Ignition control method and device for internal combustion engine

Abstract

To respond to a sudden request for changing ignition timing after setting ignition timing ADV and electric conduction start timing ON.SOLUTION: Ignition timing ADV1 of a cylinder whose ignition order arrives and electric conduction start timing ON1 corresponding to the ignition timing are set when a reference pulse signal REF-1 that is one signal before a reference pulse signal REF0 of the cylinder is detected. After that, when a sudden timing delay request or the like is made, whether or not the corresponding electric conduction start timing ON if the ignition timing ADV is changed in accordance with the request reaches a delay side of a predetermined non-changeable range ΔNG is determined in consideration of engine speed and battery voltage. If temporarily set electric conduction start timing ON2 is on the delay side of the non-changeable range ΔNG, electric conduction start timing ON2 and ignition timing ADV2 are reset. If the electric conduction start timing ON2 is within the non-changeable range ΔNG, only the ignition timing ADV2 is changed.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to an ignition control for an internal combustion engine that quickly responds to a sudden request for changing the ignition timing based on, for example, knocking detection. [Background technology]

[0002] Generally, an ignition device for an internal combustion engine is configured so that a discharge occurs between the electrodes of the spark plug connected to the secondary coil by passing and interrupting a primary current through the primary coil of the ignition coil. The ignition timing (i.e., the timing when the primary current is interrupted) is set according to the operating conditions, and the timing when current begins to flow is determined from this ignition timing.

[0003] Patent Document 1 discloses an ignition technology that retards the ignition timing of the next cylinder in the ignition order when knocking is detected in a cylinder. In particular, it discloses that an ignition signal calculated by an ECU based on knocking detection is reflected in the next cylinder in the ignition order when possible, and when it cannot be reflected, only the energization end timing (in other words, the ignition timing) is retarded. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-108383 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the above-mentioned Patent Document 1 does not specifically disclose how a sudden change in ignition timing, such as retardation based on knocking detection, is actually reflected in the next cylinder. [Means for solving the problem]

[0006] The present invention is an ignition control method for an internal combustion engine, which sets a start time for energizing an ignition coil when a first reference pulse signal that is one pulse earlier than a second reference pulse signal that is before an ignition timing is detected as a reference pulse signal indicating a reference crank angle position of each cylinder in a multi-cylinder internal combustion engine, and energizes the ignition coil when the corresponding crank angle is reached, when a request for changing the ignition timing is made between the first reference pulse signal and the second reference pulse signal, determining whether the corresponding current supply start timing when the ignition timing is changed in response to the request will be delayed from a predetermined non-changeable range from the second reference pulse signal, taking into consideration at least one of the engine rotation speed and the battery voltage; If the timing is delayed beyond a predetermined range that cannot be changed, the current supply start timing is reset in response to the ignition timing change request, and current is supplied.

[0007] In other words, under normal circumstances, the energization start timing is set when the first reference pulse signal, which is one signal earlier than the second reference pulse signal, is detected, and unless there is a sudden request to change the ignition timing thereafter, energization is performed at this energization start timing.

[0008] If a sudden ignition timing change request is made between the detection of the first reference pulse signal and the detection of the second reference pulse signal, it is determined whether the current supply start timing corresponding to the ignition timing when changed in accordance with the request is later than a predetermined non-changeable range from the second reference pulse signal. Since the current supply start timing is affected by the engine speed and the battery voltage, it is determined whether the current supply start timing can be changed when the ignition timing is changed, taking into account the engine speed and / or the battery voltage. [Effects of the Invention]

[0009] According to the present invention, it is possible to respond to a sudden request to change the ignition timing while maintaining the current application time as appropriately as possible. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a diagram illustrating the configuration of an internal combustion engine equipped with an ignition device according to an embodiment of the present invention; [Figure 2] 4 is a flowchart showing a process flow of ignition control according to an embodiment. [Figure 3] 10 is a time chart showing a case where a retard request is processed as an interrupt. [Figure 4] 10 is a time chart showing a case where an advance angle request is processed as an interrupt. DETAILED DESCRIPTION OF THE INVENTION

[0011] An embodiment of the present invention will now be described in detail with reference to the accompanying drawings.

