Controller of internal combustion engine

Abstract

To provide a controller of an internal combustion engine capable of estimating a deposit accumulation amount without providing dedicated sensors and performing deposit removal operation.SOLUTION: A controller of an internal combustion engine comprises: a knocking sensor 25 that detects the occurrence of knocking in an engine 2; an engine speed sensor 26 that detects an engine speed of the engine 2; and an ECU 3 that estimates an actual in-cylinder compression ratio from the engine speed of the engine 2 and a load when knocking occurs, estimates a deposit amount accumulated in a combustion chamber 7 of the engine 2 based on the estimated actual in-cylinder compression ratio, and performs deposit removal operation according to the estimated deposit amount.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a control device for an internal combustion engine. [Background technology]

[0002] As the operating time of an internal combustion engine increases, the amount of deposits that accumulate in the combustion chamber increases. Deposit accumulation can cause abnormal combustion such as knocking and pre-ignition, but pre-ignition in particular can cause significant damage to the internal combustion engine.

[0003] Therefore, when the amount of deposits increases, it is necessary to carry out deposit removal operations at an appropriate time to suppress the occurrence of pre-ignition.

[0004] Patent Document 1 describes that a dedicated sensor for obtaining the thickness of the deposit is provided to determine whether or not the deposit has accumulated to the extent that removal operation is necessary. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Publication No. 2013 / 084309 Summary of the Invention [Problem to be solved by the invention]

[0006] However, the configuration described in Patent Document 1 inevitably leads to problems such as an increase in weight due to the addition of sensors and an increase in the number of steps required to change the hardware layout.

[0007] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a control device for an internal combustion engine that can estimate the amount of deposits accumulated and perform deposit removal operation without providing dedicated sensors. [Means for solving the problem]

[0008] In order to solve the above problems, the present invention provides a control device for an internal combustion engine having a knocking sensor that detects the occurrence of knocking in an internal combustion engine and an engine speed sensor that detects the rotation speed of the internal combustion engine, and is equipped with a control unit that estimates the actual in-cylinder compression ratio from the rotation speed and load of the internal combustion engine when knocking occurs, estimates the amount of deposits accumulated in the combustion chamber of the internal combustion engine based on the estimated actual in-cylinder compression ratio, and performs deposit removal operation according to the estimated deposit amount. [Effects of the Invention]

[0009] In this way, according to the present invention, the amount of accumulated deposits can be estimated and deposit removal operation can be carried out without providing any dedicated sensors. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic diagram of a vehicle equipped with an internal combustion engine control device according to an embodiment of the present invention. [Figure 2] 2A and 2B are diagrams showing examples of maps for determining the actual in-cylinder compression ratio of an engine from the engine speed and load when engine knocking occurs in an internal combustion engine control device according to one embodiment of the present invention, where FIG. 2A shows an example of the initial state of the map, and FIG. 2B shows an example of when the knocking region of the map has expanded. [Figure 3] FIG. 3 is a flowchart showing the procedure of the deposit removal control process of the control device for an internal combustion engine according to one embodiment of the present invention. [Figure 4] FIG. 4 is a time chart showing changes in knocking count due to the deposit removal control process of the control device for an internal combustion engine according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0011] A control device for an internal combustion engine according to one embodiment of the present invention is a control device for an internal combustion engine having a knocking sensor that detects the occurrence of knocking in the internal combustion engine and an engine speed sensor that detects the rotation speed of the internal combustion engine, and is configured to include a control unit that estimates the actual in-cylinder compression ratio from the rotation speed and load of the internal combustion engine when knocking occurs, estimates the amount of deposits accumulated in the combustion chamber of the internal combustion engine based on the estimated actual in-cylinder compression ratio, and performs deposit removal operation according to the estimated deposit amount.

[0012] As a result, the control device for an internal combustion engine according to one embodiment of the present invention can estimate the amount of deposit buildup and perform deposit removal operation without providing any dedicated sensors. [Example]

[0013] Hereinafter, a control device for an internal combustion engine according to an embodiment of the present invention will be described in detail with reference to the drawings.

[0014] In FIG. 1, a vehicle 1 equipped with an internal combustion engine control device according to one embodiment of the present invention includes an internal combustion engine 2 and an ECU (Electronic Control Unit) 3 as a control unit.

[0015] The engine 2 is formed with a cylinder 5 as a cylinder. A piston 6 that can reciprocate up and down within the cylinder 5 is housed in the cylinder 5. A combustion chamber 7 is provided above the cylinder 5.

[0016] The engine 2 is a so-called four-stroke gasoline engine in which, while the piston 6 reciprocates within the cylinder 5, a series of four strokes is performed, which are an intake stroke, a compression stroke, an expansion stroke, and an exhaust stroke.

