JP6406301B2 - Engine control device - Google Patents

Description

  The technology disclosed herein relates to a control device that controls an engine with a turbocharger.

  In an engine with a turbocharger, a turbine is provided in an exhaust passage, a compressor connected to the turbine is provided in an intake passage, and the turbine is driven to rotate by exhaust exhausted from a combustion chamber of the engine body. As a result, the compressor is driven to rotate, and the amount of intake air into the combustion chamber is increased. In this type of turbocharger, it is known that an air backflow phenomenon in a compressor called surging can occur when the throttle valve opening is reduced.

  In surging, when the throttle valve opening is throttled, the amount of intake air to the engine body decreases, but the turbine continues to rotate for a while, so that there is a gap between the compressor and the throttle valve provided on the downstream side. This is caused by maintaining the intake pressure (supercharging pressure). In order to suppress the occurrence of this surging, it is known to provide an intake air recirculation mechanism including a bypass passage that bypasses the compressor and a bypass valve that opens and closes the bypass passage. The intake air recirculation mechanism is a mechanism for releasing the supercharging pressure to the upstream side of the compressor through the bypass passage by opening the bypass valve when surging is predicted to occur.

  An engine including such an intake air recirculation mechanism is disclosed in Patent Document 1, for example. In the engine disclosed in Patent Document 1, it is predicted whether surging will occur based on the compressor pressure ratio, which is the pressure ratio between the upstream and downstream of the compressor, and the compressor passage flow rate, which is the flow rate of intake air passing through the compressor. In this engine, the throttle valve passage flow rate, which is the flow rate of the intake air that passes through the throttle valve, is calculated based on the throttle valve opening and the upstream and downstream pressures of the throttle valve, and surging occurs by regarding this as the compressor passage flow rate. It is used to determine whether or not.

JP2015-190410A

  In the engine having the intake air recirculation mechanism described above, when the bypass valve is closed, only the flow rate corresponding to the throttle valve passage flow rate becomes the compressor passage flow rate, but the bypass valve is opened and a part of the intake air is passed through the bypass passage. When the compressor is refluxed from the downstream side to the upstream side, in addition to the throttle valve passage flow rate, the circulation flow rate that is the flow rate of the recirculated intake air becomes the compressor passage flow rate.

  Therefore, the actual flow rate through the compressor when the bypass valve is opened is larger than the flow rate through the throttle valve by the circulation flow rate. Therefore, as disclosed in Patent Document 1, when the occurrence of surging is predicted by regarding the flow rate through the throttle valve as the flow rate through the compressor regardless of whether the bypass valve is closed or open, when the bypass valve is open, It is determined whether or not the bypass valve is closed based on the smaller compressor passage flow rate.

  According to such determination, the bypass valve closes early because the circulation flow rate is not considered in the compressor passage flow rate. Then, when the bypass valve is closed, the flow rate of the intake air that is sent to the downstream side of the compressor is higher than expected, so the pressure on the downstream side of the compressor is increased by that much, and the occurrence of surging is predicted immediately. And is opened as soon as the bypass valve is closed. Due to this, there is a possibility that hunting in which the opening operation and the closing operation are repeated in a short cycle in the opening / closing control of the bypass valve may occur. When hunting occurs in the opening / closing control of the bypass valve, there is a concern that the operation control of the engine may be affected and become unstable.

  In order to prevent the occurrence of hunting in the opening / closing control of the bypass valve, it is conceivable to provide hysteresis between the condition when the bypass valve is closed from the open state and the condition when the bypass valve is opened from the closed state. However, in this case, the supercharging pressure may be released through the bypass passage even when the pressure upstream and downstream of the compressor and the flow rate through the compressor do not cause surging, so that the supercharging performance is deteriorated. A decrease in supercharging performance leads to a deterioration in drivability and fuel consumption of the automobile.

  The technology disclosed herein has been made in view of such a point, and its purpose is to suppress the occurrence of hunting in the opening / closing control of the bypass valve without deteriorating the supercharging performance. There is.

  In order to achieve the above object, in the technique disclosed herein, the bypass valve is closed from the open state in consideration of the circulation flow rate of the intake air recirculated through the bypass passage.

