downstream pressure divided by the upstream pressure.

The resonance condition can be, for example, whether or not the intake pulsation frequency matches the resonance frequency of the intake passage 7 . The intake pulsation frequency has a component proportional to the order of the engine speed. More specifically, the intake pulsation frequency has a fundamental order component of frequency corresponding to the engine speed and a harmonic component directly proportional to the fundamental order component. Further, the resonance condition here is a condition in which the opening degree of the diffuser vane 32 described later (hereinafter simply referred to as "vane opening degree") is a predetermined efficiency-priority vane opening degree.

When the vane opening degree is a predetermined efficiency-prioritizing vane opening degree, and the fundamental order component or the harmonic component is the engine speed that matches the resonance frequency of the intake passage 7, the engine state acquisition unit 61 determines the engine speed satisfies the resonance condition. In this case, the intake pulsation sound of the engine 1 may be amplified and cause a problem. On the other hand, when the vane opening degree is a predetermined efficiency-prioritizing vane opening degree and the fundamental order component or the harmonic component is not at an engine speed that matches the resonance frequency of the intake passage 7, the engine state acquisition unit 61 It is determined that the rotation speed does not satisfy the resonance condition. In this case, the intake pulsating sound of the engine 1 is not amplified by resonance, so compared to the case where the engine speed satisfies the resonance condition, the intake pulsating sound of the engine 1 is less likely to cause a problem.

The compressor state acquisition unit 62 acquires the compressor state based on the detection results of the sensors 53-56. A compressor state means an operating state of the compressor 23 . The compressor state is represented by compressor state quantities including, for example, the flow rate of the compressor 23, the pressure ratio before and after the compressor 23, and the turbine speed. Specifically, the compressor state acquisition unit 62 acquires the intake air amount as the flow rate of the compressor 23 . The compressor state acquisition unit 62 acquires a value obtained by dividing the downstream pressure by the upstream pressure as the pressure ratio before and after the compressor 23 . A compressor state acquisition unit 62 acquires the turbine rotation speed detected by the turbine rotation speed sensor 56 .

Note that the compressor state acquisition unit 62 obtains, for example, a target value of the downstream pressure of the compressor 23 and a target value of the pressure ratio before and after the compressor 23 (hereinafter referred to as "target pressure ratio") based on the target intake air amount by a known method. ), and a target value of the flow rate of the compressor 23 (hereinafter also referred to as “target flow rate”). The compressor state acquisition unit 62 may calculate a target value of the turbine rotation speed (hereinafter also referred to as “target turbine rotation speed”) from the target pressure ratio, the target flow rate, and the compressor characteristics.

FIG. 6 is a schematic diagram illustrating compressor characteristics. The horizontal axis of FIG. 6 indicates the flow rate of the compressor 23 and the vertical axis indicates the pressure ratio before and after the compressor 23 . FIG. 6 shows, as an example, the compressor characteristic CR1 when the vane opening is an efficiency-prioritizing vane opening, which will be described later.

As shown in FIG. 6, the compressor characteristic CR1 includes lines N1, N2, and N3 connecting operating points of the compressor 23 when the turbine speed is constant. The operating point of the compressor 23 (hereinafter also simply referred to as "operating point") means a coordinate point determined by the flow rate and pressure ratio within the range of the flow rate and pressure ratio in which the compressor 23 can operate. In lines N1, N2, and N3, the turbine speed increases in the order of lines N1, N2, and N3. As shown in FIG. 6, when the turbine speed is constant, the pressure ratio across the compressor 23 tends to decrease significantly as the flow rate increases beyond a certain flow rate.

FIG. 7 is a schematic diagram for explaining compressor efficiency. The horizontal axis of FIG. 7 indicates the flow rate of the compressor 23 and the vertical axis indicates the pressure ratio before and after the compressor 23 . In FIG. 7, as an example, similar to FIG. 6, the vane opening is set to the efficiency-priority vane opening described later. As shown in FIG. 7, the compressor 23 has compressor efficiency depending on the operating point. For example, by connecting point groups of operating points having the same efficiency, it is possible to obtain a distribution of compressor efficiency as indicated by a plurality of contour lines E1, E2, etc. in FIG. Compressor efficiency is a kind of indicator of the supercharging performance of the turbocharger 21 and is represented by, for example, the ratio between the upstream pressure of the compressor 23 and the flow rate. Compressor efficiency can be identified, for example, by simulated performance prediction or performance evaluation.

