Internal combustion engine control system

Abstract

To provide a control system for an internal combustion engine capable of executing optimal fuel injection in accordance with an operating state of the internal combustion engine.SOLUTION: A control system for an internal combustion engine includes: an intake port connected to a first cylinder of the internal combustion engine; a fuel injection valve disposed in the intake port and injecting fuel toward a connection part between the first cylinder and the intake port; and a control device controlling the internal combustion engine. The control device performs switching between first control for causing the fuel injection valve to perform one-stage injection and second control to cause the fuel injection valve to perform multistage injection in accordance with an operating state of the internal combustion engine.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to control systems for internal combustion engines. [Background technology]

[0002] Conventionally, there has been known a control system for an internal combustion engine that injects fuel into an intake port (see, for example, Patent Document 1 and Patent Document 2). As such a system for injecting fuel into an intake port, there are known a port injection system that forms an air-fuel mixture in the intake port, and a semi-direct injection system that directly injects fuel from the intake port into the cylinder. Patent Document 1 and Patent Document 2 disclose a control system for an internal combustion engine that uses a semi-direct injection system. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-139410 A [Patent Document 2] Patent Publication No. 2021-32131 Summary of the Invention [Problem to be solved by the invention]

[0004] Patent Document 1 focuses on emissions from an internal combustion engine and discloses a control system for an internal combustion engine in which one of two fuel injectors injects fuel during one cycle from the intake stroke to the exhaust stroke. Patent Document 2 focuses on early warm-up of a catalyst and discloses a control system for an internal combustion engine in which one of two fuel injectors injects fuel. However, Patent Document 1 and Patent Document 2 do not disclose how to make the fuel injector inject fuel depending on the operating state of the internal combustion engine.

[0005] An object of the present disclosure is to provide an internal combustion engine control system that can execute optimal fuel injection according to the operating state of the internal combustion engine. [Means for solving the problem]

[0006] A control system for an internal combustion engine according to the present disclosure includes an intake port connected to a first cylinder of the internal combustion engine, a fuel injection valve disposed in the intake port and configured to inject fuel toward a connection between the first cylinder and the intake port, and a control device configured to control the internal combustion engine. The control device controls the internal combustion engine in a first rotation region in which the rotation speed of the internal combustion engine is lower than a predetermined rotation speed, a second rotation region in which the rotation speed of the internal combustion engine is higher than the first rotation region, a first load region in which the output of the internal combustion engine is lower than a predetermined output, and a second load region in which the load of the internal combustion engine is higher than the first load region, and when controlling the internal combustion engine in the first load region, the control device executes the first control in the first rotation region and the second rotation region, and when controlling the internal combustion engine in the second load region, the control device executes the first control when controlling the internal combustion engine in the second rotation region, and when executing the first control in the first load region, injects fuel from the exhaust stroke to the intake stroke of the internal combustion engine, and when executing the first control in the second load region and the second rotation region, injects fuel in the intake stroke of the internal combustion engine.

[0007] According to this internal combustion engine control system, by switching between single-stage injection and multi-stage injection according to the operating state of the internal combustion engine, it is possible to perform optimal fuel injection according to the operating range of the internal combustion engine. As a result, this internal combustion engine control system can optimize the output, emissions, etc. according to the operating state of the internal combustion engine. As a result, this internal combustion engine control system can achieve optimal operation of the internal combustion engine. Effect of the Invention

[0008] According to the present disclosure, it is possible to provide a control system for an internal combustion engine that can execute optimal fuel injection according to the operating state of the internal combustion engine. [Brief description of the drawings]

[0009] [Figure 1] 1 is a system diagram of an internal combustion engine control system according to an embodiment of the present disclosure. [Diagram 2] 1 is a diagram of an internal combustion engine according to an embodiment of the present disclosure. [Diagram 3] 1 is a close-up view of a cylinder of an internal combustion engine according to an embodiment of the present disclosure. [Figure 4] 1 is a diagram illustrating operating regions of an internal combustion engine according to an embodiment of the present disclosure. [Diagram 5] FIG. 4 illustrates fuel injection timing and duration according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, an embodiment of the present disclosure will be described with reference to the drawings. In the following description, the upstream side with respect to the flow direction of intake air or exhaust air will be referred to as "upstream" and the downstream side will be referred to as "downstream".