Specifically, the technology disclosed herein includes a turbocharger having a compressor provided in an intake passage, a bypass passage provided in the intake passage and bypassing the compressor, and a bypass provided in the bypass passage. The present invention is directed to an engine control device including a bypass valve that opens and closes a passage. The control device includes a valve control unit which controls the opening and closing of the bypass valve, and the circulation flow rate calculation unit that calculates a circulation flow rate is the flow rate of intake air that is circulated to the upstream side from the downstream side of the compressor via the bypass passage, the compressor A compressor output calculation unit that calculates a compressor output that is an output of the compressor . The compressor output calculation unit includes a compressor upstream pressure that is an intake pressure upstream of the compressor, a target boost pressure that is an intake pressure downstream of the compressor, and an upstream side of the bypass passage in the intake passage. The compressor output is calculated based on the intake flow rate on the downstream side and the circulation flow rate, and the valve control unit closes the bypass valve from the open state based on the compressor output .

The technology disclosed herein also includes a turbocharger having a compressor provided in the intake passage, a bypass passage provided in the intake passage and bypassing the compressor, and provided in the bypass passage for opening and closing the bypass passage. The present invention is directed to an engine control device including a bypass valve. The control device includes: a valve control unit that performs opening / closing control of the bypass valve; a circulation flow rate calculation unit that calculates a circulation flow rate that is a flow rate of intake air that is circulated from the downstream side to the upstream side of the compressor via the bypass passage; A compressor output calculation unit that calculates a compressor output that is an output of the compressor. The compressor output calculation unit bypasses the compressor upstream pressure that is the pressure of the intake air upstream of the compressor, the compressor downstream pressure that is detected by the intake pressure sensor that is the pressure of intake air downstream of the compressor, and the bypass of the intake passage. The compressor output is calculated based on the intake flow rate upstream and downstream of the passage and the circulation flow rate, and the valve control unit closes the bypass valve from the open state based on the compressor output.

According to these configurations, the compressor upstream pressure, the compressor downstream pressure (target boost pressure or pressure detected by the sensor), and the intake air upstream or downstream of the bypass passage are used to determine whether or not the bypass valve is closed from the open state. Since the circulation flow rate is taken into consideration in addition to the flow rate, the timing for closing the bypass valve can be precisely controlled according to the actual compressor passage flow rate. This prevents the bypass valve from closing quickly because the circulation flow rate is not considered in the compressor passage flow rate, thereby preventing the occurrence of hunting in the opening / closing control of the bypass valve. Further, according to such bypass valve closing control, the bypass valve is closed in accordance with the actual state of the compressor driving state, so that the supercharging performance is not lowered.

Further, when the bypass valve is closed, the intake air corresponding to the circulation flow rate flows downstream of the compressor, so that the pressure downstream of the compressor is increased, but the extent becomes larger as the compressor output is higher when the bypass valve is open. . According to the above configuration, since the determination as to whether or not the bypass valve is closed from the open state is made based on the compressor output, the above-described effect of being able to precisely control the closing timing of the bypass valve is specifically obtained. be able to.

In the above control device, the circulation flow quantity calculating unit includes a compressor upstream pressure, a pressure of intake air in the downstream side of the compressor, the compressor downstream pressure detected by the intake pressure sensor, based on the flow passage area of the bypass passage It is preferable to calculate the circulation flow rate.

According to this configuration, the circulation flow rate can be easily calculated by using Bernoulli's theorem.

  According to the engine control apparatus, it is possible to suppress occurrence of hunting in the opening / closing control of the bypass valve without deteriorating the supercharging performance. As a result, it is possible to stabilize the engine operation control and to prevent the deterioration of the drivability and fuel consumption of the automobile.

It is a schematic block diagram of an engine. It is a functional block diagram of ECU. It is an image figure of a compressor performance map. It is a block diagram which shows the opening / closing control method of a bypass valve.

  Hereinafter, exemplary embodiments will be described in detail with reference to the drawings.

  FIG. 1 shows a schematic configuration diagram of an engine 1 to which a control device according to this embodiment is applied.

