Control system for auxiliary chamber type internal combustion engine

Abstract

To provide a control system for an auxiliary chamber type internal combustion engine, which can suppress knocking.SOLUTION: A control system for an auxiliary chamber type internal combustion engine comprises a main combustion chamber, an auxiliary combustion chamber that is disposed separatedly from the main combustion chamber by a partition wall, a fuel injection valve that is disposed in the main combustion chamber and injects fuel toward the auxiliary combustion chamber, a knocking detection device that detects knocking, and a control device that controls the fuel injection valve. The control device performs an intake stroke injection to inject fuel during an intake stroke and a compression stroke injection to inject fuel during a compression stroke, and switches from the compression stroke injection to the intake stroke injection when knocking is detected.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a control system for an internal combustion engine with a separate combustion chamber. [Background technology]

[0002] Conventionally, a pre-combustion chamber type internal combustion engine is known (see, for example, Patent Document 1). The pre-combustion chamber type internal combustion engine of Patent Document 1 comprises a main combustion chamber and a pre-combustion chamber, an ignition device disposed in the pre-combustion chamber, and a fuel injection valve disposed in the main combustion chamber. The pre-combustion chamber type internal combustion engine of Patent Document 1 forms an air-fuel mixture in the pre-combustion chamber by supplying fuel injected from the main combustion chamber to the pre-combustion chamber. The air-fuel mixture formed in the pre-combustion chamber is ignited by the ignition device to form a flame. The flame formed in the pre-combustion chamber is injected into the main combustion chamber via a communication passage. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2022 / 208575 Summary of the Invention [Problem to be solved by the invention]

[0004] In such a pre-chamber type internal combustion engine, knocking may occur due to an increase in the temperature of the pre-chamber or the spark plug during high load operation or high speed operation.

[0005] An object of the present disclosure is to provide a control system for a pre-chamber internal combustion engine that can suppress knocking. [Means for solving the problem]

[0006] The control system for an auxiliary combustion engine according to the present disclosure includes a main combustion chamber, an auxiliary combustion chamber separated from the main combustion chamber by a partition wall, a fuel injection valve disposed in the main combustion chamber and injecting fuel toward the auxiliary combustion chamber, a knocking detection device that detects knocking, and a control device that controls the fuel injection valve, wherein the control device performs intake stroke injection to inject fuel during the intake stroke and compression stroke injection to inject fuel during the compression stroke, and switches from the compression stroke injection to the intake stroke injection when knocking is detected. [Effects of the Invention]

[0007] According to this control system for an internal combustion engine with a pre-combustion chamber, knocking can be suppressed by switching from compression stroke injection to intake stroke injection. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a system diagram of a control system for an internal combustion engine with a pre-combustion chamber according to an embodiment of the present disclosure; [Figure 2] 4 is a flowchart illustrating a control procedure executed by a control device according to an embodiment of the present disclosure. [Figure 3] FIG. 2 is a diagram showing injection timing of an internal combustion engine with a pre-combustion chamber according to an embodiment of the present disclosure. [Figure 4] FIG. 10 is a system diagram of a control system for an internal combustion engine with a pre-combustion chamber according to a second embodiment. [Figure 5] FIG. 10 is a system diagram of injection timing for an internal combustion engine with a pre-chamber according to another embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] First Embodiment A first embodiment of the present disclosure will be described below with reference to the drawings. In the drawings, the sliding direction of the piston 8 is indicated as P, the side where the intake valve 14 is located is indicated as the intake side IN, and the side where the exhaust valve 16 is located is indicated as the exhaust side EX.

[0010] As shown in FIG. 1, the control system 1 for the auxiliary combustion chamber type internal combustion engine E includes a main combustion chamber 2, an auxiliary combustion chamber 3, a communication passage 4, an ignition device 6, a piston 8, a first fuel injection valve 9, a second fuel injection valve 10, a fuel pressure adjustment device 13, a knocking detection device 15, and a control device 20.

