JP7632340B2 - Internal combustion engine control system - Google Patents

Description

This disclosure relates to a control system for an internal combustion engine.

Internal combustion engine control systems that inject fuel into an intake port are known (see, for example, Patent Document 1 and Patent Document 2). Such systems that inject fuel into an intake port include a port injection system that forms an air-fuel mixture in the intake port, and a semi-direct injection system that injects fuel directly from the intake port into the cylinder. Patent Document 1 and Patent Document 2 disclose internal combustion engine control systems that use the semi-direct injection system.

JP 2020-139410 A JP 2021-32131 A

In an internal combustion engine that injects fuel into such intake ports, the fuel adhering to the intake ports causes variations in the air-fuel ratio between the intake ports. Patent Document 1 focuses on the emissions of the internal combustion engine and discloses an internal combustion engine control system that injects from one of two fuel injection valves during one cycle from the intake stroke to the exhaust stroke. Patent Document 2 focuses on early warm-up of the catalyst and discloses an internal combustion engine control system that injects from one of two fuel injection valves. Therefore, in the internal combustion engine control systems of Patent Document 1 and Patent Document 2, one of the two fuel injection valves may not inject fuel, causing variations in the air-fuel ratio between the intake ports. Neither Patent Document 1 nor Patent Document 2 discloses an internal combustion engine control system that focuses on the variations in the air-fuel ratio between the intake ports.

The objective of this disclosure is to provide an internal combustion engine control system that can suppress variations in the air-fuel ratio between intake ports.

The control system for an internal combustion engine according to the present disclosure includes a first intake port, a second intake port, a first fuel injection valve arranged in the first intake port, a second fuel injection valve arranged in the second intake port, an engine temperature acquisition unit that acquires the temperature of the internal combustion engine, a first port intake detection unit arranged in the first intake port that detects a first intake temperature and a first intake volume of the intake air flowing into the first intake port, a second port intake detection unit arranged in the second intake port that detects a second intake temperature and a second intake volume of the intake air flowing into the second intake port, and a control device that controls the internal combustion engine. The control device includes a first control that uses the first intake air amount and the second intake air amount to change at least one of the injection amount of the first fuel injection valve and the injection amount of the second fuel injection valve, and a second control that uses the first intake air temperature and the second intake air temperature to change at least one of the injection amount of the first fuel injection valve and the injection amount of the second fuel injection valve, and executes either the first control or the second control with priority based on the temperature of the internal combustion engine acquired by the engine temperature acquisition unit.

This internal combustion engine control system can suppress variations in the air-fuel ratio between the first intake port and the second intake port by prioritizing execution of either the first control or the second control based on the temperature of the internal combustion engine acquired from the engine temperature acquisition unit.

This disclosure provides an internal combustion engine control system that can suppress variations in the air-fuel ratio between intake ports.

1 is a system diagram of an internal combustion engine control system according to an embodiment of the present disclosure. 1 is a close-up view of a cylinder of an internal combustion engine according to an embodiment of the present disclosure. 4 is a flowchart showing a control procedure of a control device according to an embodiment of the present disclosure.

Embodiments of the present disclosure will be described below with reference to the drawings. Note that in the following specification, the upstream side in the flow direction of intake or exhaust air will be referred to as "upstream" and the downstream side will be referred to as "downstream."

As shown in FIG. 1, the control system 1 of the internal combustion engine 2 includes a plurality of intake ports 4, a plurality of fuel injection valves 6, a plurality of port intake detectors 8, a temperature detector (an example of an engine temperature acquisition unit) 10, and a control device 20. The internal combustion engine 2 of this embodiment is an in-line type internal combustion engine 2 in which a plurality of cylinders (an example of a first cylinder) 10 are arranged in series. However, the arrangement and number of the cylinders 11 can be changed. Specifically, the cylinders 11 of the internal combustion engine 2 may be arranged in a V-type or horizontally opposed type. The number of cylinders 11 may range from 1 to 12. The internal combustion engine 2 of this embodiment is a gasoline engine that ignites an air-fuel mixture by a spark plug (not shown).

The internal combustion engine 2 of this embodiment has an air cleaner 13, a turbocharger 14, and an intake manifold 17, and the intake air drawn in from the air cleaner 13 is turbocharged by the compressor 14a of the turbocharger 14. The turbocharged intake air is cooled by an intercooler 15 and supplied to the intake port 4 via the intake manifold 17. The internal combustion engine 2 also has an exhaust valve 16 and an exhaust purification catalyst 18, and exhaust gas is supplied to the exhaust purification catalyst 18 via the turbine 14b of the turbocharger 14. However, the internal combustion engine 2 may be an internal combustion engine 2 that does not have a turbocharger 14 or the like.