  The engine 1 is a spark ignition direct injection engine with a supercharger. As shown in FIG. 1, the engine 1 mainly burns a mixture of intake air (air) and fuel, and the engine body 3. An intake passage 5 through which intake air introduced into the engine flows, an exhaust passage 7 through which exhaust gas generated by combustion of the air-fuel mixture in the engine body 3 flows, and a turbocharger that supercharges intake air using the energy of the exhaust gas 8, an external EGR mechanism 9 for performing external EGR, sensors for detecting information used for controlling the engine 1, and an ECU (Engine Control Unit) 11 for controlling the engine 1 as a whole. .

<Engine body>
The engine body 3 includes a cylinder block 15 in which a plurality of cylinders 13 (for example, four, only one is shown in FIG. 1) are provided in series, and a cylinder head 17 disposed on the cylinder block 15. Inside the cylinder block 15 and the cylinder head 17, although not shown, a water jacket through which engine coolant flows is provided.

  Each cylinder 13 is fitted with a piston 21 that divides a combustion chamber 19 for burning the air-fuel mixture so as to reciprocate. The piston 21 is connected to the crankshaft 25 via a connecting rod 23. Further, the engine body 3 is provided with a fuel injection device 27 called an injector. The fuel injection device 27 injects fuel (for example, gasoline) toward the combustion chamber 19 at a predetermined timing in accordance with a control signal from the ECU 11.

  Further, the cylinder head 17 is formed with an intake port 29 and an exhaust port 31 that are opened on the ceiling surface of the combustion chamber 19 for each cylinder 13. The intake port 29 is provided with an intake valve 33 that opens and closes the opening on the combustion chamber 19 side. On the other hand, the exhaust port 31 is provided with an exhaust valve 35 for opening and closing the opening on the combustion chamber 19 side.

  The intake valve 33 and the exhaust valve 35 are connected to the crankshaft 25 via a power transmission mechanism (not shown) provided in the engine body 3. The power transmission mechanism reciprocates the intake valve 33 and the exhaust valve 35 between the open position and the closed position in conjunction with the rotation of the crankshaft 25. By this driving, the intake valve 33 opens and closes the intake port 29 and the exhaust valve 35 opens and closes the exhaust port 31 at predetermined timings.

  The cylinder head 17 is further provided with a spark plug 37 for igniting the air-fuel mixture in the combustion chamber 19 for each cylinder 13. The spark plug 37 generates a spark at a predetermined timing in accordance with a control signal from the ECU 11 and causes the air-fuel mixture to explode and burn with the spark. By this explosion combustion, the piston 21 reciprocates in the cylinder 13, and the reciprocating motion of the piston 21 is converted into the rotational motion of the crankshaft 25 and output as torque (rotational power).

<Intake passage>
In the intake passage 5, in order from the upstream side, an air cleaner 39 that purifies the intake air by removing foreign matters such as dust contained in the air sucked from the outside, a compressor 41 that boosts the intake air that passes through, and the intake air that passes through An intercooler 43 for cooling, a throttle valve 45 for adjusting the flow rate of intake air introduced into the engine body 3, and a surge tank 47 for temporarily storing intake air supplied to the engine body 3 are provided.

  The intake passage 5 is further provided with an intake recirculation mechanism 48 for circulating a part of the intake air supercharged by the compressor 41 to the upstream side of the compressor 41. The intake air recirculation mechanism 48 includes an intake bypass passage 49 that connects the downstream side and the upstream side of the compressor 41 in the intake passage 5, and a bypass valve 51 provided in the intake bypass passage 49.

  The bypass valve 51 is a so-called on / off valve that can switch the intake bypass passage 49 between a fully closed state and a fully open state. In a state where the bypass valve 51 is closed, intake air cannot flow through the intake bypass passage 49, so that the supercharging pressure is not released. On the other hand, in a state where the bypass valve 51 is opened, intake air can flow through the intake bypass passage 49, so that a part of the supercharged intake air is circulated upstream of the compressor 41 and the supercharging pressure is released.

  The portion of the intake passage 5 downstream of the surge tank 47 is constituted by an intake manifold 52 having a plurality of independent intake passages branched for each cylinder 13 of the engine body 3, although not shown in detail. The surge tank 47 is included in the intake manifold 52.