In FIG. 7, a region surrounded by a dashed line L1 corresponds to a region where an operating point can exist within the range of operable turbine speeds when the vane opening degree is the efficiency-prioritizing vane opening degree. A dashed-dotted line L2 is a line connecting operating points at which the compressor 23 operates at maximum efficiency at each flow rate (a so-called maximum efficiency operating line). Note that when the vane opening is a resonance suppression vane opening, which will be described later, compared to the case where the vane opening is the efficiency-prioritizing vane opening as shown in FIG. Shift to the low flow rate side.

As shown in FIGS. 6 and 7, an area A2 surrounded by a dashed line L3 is an area where the flow rate of the compressor 23 is larger (on the high flow side) than that of the dashed line L2. In the region A2, compared to the region A1 where the flow rate of the compressor 23 is smaller than the flow rate of the compressor 23 (on the low flow side) than that of the dashed line L2 in the region surrounded by the dashed line L1, the compressor efficiency when the turbine rotation speed is constant is higher than the flow rate. It decreases remarkably with the increase. In the region A2, it is considered that the compressor efficiency tends to decrease remarkably as described above due to the intermittent (or localized) choke phenomenon of the compressor 23, for example.

The vane opening data storage unit 63 stores vane opening data representing a preset vane opening for controlling the variable diffuser vanes 21a. The vane opening degree data storage unit 63 may be the ROM of the ECU 60, for example. The vane opening data includes reference vane opening data and resonance suppression vane opening data.

The reference vane opening degree data is data that serves as a reference for controlling the vane opening degree, and is set in advance so that the vane opening degree becomes the efficiency-priority vane opening degree. The efficiency-prioritized vane opening is a vane opening that gives priority to compressor efficiency over suppression of intake pulsation resonance, and is set according to the flow rate of the compressor 23 and the turbine rotation speed to maximize the compressor efficiency. The efficiency-prioritizing vane opening degree can be set, for example, to an angle along the streamline direction of the airflow that is less likely to cause separation in the airflow that has flowed from the compressor impeller 26 to the diffuser vane 32 . The efficiency-priority vane opening is set in advance by, for example, a compressor performance test or performance prediction simulation. The efficiency-priority vane opening may correspond to, for example, the open state of the diffuser vanes as shown in FIG. 3(a).

The resonance suppression vane opening data is vane opening data used to suppress resonance of intake pulsation, and is preset so that the vane opening is the resonance suppression vane opening. The resonance suppression vane opening is a vane opening that prioritizes suppression of intake pulsation resonance over compressor efficiency, and is set so that the compressor efficiency is lower than the maximum according to the flow rate of the compressor 23 and the turbine rotation speed. be.

The resonance suppression vane opening is, for example, a vane opening on the closing side compared to the efficiency priority vane opening. The closed side of the vane opening means that the crossing angle with respect to the air flow from the compressor impeller 26 becomes larger, and means that the diffuser vane is brought closer to the closed state as shown in FIG. 3(b). The resonance suppression vane opening may be, for example, a vane opening that causes the compressor 23 to choke at least intermittently. The resonance suppression vane opening may be set as a vane opening correction value for correcting the vane opening to the closing side based on the vane opening of the reference vane opening data, or the vane opening of the reference vane opening data. may be the value of the vane opening itself set on the closing side with reference to . The resonance suppression vane opening degree can be set in advance by comparing the decrease in the pressure amplitude upstream of the compressor 23 obtained by, for example, a compressor performance test or performance prediction simulation and the effect of damping intake pulsation.

The nozzle opening degree data storage unit 64 stores nozzle opening degree data representing a preset opening degree (nozzle opening degree) of the variable nozzle 21b for controlling the variable nozzle 21b. The nozzle opening degree data storage unit 64 may be the ROM of the ECU 60, for example. The nozzle opening data includes reference nozzle opening data and acceleration nozzle opening data.