As shown in FIG. 2, the intake port 4 is connected to each of the four cylinders 11. The intake port 4 is provided in the cylinder head 2a (see FIG. 1), and has a first intake port 4a and a second intake port 4b that are branched by a port wall 2b formed by the cylinder head 2a. The first intake port 4a and the second intake port 4b are arranged adjacent to each other in the arrangement direction of the cylinders 11, and are connected to the same cylinder 11. The first intake port 4a has a port outlet that connects to the cylinder 11 opened and closed by the first intake valve 12a. The second intake port 4b has a port outlet that connects to the cylinder 11 opened and closed by the second intake valve 12b, similar to the first intake port 4a.

The fuel injection valve 6 is disposed in each of the first intake port 4a and the second intake port 4b. Specifically, the first fuel injection valve 6a is disposed in the first intake port 4a, and the second fuel injection valve 6b is disposed in the second intake port 4b. As shown in Figs. 1 and 2, the first fuel injection valve 6a and the second fuel injection valve 6b are supplied with fuel from a delivery pipe 6c. The first fuel injection valve 6a and the second fuel injection valve 6b are each electrically connected to a control device 20, and the control device 20 controls the fuel injection period and fuel injection timing.

2, the first fuel injection valve 6a has a nozzle hole for injecting fuel arranged closer to the cylinder 11 than the upstream end 2c of the port wall 2b, and injects fuel toward the cylinder 11 when the first intake valve 12a is open. The second fuel injection valve 6b, like the first fuel injection valve 6a, has a nozzle hole for injecting fuel arranged closer to the cylinder 11 than the upstream end 2c of the port wall 2b, and injects fuel toward the cylinder 11 when the second intake valve 12b is open. In other words, the internal combustion engine 2 of this embodiment is a semi-direct injection type internal combustion engine 2 that forms a mixture in the first intake port 4a and the second intake port 4b and can also inject fuel into the cylinder 11.

The port intake detection unit 8 is a sensor that detects the intake temperature Ti and the intake volume Qr flowing through the intake port 4. In this embodiment, the port intake detection unit 8 detects the intake temperature Ti, converts the detected intake temperature Ti into a signal, and transmits it to the control device 20. The control device 20 converts the signal based on the intake temperature Ti into the intake volume Qr based on a stored map. However, the port intake detection unit 8 may be a sensor that detects the intake temperature Ti and the intake volume Qr separately.

In this embodiment, the port intake detector 8 is disposed in each of the first intake port 4a and the second intake port 4b. Specifically, the first port intake detector 8a is disposed in the first intake port 4a, and the second port intake detector 8b is disposed in the second intake port 4b. The first port intake detector 8a is attached near the tip of the first fuel injection valve 6a, and the second port intake detector 8b is attached near the tip of the second fuel injection valve 6b. This allows the first port intake detector 8a to detect the first intake temperature Ti1 and the first intake amount Q1 of the first intake port 4a. The second port intake detector 8b can detect the second intake temperature Ti2 and the second intake amount Q2 of the second intake port 4b.

As shown in FIG. 1, in this embodiment, the temperature detection unit 10 is a sensor that detects the engine temperature Te of the internal combustion engine 2. The engine temperature Te is a value that indicates the temperature state of the internal combustion engine 2. In this embodiment, the temperature detection unit 10 is a water temperature sensor that detects the temperature of the cooling water flowing through the cylinder head 2a and a cylinder block (not shown) of the internal combustion engine 2 and transmits the temperature to the control device 20. However, the temperature detection unit 10 may be, for example, an oil temperature sensor that detects the temperature of the oil filled in the internal combustion engine 2 and transmits the temperature to the control device 20. In addition, the engine temperature Te may be obtained by the control device 20 estimating the engine temperature Te of the internal combustion engine 2 based on the airflow temperature Ta detected by the airflow sensor 22, for example. In any case, any method may be used as long as the control device 20 can obtain the engine temperature Te.

The control device 20 detects the accelerator opening Th from the accelerator position sensor 30a attached to the accelerator pedal 30, and controls the internal combustion engine 2 according to the accelerator opening Th. In this embodiment, the control device 20 determines the target intake air amount Qt and the target air-fuel ratio AFt based on the accelerator opening Th. The control device 20 determines the target fuel injection amount P based on the target intake air amount Qt so that the air-fuel ratio of the mixture supplied to the cylinder 11 becomes the target air-fuel ratio AFt. The control device 20 then determines the target fuel injection amount P based on the first intake temperature Ti1 and the second intake temperature Ti2, or the first intake amount Q1 and the second intake amount Q2, detected by the first port intake detection unit 8a and the second port intake detection unit 8b. Specifically, of the target fuel injection amount P, a first target fuel injection amount P1 (an example of the injection amount of the first fuel injection valve 6a) to be injected by the first fuel injection valve 6a and a second target fuel injection amount P2 (an example of the injection amount of the second fuel injection valve 6b) to be injected by the second fuel injection valve 6b are determined.

