Engine control device

Abstract

To suppress formation of deposits.SOLUTION: An engine control device has a throttle valve attached to an intake system of an engine. The engine control device has an injector attached to a combustion chamber of the engine, in which a water supply passage is connected to the injector. The engine control device has a control system that controls the injector. The control system opens the injector to connect the water supply passage to the combustion chamber when a throttle valve opening is below a threshold and an engine rotation speed is above a threshold.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] The present disclosure relates to an engine control device. [Background technology]

[0002] In order to increase the thermal efficiency of internal combustion engines, water injection systems that inject water into the combustion chamber or intake port have been developed (see Patent Documents 1-4). In addition, by injecting water into the combustion chamber using a water injection system, the gas temperature in the combustion chamber can be lowered, thereby suppressing knocking. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Utility Model Application Publication No. 60-61472 [Patent Document 2] JP 2021-110327 A [Patent Document 3] Patent Publication No. 2022-38045 [Patent Document 4] JP 2007-162665 A Summary of the Invention [Problem to be solved by the invention]

[0004] Incidentally, deposits, which are products of incomplete combustion of fuel and oil, accumulate inside the engine, such as in the combustion chamber and intake port. Since these deposits are a cause of abnormal combustion such as knocking, there is a need to suppress the formation of deposits. [Means for solving the problem]

[0005] According to the present disclosure, an engine control device has a throttle valve attached to an intake system of an engine. The engine control device has an injector attached to a combustion chamber of the engine and connected to a water supply passage. The engine control device has a control system that controls the injector. When a throttle valve opening degree falls below a threshold and an engine speed exceeds a threshold, the control system opens the injector to communicate the water supply passage with the combustion chamber. Effect of the Invention

[0006] According to the present disclosure, the formation of deposits can be suppressed. [Brief description of the drawings]

[0007] [Figure 1] 1 is a diagram illustrating an example of a vehicle equipped with an engine control device according to an embodiment of the present disclosure. [Diagram 2] FIG. 1 illustrates an example of an engine and control system. [Diagram 3] FIG. 2 is a diagram illustrating an example of a basic structure of an electronic control unit. [Figure 4] 4 is a flowchart showing an example of a procedure for executing deposit reduction control. [Diagram 5] FIG. 13 is a diagram illustrating an example of an execution status of a normal injection mode. [Figure 6] FIG. 13 is a diagram illustrating an example of an execution status of a coast supply mode. [Figure 7] 4 is a timing chart showing an example of an execution state of deposit reduction control. [Figure 8] FIG. 4 is a diagram illustrating a portion of an engine control device according to a second embodiment of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In the following description, the same or substantially the same configurations and elements will be denoted by the same reference numerals and repeated description will be omitted.

[0009] First Embodiment <Vehicle> Fig. 1 is a diagram showing an example of a vehicle 11 equipped with an engine control device 10 according to an embodiment of the present disclosure. As shown in Fig. 1, the vehicle 11 has a power unit 14 consisting of an engine 12 and a transmission 13. An output shaft 15 of the power unit 14 is connected to wheels 18 via a propeller shaft 16 and a differential mechanism 17. Note that the illustrated power unit 14 is a rear-wheel drive power unit, but is not limited thereto and may be a front-wheel drive or all-wheel drive power unit.

[0010] <Engine> FIG. 2 is a diagram showing an example of the engine 12 and a control system 90. As shown in FIG. 2, the engine 12 has a cylinder block 21 that houses a piston 20, and a cylinder head 22 that is mounted on the cylinder block 21. The piston 20 is housed in the cylinder block 21 so that it can reciprocate, and a crankshaft 23 that is connected to the piston 20 is rotatably supported. In addition, an intake port 25 that communicates with a combustion chamber 24 is formed in the cylinder head 22, and an intake valve 26 that opens and closes the intake port 25 is attached. Similarly, an exhaust port 27 that communicates with the combustion chamber 24 is formed in the cylinder head 22, and an exhaust valve 28 that opens and closes the exhaust port 27 is attached. In addition, an intake camshaft 29 that drives the intake valve 26 and an exhaust camshaft 30 that drives the exhaust valve 28 are attached to the cylinder head 22.