The reference nozzle opening degree data is nozzle opening degree data that serves as a reference for controlling the nozzle opening degree. The reference nozzle opening data is set in advance, for example, as a nozzle opening such that the flow velocity of the exhaust gas flowing from the turbine wheel 24 into the nozzle vanes 42 is such that the turbine rotation speed determined by a predetermined exhaust request can be achieved. there is

The speed-increasing nozzle opening data is nozzle opening data used to increase the turbine speed. The speed-increasing nozzle opening data is, for example, a nozzle at which the flow velocity of the exhaust gas flowing from the turbine wheel 24 into the nozzle vane 42 becomes a flow velocity capable of achieving a higher turbine rotation speed than the exhaust request based on the reference nozzle opening data. The degree of opening is set in advance. The acceleration nozzle opening data may be set, for example, as a nozzle opening correction value for correcting the nozzle opening to the closing side with reference to the nozzle opening of the reference nozzle opening data, It may be the value of the nozzle opening itself which is set to the closing side with reference to the opening. The speed-increasing nozzle opening data may be at least an opening closer to the closing side (full-closed opening side) than the reference nozzle opening data. It should be noted that the open side of the nozzle opening means that the cross-sectional area of the exhaust gas flow path increases, and means that the nozzle vane is brought closer to the open state as shown in FIG. 4(a). The closing side of the nozzle opening means that the flow velocity of the exhaust gas increases, and means that the nozzle vanes are brought closer to the closed state as shown in FIG. 4(b).

When the engine speed satisfies a predetermined resonance condition, the vane opening degree control unit 65 controls the resonance suppression vane opening degree, which is the vane opening degree closer to the closing side than the efficiency priority vane opening degree, based on the vane opening degree data. The variable diffuser vane 21a is controlled so that

Specifically, for example, when the engine state acquisition unit 61 determines that the engine speed does not satisfy the resonance condition, the vane opening control unit 65 adjusts the variable diffuser vanes 21a using the reference vane opening data. Control. More specifically, when the vane opening degree is the efficiency-prioritizing vane opening degree, for example, the vane opening degree control unit 65 controls the engine speed at which the fundamental order component or the harmonic component does not match the resonance frequency of the intake passage 7. , the variable diffuser vane 21a is controlled so that the vane opening becomes the efficiency-priority vane opening.

For example, when the engine state acquisition unit 61 determines that the engine speed satisfies the resonance condition, the vane opening degree control unit 65 controls the variable diffuser vane 21a using the resonance suppression vane opening degree data. More specifically, when the vane opening degree is the efficiency-prioritizing vane opening degree, the vane opening degree control unit 65 determines that the engine speed is such that the fundamental order component or the harmonic component matches the resonance frequency of the intake passage 7. The variable diffuser vane 21a is controlled so that the vane opening becomes the resonance suppression vane opening when the state acquiring unit 61 determines. That is, the vane opening degree is set to the closing side vane opening degree compared to the efficiency-priority vane opening degree.

FIG. 8 is a schematic diagram for explaining the vane opening degree control of the ECU 60. As shown in FIG. The horizontal axis of FIG. 8 indicates the flow rate of the compressor 23 and the vertical axis indicates the pressure ratio before and after the compressor 23 . In FIG. 8, the compressor characteristic CR1 in the case of the efficiency-prioritizing vane opening shown in FIG. 6 is indicated by a dashed line, and the compressor characteristic CR2 in the case of the resonance suppression vane opening is indicated by a solid line. The compressor characteristic CR2 includes lines M1, M2, and M3 connecting operating points of the compressor 23 when the turbine speed is constant. The turbine speeds at lines M1, M2, M3 are equal to the turbine speeds at lines N1, N2, N3, respectively.