[0017] The piston 6 is connected to a crankshaft 9 via a connecting rod 8. The connecting rod 8 converts the reciprocating motion of the piston 6 into the rotational motion of the crankshaft 9.

[0018] The combustion chamber 7 is also provided with an ignition plug 10 and an injector 11. The ignition plug 10 is disposed with an electrode protruding into the combustion chamber 7, and the ignition timing thereof is adjusted by the ECU 3.

[0019] The injector 11 is a so-called in-cylinder fuel injection valve that injects fuel supplied from a fuel tank (not shown) by a fuel pump into the combustion chamber 7.

[0020] The engine 2 is provided with an intake port 12 and an exhaust port 21. The intake port 12 communicates between the combustion chamber 7 and an intake passage 14a (described later). An intake valve 13 is provided in the intake port 12.

[0021] The intake valve 13 opens and closes to connect or block the intake passage 14a and the combustion chamber 7.

[0022] An intake pipe 14 is connected to the intake port 12. An intake passage 14a that communicates with the intake port 12 is formed inside the intake pipe 14. An electronically controlled throttle valve 15 is provided in the intake passage 14a. The throttle valve 15 is electrically connected to the ECU 3.

[0023] The throttle valve 15 adjusts the amount of intake air of the engine 2 by controlling the throttle opening in response to a command signal from the ECU 3 .

[0024] On the other hand, an exhaust valve 22 is provided in the exhaust port 21. The exhaust valve 22 opens and closes to connect or block an exhaust passage 24a (described later) and the combustion chamber 7.

[0025] An exhaust pipe 24 is connected to the exhaust port 21. An exhaust passage 24a communicating with the exhaust port 21 is formed inside the exhaust pipe 24.

[0026] The engine 2 configured as described above is an ignition engine in which a mixture of intake air, the flow rate of which is adjusted by the throttle valve 15, and fuel injected by the injector 11 is ignited by the spark plug 10.

[0027] The ECU 3 is configured by a computer unit that includes a CPU (Central Processing Unit), a RAM (Random Access Memory), a ROM (Read Only Memory), a flash memory, an input port, and an output port.

[0028] The ROM of this computer unit stores various control constants, various maps, etc., as well as a program for causing the computer unit to function as the ECU 3. That is, the computer unit functions as the ECU 3 when the CPU executes the program stored in the ROM.

[0029] To the input port of the ECU 3, various sensors such as a knocking sensor 25, an engine revolution sensor 26, an accelerator opening sensor 28, a vehicle speed sensor 29, etc. are connected.

[0030] The knocking sensor 25 detects knocking vibrations of the engine 2 and outputs a knock signal according to the magnitude of the knocking vibrations.

[0031] The engine speed sensor 26 outputs an engine speed pulse signal having a number of pulses proportional to the rotation speed of the crankshaft 9 based on the rotation of the crankshaft 9 of the engine 2. The ECU 3 is configured to detect the engine speed based on the engine speed pulse signal.

[0032] The accelerator opening sensor 28 detects the accelerator opening, which indicates the amount of operation of the accelerator pedal 27. The vehicle speed sensor 29 detects the speed of the vehicle 1.

[0033] On the other hand, various control targets such as a spark plug 10, an injector 11, a throttle valve 15, etc. are connected to the output port of the ECU 3.

[0034] The ECU 3 calculates the required load of the engine 2 based on the accelerator opening detected by the accelerator opening sensor 28, and calculates the target ignition timing, fuel injection amount, and intake air amount of the engine 2 according to the required load.The ECU 3 then controls the operating state of the engine 2 by controlling the spark plug 10, the injector 11, and the throttle valve 15 so that the calculated target ignition timing, fuel injection amount, and intake air amount are achieved.

[0035] In this embodiment, the ECU 3 estimates the amount of deposits in the combustion chamber 7 of the engine 2. For example, the ECU 3 estimates the actual in-cylinder compression ratio of the engine 2 from the engine speed and load of the engine 2 when knocking occurs, estimates the amount of deposits accumulated in the combustion chamber 7 of the engine 2 from the estimated actual in-cylinder compression ratio, and performs deposit removal operation on the engine 2 according to the amount of deposits.

[0036] As a deposit removal operation, the ECU 3 performs a forced removal operation, for example, by advancing the ignition timing to forcibly cause knocking, and using the resulting shock waves to remove deposits on the wall surfaces of the combustion chamber 7. The ECU 3 changes the amount of advance of the ignition timing depending on the amount of deposit accumulation estimated from the estimated actual in-cylinder compression ratio. Note that the deposit removal operation may be performed only when the estimated actual in-cylinder compression ratio is equal to or greater than a predetermined value.