<Exhaust passage>
In the exhaust passage 7, in order from the upstream side, a turbine 53 that is rotated by exhaust gas passing through, and harmful air pollution such as NOx (nitrogen oxide), CO (carbon monoxide), and HC (hydrocarbon) contained in the exhaust gas. An exhaust purification device 55 for purifying the substance is provided.

  The exhaust purification device 55 is formed by using, for example, two catalytic converters 61 that internally support an exhaust purification catalyst such as a three-way catalyst. The portion of the exhaust passage 7 upstream of the exhaust bypass passage 57 includes an exhaust manifold 60 having a plurality of independent exhaust passages branched for each cylinder 13 of the engine body 3, although not shown in detail.

  The exhaust passage 7 is further provided with an exhaust bypass passage 57 for bypassing the exhaust gas flowing through the exhaust passage 7 by bypassing the turbine 53. The exhaust bypass passage 57 is provided with a waste gate valve 59 for adjusting the flow rate of the exhaust gas flowing through the exhaust bypass passage 57. The waste gate valve 59 is a so-called linear valve that can change the opening of the exhaust bypass passage 57 continuously or in multiple stages between a fully open state and a fully closed state.

<Turbocharger>
The turbocharger 8 includes the compressor 41 provided in the intake passage 5 and the turbine 53 provided in the exhaust passage 7. The compressor 41 and the turbine 53 are connected via a shaft and rotate integrally. In the turbocharger 8, when the turbine 53 rotates in response to the exhaust flow, the compressor 41 sends the intake air to the downstream side using the rotational force of the turbine 53, and compresses (supercharges) the intake air.

<External EGR mechanism>
The external EGR mechanism 9 circulates through the EGR passage 63 that recirculates part of the exhaust discharged to the exhaust passage 7 to the intake passage 5, the EGR cooler 65 that cools the exhaust recirculated through the EGR passage 63, and the EGR passage 63. And an EGR valve 67 for controlling the exhaust gas recirculation amount, that is, the EGR flow rate.

  The EGR passage 63 connects the intake manifold 52 and the exhaust manifold 60, and allows the manifolds 52 and 60 to communicate with each other. The EGR cooler 65 and the EGR valve 67 are provided in the EGR passage 63 in order from the upstream side (exhaust passage 7 side). The EGR valve 67 is a linear valve that can change the opening of the EGR passage 63 continuously or in multiple stages between a fully open state and a fully closed state.

<Sensors>
Sensors are provided in the engine main body 3, the intake passage 5, the exhaust passage 7, and the external EGR mechanism 9 described above.

  Specifically, the engine body 3 is provided with a crank angle sensor 69 that detects the rotation angle of the crankshaft 25 and a water temperature sensor 71 that detects the engine water temperature, which is the temperature of the engine coolant in the water jacket. Yes.

  In the intake passage 5, an air flow sensor 73 that detects an intake air flow rate is provided between the air cleaner 39 and the compressor 41. The air flow sensor 73 has a built-in temperature sensor that detects the intake air temperature. Further, the intake air passage 5 between the compressor 41 and the throttle valve 45 and on the downstream side of the intercooler 43 has a first intake pressure that detects the pressure of the intake air compressed by the turbocharger 8, that is, the supercharging pressure. A sensor 75 is provided.

  The intake passage 5 is further provided with a throttle opening sensor 77 that detects the opening of the throttle valve 45. The intake passage 5 on the downstream side of the throttle valve 45, specifically the surge tank 47, is provided with a second intake pressure sensor 79 that detects the intake manifold pressure that is the pressure in the surge tank 47. The second intake pressure sensor 79 includes a temperature sensor that detects the intake manifold temperature, which is the temperature in the surge tank 47.

In the exhaust passage 7, a WG opening degree sensor 81 that detects the opening degree of the waste gate valve 59 is provided. Further, O ₂ sensors 83 and 85 are provided in the exhaust passage 7 between the turbine 53 and the exhaust purification device 55 and the exhaust passage 7 between the two catalytic converters 61, respectively. The detection values of these two O ₂ sensors 83 and 85 are used for feedback control of the air-fuel ratio in the combustion chamber 19.