[0011] An intake system 40 that guides intake air toward the intake port 25 and an exhaust system 50 that guides exhaust gas discharged from the exhaust port 27 are connected to the cylinder head 22. The intake system 40 is composed of an air cleaner box 41, a throttle valve 42, a surge tank 43, an intake manifold 44, and intake pipes 45, 46 that connect these components. The exhaust system 50 is composed of an exhaust manifold 51, a catalytic converter 52, a silencer 53, and exhaust pipes 54, 55 that connect these components. The intake air taken into the air cleaner box 41 is supplied to the combustion chamber 24 via the throttle valve 42, the surge tank 43, the intake manifold 44, and the intake port 25. The exhaust gas discharged from the combustion chamber 24 is discharged to the outside via the exhaust manifold 51, the catalytic converter 52, and the silencer 53.

[0012] The engine 12 has an EGR system 60 that supplies a part of the exhaust gas (hereinafter, referred to as EGR gas) from the exhaust system 50 to the intake system 40. EGR is an abbreviation for "Exhaust Gas Recirculation." The EGR system 60 has a gas flow path 61 that guides the exhaust gas from the exhaust system 50 to the intake system 40. The gas flow path 61 is composed of a gas pipe 62 connected to the exhaust pipe 54 of the exhaust system 50 and a gas pipe 63 connected to the surge tank 43 of the intake system 40. An EGR valve 64 is provided between the gas pipe 62 and the gas pipe 63, and an EGR cooler 65 that cools the EGR gas is provided in the gas pipe 62. When the EGR valve 64 is opened, the EGR gas is supplied from the exhaust system 50 to the surge tank 43 of the intake system 40 through the gas pipe 62 and the gas pipe 63. In this way, the EGR gas flows into the surge tank 43, and condensed water α derived from the exhaust gas is generated in the surge tank 43.

[0013] The engine 12 has a water injection system 70 that injects water into the combustion chamber 24. The water injection system 70 has a water injector (injector) 71 attached to the cylinder head 22, and a water supply passage 72 connected to the water injector 71. The water supply passage 72 is composed of a water supply pipe 73 connected to the water injector 71, a water supply pipe 74 connecting the water supply pipe 73 to a water tank 79, and a water supply pipe 75 connecting the water supply pipe 73 to a surge tank 43. A water pump 76 is attached to the water supply pipe 74, and an electromagnetic valve 77 and a check valve 78 are attached to the water supply pipe 75. In addition, the water injection system 70 has, as operation modes, a normal injection mode in which water is injected into the combustion chamber 24 when the engine 12 is in a high load operating state, and a coast supply mode in which water is supplied to the combustion chamber 24 when the engine 12 is in a coast operating state.

[0014] The water injector 71 can be operated in an open state in which an injection hole at the tip (not shown) is open, and in a closed state in which the injection hole is closed. The water pump 76 that pumps water toward the water injector 71 may be driven by the intake camshaft 29 or the exhaust camshaft 30, or may be driven by an electric motor. The water tank 79 may be filled with, for example, only water, a mixture of water and alcohol, or a mixture of water, alcohol, and oil. The cylinder head 22 is fitted with a fuel injector 80 that injects fuel such as gasoline into the combustion chamber 24, and an ignition device 81 that ignites the air-fuel mixture in the combustion chamber 24. The ignition device 81 is composed of an igniter, a spark plug, or the like.

[0015] <Control system> As shown in FIG. 2, the engine control device 10 has a control system 90 consisting of an electronic control unit 91 for controlling the throttle valve 42, the EGR system 60, the water injection system 70, the fuel injector 80, and the ignition device 81. Sensors connected to the electronic control unit 91 include an accelerator sensor 92 for detecting the amount of operation of an accelerator pedal, a brake sensor 93 for detecting the amount of operation of a brake pedal, and a vehicle speed sensor 94 for detecting the vehicle speed, which is the traveling speed of the vehicle 11. Sensors connected to the electronic control unit 91 include an engine rotation sensor 95 for detecting the engine speed, which is the rotation speed of the crankshaft 23, and a throttle opening sensor 96 for detecting the throttle valve opening, which is the opening of the throttle valve 42 (hereinafter, referred to as throttle opening). A start switch 97 that is operated by the driver when starting up the control system 90 is also connected to the electronic control unit 91.