[0011] As shown in FIG. 1 and FIG. 2, the control system 1 of the internal combustion engine 2 includes a plurality of intake ports 4, a plurality of exhaust ports 5, a plurality of fuel injection valves 6, a plurality of intake valves 8, an intake valve timing variable device 9, a plurality of exhaust valves 12, an exhaust valve timing variable device 13, 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 11 (an example of a first cylinder) are arranged in line. However, the arrangement and number of the cylinders 11 can be changed. Specifically, the internal combustion engine 2 may have the cylinders 11 arranged in a V-type or horizontally opposed type. The number of the cylinders 11 may range from about 1 to about 12. The internal combustion engine 2 of this embodiment is a gasoline engine in which an air-fuel mixture is ignited by an ignition plug 10.

[0012] The internal combustion engine 2 of this embodiment has a turbocharger 14, an intake manifold 17, and an air cleaner 21, and intake air sucked from the air cleaner 21 is supercharged by a compressor 14a of the turbocharger 14. The supercharged 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 a turbine 14b of the turbocharger 14. However, the internal combustion engine 2 may be an internal combustion engine 2 that does not have the turbocharger 14 or the like.

[0013] As shown in FIG. 2 and FIG. 3, the intake port 4 is connected to each of the four cylinders 11. The intake port 4 is provided in the cylinder head 2a. The intake port 4 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 intake valve 8 has a first intake valve 8a and a second intake valve 8b. The first intake port 4a has a port outlet (an example of a connection portion) that connects to the cylinder 11 opened and closed by the first intake valve 8a. The second intake port 4b has a port outlet that connects to the cylinder 11 opened and closed by the second intake valve 8b, similar to the first intake port 4a.

[0014] The exhaust ports 5 are connected to the four cylinders 11, respectively. The exhaust ports 5 are provided in the cylinder head 2a. The exhaust port 5 has a first exhaust port 5a and a second exhaust port 5b, which are branched by a port wall 2d formed by the cylinder head 2a. The first exhaust port 5a and the second exhaust port 5b are arranged adjacent to each other in the arrangement direction of the cylinders 11, and are connected to the same cylinder 11. The exhaust valve 12 has a first exhaust valve 12a and a second exhaust valve 12b. The first exhaust port 5a has a port inlet (an example of a connection portion) connected to the cylinder 11 that is opened and closed by the first exhaust valve 12a. The second exhaust port 5b has a port inlet connected to the cylinder 11 that is opened and closed by the second exhaust valve 12b, similar to the first exhaust port 5a.

[0015] The intake valve 8 is driven by an intake cam 8c. The phase of the intake cam 8c can be changed by an intake valve timing variable device 9. The exhaust valve 12 is driven by an exhaust cam 12c. The phase of the exhaust cam 12c can be changed by an exhaust valve timing variable device 13. The intake valve timing variable device 9 and the exhaust valve timing variable device 13 are electrically connected to a control device 20. The intake valve timing variable device 9 and the exhaust valve timing variable device 13 have the phase of the intake cam 8c and the phase of the exhaust cam 12c controlled by the control device 20, respectively.

[0016] The fuel injection valve 6 has a first fuel injection valve 6a and a second fuel injection valve 6b. The fuel injection valve 6 is disposed in each of the first intake port 4a and the second intake port 4b. Specifically, as shown in FIG. 3, 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 FIG. 1, the fuel injection valve 6 is 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 the fuel injection timing.