As shown in FIG. 8, first, at the operating point P1, the vane opening is set to the efficiency-priority vane opening, and the turbine rotation speed corresponds to the line N2. In this state, when the engine state acquisition unit 61 determines that the engine speed is such that the fundamental order component or the harmonic component matches the resonance frequency of the intake passage 7, the opening of the vane becomes the opening of the resonance suppression vane. The variable diffuser vanes 21a are controlled in such a manner that the opening of the vanes is on the closing side compared to the opening of the vanes prioritizing efficiency. As a result, the compressor 23 is operated at the operating point P2 in the compressor characteristic CR2. At the operating point P2, the variation gradient of the pressure ratio before and after the compressor 23 with respect to the change in flow rate (slope of the tangent line of the line M2 at the operating point P2) is the variation gradient at the compressor characteristic CR1 (the tangent line of the line N2 at the operating point P1 slope).

Here, the operating point P1 and the operating point P2 have different vane openings, but the engine speed, the opening and closing timings of the intake valves of the cylinders 3, etc. are the same. Therefore, at the operating point P1 and the operating point P2, the intake pulsation on the downstream side of the compressor 23 is the same, and the amplitude of the intake pulsation (pressure amplitude downstream of the compressor 23) can be said to be the same. On the other hand, in the pressure amplitude ratio corresponding to the pressure ratio, the numerator is the pressure amplitude downstream of the compressor 23 and the denominator is the pressure amplitude upstream of the compressor 23. At the operating point P2 of the compressor characteristic CR2, the pressure amplitude The variation gradient of the pressure ratio corresponding to the ratio is larger than the operating point P1. That is, at the operating point P2, the pressure amplitude downstream of the compressor 23 is the same as that at the operating point P1, whereas the intake pulsation amplitude upstream of the compressor 23 (pressure amplitude upstream of the compressor 23) is smaller. It turns out that there is In other words, when the pressure amplitude (the magnitude of the intake pulsating noise) downstream of the compressor 23, which is the source of the intake pulsating noise, is substantially constant, the engine speed satisfies the resonance conditions. is smaller than the pressure amplitude upstream of the compressor 23 when the engine speed does not satisfy the resonance condition. As a result, the intake pulsating noise that propagates upstream of the compressor 23 is attenuated when the engine speed satisfies the resonance condition. At the operating point P2 of the compressor characteristic CR2, for example, a choke phenomenon may occur intermittently.

By the way, for example, if you try to suppress the occurrence of intake pulsation itself while maintaining the state where the vane opening is the efficiency priority vane opening, the intake air entering the combustion chamber will deviate from the optimal state. This may lead to a decrease in the volumetric efficiency of the cylinder 3. As a result, there is a possibility that the flow rate of the compressor 23 will decrease, leading to a decrease in the output performance and fuel efficiency of the engine 1 . In this respect, as described above, by setting the vane opening degree on the closing side as compared to the vane opening degree prioritizing efficiency, it is possible to attenuate the intake pulsation on the upstream side of the compressor 23 by utilizing the increased fluctuation of the pressure ratio. It becomes possible. As a result, compared with the case where the volumetric efficiency of the cylinder 3 is lowered, the decrease in the flow rate of the compressor 23 is suppressed, and the deterioration in the output performance and fuel efficiency of the engine 1 can be suppressed.

The nozzle opening controller 66 may control the variable nozzle 21b so that the compressor state quantity approaches the reference compressor state quantity when the engine speed satisfies the resonance condition. The reference compressor state quantity is a compressor state quantity when the vane opening is the efficiency-priority vane opening. As the reference compressor state quantity, for example, the target pressure ratio when the vane opening is the efficiency-prioritizing vane opening can be used. For example, the target turbine speed may be used as the reference compressor state quantity.

Specifically, for example, when the engine state acquisition unit 61 determines that the engine speed does not satisfy the resonance condition, the nozzle opening control unit 66 controls the variable nozzle 21b using the reference nozzle opening data. do. For example, when the vane opening control unit 65 controls the variable diffuser vanes 21a so that the efficiency-prioritizing vane opening is achieved, the nozzle opening control unit 66 controls the variable nozzles 21b using the reference nozzle opening data. .

For example, when the engine state acquisition unit 61 determines that the engine speed satisfies the resonance condition, the nozzle opening control unit 66 controls the variable nozzle 21b so that the turbine speed becomes the target turbine speed. . For example, when the vane opening control unit 65 controls the variable diffuser vanes 21a to achieve the resonance suppression vane opening, the nozzle opening control unit 66 increases the turbine rotation speed to the target turbine rotation speed. The variable nozzle 21b is controlled using the fast nozzle opening data. That is, the nozzle opening degree is set to a nozzle opening degree on the closed side compared to the reference nozzle opening degree.