  The external EGR mechanism 9 is provided with an EGR opening sensor 87 that detects the opening of the EGR valve 67. Further, the EGR passage 63 between the EGR cooler 65 and the EGR valve 67 is provided with an exhaust pressure sensor 89 that detects an EGR valve upstream pressure that is an exhaust pressure upstream of the EGR valve 67.

  In addition, the engine 1 includes an atmospheric pressure sensor 91 that detects the atmospheric pressure, a vehicle speed sensor 93 that detects the speed of the automobile, an accelerator sensor 95 that detects the accelerator opening according to the amount of depression of the accelerator pedal, and the like.

  The detected values of these various sensors 69 to 95 are output to the ECU 11 during driving of the automobile.

<ECU>
The ECU 11 is activated by a hardware such as an internal memory such as a CPU (Central Processing Unit), a ROM (Read Only Memory) or a RAM (Random Access Memory), a basic control program such as an OS (Operating System), and a specific function activated on the OS. And a computer composed of software including an application program for realizing the above, and comprehensively controls the operation of the engine 1 including intake air recirculation control using the intake air recirculation mechanism 48 based on the detection values of the sensors. The ECU 11 is an example of a control device for the engine 1.

  FIG. 2 shows a functional configuration diagram of the ECU 11 with a focus on the portion related to the opening degree control of the bypass valve 51. As shown in FIG. 2, the ECU 11 functionally has a target boost pressure setting unit 101 that sets a target boost pressure that is a target value of the boost pressure required according to the operating state of the engine 1; A circulation flow rate calculation unit 103 that calculates a circulation flow rate that is a flow rate of intake air that is recirculated from the downstream side to the upstream side of the compressor 41 via the intake bypass passage 49; a valve control unit 105 that performs opening / closing control of the bypass valve 51; And a storage unit 107 for storing various data.

  The target boost pressure setting unit 101 sets the target boost pressure based on the boost pressure map stored in advance in the storage unit 107. The supercharging pressure map defines a target charging efficiency and engine speed, which are target values of the charging efficiency, and a target supercharging pressure corresponding to them. The target boost pressure is set by comparing the target charging efficiency and the engine speed with the boost pressure map. The engine speed is calculated from the detection value of the crank angle sensor 69 (the same applies hereinafter).

  The target charging efficiency is calculated based on the engine speed and the target indicated mean effective pressure that is a target value of the indicated mean effective pressure. The target indicated mean effective pressure is calculated based on the mechanical resistance and pump loss (pumping loss) that become torque loss and the target torque that is the target value of the output torque of the engine 1. The target torque is obtained based on the vehicle speed detected by the vehicle speed sensor 93 and the accelerator opening detected by the accelerator sensor 95.

  When the bypass valve 51 is open, the circulation flow rate calculation unit 103 is configured so that the compressor upstream pressure that is the pressure of the intake air upstream of the compressor 41, the compressor downstream pressure that is the pressure of intake air downstream of the compressor 41, and the intake air bypass. Based on the flow area of the passage 49, the circulation flow rate is calculated using Bernoulli's theorem. Here, the compressor upstream pressure corresponds to atmospheric pressure. For this reason, the atmospheric pressure detected by the atmospheric pressure sensor 91 is used as the compressor upstream pressure. Further, the boost pressure detected by the first intake pressure sensor 75 is used as the compressor downstream pressure. The flow passage area of the intake bypass passage 49 is known.

  The circulation flow rate calculation unit 103 calculates the circulation flow rate as 0 (no flow rate) when the bypass valve 51 is closed.

  The valve control unit 105 includes a target compressor output calculation unit 109 as a compressor output calculation unit that calculates a target compressor output that is a target value of the output (driving force) of the compressor 41, and intake air pressures upstream and downstream of the compressor 41. A surge generation pressure ratio acquisition unit 111 that sets a surge generation pressure ratio that is a pressure ratio at which surging occurs, and an upper limit compressor output that is a threshold value of the output of the compressor 41 at which surging occurs is calculated. And an upper limit compressor output calculation unit 113.

  The target compressor output calculation unit 109 includes a gas constant of intake air, a specific heat ratio of intake air, a compressor passage flow rate that is a flow rate of intake air that passes through the compressor 41, an intake air temperature detected by the air flow sensor 73, and an atmospheric pressure sensor 91. The target compressor output is calculated by the following equation (1) based on the atmospheric pressure detected by the above and the target boost pressure set by the target boost pressure setting unit 101.