[0011] The main combustion chamber 2 is a space surrounded by the cylinder 11a of the cylinder block 11, the cylinder head 12, and the piston 8. In this embodiment, the main combustion chamber 2 has a pent roof shape, with two slopes formed toward the intake port 12a side and the exhaust port 12b side of the cylinder head 12. The main combustion chamber 2 is connected to the intake port 12a via an intake valve 14. The intake port 12a is connected, for example, to an intake passage (not shown). The main combustion chamber 2 is connected to the exhaust port 12b via an exhaust valve 16. The exhaust port 12b is connected, for example, to an exhaust passage (not shown).

[0012] The auxiliary combustion chamber 3 protrudes from the cylinder head 12 toward the main combustion chamber 2, and is separated from the main combustion chamber 2 by an auxiliary combustion chamber wall (an example of a partition wall) 5. The auxiliary combustion chamber 3 of this embodiment is located adjacent to the main combustion chamber 2 at the top of the pent roof shape, and has a space surrounded by the auxiliary combustion chamber wall 5.

[0013] The auxiliary combustion chamber wall 5 has a side wall 51 and a bottom wall 52. In this embodiment, the side wall 51 is formed in a cylindrical shape, and the bottom wall 52 is formed in a hollow hemispherical shape.

[0014] The communication passages 4 are provided in the auxiliary combustion chamber wall 5. The communication passages 4 communicate between the main combustion chamber 2 and the auxiliary combustion chamber 3. In this embodiment, a total of six communication passages 4 are provided, three toward the intake side and three toward the exhaust side.

[0015] As shown in Fig. 1, the ignition device 6 is disposed in the auxiliary combustion chamber 3. The ignition device 6 discharges the current flowing through the ignition coil using the central electrode and the side electrode, igniting the air-fuel mixture in the auxiliary combustion chamber 3. The ignition device 6 is electrically connected to the control device 20, and the ignition timing is controlled by the control device 20.

[0016] The piston 8 is housed in the cylinder 11a and slides within the cylinder 11a. The piston 8 surrounds the main combustion chamber 2 from below.

[0017] The first fuel injection valve 9 injects fuel toward the auxiliary combustion chamber 3 to form an air-fuel mixture in the auxiliary combustion chamber 3. As shown in the normal injection timing in FIG. 3, the first fuel injection valve 9 has the function of supplying fuel to the auxiliary combustion chamber 3 via the communication passage 4 by performing compression stroke injection F1, which injects fuel during the compression stroke. As shown in FIG. 1, in this embodiment, the first fuel injection valve 9 is arranged on the intake side IN. The first fuel injection valve 9 is an in-cylinder injection valve that injects fuel directly into the main combustion chamber 2. The first fuel injection valve 9 is electrically connected to a control device 20, and the fuel injection timing and injection amount are controlled by the control device 20.

[0018] The second fuel injection valve 10 injects fuel into the intake port 12a. The second fuel injection valve 10 is a port injection valve disposed in the intake port 12a. As shown in the normal injection timing in FIG. 3, the second fuel injection valve 10 executes port injection F2 mainly between the exhaust stroke and the intake stroke, so that the fuel mixes with air in the intake port 12a and flows into the main combustion chamber 2 to form an air-fuel mixture. As shown in FIG. 1, the second fuel injection valve 10 is electrically connected to a control device 20, and the control device 20 controls the fuel injection timing and injection amount.

[0019] The fuel pressure regulating device 13 adjusts the pressure of the fuel supplied to the first fuel injection valve 9. In this embodiment, the fuel pressure regulating device 13 is a mechanical pump driven by an intake cam (not shown) that drives the intake valve 14 or an exhaust cam (not shown) that drives the exhaust valve 16. However, the fuel pressure regulating device 13 may also be an electric pump. The fuel pressure regulating device 13 is supplied with fuel from a fuel tank (not shown). The fuel pressure regulating device 13 is electrically connected to a control device 20, and the control device 20 controls a valve that adjusts the pressure of the fuel, thereby adjusting the pressure of the fuel supplied to the first fuel injection valve 9.

[0020] The knocking detection device 15 detects knocking that occurs in the main combustion chamber 2. In this embodiment, the knocking detection device 15 is a knocking sensor disposed in the cylinder block 11. The knocking sensor detects knocking that occurs in the main combustion chamber 2 by detecting vibrations of the cylinder block 11. However, the knocking detection device 15 may also be an in-cylinder pressure sensor that detects the in-cylinder pressure of the main combustion chamber 2. The knocking detection device 15 is electrically connected to the control device 20, converts the detected vibrations, etc. into an electric signal, and transmits it to the control device 20.