[0016] Fig. 3 is a diagram showing an example of a basic structure of an electronic control unit 91. As shown in Fig. 3, the electronic control unit 91 has a microcontroller 102 incorporating a processor 100, a main memory (memory) 101, and the like. A predetermined program is stored in the main memory 101, and the program is executed by the processor 100. The processor 100 and the main memory 101 are connected to each other so as to be able to communicate with each other. Note that a plurality of processors 100 may be incorporated in the microcontroller 102, and a plurality of main memories 101 may be incorporated in the microcontroller 102.

[0017] The electronic control unit 91 also has an input circuit 103, a drive circuit 104, a communication circuit 105, an external memory 106, and a power supply circuit 107. The input circuit 103 converts signals input from various sensors into signals that can be input to the microcontroller 102. The drive circuit 104 generates drive signals for devices such as the throttle valve 42 described above based on signals output from the microcontroller 102. The communication circuit 105 converts signals output from the microcontroller 102 into communication signals directed to other electronic control units 91, etc. The communication circuit 105 also converts communication signals received from other electronic control units 91, etc. into signals that can be input to the microcontroller 102. The power supply circuit 107 supplies a stable power supply voltage to the microcontroller 102, the input circuit 103, the drive circuit 104, the communication circuit 105, the external memory 106, etc. The external memory 106, which is a non-volatile memory, etc., stores programs and various data, etc.

[0018] <Deposit suppression control: Flow chart> Deposit prevention control for suppressing the formation of deposits inside the engine will be described. Note that deposits are products of incomplete combustion of fuel and oil that accumulate on the wall surfaces of the combustion chamber 24, etc. FIG. 4 is a flowchart showing an example of the execution procedure of deposit prevention control. Each step of the deposit prevention control shown in FIG. 4 is executed by a processor 100 constituting a control system 90. Moreover, the deposit prevention control shown in FIG. 4 is control that is executed by the control system 90 at predetermined intervals after the control system 90 is started by operating a start switch 97.

[0019] As shown in FIG. 4, the control system 90 proceeds to step S10 and sets the operation mode of the water injection system 70 to a normal injection mode in which water is injected when the engine 12 is in a high load operation state. Here, FIG. 5 is a diagram showing an example of an execution state of the normal injection mode. As shown in FIG. 5, when the control system 90 sets the normal injection mode as the operation mode, it controls the electromagnetic valve 77 to a closed state to block the water supply pipe 75. Then, when the control system 90 determines that the engine operation region is a high load region, that is, when the engine load exceeds a predetermined value and the engine speed exceeds a predetermined value, it controls the water pump 76 and the water injector 71 to inject water into the combustion chamber 24 (arrow W1). As a result, when the engine 12 is in a high load operation, the gas temperature in the combustion chamber 24 can be lowered by water injection, and the thermal efficiency of the engine 12 can be improved. Note that, when the control system 90 determines that the engine operation region is outside the high load region, it stops the water pump 76 to stop water injection into the combustion chamber 24.

[0020] As shown in Fig. 4, the control system 90 proceeds to step S11, where it determines whether or not the vehicle speed exceeds a predetermined threshold value V1. If the control system 90 determines in step S11 that the vehicle speed exceeds the threshold value V1, it proceeds to step S12, where it determines whether or not the throttle opening degree falls below a predetermined threshold value S1. If the control system 90 determines in step S12 that the throttle opening degree falls below the threshold value S1, it proceeds to step S13, where it determines whether or not the engine speed exceeds a predetermined threshold value N1. If the control system 90 determines in step S13 that the engine speed exceeds the threshold value N1, it proceeds to step S14, where it determines whether or not the fuel injection from the fuel injector 80 has been cut off.

[0021] In the above-mentioned steps S11 to S14, the control system 90 determines that the vehicle speed exceeds the threshold V1, the throttle opening is below the threshold S1, the engine speed exceeds the threshold N1, and fuel injection is cut off, which is a coasting state in which the engine brake is activated and the vehicle speed decreases gradually. In other words, this is a state in which the accelerator pedal is released while the vehicle is traveling, the engine brake is activated, and the vehicle speed decreases gradually. When the control system 90 determines that the above-mentioned coasting state exists, the process proceeds to step S15, where the operation mode of the water injection system 70 is switched from the normal injection mode to the coast supply mode, and the coast supply mode is executed.

