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 first 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 first 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 when knocking is detected, performs a first control to increase the injection amount of the intake stroke injection.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] A 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 first 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 first 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 when knocking is detected, performs first control to increase the injection amount of the intake stroke injection. [Effects of the Invention]

[0007] According to this control system for a pre-combustion chamber type internal combustion engine, the amount of fuel injected during the intake stroke is increased, thereby allowing the pre-combustion chamber to be cooled by the latent heat of vaporization of the fuel, thereby suppressing knocking. [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. 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 6] FIG. 10 is a system diagram of a control system for an internal combustion engine with a pre-combustion 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 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 5, assuming that the maximum value of the knocking intensity Ki is 10. If the control device 20 determines that the knocking intensity Ki is equal to or greater than the predetermined value TKi (YES in step S2), the control device 20 proceeds to step S3.

[0025] In steps S3 and S4, the control device 20 executes a first control. The first control is a control that increases the injection amount of the intake stroke injection F1a when knocking is detected while the first fuel injection valve 9 is executing the compression stroke injection F1 in which fuel is injected during the compression stroke. In other words, the first control is a control that is executed when knocking is detected while the first fuel injection valve 9 is supplying fuel to the auxiliary combustion chamber 3.

[0026] 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.

[0027] In step S4, the control device 20 reduces the injection amount Q1 of the compression stroke injection F1 of the first fuel injector 9. Reducing the injection amount 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.

[0028] In the first control, the control device 20 decreases the injection amount of the compression stroke injection F1 by a first injection amount and increases the injection amount of the intake stroke injection F1a by a first injection amount. As shown in FIG. 3 when the knocking intensity Ki is equal to or greater than a predetermined value TKi (Ki≧TKi), in this embodiment, the increased injection amount ΔQ1a (an example of the first injection amount) of the intake stroke injection F1a matches the decreased injection amount ΔQ1 of the compression stroke injection F1. This allows the air-fuel ratio to be maintained without reducing the injection amount Q2 of the second fuel injector. As shown in FIG. 2, after decreasing the injection amount Q1 of the compression stroke injection F1 of the first fuel injector 9, the control device 20 proceeds to step S5.

[0029] In step S5, 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 S5), the control device 20 proceeds to step S6.

[0030] In step S6, the control device 20 controls the fuel pressure regulator 13 to execute pressure reduction control to reduce the fuel pressure. Executing pressure reduction control reduces the speed of the spray injected from the first fuel injection valve 9. This reduces the amount of spray bouncing back when it collides with the auxiliary combustion chamber wall 5. Furthermore, pressure reduction control increases the size of the spray droplets injected from the first fuel injection valve 9. This increases the amount of fuel that adheres to the auxiliary combustion chamber wall 5. This makes it easier to cool the auxiliary combustion chamber 3. In the pressure reduction control, the control device 20 may execute control to reduce the fuel pressure as the knocking intensity Ki increases.

[0031] After executing the process of step S6, the control device 20 proceeds to step S3, where, as long as knocking occurs, the control device 20 increases the injection amount Q1a of the intake stroke injection F1a while decreasing the injection amount Q1 of the compression stroke injection F1. If the injection amount Q1 of the compression stroke injection F1 is the minimum injection amount Q1min of the first fuel injector 9 and knocking occurs (YES in step S5), the control device 20 may execute pressure reduction control.

[0032] If the control device 20 determines in step S1 that knocking has not occurred (NO in step S1), the control device 20 will not execute this control until knocking occurs. If the control device 20 determines in step S5 that knocking has not occurred (NO in step S5), the control device 20 proceeds to the process in step S1 and ends the first control.

[0033] In step S2, if the control device 20 determines that the knocking intensity Ki is less than the predetermined value TKi (step S2 NO), the control device 20 advances the process to step S7.

[0034] In steps S7 and S8, the control device 20 executes second control. The second control is control for reducing the injection amount Q2 of port injection F2 by the second fuel injection valve 10 and increasing the injection amount of intake stroke injection of the first fuel injection valve 9 or the second fuel injection valve 10 when knocking is detected during the execution of compression stroke injection F1 in which the first fuel injection valve 9 injects fuel in the compression stroke. In the present embodiment, the control device 20 reduces the injection amount Q2 of port injection F2 by the second fuel injection valve 10 by a second injection amount reduction and increases the injection amount of intake stroke injection of the first fuel injection valve 9 or the second fuel injection valve 10 by a second injection amount increase.

[0035] In step S7, the control device 20 increases the injection amount Q1a of intake stroke injection F1a of the first fuel injection valve 9. When the control device 20 increases the injection amount Q1a of intake stroke injection F1a of the first fuel injection valve 9, the process proceeds to step S8.