In addition, the control device 20 may control each device, such as the throttle valve 24, the injection timing and injection period of the fuel injection valve 6, the valve overlap of the intake valve 12 and the exhaust valve 16, and the boost pressure of the supercharger 14, so that the internal combustion engine 2 is in a desired operating state, based on values obtained from sensors such as the port intake detection unit 8, the temperature detection unit 10, the airflow sensor 22, and the accelerator position sensor 30a. The control device 20 is actually an ECU (Electronic Control Unit) composed of a microcomputer including a calculation device, a memory, an input/output buffer, etc. The control device 20 controls each device so that the internal combustion engine 2 is in a desired operating state, based on maps and programs stored in the memory. Note that the various controls are not limited to software processing, and can also be processed by dedicated hardware (electronic circuits).

Next, the control procedure executed by the control device 20 will be described using the flowchart in FIG. 3. The control device 20 starts the control procedure when an ignition switch (not shown) is turned on.

In step S1, the control device 20 acquires the engine temperature Te. After acquiring the engine temperature Te, the control device 20 proceeds to step S2. In step S2, the control device 20 determines whether the engine temperature Te is less than a predetermined temperature Td.

Here, the predetermined temperature Td is the temperature at which the fuel adhering to the port wall 2b vaporizes. For example, when the internal combustion engine 2 is in a cold state (for example, the value of the water temperature sensor is 80°C or less), the fuel adhering to the port wall 2b is unlikely to vaporize. Therefore, the air-fuel ratio is unlikely to vary between the first intake port 4a and the second intake port 4b. Therefore, the control device 20 can determine the first target fuel injection amount P1 and the second target fuel injection amount P2 without taking the amount of adhering fuel into consideration. Therefore, the control device 20 can determine the first target fuel injection amount P1 and the second target fuel injection amount P2 based on the first intake amount Q1 and the second intake amount Q2.

If the control device 20 determines in step S2 that the engine temperature Te is less than the predetermined temperature Td (YES in step S2), the process proceeds to step S3, where the control device 20 acquires the first intake air amount Q1 and the second intake air amount Q2. After acquiring the first intake air amount Q1 and the second intake air amount Q2, the control device 20 proceeds to step S4.

In steps S4 to S7, the control device 20 executes a first control to change at least one of the first target fuel injection amount P1 and the second target fuel injection amount P2 using the first intake air amount Q1 and the second intake air amount Q2.

In this embodiment, the control device 20 compares the first intake air amount Q1 and the second intake air amount Q2 in step S4 and determines whether the first intake air amount Q1 is greater than the second intake air amount Q2. If the control device 20 determines that the first intake air amount Q1 is greater than the second intake air amount Q2 (YES in step S4), the control device 20 proceeds to step S5. In step S5, the control device 20 increases the first target fuel injection amount P1 and decreases the second target fuel injection amount P2.

The increase amount P1i of the first target fuel injection amount P1 may be calculated by, for example, calculating the difference between the first intake amount Q1 and the second intake amount Q2 in the current cycle, and adding the increase amount P1i according to the difference to the target fuel injection amount P to calculate the next first target fuel injection amount P1n, which is the first target fuel injection amount P1 in the next cycle. Then, the control device 20 may inject the next first target fuel injection amount P1n in the next cycle. The control device 20 may set the decrease amount P2d of the second target fuel injection amount P2 to the same amount as P1i. The control device 20 may subtract the decrease amount P2d from the second target fuel injection amount P2 to calculate the next second target fuel injection amount P2n, which is the second target fuel injection amount P2 in the next cycle. The control device 20 may inject the next second target fuel injection amount P2n in the next cycle.

The control device 20 may, for example, calculate the ratio between the first intake air amount Q1 and the second intake air amount Q2 in the current cycle, and calculate an increase P1i and a decrease P2d in the target fuel injection amount P according to the ratio. In any case, the control device 20 only needs to increase the first target fuel injection amount P1 and decrease the second target fuel injection amount P2 in step S5.