[0037] The ECU 3 stores, for example, a map for determining the actual in-cylinder compression ratio of the engine 2 from the engine speed and load of the engine 2 when knocking of the engine 2 occurs.

[0038] 2, the ECU 3 associates the actual in-cylinder compression ratio of the engine 2, which is estimated from the engine speed and load of the engine 2 when knocking occurs, with a plurality of regions. Each region is a region where knocking is likely to occur in the corresponding state of the actual in-cylinder compression ratio.

[0039] The more deposits accumulate in the combustion chamber 7, the higher the in-cylinder actual compression ratio becomes, making knocking more likely to occur. The ECU 3 defines the region corresponding to the estimated current in-cylinder actual compression ratio as the knocking region, counts the number of times knocking has occurred at engine speeds and loads outside the knocking region for each region, and when the counted value reaches or exceeds a predetermined judgment value, it estimates that the in-cylinder actual compression ratio of the engine 2 has reached the in-cylinder actual compression ratio corresponding to that region, and expands the knocking region to that region.

[0040] FIG. 2(a) is a diagram showing a map in an initial state, and in the initial state, the region where the actual in-cylinder compression ratio ε is A is the initial knocking region.

[0041] The black dots in the diagram indicate points corresponding to the engine speed and load when the values ​​of the engine speed and load of engine 2 at the time when knocking of engine 2 occurs are outside the incipient knocking region.

[0042] In FIG. 2(a), when the counted value in the region where the actual in-cylinder compression ratio ε = C (the region between the dotted line where ε = B and the dotted line where ε = C in the figure) reaches or exceeds the judgment value, the estimated actual in-cylinder compression ratio ε becomes C, as shown in FIG. 2(b), and the knocking region is expanded to that region.

[0043] The ECU 3 may subtract 1 from the counted value after a predetermined time has elapsed. The ECU 3 may also change the determination value for each region. The determination value is set to be smaller for regions with higher in-cylinder actual compression ratios. When deposit removal operation has been performed, the ECU 3 may return the knocking region to its initial state.

[0044] When the estimated actual in-cylinder compression ratio is equal to or greater than a predetermined value, the ECU 3 performs pre-ignition suppression control.

[0045] The ECU 3 performs pre-ignition suppression control, which involves limiting the load on the engine 2, such as limiting the amount of intake air or the amount of fuel injection.

[0046] The deposit removal control process performed by the control device for an internal combustion engine according to this embodiment configured as described above will be described with reference to Fig. 3. The deposit removal control process described below is started when the ECU 3 starts operating, and is executed at preset time intervals.

[0047] In step S1, the ECU 3 determines whether knocking of the engine 2 is detected.

[0048] If it is determined that knocking is detected, the ECU 3 executes the process of step S2. If it is determined that knocking is not detected, the ECU 3 executes the process of step S1.

[0049] In step S2, the ECU 3 adds 1 to the knocking count for the region corresponding to the engine speed and load at the time of knocking occurrence. After executing the process of step S2, the ECU 3 executes the process of step S3.

[0050] In step S3, the ECU 3 determines whether the incremented count value is equal to or greater than a determination value.

[0051] If it is determined that the count value is equal to or greater than the determination value, the ECU 3 executes the process of step S6. If it is determined that the count value is not equal to or greater than the determination value, the ECU 3 executes the process of step S4.

[0052] In step S4, the ECU 3 determines whether a predetermined time has elapsed since the previous count was subtracted.

[0053] If it is determined that the predetermined time has elapsed, the ECU 3 executes the process of step S5. If it is determined that the predetermined time has not elapsed, the ECU 3 executes the process of step S1.

[0054] In step S5, the ECU 3 subtracts 1 from the counted values ​​in all areas. After executing the process of step S5, the ECU 3 executes the process of step S1.

[0055] In step S6, the ECU 3 estimates the actual in-cylinder compression ratio from the region corresponding to the incremented count. After executing the process of step S6, the ECU 3 executes the process of step S7.

[0056] In step S7, the ECU 3 determines whether the estimated actual in-cylinder compression ratio is greater than a predetermined value.

[0057] If it is determined that the estimated value of the actual in-cylinder compression ratio is greater than the predetermined value, the ECU 3 executes the process of step S8. If it is determined that the estimated value of the actual in-cylinder compression ratio is not greater than the predetermined value, the ECU 3 executes the process of step S9.

[0058] In step S8, the ECU 3 executes pre-ignition suppression control. After executing the process of step S8, the ECU 3 ends the deposit removal control process.

[0059] In step S9, the ECU 3 executes the deposit removal operation. After executing the process of step S9, the ECU 3 ends the deposit removal control process.

[0060] The change in knocking count due to such deposit removal control processing will be described with reference to FIG.