[0021] The control device 20 receives a signal from the knocking detection device 15 and controls the first fuel injection valve 9, the second fuel injection valve 10, and the fuel pressure regulator 13. The control device 20 is actually an ECU (Electronic Control Unit) configured by a microcomputer including an arithmetic unit, a memory, an input / output buffer, etc. The control device 20 controls the first fuel injection valve 9, the second fuel injection valve 10, and the fuel pressure regulator 13 based on maps and programs stored in the memory.

[0022] Next, a control procedure executed by the control device 20 will be described with reference to the flowchart of Fig. 2 and Fig. 3. The control device 20 starts the control procedure when an ignition switch (not shown) is turned on.

[0023] In step S1, the control device 20 acquires a signal from the knocking detection device 15 and determines whether knocking has occurred (detected). In this embodiment, the control device 20 determines that knocking has occurred if the amplitude and frequency of the vibration acquired by the knock sensor are equal to or greater than a predetermined amplitude or a predetermined frequency. When knocking occurs, combustion becomes unstable and pressure fluctuations within the cylinder increase. The knock sensor detects the sound caused by this pressure fluctuation within the cylinder as vibration. The in-cylinder pressure sensor directly detects this pressure change. If the control device 20 determines that knocking has occurred (YES in step S1), the control device 20 proceeds to step S2.

[0024] In step S2, the control device 20 determines whether the injection quantity Q1 of the compression stroke injection F1 is equal to or greater than the minimum injection quantity Q1min (an example of a predetermined injection quantity). The minimum injection quantity Q1min is the smallest value of the injection quantity that the first fuel injector 9 can inject. As the injection quantity Q1 of the compression stroke injection F1 is reduced in step S4, which will be described later, the injection quantity Q1 approaches the minimum injection quantity Q1min. Therefore, the first fuel injector 9 cannot perform injection at or below the minimum injection quantity Q1min. The minimum injection quantity Q1min may be a value that allows some margin for the smallest value of the injection quantity that the first fuel injector 9 can actually inject. If the control device 20 determines that the injection quantity Q1 is equal to or greater than the minimum injection quantity Q1min (YES in step S2), the control device 20 proceeds to step S3.

[0025] In step S3, the control device 20 increases the injection quantity Q1a of the intake stroke injection F1a of the first fuel injector 9 (DI in FIG. 2). If the first fuel injector 9 is not currently performing the intake stroke injection F1a, the control device 20 may start the intake stroke injection F1a. By performing the intake stroke injection F1a in this manner, fuel adheres to the pre-combustion chamber wall 5 of the pre-combustion chamber 3. This cools the pre-combustion chamber wall 5, lowering the temperature of the pre-combustion chamber 3. As a result, knocking is suppressed. This cooling effect of the pre-combustion chamber 3 becomes more pronounced by increasing the injection quantity in the first half of the intake stroke. After increasing the injection quantity Q1a of the intake stroke injection F1a of the first fuel injector 9 (DI in FIG. 2), the control device 20 proceeds to step S4.

[0026] In step S4, the control device 20 reduces the injection quantity Q1 of the compression stroke injection F1 of the first fuel injector 9. Reducing the injection quantity Q1 of the compression stroke injection F1 weakens the momentum of the jet flame injected from the auxiliary combustion chamber 3 through the communication passage 4 into the main combustion chamber 2, thereby suppressing knocking. The control device 20 may also match the increased injection quantity ΔQ1a of the intake stroke injection F1a with the decreased injection quantity ΔQ1 of the compression stroke injection F1. This makes it possible to maintain the air-fuel ratio without reducing the injection quantity Q2 of the second fuel injector. After reducing the injection quantity Q1 of the compression stroke injection F1 of the first fuel injector 9, the control device 20 proceeds to step S5.