When the control device 20 determines that the first intake air amount Q1 is not greater than the second intake air amount Q2 (step S4: NO), the control device 20 proceeds to step S6. In step S6, the control device 20 determines whether the first intake air amount Q1 is less than the second intake air amount Q2. When the control device 20 determines in step S6 that the first intake air amount Q1 is less than the second intake air amount Q2 (step S6: YES), the control device 20 proceeds to step S7. In step S7, the control device 20 reduces the first target fuel injection amount P1 and increases the second target fuel injection amount P2. The calculation method of the reduction amount P1d and the increase amount P2i at this time is the same as that in step S5, so the explanation is omitted. When the control device 20 determines in step S5 and step S6 that the first intake air amount Q1 is greater than the second intake air amount Q2 (step S6: NO), and when the control device 20 executes the processing of step S7, the control device 20 proceeds to step S1.

In this way, in the first control, if the second intake air amount Q2 decreases, the control device 20 reduces the next second target fuel injection amount P2n for the fuel injection timing in the next cycle and increases the next first target fuel injection amount P1n. Conversely, if the first intake air amount Q1 decreases, the control device 20 reduces the next first target fuel injection amount P1n for the fuel injection timing in the next cycle and increases the next second target fuel injection amount P2n. Note that the control device 20 does not need to change the next first target fuel injection amount P1n and the next second target fuel injection amount P2n if there is no change in the first intake air amount Q1 and the second intake air amount Q2.

In this way, when the engine temperature Te is less than the predetermined temperature Td, the control device 20 prioritizes execution of the first control, thereby suppressing variations in the air-fuel ratio between the first intake port 4a and the second intake port 4b.

When the control device 20 determines in step S2 that the engine temperature Te is equal to or higher than the predetermined temperature Td (step S2 NO), the control device 20 proceeds to step S8. At or above the predetermined temperature Td, the fuel adhering to the port wall 2b vaporizes, and the heat of vaporization reduces the intake temperature Ti. For this reason, variations in the air-fuel ratio tend to occur between the first intake port 4a and the second intake port 4b. Therefore, the control device 20 needs to determine the first target fuel injection amount P1 and the second target fuel injection amount P2, taking into account the amount of adhering fuel. For this reason, the control device 20 determines the first target fuel injection amount P1 and the second target fuel injection amount P2 using the first intake temperature Ti1 and the second intake temperature Ti2.

Then, in step S8, the control device 20 acquires the first intake air temperature Ti1 and the second intake air temperature Ti2. After acquiring the first intake air temperature Ti1 and the second intake air temperature Ti2, the control device 20 proceeds to step S9.

In steps S9 to S12, the control device 20 executes a second control to change at least one of the first target fuel injection amount P1 and the second target fuel injection amount P2 using the first intake air temperature Ti1 and the second intake air temperature Ti2.

In this embodiment, the control device 20 determines whether the first intake temperature Ti1 has decreased in step S9. For example, the control device 20 may compare the first intake temperature Ti1 with the second intake temperature Ti2, and determine that the first intake temperature Ti1 has decreased if the first intake temperature Ti1 is lower than the second intake temperature Ti2. The control device 20 may have a sensor (not shown) that detects the temperature of the intake manifold 17, and may compare the temperature acquired by this sensor with the first intake temperature Ti1 to determine that the first intake temperature Ti1 has decreased. Alternatively, the control device 20 may compare the first intake temperature Ti1 with the airflow temperature Ta and determine that the first intake temperature Ti1 has decreased. In any case, if the first intake temperature Ti1 has decreased, there is a possibility that the fuel adhering to the port wall 2b of the first intake port 4a has vaporized and the adhering fuel has been supplied to the cylinder 11.

Therefore, if the control device 20 determines that the first intake temperature Ti1 has decreased (step S9 YES), the process proceeds to step S10 and reduces the first target fuel injection amount P1.

The reduction amount P1d by which the first target fuel injection amount P1 is reduced may be determined by, for example, storing an appropriate first fuel injection amount P1g, which is an appropriate fuel injection amount according to the first intake air temperature Ti1, as a map in the control device 20. In this case, the control device 20 may calculate the difference between the appropriate first fuel injection amount P1g and the first target fuel injection amount P1, and subtract the difference as the reduction amount P1d from the next first target fuel injection amount P1n.

When the control device 20 determines that the first intake air temperature Ti1 has not decreased (step S9 NO), the process proceeds to step S11, where the control device 20 determines whether the second intake air temperature Ti2 has decreased. When the control device 20 determines that the second intake air temperature Ti2 has decreased (step S11 YES), the process proceeds to step S12, where the control device 20 reduces the second target fuel injection amount P2. The method of reducing the second target fuel injection amount P2 is the same as that of the first target fuel injection amount P1, and therefore will not be described. After executing the processes of steps S10 and S12, the control device 20 proceeds to step S1. When the control device 20 determines that the second intake air temperature Ti2 has not decreased (step S11 NO), the control device 20 proceeds to step S1. The control device 20 repeatedly executes such processes at predetermined intervals.