[0022] FIG. 6 is a diagram showing an example of the execution status of the coast supply mode. As shown in FIG. 6, when executing the coast supply mode, the control system 90 controls the solenoid valve 77 to an open state to communicate the water supply pipe 75, and controls the water injector 71 to an open state to open the injection hole of the water injector 71. That is, when executing the coast supply mode, the control system 90 opens the water injector 71 to communicate the water supply passage 72 with the combustion chamber 24. Furthermore, in a coasting state, the pressure in the combustion chamber 24 is lower than that in the surge tank 43, so that the water in the surge tank 43, i.e., the condensed water α, is supplied to the combustion chamber 24 from the water supply passage 72 through the water injector 71 as shown by the arrow W2. Note that, when executing the coast supply mode, the control system 90 controls the water pump 76 to a stopped state.

[0023] Incidentally, a coasting state in which the coast supply mode is executed is a state in which intake air is pumped from the intake system 40 to the exhaust system 50 while the throttle valve 42 is held in a fully closed position. In other words, it is a state in which the pressure in the combustion chamber 24 drops significantly, and the oil β in the crankcase 82 may leak into the combustion chamber 24 due to an increase in the pressure difference between the combustion chamber 24 and the crankcase 82. The leakage of oil β into the combustion chamber 24 due to so-called oil rising is a factor that causes a large amount of oil β to adhere to the piston crown surface 20a, and is a factor that causes oil-derived deposits to form on the piston crown surface 20a.

[0024] Therefore, as described above, in a coasting driving situation where oil β is likely to adhere to the piston crown surface 20a, the control system 90 executes the coast supply mode to supply condensed water α to the combustion chamber 24. As a result, even in a situation where oil β adheres to the piston crown surface 20a, the temperature of the combustion chamber 24 can be actively lowered, thereby suppressing the formation of deposits whose precursor is oil β. Moreover, since the condensed water α accumulated in the surge tank 43 is supplied to the combustion chamber 24, it is also possible to appropriately remove the condensed water α in the surge tank 43.

[0025] The coast supply mode for supplying the condensed water α is stopped when the coasting state is eliminated. That is, as shown in Fig. 4, when the control system 90 executes the coast supply mode in step S15, the process proceeds to step S16, where it determines whether the throttle opening exceeds a threshold value S2 that is greater than the threshold value S1. When the control system 90 determines in step S16 that the throttle opening is equal to or less than the threshold value S2, it proceeds to step S17, where it determines whether the engine speed falls below a threshold value N2 that is less than the threshold value N1. When the control system 90 determines in step S17 that the engine speed is equal to or greater than the threshold value N2, it proceeds to step S18, where it determines whether fuel injection from the fuel injector 80 is being performed.

[0026] If the control system 90 determines in step S18 that fuel is being cut, the coasting state continues, and the process returns to step S15 to continue the execution of the coast supply mode. On the other hand, if the control system 90 determines in step S16 that the throttle opening exceeds the threshold value S2, if the control system 90 determines in step S17 that the engine speed falls below the threshold value N2, or if the control system 90 determines in step S18 that fuel is being injected, the control system 90 determines that the coasting state that causes oil to rise has been resolved, and proceeds to step S19. Then, in step S19, the control system 90 switches the operation mode of the water injection system 70 from the coast supply mode to the normal injection mode.

[0027] <Deposit suppression control: timing chart> The above-mentioned deposit reduction control will now be described with reference to a timing chart, Fig. 7, which shows an example of the execution status of the deposit reduction control.

[0028] As shown at time t1 in FIG. 7, when the accelerator pedal is depressed while the vehicle is running (symbol a1), the operation mode of the water injection system 70 is set to the normal injection mode (symbol b1). Then, as shown at time t2, when the accelerator pedal is released (symbol a2), the throttle opening is controlled to "0" below the threshold value S1 (symbol c1), and fuel injection by the fuel injector 80 is cut off (symbol d1). At this time, the vehicle speed exceeds the threshold value V1 (symbol c1) and the engine speed exceeds the threshold value N1 (symbol f1), so the operation mode of the water injection system 70 is set to the coast supply mode (symbol b2). After that, as shown at time t3, when the accelerator pedal is depressed again (symbol a3), fuel injection by the fuel injector 80 is resumed (symbol d2), and the operation mode of the water injection system 70 is set to the normal injection mode (symbol b3).