As shown in FIG. 8, as a result of controlling the variable diffuser vanes 21a so that the vane opening degree changes from the efficiency-prioritizing vane opening degree to the resonance suppression vane opening degree, the compressor 23 operating at the operating point P1 is , the operating point P2. As a result, the pressure ratio at the operating point P2 is lower than the target pressure ratio (that is, the pressure ratio at the operating point P1).

Therefore, the target turbine rotation speed is calculated by the compressor state obtaining unit 62 as the turbine rotation corresponding to the line M3 from the target flow rate, the target pressure ratio, and the compressor characteristic CR2. Therefore, since the target turbine rotation speed is increased from the turbine rotation corresponding to the line M2 to the turbine rotation corresponding to the line M3, the variable nozzle 21b is controlled using the speed increasing nozzle opening data. In other words, the compressor 23 operating at the operating point P2 now operates at the operating point P3, and the pressure ratio across the compressor 23 approaches the target pressure ratio. As a result, even when the vane opening is set to the resonance suppression vane opening, it is possible to compensate for a decrease in the pressure ratio before and after the compressor 23, thereby suppressing a decrease in the output performance and fuel efficiency of the engine 1. becomes possible. Incidentally, the operating points P1 and P3 are deviated in the horizontal direction for the sake of clarity in FIG. has a flow rate substantially equal to the flow rate at the operating point P1 near the intersection of .

Next, an example of processing by the ECU 60 will be described with reference to FIG. FIG. 9 is a flowchart illustrating the processing of the ECU of FIG. 1; The process of FIG. 9 is executed, for example, while the engine 1 is running.

As shown in FIG. 9, in S11, the ECU 60 acquires the engine state using the engine state acquiring section 61. FIG. The engine state acquisition unit 61, for example, acquires the engine speed of the engine 1 and calculates the target intake air amount.

In S12, the ECU 60 uses the engine state acquisition unit 61 to determine whether or not the engine speed satisfies the resonance condition. The engine state acquisition unit 61 determines whether or not the engine speed satisfies the resonance condition based on the engine speed.

When the engine state acquisition unit 61 determines that the engine speed does not satisfy the resonance condition (S12: NO), the ECU 60 causes the vane opening control unit 65 to control the variable diffuser using the reference vane opening data in S13. It controls the vanes 21a. In S14, the ECU 60 controls the variable nozzle 21b using the reference nozzle opening data by the nozzle opening controller 66. FIG. After that, the ECU 60 terminates the processing of FIG.

On the other hand, if the engine state acquisition unit 61 determines that the engine speed satisfies the resonance condition (S12: YES), the ECU 60 causes the vane opening control unit 65 to use the resonance suppression vane opening data in S15. It controls the variable diffuser vanes 21a. In S16, the ECU 60 controls the variable nozzle 21b by using the nozzle opening control section 66 using the speed increasing nozzle opening data.

In S<b>16 , the ECU 60 acquires the compressor state quantity using the compressor state acquisition unit 62 . The compressor state acquisition unit 62 acquires the flow rate of the compressor 23, the pressure ratio before and after the compressor 23, and the turbine rotation speed. The compressor state acquisition unit 62 calculates the target turbine speed from the target pressure ratio, target flow rate, and compressor characteristics. The compressor state acquisition unit 62 calculates a target pressure ratio and a target flow rate based on the target intake air amount, and calculates a target turbine speed from the target pressure ratio and the target flow rate. The nozzle opening degree control unit 66 controls the variable nozzle 21b so that the turbine rotation speed becomes the target turbine rotation speed. After that, the ECU 60 terminates the processing of FIG.