In this way, in the second control, if the first intake air temperature Ti1 decreases, the control device 20 reduces the next first target fuel injection amount P1n for the fuel injection timing in the next cycle. Conversely, if the second intake air temperature Ti2 decreases, the control device 20 reduces the next second target fuel injection amount P2n for the fuel injection timing in the next cycle.

In this way, when the engine temperature Te is equal to or higher than the predetermined temperature Td, the control device 20 performs the second control with priority, thereby correcting the air-fuel ratio that becomes richer due to the adhering fuel, and suppressing the variation in the air-fuel ratio between the first intake port 4a and the second intake port 4b.

As described above, according to the control system 1 for the internal combustion engine 2, the variation in the air-fuel ratio between the first intake port 4a and the second intake port 4b can be suppressed by preferentially executing either the first control or the second control based on the engine temperature Te of the internal combustion engine 2 acquired by the temperature detection unit 10.

<Other embodiments>
Although the embodiment of the present disclosure has been described above, the present disclosure is not limited to the above embodiment, and various modifications are possible without departing from the gist of the invention. In particular, the multiple modifications described in this specification can be arbitrarily combined as necessary.

For example, in the above embodiment, the first intake port 4a and the second intake port 4b connected to one cylinder 11 are used as an example, but the present disclosure is not limited to this. For example, the control of the present disclosure may be applied to suppress the variation in the air-fuel ratio between the intake port 4 connected to a cylinder 11 and the intake port 4 connected to an adjacent cylinder 11. The control may also be applied to a plug-in hybrid vehicle (PHEV) that is capable of external charging or external power supply.

1: control system, 2: internal combustion engine, 4: intake port, 4a: first intake port, 4b: second intake port, 6: fuel injection valve, 6a: first fuel injection valve, 6b: second fuel injection valve, 8: port intake detection unit,
8a: First port intake detection unit, 8b: Second port intake detection unit, 10: Temperature detection unit, 11: Cylinder, 20: Control device, P1: First target fuel injection amount, P1n: Next first target fuel injection amount, P2: Second target fuel injection amount, P2n: Next second target fuel injection amount, Q1: First intake amount, Q2: Second intake amount, Td: Predetermined temperature, Te: Engine temperature, Ti1: First intake temperature, Ti2: Second intake temperature

Claims (6)

A first intake port;
A second intake port;
a first fuel injection valve disposed in the first intake port;
a second fuel injection valve disposed in the second intake port;
an engine temperature acquisition unit that acquires a temperature of the internal combustion engine;
a first port intake detection unit disposed in the first intake port and configured to detect a first intake temperature and a first intake amount of the intake air flowing into the first intake port;
a second port intake detection unit disposed in the second intake port and configured to detect a second intake air temperature and a second intake air amount of the intake air flowing into the second intake port;
A control device for controlling the internal combustion engine;
Equipped with
The control device includes:
a first control that changes at least one of an injection amount of the first fuel injection valve and an injection amount of the second fuel injection valve by using the first intake air amount and the second intake air amount;
a second control for changing at least one of an injection amount of the first fuel injection valve and an injection amount of the second fuel injection valve by using the first intake air temperature and the second intake air temperature;
Including,
executes either the first control or the second control with priority based on the temperature of the internal combustion engine acquired by the engine temperature acquisition unit.
Control system for internal combustion engines. the internal combustion engine has a first cylinder,
the first intake port and the second intake port are connected to the first cylinder.
2. The control system for an internal combustion engine according to claim 1. The control device prioritizes the first control when the temperature of the internal combustion engine acquired by the engine temperature acquisition unit is lower than a predetermined temperature.
3. A control system for an internal combustion engine according to claim 1 or 2. When the first intake amount is decreased in the first control, the control device reduces an injection amount of the first fuel injection valve and increases an injection amount of the second fuel injection valve at a next fuel injection timing.
4. A control system for an internal combustion engine according to claim 1. The control device prioritizes the second control when the temperature of the internal combustion engine acquired by the engine temperature acquisition unit is equal to or higher than a predetermined temperature.
5. A control system for an internal combustion engine according to claim 1. When the first intake air temperature is decreased, the control device reduces an injection amount of the first fuel injection valve at a next fuel injection timing in the second control.
A control system for an internal combustion engine according to any one of claims 1 to 5.