[0017] As shown in FIG. 3, the first fuel injection valve 6a has a nozzle hole for injecting fuel that is disposed closer to the cylinder 11 than the upstream end 2c of the port wall 2b. The first fuel injection valve 6a injects fuel toward the cylinder 11 when the first intake valve 8a is open. The second fuel injection valve 6b has a nozzle hole for injecting fuel that is disposed closer to the cylinder 11 than the upstream end 2c of the port wall 2b, similar to the first fuel injection valve 6a. The second fuel injection valve 6b injects fuel toward the cylinder 11 when the second intake valve 8b is open. That is, the internal combustion engine 2 of this embodiment is a semi-direct injection type internal combustion engine 2 that forms an air-fuel mixture in the first intake port 4a and the second intake port 4b and is also capable of injecting fuel into the cylinder 11.

[0018] 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 controls the first fuel injection valve 6a and the second fuel injection valve 6b according to the operating state of the internal combustion engine 2, and controls the fuel injection timing and the fuel injection period. Specifically, the control device 20 controls the first fuel injection valve 6a and the second fuel injection valve 6b according to the operating state of the internal combustion engine 2. The control device 20 controls the first fuel injection valve 6a and the second fuel injection valve with a first control and a second control. The first control is a control for causing at least one of the first fuel injection valve 6a and the second fuel injection valve 6b to perform a single-stage injection. The second control is a control for causing at least one of the first fuel injection valve 6a and the second fuel injection valve 6b to perform a multi-stage injection. The control device 20 executes a control for switching between the first control and the second control. Furthermore, the control device 20 controls the valve opening and closing timing of the intake valve 8 and the exhaust valve 12 by changing the phases of the intake cam 8c and the exhaust cam 12c in accordance with the operating conditions.

[0019] Furthermore, the control device 20 may control each device, such as the throttle valve 24 and the supercharging pressure of the supercharger 14, so that the internal combustion engine 2 is in a desired operating state, based on values ​​acquired from sensors such as the airflow sensor 22 and the accelerator position sensor 30a. The control device 20 is actually an ECU (Electronic Control Unit) configured by a microcomputer including a calculation device, a memory, an input / output buffer, and the like. 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 being processed by software, and can also be processed by dedicated hardware (electronic circuits).

[0020] Next, the control executed by the control device 20 will be described with reference to Fig. 4 and Fig. 5. The valve timing graph in Fig. 5 is a graph showing the valve lift amount (vertical axis) of the intake valve 8 and the exhaust valve 12 from the expansion stroke to the compression stroke, and the valve opening and closing timing. The graph of area A is a graph showing the fuel injection timing, injection period, and fuel injection amount (vertical axis) in area A of the operation area of ​​the internal combustion engine 2 described later. Similarly, the graph of area B is a graph showing the fuel injection timing, injection period, and fuel injection amount (vertical axis) in area B of the operation area of ​​the internal combustion engine 2. The graph of area C is a graph showing the fuel injection timing, injection period, and fuel injection amount (vertical axis) in area C of the operation area of ​​the internal combustion engine 2.

[0021] As shown in FIG. 4, the control device 20 controls the operation region (one example of the operation state) of the internal combustion engine 2 by dividing it into, for example, three regions. Region A is a region (one example of a first rotation region) of low to medium rotation in which the rotation speed of the internal combustion engine 2 is lower than a predetermined rotation speed, and is a region (one example of a second load region) of medium to high load in which the output or torque (load) of the internal combustion engine 2 is higher than the predetermined output or predetermined torque (load). The predetermined rotation speed may be, for example, a rotation speed near half the maximum rotation speed of the internal combustion engine 2. The predetermined output may be, for example, an output near half the maximum torque (load) of the internal combustion engine 2. The predetermined torque (load) may be, for example, a load near half the maximum torque (load) of the internal combustion engine 2. Region B is an operation region in which the load is lower than region A (one example of a first load region). Region C is a region (one example of a second rotation region) in which the rotation speed (engine speed) of the internal combustion engine 2 is higher than region A.