As described above, in the control device 100 for the internal combustion engine, when the engine speed satisfies the predetermined resonance condition, the pressure downstream of the compressor 23 of the turbocharger 21 is higher than when the engine speed does not satisfy the resonance condition. The turbocharger 21 is controlled so that the pressure amplitude ratio obtained by dividing the amplitude by the pressure amplitude upstream of the compressor 23 increases (so that the gradient of the pressure ratio before and after the compressor 23 changes with respect to changes in flow rate increases). As a result, for example, if the pressure amplitude (magnitude of the intake pulsating noise) downstream of the compressor 23 of the turbocharger 21, which is the source of the intake pulsating noise, is substantially constant, the engine speed satisfies the resonance condition. The pressure amplitude upstream of the compressor 23 is smaller than the pressure amplitude upstream of the compressor 23 when the engine speed does not satisfy the resonance condition. In this way, since the pressure amplitude propagating upstream of the compressor 23 is reduced by controlling the turbocharger 21, the intake pulsating noise upstream of the compressor 23 can be reduced without adding a component for reducing the intake pulsating noise. Energy can be attenuated. Therefore, according to the control device 100 for an internal combustion engine, it is possible to reduce intake pulsation noise while suppressing an increase in mounting space and cost for components.

In the control device 100 for an internal combustion engine, the turbocharger 21 is a variable displacement turbocharger including a variable diffuser vane 21a provided on the compressor 23 side, and the ECU 60 stores in advance when the engine speed satisfies the resonance condition. Based on the obtained vane opening data, the variable diffuser vanes are adjusted so that the resonance suppression vane opening is the vane opening on the closing side compared to the efficiency priority vane opening which is the vane opening giving priority to the compressor efficiency. 21a. Thus, by controlling the vane opening of the variable diffuser vane 21a, the energy of the intake pulsating noise upstream of the compressor 23 can be attenuated.

In the control device 100 for an internal combustion engine, the vane opening degree data includes the reference vane opening degree data preset so that the vane opening degree becomes the efficiency-prioritizing vane opening degree, and the vane opening degree data set in advance so that the vane opening degree becomes the resonance suppression vane opening degree. and resonance suppression vane opening data preset to . When the ECU 60 determines that the engine speed does not satisfy the resonance condition, the ECU 60 controls the variable diffuser vanes 21a using the reference vane opening data. When the ECU 60 determines that the engine speed satisfies the resonance condition, the ECU 60 controls the variable diffuser vane 21a using the resonance suppression vane opening data. As a result, the variable diffuser vanes 21a can be controlled by appropriately using the reference vane opening data and the resonance suppression vane opening data according to the determination result of whether or not the engine speed satisfies the resonance condition.

The internal combustion engine control device 100 includes a downstream pressure sensor 54 that detects a compressor state quantity including at least the downstream pressure of the compressor 23 . The turbocharger 21 includes a variable nozzle 21b provided on the turbine 22 side. When the engine speed satisfies the resonance condition, the ECU 60 controls the variable nozzle 21b so that the compressor state quantity approaches the reference compressor state quantity, which is the compressor state quantity when the vane opening is the efficiency-prioritizing vane opening. do. As a result, the compressor state quantity (for example, the pressure ratio) is brought closer to the reference compressor state quantity (for example, the target pressure ratio) while the energy of the intake pulsation sound upstream of the compressor 23 is attenuated, so that the intake pulsation sound is reduced and the engine It is possible to achieve both the maintenance of the output of 1 and the fuel efficiency performance.

In the control device 100 for an internal combustion engine, the ECU 60 controls the turbocharger 21 so as to cause the choke phenomenon of the compressor 23 at least intermittently when the engine speed satisfies the resonance condition. As a result, the energy of the intake pulsating noise upstream of the compressor 23 can be attenuated by utilizing the characteristic of the compressor 23 that causes the choke phenomenon.

[Modification]
Although the embodiments according to the present invention have been described above, the present invention is not limited to the above-described embodiments.

In the above embodiment, as an example, as shown in FIG. 9, the control of the vane opening and the nozzle opening when the engine speed satisfies the resonance condition is feedforward control (the vane opening and the nozzle opening). The resonance suppressing vane opening data and speed-increasing nozzle opening data are set so that the degree of opening becomes a predetermined degree in one process, for example, but as shown in FIG. The control of the vane opening and the nozzle opening when the resonance condition is satisfied may be feedback control.