[0027] In step S5, the control device 20 controls the fuel pressure regulator 13 to perform pressure reduction control to reduce the fuel pressure. Performing pressure reduction control reduces the velocity of the spray injected from the first fuel injector 9. This reduces the amount of rebound when the spray hits the auxiliary combustion chamber wall 5. Furthermore, pressure reduction control increases the size of the spray droplets injected from the first fuel injector 9. This increases the amount of fuel that adheres to the auxiliary combustion chamber wall 5. As a result, the auxiliary combustion chamber 3 is more likely to be cooled. After performing the process of step S5, the control device 20 proceeds to step S1, where, as long as knocking occurs, the control device 20 decreases the injection amount Q1 of the compression stroke injection F1 while increasing the injection amount Q1a of the intake stroke injection F1a.

[0028] In step S1, if the control device 20 determines that knocking has not occurred (step S1 NO), this control is not executed until knocking occurs.

[0029] In step S2, when the control device 20 determines that the injection amount Q1 of the compression stroke injection F1 is less than the predetermined injection amount (step S2 NO), the process proceeds to step S8.

[0030] In step S8, the control device 20 determines the knocking intensity from the value detected by the knocking detection device 15, and determines whether the knocking intensity Ki is equal to or greater than a predetermined value TKi. The knocking intensity Ki is an index that indicates the intensity of knocking. The larger the knocking intensity Ki, the stronger the knocking that is occurring. In this embodiment, the larger the amplitude detected by the knock sensor, the higher the knocking intensity. The predetermined value TKi is a value of about 7, assuming that the maximum value of the knocking intensity Ki is 10. If the control device 20 determines that the knocking intensity Ki is less than the predetermined value TKi (NO in step S8), the control device 20 proceeds to step S9.

[0031] In step S9, the control device 20 advances the injection timing of the compression stroke injection F1. As shown in the graph in FIG. 3 where the injection quantity Q1 is equal to or less than the minimum injection quantity Q1min and the knocking intensity Ki is less than the predetermined value TKi, in this embodiment, the control device 20 maintains the injection quantity Q1 of the first fuel injector 9 at the minimum injection quantity Q1min and advances the injection timing of the compression stroke injection F1 relative to the injection timing when the first fuel injector 9 injected the minimum injection quantity Q1min. This reduces the amount of fuel entering the auxiliary combustion chamber 3 and weakens the momentum of the jet flame. Furthermore, when the injection timing of the compression stroke injection F1 is advanced, it is difficult to generate a fuel-rich mixture around the auxiliary combustion chamber wall 5. As a result, the combustion speed in the main combustion chamber 2 is slowed, and knocking is suppressed. As shown in FIG. 2, after advancing the injection timing of the compression stroke injection F1, the control device 20 proceeds to step S10.

[0032] In step S8, if the control device 20 determines that the knocking intensity Ki is equal to or greater than the predetermined value TKi (YES in step S8), the control device 20 advances the process to step S11.

[0033] In step S11, the control device 20 not only advances the injection timing of the compression stroke injection F1, but also executes ignition retard control, which retards the ignition timing of the ignition device 6. This causes an ignition delay in the pre-combustion chamber 3. As a result, the momentum of the jet flame is further weakened. After executing the ignition retard control, the control device 20 proceeds to step S10.

[0034] In step S10, the control device 20 acquires a signal from the knocking detection device 15 and determines whether knocking has occurred (detected). If the control device 20 determines that knocking has occurred (YES in step S10), the control device 20 proceeds to step S12. If the control device 20 determines that knocking has not occurred in step S10 (NO in step S10), the control device 20 proceeds to step S1.

[0035] In step S12, the control device 20 determines whether the angle Ad by which the injection timing of the compression stroke injection F1 has been advanced is equal to or greater than a predetermined angle TAd. If the injection timing of the compression stroke injection F1 is continued to be advanced, the injection timing of the compression stroke injection F1 will enter the intake stroke. The predetermined angle TAd is the angle Ad at which the compression stroke injection F1 will not enter the intake stroke. In this embodiment, the advanced angle Ad is the amount by which the injection start timing of the compression stroke injection F1 is advanced. The predetermined angle TAd is the angle from the injection start timing to the intake stroke when the compression stroke injection F1 is executed with the minimum injection quantity Q1min. If the injection timing of the minimum injection quantity Q1min is advanced by the predetermined angle TAd, the injection timing will enter the intake stroke. If the control device 20 determines that the advance angle Ad of the injection timing of the compression stroke injection F1 is less than the predetermined angle TAd, the control device 20 proceeds to step S8, where it advances the injection timing of the compression stroke injection F1 and executes ignition retard control according to the knock intensity.If the control device 20 determines that the advance angle Ad of the injection timing of the compression stroke injection F1 is equal to or greater than the predetermined angle TAd (YES in step S12), the control device 20 proceeds to step S13.