[0022] 4, the control device 20 executes valve overlap control to overlap the closing timing of the exhaust valve 12 and the opening timing of the intake valve 8. This is expected to improve the charging efficiency by inertia supercharging. On the other hand, when supercharging is performed by the supercharger 14 as in this embodiment, the pressure in the intake manifold 17 becomes positive.

[0023] In the case of the semi-direct injection type internal combustion engine 2 of this embodiment, in such region A, it is preferable to take into consideration: (1) the air-fuel mixture formed in the first intake port 4a and the second intake port 4b by valve overlap control blowing through to the exhaust port 5, and (2) the adhesion of fuel to the first intake port 4a and the second intake port 4b due to the intake manifold 17 becoming a positive pressure. It is preferable to take into consideration (1) in the fuel injection during the intake stroke in which fuel is directly supplied into the cylinder 11. It is preferable to take into consideration (2) in the fuel injection during the exhaust stroke in which a mixture is formed in the intake port 4.

[0024] Therefore, in region A, the control device 20 executes a second control in which the fuel injection valve 6 performs multi-stage injection. More specifically, as shown in Fig. 5, the second control in region A executes a first stage fuel injection (an example of a first injection) by the first fuel injection valve 6a and the second fuel injection valve 6b in the exhaust stroke to form an air-fuel mixture. Thereafter, a second stage fuel injection (an example of a second injection) is executed by the first fuel injection valve 6a and the second fuel injection valve 6b in the intake stroke.

[0025] Here, the amount of fuel injected in the second stage is greater than the amount of fuel injected in the first stage, thereby preventing the fuel injected in the exhaust stroke from adhering to the first intake port 4a and the second intake port 4b.

[0026] 5, the control device 20 executes the second-stage fuel injection when there is no valve overlap, that is, when the exhaust valve 12 is closed (both the first exhaust valve 12a and the second exhaust valve 12b are closed). This makes it possible to prevent the fuel injected during the intake stroke from blowing through to the exhaust port 5.

[0027] 4, the control device 20 does not execute valve overlap control. In addition, in such a low load region, there is no supercharging by the supercharger 14. Therefore, the pressure in the intake manifold 17 is negative, and the amount of fuel injection is also small.

[0028] In the case of the semi-direct injection type internal combustion engine 2 of this embodiment, in such region B, it is preferable to take into consideration (3) the dynamic range (flow rate characteristics) of the first fuel injector 6a and the second fuel injector 6b.

[0029] Therefore, in region B, the control device 20 executes a first control to perform single-stage injection from the fuel injection valve 6 from the exhaust stroke to the intake stroke. More specifically, as shown in region B of FIG. 5, fuel injection is performed in a single stage from the exhaust stroke to the intake stroke. This allows the fuel injection amount in one injection to be increased compared to multi-stage injection. As a result, the fuel injection amount of the first fuel injection valve 6a and the second fuel injection valve 6b can be prevented from falling below the flow characteristic lower limit (dynamic range lower limit). Note that, when the fuel injection amount approaches the dynamic range lower limit in region B, the control device 20 may execute fuel injection from either the first fuel injection valve 6a or the second fuel injection valve 6b.

[0030] 4, the control device 20 does not execute valve overlap control. However, this is a region where the supercharging pressure by the supercharger 14 is high. Therefore, the pressure in the intake manifold 17 is positive.

[0031] In the case of the semi-direct injection type internal combustion engine 2 of the present embodiment, in such region B, it is preferable to take into consideration (4) cooling of the cylinder 11 by the heat of vaporization of fuel.