Specifically, in the flowchart of FIG. 10, the processing of S17 and S18 is added to the flowchart of FIG. 9, and the vane opening degree and the nozzle opening degree change gradually as the feedback control is repeated. , the resonance suppression vane opening data and the acceleration nozzle opening data are set as feedback correction values (for example, proportional correction values, integral correction values, etc.).

In S<b>17 of FIG. 10 , the ECU 60 acquires the compressor state quantity using the compressor state acquisition unit 62 . The compressor state acquisition unit 62 acquires, for example, the pressure ratio before and after the compressor 23 as a pressure amplitude ratio. In S18, the ECU 60 uses the compressor state acquisition section 62 to determine whether or not the pressure amplitude ratio is equal to or greater than a predetermined target value. The compressor state acquisition unit 62 determines whether or not the pressure amplitude ratio is equal to or greater than a target value based on the upstream pressure and downstream pressure of the compressor 23 . The target value here is the target value of the pressure amplitude ratio that reduces the pressure amplitude upstream of the compressor 23 so that the intake pulsation damping effect is greater than or equal to a desired constant effect.

When the compressor state acquisition unit 62 determines that the pressure amplitude ratio is not equal to or greater than the target value (S18: NO), the ECU 60 performs the processes of S15 and S16 again. On the other hand, when the compressor state acquisition unit 62 determines that the pressure amplitude ratio is equal to or greater than the target value (S18: YES), the ECU 60 terminates the processing of FIG. As described above, since the pressure amplitude ratio becomes equal to or higher than the target value, it is possible to obtain an intake pulsation damping effect equal to or higher than a desired constant effect.

In the above-described embodiment, the engine rotation speed sensor 51 is used as an example of the rotation speed detection unit, but other sensors may be used as long as they can detect the rotation speed of the internal combustion engine.

In the above embodiment, the air flow sensor 53, the downstream pressure sensor 54, and the upstream pressure sensor 55 were exemplified as the compressor state quantity detectors. A part of the sensors may be omitted, or other sensors or the like may be used. Further, the compressor state quantity including at least the downstream pressure of the compressor may be detected using a known estimation technique.

Note that the nozzle opening degree control unit 66 may feedback-control the variable nozzle 21b based on the determination result as to whether or not the turbine rotation speed has reached the target turbine rotation speed. In this case, the nozzle opening controller 66 feedback-controls the variable nozzle 21b using the speed-increasing nozzle opening data based on the determination result that the turbine rotation speed is less than the target turbine rotation speed. The nozzle opening controller 66 feedback-controls the variable nozzle 21b using the reference nozzle opening data based on the determination result that the turbine rotation speed has reached the target turbine rotation speed.

In the above embodiment, the control of the variable nozzle 21b is performed by the nozzle opening degree control section 66, but it is not necessarily performed from the viewpoint of reducing intake pulsating noise. In this case, the variable nozzle 21b of the turbocharger 21, the turbine speed sensor 56, the nozzle opening degree data storage section 64, and the nozzle opening degree control section 66 may be omitted.

In the above embodiment, the resonance suppressing vane opening has been described as a vane opening that causes the choke phenomenon of the compressor 23 at least intermittently. is sufficient as long as the variation gradient of is large, and the choke phenomenon does not necessarily have to occur.

In the above embodiment, control of the variable diffuser vane 21a was shown as an example of the control target of the turbocharger 21 when the engine speed satisfies the resonance condition, but the control target of the turbocharger 21 is other than the variable diffuser vane 21a. There may be.

In the above embodiment, the pressure amplitude downstream of compressor 23 corresponded to the downstream pressure detected by downstream pressure sensor 54, and the pressure amplitude upstream of compressor 23 corresponded to the upstream pressure detected by upstream pressure sensor 55. However, each pressure amplitude is not limited to these. For example, each pressure amplitude may be the amplitude of the sound pressure of intake pulsation sound upstream or downstream of the compressor 23 . The pressure amplitude ratio corresponds to the pressure ratio before and after the compressor 23, which is the downstream pressure divided by the upstream pressure. may be a value divided by the amplitude of