[0036] In step S13, the control device 20 switches the compression stroke injection F1 by the first fuel injection valve 9 to intake stroke injection F1a. That is, the control device 20 stops the compression stroke injection F1 and executes the intake stroke injection F1a. If the intake stroke injection F1a is already being executed, the control device 20 may stop the compression stroke injection F1. In the intake stroke injection F1a, the control device 20 simply ensures that the injection end timing of the intake stroke injection F1a does not fall into the compression stroke. This makes it possible to cool the auxiliary combustion chamber 3 without increasing the amount of fuel supplied to the auxiliary combustion chamber 3. As a result, knocking is suppressed. After switching the compression stroke injection F1 to the intake stroke injection F1a, the control device 20 proceeds to step S14.

[0037] In step S14, the control device 20 enriches the air-fuel ratio. The control device 20 of this embodiment operates the auxiliary combustion chamber type internal combustion engine E in lean burn with a target air-fuel ratio of approximately 20 to 25. The control device 20 lowers the target air-fuel ratio by approximately 1 to enrich the air-fuel ratio. This increases the injection amounts of the first fuel injection valve 9 and the second fuel injection valve 10. The control device 20 may increase the proportion of the injection amount of the first fuel injection valve 9, which is an in-cylinder injection valve, compared to the second fuel injection valve 10. This further cools the auxiliary combustion chamber 3.

[0038] Second Embodiment Next, a second embodiment of the present disclosure will be described with reference to Fig. 4. Regarding the second embodiment, only differences from the first embodiment will be described.

[0039] 4, control system 201 for auxiliary combustion chamber type internal combustion engine E includes main combustion chamber 202, auxiliary combustion chamber 203, communication passage 204, ignition device 206, piston 208, first fuel injection valve 209, second fuel injection valve 210, fuel pressure adjustment device 213, knocking detection device 215, and control device 220. Fuel pressure adjustment device 213 includes first fuel pressure adjustment device 213a that adjusts the pressure of fuel in first fuel injection valve 9, and second fuel pressure adjustment device 213b that adjusts the pressure of fuel in second fuel injection valve 10.

[0040] The first fuel injection valve 209 is the same as in the first embodiment. The second fuel injection valve 210 is an in-cylinder injection valve arranged in the main combustion chamber 2. The first fuel injection valve 209 performs compression stroke injection F1, which injects fuel toward the auxiliary combustion chamber 203 during the compression stroke. The second fuel injection valve 210 performs intake stroke injection F1a, which injects fuel toward the main combustion chamber 2 during the intake stroke. The second fuel injection valve 210 forms an air-fuel mixture in the main combustion chamber 202 by the intake stroke injection F1a.

[0041] In the second embodiment, when the control device 220 determines that knocking has occurred (see step S1 in FIG. 2: YES), the control device 220 may increase the intake stroke injection F1a of the second fuel injection valve 210 to inject fuel equivalent to the decrease in the compression stroke injection F1 (see step S2 in FIG. 2).

[0042] Furthermore, in the second embodiment, when switching to intake stroke injection (see step S13 in FIG. 2), the injection from the first fuel injection valve 209 may be stopped and the intake stroke injection F1a from the second fuel injection valve 210 may be performed.

[0043] The control system 201 for the pre-combustion chamber type internal combustion engine E of the second embodiment can also cool the pre-combustion chamber 203 and weaken the power of the jet flame, thereby suppressing knocking.

[0044] As described above, according to the present disclosure, it is possible to provide a control system 1 for an auxiliary combustion chamber type internal combustion engine E that can suppress knocking by cooling the auxiliary combustion chamber 3.