[0029] <Second embodiment> In the example shown in Fig. 2, the water injector 71 and the surge tank 43 are connected to each other via a water supply pipe 75 and a water supply pipe 73, but the present invention is not limited to this. Fig. 8 is a diagram showing a part of an engine control device 110 according to a second embodiment of the present disclosure. In Fig. 8, parts similar to those shown in Fig. 2 are denoted by the same reference numerals and their description will be omitted.

[0030] As shown in FIG. 8, the engine 12 has a water injection system 111 that injects water into the combustion chamber 24. The water injection system 111 has a water injector 71 attached to the cylinder head 22 and a water supply passage 112 connected to the water injector 71. The water supply passage 112 is connected to a water tank 79, and a water pump 76 is attached to the water supply passage 112. When the coast supply mode is executed in accordance with the coasting driving situation, the water pump 76 and the water injector 71 are controlled, and water α2 from the water tank 79 is injected into the combustion chamber 24 (arrow W3). As a result, even in a situation where oil β adheres to the piston crown surface 20a, the temperature of the combustion chamber 24 can be actively lowered, and therefore the generation of deposits using the oil β as a precursor can be suppressed.

[0031] <Other embodiments> The present disclosure is not limited to the above-described embodiment, and various modifications are possible without departing from the spirit of the present disclosure. In the above description, the control system 90 is configured by one electronic control unit 91, but the present invention is not limited to this, and the control system 90 may be configured by multiple electronic control units. In the above description, the water injector 71 is held in an open state when the coast supply mode is executed, but the present invention is not limited to this, and the water injector 71 may be controlled to open and close based on the crank angle, etc., when the coast supply mode is executed. In other words, the water injector 71 may be alternately switched between an open state and a closed state when the coast supply mode is executed.

[0032] In the example shown in FIG. 4, the coast supply mode is executed when the vehicle speed exceeds the threshold V1, the throttle opening is below the threshold S1, the engine speed exceeds the threshold N1, and fuel injection is cut off, but the present invention is not limited to this. For example, the coast supply mode may be executed when the throttle opening is below the threshold S1 and the engine speed exceeds the threshold N1. The coast supply mode may also be executed when the throttle opening is below the threshold S1, the engine speed exceeds the threshold N1, and fuel injection is cut off. The coast supply mode may also be executed when the vehicle speed exceeds the threshold V1, the throttle opening is below the threshold S1, and the engine speed exceeds the threshold N1. [Explanation of symbols]

[0033] 10...engine control device, 12...engine, 24...combustion chamber, 40...intake system, 42...throttle valve, 43...surge tank, 50...exhaust system, 61...gas flow path, 71...water injector (injector), 72...water supply flow path, 90...control system, 100...processor, 101...main memory (memory), 110...engine control device, 112...water supply flow path, V1...threshold, S1...threshold, N1...threshold, α...condensed water (water), α2...water, β...oil

Claims

1. An engine control device for controlling an engine, a throttle valve attached to an intake system of the engine; an injector attached to a combustion chamber of the engine and connected to a water supply passage; a control system for controlling the injector, the control system comprising a processor and a memory communicatively connected to each other; having The control system includes: when a throttle valve opening degree falls below a threshold value and an engine speed exceeds a threshold value, the injector is opened to connect the feed water passage to the combustion chamber. Engine control device.

2. 2. The engine control device according to claim 1, The control system includes: when a throttle valve opening falls below a threshold value, an engine speed exceeds a threshold value, and fuel injection of the engine is cut off, the injector is opened to connect the feed water passage to the combustion chamber; Engine control device.

3. 2. The engine control device according to claim 1, The control system includes: When a throttle valve opening falls below a threshold and an engine speed exceeds a threshold in a state where a vehicle speed exceeds a threshold, the injector is opened to connect the water supply passage to the combustion chamber. Engine control device.

4. 2. The engine control device according to claim 1, The water supply passage is connected to a surge tank provided in the intake system. Engine control device.

5. 5. The engine control device according to claim 4, a gas flow passage connected to the surge tank for guiding exhaust gas from an exhaust system to the intake system; Engine control device.

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