In the above-described embodiment, the ECU 60 changes the pressure amplitude downstream of the compressor 23 of the turbocharger 21 to the pressure upstream of the compressor 23 when the engine speed satisfies the resonance condition compared to when the engine speed does not satisfy the resonance condition. Although the turbocharger 21 is controlled so as to increase the pressure amplitude ratio divided by the amplitude, substantially the same control may be performed by replacing the numerator and denominator of the pressure amplitude ratio. That is, the ECU 60 divides the pressure amplitude upstream of the compressor 23 of the turbocharger 21 by the pressure amplitude downstream of the compressor 23 when the engine speed satisfies the resonance condition compared to when the engine speed does not satisfy the resonance condition. The turbocharger 21 may be controlled so that the pressure amplitude ratio (reciprocal) becomes smaller.

In the above embodiment, the engine 1 as a diesel engine is exemplified as the internal combustion engine, but other internal combustion engines such as a gasoline engine may be used. The engine 1 does not necessarily have to be mounted on a vehicle or the like.

DESCRIPTION OF SYMBOLS 1... Engine (internal combustion engine), 7... Intake passage, 21... Turbocharger, 21a... Variable diffuser vane, 21b... Variable nozzle, 23... Compressor, 51... Engine rotation speed sensor (rotation speed detection part), 53... Airflow sensor (Compressor state quantity detector) 54 Downstream pressure sensor (compressor state quantity detector) 55 Upstream pressure sensor (compressor state quantity detector) 60 ECU (controller) 100 Internal combustion engine control device.

Claims (5)

A control device for an internal combustion engine having a turbocharger in an intake passage,
a rotation speed detection unit that detects the rotation speed of the internal combustion engine;
Based on the rpm, the pressure amplitude downstream of the compressor of the turbocharger is reduced when the rpm satisfies a predetermined resonance condition compared to when the rpm does not satisfy the resonance condition, compared to the pressure amplitude upstream of the compressor. a control unit that controls the turbocharger so that the pressure amplitude ratio divided by the pressure amplitude increases ,
The resonance condition is a condition corresponding to whether or not the intake sound of the internal combustion engine resonates due to the intake pulsation of the internal combustion engine,
The control unit compares states in which the pressure amplitude downstream of the compressor is substantially constant, and when the rotational speed satisfies the resonance condition, the pressure amplitude upstream of the compressor is adjusted so that the rotational speed satisfies the resonance condition. A controller for an internal combustion engine that controls the turbocharger to be less than the pressure amplitude upstream of the compressor if conditions are not met . The turbocharger is a variable displacement turbocharger including a variable diffuser vane provided on the compressor side,
The control unit
When the rotational speed satisfies the resonance condition, the vane opening is on the closing side compared to the efficiency-prioritized vane opening, which is the vane opening giving priority to the compressor efficiency, based on the pre-stored vane opening data. 2. The control device for an internal combustion engine according to claim 1, wherein said variable diffuser vane is controlled so as to achieve a certain resonance suppression vane opening degree. The vane opening data includes reference vane opening data preset so that the vane opening is the efficiency-prioritizing vane opening, and preset vane opening so that the vane opening is the resonance suppression vane opening. and resonance dampened vane opening data;
The control unit
controlling the variable diffuser vane using the reference vane opening data when it is determined that the rotational speed does not satisfy the resonance condition;
3. The control device for an internal combustion engine according to claim 2, wherein said variable diffuser vane is controlled using said resonance suppression vane opening data when it is determined that said rotational speed satisfies said resonance condition. A compressor state quantity detection unit that detects a compressor state quantity including at least the downstream pressure of the compressor,
The variable displacement turbocharger includes a variable nozzle provided on the turbine side,
The control unit
The variable nozzle is configured such that, when the rotational speed satisfies the resonance condition, the compressor state quantity approaches a reference compressor state quantity, which is the compressor state quantity when the vane opening is the efficiency-priority vane opening. 4. The control device for an internal combustion engine according to claim 2 or 3, which controls the 5. The control unit according to any one of claims 1 to 4, wherein the control unit controls the turbocharger so as to cause choke phenomenon of the compressor at least intermittently when the rotational speed satisfies the resonance condition. internal combustion engine controller.

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