[0036] In step S8, the control device 20 reduces the injection amount Q2 of port injection F2 by the second fuel injection valve 10. As shown by the knocking intensity Ki in FIG. 3 being less than the predetermined value TKi (Ki < TKi), in the present embodiment, the increased injection amount ΔQ1b (an example of the second injection amount) of intake stroke injection F1a and the decreased injection amount ΔQ2 (an example of the second injection amount) of port injection F2 by the second fuel injection valve 10 match. Thereby, the air-fuel ratio can be maintained. As shown in FIG. 2, when the control device 20 reduces the injection amount Q2 of port injection F2 of the second fuel injection valve 10, the process proceeds to step S9.

[0037] In step S9, the control device 20 acquires a signal from the knocking detection device 15 and determines whether knocking has occurred. When the control device 20 determines that knocking has not occurred (step S9 NO), the control device 20 proceeds to step S1.

[0038] If the control device 20 determines in step S9 that knocking is occurring (YES in step S9), the control device 20 proceeds to step S3 and executes the first control, which reduces the injection amount of the compression stroke injection F1 by the first fuel injector 9, weakens the momentum of the jet flame, and suppresses knocking.

[0039] The control device 20 may periodically perform the intake stroke injection F1a regardless of the occurrence of knocking. This makes it possible to remove deposits that tend to accumulate on the first fuel injection valve 9. Furthermore, the control device 20 may perform ignition retard control to retard the ignition timing of the ignition device 6 in addition to the first control and the second control.

[0040] Second Embodiment Next, a second embodiment will be described with reference to Figures 4 and 5. Regarding the second embodiment, only the differences from the first embodiment will be described.

[0041] 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 regulating device 213, knocking detection device 215, and control device 220. Fuel pressure regulating device 213 includes first fuel pressure regulating device 213a that regulates the pressure of fuel in first fuel injection valve 9, and second fuel pressure regulating device 213b that regulates the pressure of fuel in second fuel injection valve 10.

[0042] The first fuel injection valve 209 is the same as the first fuel injection valve 9 of the first embodiment. The second fuel injection valve 210 is an in-cylinder injection valve arranged in the main combustion chamber 2. As shown in FIGS. 4 and 5, under normal circumstances, the first fuel injection valve 209 (DI1 in FIG. 5) performs compression stroke injection F1, which injects fuel toward the auxiliary combustion chamber 203 during the compression stroke. The second fuel injection valve 210 (DI2 in FIG. 5) performs first half of intake stroke injection F3, which injects fuel toward the main combustion chamber 2 from the first half of the intake stroke. The second fuel injection valve 210 forms an air-fuel mixture in the main combustion chamber 202 by the first half of intake stroke injection F3. When knocking occurs, the control device 220 performs the first control. In the first control, the control device 220 may start the intake stroke injection F1a by the first fuel injection valve 209 and increase the injection amount of the intake stroke injection F1a (see first control pattern A in FIG. 5), or may increase the injection amount of the first half of the intake stroke injection F3 by the second fuel injection valve 210 (see first control pattern B in FIG. 5). The other configurations are the same as those in the above embodiment, and therefore description thereof will be omitted.

[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 the first embodiment described above, an example was described in which the intake stroke injection F1a by the first fuel injection valve 9 was increased during the second control, but the present disclosure is not limited to this. In the second control, the control device 20 may execute the intake stroke injection F1a by 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 second embodiment, an example using first fuel injection valve 209 and second fuel injection valve 210 has been described, but the present disclosure is not limited to this. As shown in Fig. 6, a single fuel injection valve 309 disposed in main combustion chamber 302 may perform a plurality of injection modes. [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 213a: First fuel pressure regulator, 213b: Second 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 arranged separated from the main combustion chamber via a partition wall; a first 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 that controls the first fuel injection valve; Equipped with When the knocking is detected during execution of a compression stroke injection in which fuel is injected during a compression stroke, the control device executes a first control to increase an injection amount of an intake stroke injection. Control system for a pre-chamber internal combustion engine.

2. the first control reduces the injection amount of the compression stroke injection by a first injection amount and increases the injection amount of the intake stroke injection by the first injection amount; 2. A control system for an internal combustion engine with a pre-combustion chamber according to claim 1.

3. a fuel pressure adjusting device that adjusts the pressure of fuel supplied to the first fuel injection valve, the control device controls the fuel pressure regulating device to reduce the pressure of the fuel when executing the first control; 2. A control system for an internal combustion engine with a pre-combustion chamber according to claim 1.

4. a second fuel injection valve that injects fuel into the intake port; When the control device detects the knocking, the control device executes second control to decrease the injection amount of the port injection by the second fuel injection valve by a second injection amount and to increase the injection amount of the intake stroke injection by the second injection amount.

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

5. The control device determines a knocking intensity from the value detected by the knocking detection device, When the knocking intensity is less than a predetermined value, the second control is executed, and when the knocking is detected during the second control, the first control is executed.

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

6. The control device executes the first control when the knocking intensity is equal to or greater than the predetermined value.

6. A control system for an internal combustion engine with a pre-combustion chamber according to claim 5.

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