[0061] As shown in FIG. 4, each time knocking occurs outside the knocking region, the knocking count is incremented by 1, and at time t1, the knocking count is decremented by 1 after a predetermined time has elapsed.

[0062] Thereafter, the knocking count is incremented by one each time knocking occurs outside the knocking region, and at time t2, the knocking count is decremented by one after a predetermined time has elapsed since time t1.

[0063] Thereafter, the knocking count is incremented by 1 each time knocking occurs outside the knocking region, and at time t3, the value of the knocking count becomes equal to or greater than the judgment value, the in-cylinder actual compression ratio estimation is turned on, the in-cylinder actual compression ratio is estimated, and the corresponding control is executed.

[0064] In this way, in this embodiment, the ECU 3 estimates the actual in-cylinder compression ratio of the engine 2 from the engine speed and load of the engine 2 when knocking occurs, estimates the amount of deposits accumulated in the combustion chamber 7 of the engine 2 from the estimated actual in-cylinder compression ratio, and performs deposit removal operation of the engine 2 according to the amount of deposits accumulated.

[0065] This makes it possible to estimate the amount of deposits accumulated without providing dedicated sensors, and to carry out deposit removal operations.

[0066] In addition, the ECU 3 has a count for each region of the actual in-cylinder compression ratio, and counts the number of times knocking occurs at engine speeds and loads outside the knocking region for each region, and when the count reaches or exceeds a predetermined judgment value corresponding to the region, it estimates that the actual in-cylinder compression ratio of the engine 2 has become the actual in-cylinder compression ratio corresponding to that region.

[0067] This allows the accuracy of deposit accumulation amount estimation to be improved by estimating the actual in-cylinder compression ratio through multiple knocking detections.

[0068] The judgment value is set to be smaller in a region where the actual in-cylinder compression ratio is higher. As a result, since the higher the in-cylinder actual compression ratio, the more likely pre-ignition is to occur, by making it easier to estimate the in-cylinder actual compression ratio, which is the determination whether to perform removal operation, the occurrence of pre-ignition can be effectively suppressed.

[0069] Furthermore, the ECU 3 performs pre-ignition suppression control when the estimated actual in-cylinder compression ratio is equal to or greater than a predetermined value.

[0070] As a result, when it is estimated from the estimated actual in-cylinder compression ratio that the possibility of pre-ignition occurring is extremely high, the engine 2 can be reliably protected by implementing pre-ignition suppression control.

[0071] In this embodiment, an example has been described in which ECU 3 performs various determinations and calculations based on various sensor information, but this is not limited to this. Vehicle 1 may be provided with a communication unit capable of communicating with an external device such as an external server, and various determinations and calculations may be performed by the external device based on the detection information of various sensors transmitted from the communication unit. The determination results and calculation results may be received by the communication unit, and various controls may be performed using the received determination results and calculation results.

[0072] While an embodiment of the present invention has been disclosed, it will be apparent to one skilled in the art that modifications may be made thereto without departing from the scope of the present invention, and it is intended that all such modifications and equivalents be included in the following claims. [Explanation of symbols]

[0073] 1 vehicle 2. Engine (internal combustion engine) 3 ECU (control unit) 7. Combustion chamber 10 Spark plugs 11 Injector 15 Throttle valve 25 Knock sensor 26 Engine RPM Sensor 28 Accelerator opening sensor 29 Vehicle speed sensor

Claims

1. a knocking sensor that detects the occurrence of knocking in the internal combustion engine; an engine speed sensor for detecting a speed of the internal combustion engine, A control device for an internal combustion engine that includes a control unit that estimates an actual in-cylinder compression ratio from the engine speed and load when knocking occurs, estimates the amount of deposits accumulated in the combustion chamber of the internal combustion engine based on the estimated actual in-cylinder compression ratio, and performs deposit removal operation according to the estimated amount of deposits.

2. the control unit has a map for determining an actual in-cylinder compression ratio of the internal combustion engine from a rotation speed and a load of the internal combustion engine when knocking occurs in the internal combustion engine, The map has a plurality of regions corresponding to actual in-cylinder compression ratios, 2. The control device for an internal combustion engine according to claim 1, wherein the control unit counts the number of times knocking has occurred in the internal combustion engine for each of the regions, and when the counted value reaches or exceeds a predetermined judgment value for each of the regions, estimates that the actual in-cylinder compression ratio is the actual in-cylinder compression ratio corresponding to that region.

3. 3. The control device for an internal combustion engine according to claim 2, wherein the determination value is set to be smaller as the corresponding actual in-cylinder compression ratio increases.

4. 4. The control device for an internal combustion engine according to claim 1, wherein the control unit performs pre-ignition suppression control when the estimated actual in-cylinder compression ratio is equal to or greater than a predetermined value.

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