Here, “Ra” is the gas constant of intake air (gas constant of air). “Κa” is a specific heat ratio of intake air (specific heat ratio of air). “T1” is the compressor upstream temperature (intake air temperature). “Ga” is the compressor passage flow rate. “P1” is the compressor upstream pressure (atmospheric pressure). “P2” is the compressor downstream pressure (target boost pressure). The target compressor output P _ct calculated in this way is an output in a standard state (a state defined by a predetermined temperature, pressure, etc., and so on).

  The compressor passage flow rate “Ga” is a flow rate considering the circulation flow rate, and is calculated by adding the intake flow rate detected by the air flow sensor 73 and the circulation flow rate calculated by the circulation flow rate calculation unit 103. That is, when the bypass valve 51 is closed, there is no circulation flow rate, so the intake flow rate detected by the air flow sensor 73 is directly calculated as the compressor passage flow rate. On the other hand, when the bypass valve 51 is open, there is a circulation flow rate. Therefore, a flow rate obtained by adding the intake flow rate detected by the air flow sensor 73 to the circulation flow rate calculated by the circulation flow rate calculation unit 103 is calculated as the compressor passage flow rate. Is done.

  The surge generation pressure ratio acquisition unit 111 acquires the surge generation pressure ratio based on the compressor performance map stored in advance in the storage unit 107. FIG. 3 shows an image diagram of the compressor performance map. The compressor performance map shows the performance of the turbocharger 8. As shown in FIG. 3, the compressor performance flow is the compressor passage flow rate, the compressor pressure ratio (supercharging pressure / atmospheric pressure), and the compressor speed. Defines the relationship with the rotational speed.

  In the compressor performance map, a so-called surge region (shaded region) is defined in a region where the compressor passage flow rate is smaller than the surge line L indicated by a broken line in FIG. The surge region is defined by the relationship between the compressor passage flow rate and the compressor pressure ratio. The larger the compressor pressure ratio, the larger the surge region. This surge region is an operating region in which intake air supercharged by the compressor can flow back to the compressor 41, that is, surging can occur because the compressor pressure ratio is too high with respect to the compressor passage flow rate.

  The surge generation pressure ratio acquisition unit 111 compares the compressor pressure ratio on the surge line L corresponding to the intake flow rate as the surge generation pressure by comparing the intake flow rate detected by the air flow sensor 73 with the compressor performance map as the compressor passage flow rate. Get as a ratio. The surge generation pressure ratio acquired in this way is a compressor pressure ratio at which surging occurs when the bypass valve 51 is closed, that is, when there is no circulation flow rate.

  The upper limit compressor output calculation unit 113 includes an intake gas constant, an intake specific heat ratio, an intake flow rate and an intake temperature detected by the air flow sensor 73, and a surge generation pressure ratio acquired by the surge generation pressure ratio acquisition unit 111. Based on the above, the upper limit compressor output is calculated by the following equation (2) similar to the above equation (1).

Here, as the compressor passage flow rate “Ga _cl ”, the intake flow rate detected by the air flow sensor 73 is used as the compressor passage flow rate when the bypass valve 51 is closed. Further, a surge generation pressure ratio is used as the ratio “(P2 / P1) _sarg ” between the compressor downstream pressure and the compressor upstream pressure. Other coefficients “Ra”, “κa”, and “T1” are the same as those in the above equation (1). The upper limit compressor output P _cl calculated in this way is also an output in the standard state.

  The valve control unit 105 performs opening / closing control of the bypass valve 51 using the functions of the target compressor output calculation unit 109, the surge generation pressure ratio acquisition unit 111, and the upper limit compressor output calculation unit 113. The opening / closing control of the bypass valve 51 by the valve control unit 105 will be described below with reference to FIG. FIG. 4 is a block diagram illustrating a method for opening / closing control of the bypass valve 51.