[0045] <Other embodiments> Although the embodiments of the present disclosure have been described above, the present disclosure is not limited to the above embodiments, and various modifications are possible within the scope of the gist of the invention. In particular, the multiple modifications described in this specification can be arbitrarily combined as necessary.

[0046] (a) In step S3 of the first embodiment, an example has been described in which the intake stroke injection F1a by the first fuel injection valve 9 is increased, but the present disclosure is not limited to this. The control device 20 may execute the intake stroke injection F1a by the port injection valve of the second fuel injection valve 10. As a result, the fuel injected from the second fuel injection valve 10 passes through the intake valve 14 and flows into the main combustion chamber 2. As a result, the auxiliary combustion chamber 3 can be cooled, similar to the intake stroke injection F1a by the first fuel injection valve 9.

[0047] (b) In the first embodiment described above, an example was described in which the first fuel injection valve 9, 209 and the second fuel injection valve 10, 210 were used, but the present disclosure is not limited to this. As shown in Fig. 5, a single fuel injection valve 309 arranged in the main combustion chamber 302 may execute a plurality of injection modes. The fuel injection valve 309 may execute compression stroke injection F1, which injects fuel toward the auxiliary combustion chamber 303 during the compression stroke, and may execute intake stroke injection F1a, which injects fuel into the main combustion chamber 302 during the intake stroke. The control device 320 may form an air-fuel mixture in the auxiliary combustion chamber 3 by the compression stroke injection F1, and form an air-fuel mixture in the main combustion chamber 2 by the intake stroke injection F1a. [Explanation of symbols]

[0048] 1,201: Control system 2,202, 302: Main combustion chamber 3,203,303: Pre-combustion chamber 9: First fuel injector, 10: Second fuel injector, 309: Fuel injector 12a: Intake port 13,213: Fuel pressure regulator 15: Knocking detection device 20, 220, 320: Control device E: Pre-chamber internal combustion engine F1: Compression stroke injection, F1a: Intake stroke injection, F2: Port injection Ki: knocking intensity, TKi: predetermined value Q1: Compression stroke injection amount, Q1a: Intake stroke injection amount, Q2: Port injection injection amount

Claims

1. A main combustion chamber; an auxiliary combustion chamber disposed separated from the main combustion chamber via a partition wall; a fuel injection valve disposed in the main combustion chamber and configured to inject fuel toward the auxiliary combustion chamber; a knocking detection device that detects knocking; a control device for controlling the fuel injection valve; Equipped with the control device executes intake stroke injection in which fuel is injected in an intake stroke and compression stroke injection in which fuel is injected in a compression stroke, and switches the compression stroke injection to the intake stroke injection when the knocking is detected. Control system for a pre-chamber internal combustion engine.

2. the control device reduces the injection amount of the compression stroke injection when the injection amount of the compression stroke injection is equal to or greater than a predetermined injection amount.

2. A control system for an internal combustion engine with a pre-combustion chamber according to claim 1.

3. increasing the injection amount of the intake stroke injection by a predetermined injection amount; 3. A control system for an internal combustion engine with a pre-combustion chamber according to claim 2.

4. the control device advances the injection timing of the compression stroke injection when the injection amount of the compression stroke injection becomes less than a predetermined injection amount.

2. A control system for an internal combustion engine with a pre-combustion chamber according to claim 1.

5. Further comprising an ignition device; the control device determines a knocking intensity from the value detected by the knocking detection device, and when the knocking intensity is equal to or greater than a predetermined value, retards the ignition timing of the ignition device.

5. A control system for a pre-combustion engine according to claim 4.

6. When the advance angle of the injection timing of the compression stroke injection becomes equal to or greater than a predetermined angle and when knocking is detected, switching the compression stroke injection to the intake stroke injection; 2. A control system for an internal combustion engine with a pre-combustion chamber according to claim 1.

7. When the control device detects the knocking, the control device makes the air-fuel ratio rich.

7. A control system for an internal combustion engine with a pre-combustion chamber according to claim 1.

8. a second fuel injection valve that injects fuel during an intake stroke; the control device increases the injection amount by the second fuel injection valve to make the air-fuel ratio rich.

8. A control system for an internal combustion engine with a pre-combustion chamber according to claim 7.

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