[0032] Therefore, in the region C, the control device 20 executes the first control to perform one-stage injection from the fuel injection valve 6 during the intake stroke. More specifically, as shown in the region C of FIG. 5, fuel injection is performed in one stage during the intake stroke. This increases the amount of fuel injected in one stage, and the penetration of the spray due to the high fuel pressure is strong. This makes it difficult for fuel to adhere to the first intake port 4a and the second intake port 4b. As a result, the amount of fuel that enters the cylinder 11 also increases, and the cooling effect of the cylinder 11 due to the heat of fuel vaporization is easily generated.

[0033] In the control system 1 for the internal combustion engine 2 configured in this manner, for example, when the accelerator pedal 30 is depressed (for example, the accelerator opening Th is 80% or more), the control device 20 executes the second control in region A, and switches to the first control when the state transitions to region C. On the other hand, for example, when the accelerator pedal 30 is gently depressed (for example, the accelerator opening Th is less than 30%), the control device 20 executes the first control in region B (first load region). In this manner, the control device 20 executes optimal fuel injection according to the operating conditions of the semi-direct injection type internal combustion engine 2. This makes it possible to improve the output performance of the internal combustion engine 2, reduce emissions, and improve fuel efficiency.

[0034] As described above, according to the present disclosure, it is possible to provide a control system 1 for an internal combustion engine 2 that can execute optimal fuel injection according to the operating state of the internal combustion engine 2.

[0035] <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, the present disclosure may be applied to a plug-in hybrid electric vehicle (PHEV) capable of external charging or external power supply.

[0036] (a) In the above embodiment, the first fuel injection valve 6a and the second fuel injection valve 6b are disposed in the first intake port 4a and the second intake port 4b, respectively, but the present disclosure is not limited to this. The fuel injection valve 6 may be disposed in any manner according to the shape of the intake port as long as it can inject fuel into the connection between the intake port 4 and the cylinder 11.

[0037] (b) In the above embodiment, the second control in the region A is described using an example of two fuel injections, the first and second stages, but the present disclosure is not limited to this. The first stage may be further divided into multiple fuel injections. The same applies to the second stage. [Explanation of symbols]

[0038] 1: Control system 2: Internal combustion engine 4: Intake port 6: Fuel injection valve 11: Cylinder 20: Control device

Claims

1. A control system for an internal combustion engine, comprising: an intake port connected to a first cylinder of the internal combustion engine; a fuel injection valve disposed in the intake port and configured to inject fuel toward a connection portion between the first cylinder and the intake port; A control device for controlling the internal combustion engine; Equipped with The control device switches between a first control for causing the fuel injection valve to perform single-stage injection and a second control for causing the fuel injection valve to perform multi-stage injection according to an operating state of the internal combustion engine, the control device controls the internal combustion engine in a first rotation region in which a rotation speed of the internal combustion engine is lower than a predetermined rotation speed, a second rotation region in which the rotation speed of the internal combustion engine is higher than the first rotation region, a first load region in which an output of the internal combustion engine is lower than a predetermined output, and a second load region in which a load of the internal combustion engine is higher than the first load region, the control device executes the first control in the first rotation region and the second rotation region when controlling the internal combustion engine in the first load region, and executes the first control when controlling the internal combustion engine in the second rotation region when controlling the internal combustion engine in the second load region; When the first control is executed in the first load range, fuel is injected from an exhaust stroke to an intake stroke of the internal combustion engine, and when the first control is executed in the second load range and the second rotation range, fuel is injected in an intake stroke of the internal combustion engine. Control system for internal combustion engines.

2. The control device executes the second control when the internal combustion engine is controlled in the first rotation region.

2. The control system for an internal combustion engine according to claim 1.

3. When executing the second control, the control device executes a first injection of injecting the fuel into an exhaust stroke of the internal combustion engine and a second injection of injecting the fuel into an intake stroke of the internal combustion engine.

3. A control system for an internal combustion engine according to claim 1 or 2.

4. The injection amount of the second injection is greater than the injection amount of the first injection.

4. The control system for an internal combustion engine according to claim 3.

Images