As shown in FIG. 4, the valve control unit 105 first uses the function of the target compressor output calculation unit 109 to detect the intake air temperature detected by the air flow sensor 73, the intake air flow rate detected by the air flow sensor 73, and the circulation flow rate setting unit. 93 based on the compressor passing flow rate obtained by adding the circulating flow rate set by 93, the atmospheric pressure detected by the atmospheric pressure sensor 91, and the target boost pressure set by the target boost pressure setting unit 101. The target compressor output P _ct is calculated.

Further, the valve control unit 105 acquires the surge generation pressure ratio by referring to the compressor performance map based on the intake flow rate detected by the air flow sensor 73 by the function of the surge generation pressure ratio acquisition unit 111. Further, the valve control unit 105 calculates the upper limit compressor output P _cl based on the surge generation pressure ratio and the intake air flow rate and the intake air temperature detected by the air flow sensor 73 by the function of the upper limit compressor output calculation unit 113. .

Then, the valve control unit 105 determines whether the bypass valve 51 is opened or closed based on the target compressor output _Pct and the upper limit compressor output _Pcl . Specifically, when the target compressor output P _ct is smaller than the upper limit compressor output P _cl , the compressor 41 is driven with a work rate that is acceptable in its performance, so that surging is unlikely to occur. 51 is closed. On the other hand, when the target compressor output P _ct is equal to or higher than the upper limit compressor output P _cl , the compressor 41 is driven at a work rate exceeding its performance. Open.

  According to such opening / closing control of the bypass valve 51, since the circulation flow rate is considered as the compressor passage flow rate in determining whether or not the bypass valve 51 is closed from the open state, the bypass valve 51 is bypassed according to the actual compressor passage flow rate. The timing for closing the valve 51 is precisely controlled.

  Therefore, according to the ECU 11 of the engine 1 according to this embodiment, the bypass valve 51 is prevented from closing early because the circulation flow rate is not considered in the compressor passage flow rate, and hunting is performed in the opening / closing control of the bypass valve 51. It can be prevented from occurring. In addition, since the bypass valve 51 is closed in accordance with the actual driving state of the compressor 41, the supercharging performance is not lowered. As a result, it is possible to stabilize the operation control of the engine 1 and to prevent deterioration of the drivability of the automobile and fuel consumption.

  As described above, a preferred embodiment has been described as an example of the technique disclosed in the present application. However, the technology in the present disclosure is not limited to this, and can also be applied to embodiments in which changes, replacements, additions, omissions, and the like have been made as appropriate. Moreover, it is also possible to combine each component demonstrated by the said embodiment into a new embodiment. In addition, the constituent elements described in the accompanying drawings and the detailed description may include constituent elements that are not essential for solving the problem. For this reason, it should not be immediately recognized that these non-essential components are essential because they are described in the accompanying drawings and detailed description.

  For example, the following embodiment may be configured as follows.

In the above embodiment, the opening and closing of the bypass valve 51 is controlled by comparing the target compressor output _Pct with the upper limit compressor output _Pcl . However, the present invention is not limited to this, and instead of the target compressor output _Pct , the current engine 1 An actual compressor output that is a compressor output corresponding to the operating state may be used.

That is, the valve control unit 105 closes the bypass valve 51 when the actual compressor output is less than the upper limit compressor output P _cl, so as to open the bypass valve 51 when the actual compressor output is the upper limit compressor output P _cl more Also good. In this case, the valve control unit 105 includes an actual compressor output calculation unit that calculates an actual compressor output instead of the target compressor output calculation unit 109. The actual compressor output is calculated, for example, by using the boost pressure detected by the first intake pressure sensor 75 as the compressor downstream pressure “P2” in the above equation (1).

Moreover, although the said embodiment _{demonstrated the example} calculated _| required by what is called a L-Jetronic system which makes the compressor passage flow rate used for calculating target compressor output _Pct the detection value of the airflow sensor 73, it does not restrict to this. . The compressor passage flow rate includes the opening degree of the throttle valve 45 detected by the throttle opening degree sensor 77, the supercharging pressure detected by the first intake pressure sensor 75, and the intake manifold pressure detected by the second intake pressure sensor 79. Further, it may be obtained by a so-called D Jetronic method that is calculated based on the intake manifold temperature.

  As described above, the technology disclosed herein is useful for an engine control device including a turbocharger.

DESCRIPTION OF SYMBOLS 1 ... Engine, 3 ... Engine body, 5 ... Intake passage, 7 ... Exhaust passage, 8 ... Turbocharger,
9 ... External EGR mechanism, 11 ... ECU (engine control device), 13 ... Cylinder,
15 ... Cylinder block, 17 ... Cylinder head, 19 ... Combustion chamber, 21 ... Piston,
23 ... Connecting rod, 25 ... Crankshaft, 27 ... Fuel injection device,
29 ... Intake port, 31 ... Exhaust port, 33 ... Intake valve, 35 ... Exhaust valve,
37 ... Spark plug, 39 ... Air cleaner, 41 ... Compressor,
43 ... Intercooler, 45 ... Throttle valve, 47 ... Surge tank,
48 ... Intake recirculation mechanism, 49 ... Intake bypass passage, 51 ... Bypass valve,
52 ... Intake manifold, 53 ... Turbine, 55 ... Exhaust gas purification device,
57 ... exhaust bypass passage, 59 ... waste gate valve, 60 ... exhaust manifold,
61 ... catalytic converter, 63 ... EGR passage, 65 ... EGR cooler, 67 ... EGR valve,
69 ... Crank angle sensor, 71 ... Water temperature sensor, 73 ... Air flow sensor,
75 ... 1st intake pressure sensor, 77 ... Throttle opening sensor, 79 ... 2nd intake pressure sensor,
81 ... WG opening sensor, 83 and 85 ... _{O 2} sensor, 87 ... EGR opening degree sensor,
89 ... Exhaust pressure sensor, 91 ... Atmospheric pressure sensor, 93 ... Vehicle speed sensor, 95 ... Accelerator sensor,
101 ... Target boost pressure setting unit, 103 ... Circulation flow rate calculation unit, 105 ... Valve control unit,
107: storage unit, 109: target compressor output calculation unit (compressor output calculation unit),
111: Surge generation pressure ratio acquisition unit, 113: Upper limit compressor output calculation unit

Claims (3)

A turbocharger having a compressor provided in the intake passage;
A bypass passage provided in the intake passage and bypassing the compressor;
An engine control device comprising a bypass valve provided in the bypass passage and opening and closing the bypass passage,
A valve control unit for controlling opening and closing of the bypass valve;
A circulation flow rate calculation unit for calculating a circulation flow rate that is a flow rate of intake air circulated from the downstream side to the upstream side of the compressor via the bypass passage;
A compressor output calculation unit for calculating a compressor output which is an output of the compressor ,
The compressor output calculation unit includes a compressor upstream pressure that is an intake pressure upstream of the compressor, a target supercharging pressure that is an intake pressure downstream of the compressor, and a bypass passage out of the intake passage. Based on the intake flow rate on the upstream side or the downstream side and the circulation flow rate, the compressor output is calculated,
The valve control unit closes the bypass valve from an open state based on the compressor output, and controls the engine. A turbocharger having a compressor provided in the intake passage;
A bypass passage provided in the intake passage and bypassing the compressor;
An engine control device comprising a bypass valve provided in the bypass passage and opening and closing the bypass passage,
A valve control unit for controlling opening and closing of the bypass valve;
A circulation flow rate calculation unit for calculating a circulation flow rate that is a flow rate of intake air circulated from the downstream side to the upstream side of the compressor via the bypass passage;
A compressor output calculation unit for calculating a compressor output which is an output of the compressor,
The compressor output calculation unit includes a compressor upstream pressure that is an intake pressure upstream of the compressor, a compressor downstream pressure that is detected by an intake pressure sensor that is an intake pressure downstream of the compressor, and an intake passage. Of these, the compressor output is calculated based on the intake flow rate upstream or downstream of the bypass passage and the circulation flow rate,
The engine control device , wherein the valve control unit closes the bypass valve from an open state based on the compressor output . In the engine control apparatus according to claim 1 or 2 ,
The circulation flow amount calculating section includes: the compressor upstream pressure, a pressure in the intake downstream side of the compressor, the compressor downstream pressure detected by the intake pressure sensor, based on the flow passage area of the bypass passage, wherein An engine control device that calculates a circulation flow rate.

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