[0012] FIG. 1 is an explanatory diagram showing the system configuration of an internal combustion engine 1 equipped with an ignition device according to the present invention. Each of the multiple cylinders 2 of the internal combustion engine 1 is equipped with a piston 3 and is connected to an intake port 5 opened and closed by an intake valve 4 and an exhaust port 7 opened and closed by an exhaust valve 6. A fuel injection valve 8 is also provided to inject fuel into the cylinder. The fuel injection timing and fuel injection amount of the fuel injection valve 8 are controlled by an engine controller 10. An ignition plug 9 is provided, for example, in the center of the ceiling surface to ignite the air-fuel mixture generated in the cylinder by the fuel injection valve 8. While the illustrated example is configured as a direct-injection internal combustion engine, a port-injection configuration in which a fuel injection valve is located in the intake port 5 may also be used. Detection signals are input to the engine controller 10 from numerous sensors, including an air flow meter 21 that detects the intake air amount, a crank angle sensor 22 that detects the engine speed, a temperature sensor 23 that detects the coolant temperature, a knocking sensor 24 that detects knocking, and a battery voltage sensor 25.

[0013] The crank angle sensor 22 outputs a unit crank angle pulse signal for each relatively small unit crank angle (for example, 4° CA or 2° CA), and also outputs a reference pulse signal (REF signal) indicating a reference crank angle position of each cylinder (for example, 150° CA before top dead center of compression). In the case of a four-cylinder internal combustion engine, the reference pulse signal is output every 180° CA. The reference pulse signal is not limited to being output directly by the crank angle sensor 22, but may be obtained by appropriate arithmetic processing such as frequency division.

[0014] An ignition unit 11 is connected to each cylinder of the spark plug 9, and outputs a discharge voltage to the spark plug 9 in response to an ignition signal from an engine controller 10. The ignition unit 11 is well known and is not shown in detail, but it includes an ignition coil including a primary coil and a secondary coil, and an igniter that controls the flow and cut-off of primary current to the primary coil of the ignition coil. An on-board battery 12 rated at, for example, 14 volts is connected to the ignition unit 11 as a power source. The voltage of the on-board battery 12 is detected by a battery voltage sensor 25.

[0015] As is well known, a primary current is applied to the primary coil via an igniter in response to an ignition signal from the engine controller 10, and then the current is cut off at the target ignition timing. When the primary current is cut off, a high discharge voltage is generated in the secondary coil, causing a discharge between the electrodes of the spark plug 9. The discharge energy at this time is basically correlated with the duration of the primary current flow; furthermore, a relatively long current flow time is required to obtain the same discharge energy when the battery voltage is low. Therefore, the engine controller 10 controls the start and cut-off timings of current flow, i.e., the ignition timing, to be optimal depending on the operating conditions, etc.

[0016] Next, the control of the energization start timing and the ignition timing will be described with reference to FIGS. 2 to 4. FIG. 3 is a time chart (where the horizontal axis represents crank angle) showing the relationship between the ignition signal corresponding to the energization period of the primary current and the reference pulse signal (REF signal), etc. Here, attention is focused on only one cylinder in the ignition order, and the compression top dead center, etc. shown in column (a) corresponds to that cylinder. The reference pulse signal (shown as REF0 and REF-1) for that cylinder is output at an appropriate time before the general ignition timing and energization start timing. In the illustrated example, the reference crank angle positions are set near 150° CA before top dead center and near 330° CA before top dead center, and the reference pulse signal shown as REF-1 is detected before the reference pulse signal REF0. The illustrated example uses a four-cylinder engine as an example, and the reference pulse signal is detected every 180° CA.

[0017] The reference pulse signal REF0 before the ignition timing of the target cylinder corresponds to the "second reference pulse signal" in the claims, and the reference pulse signal REF-1 immediately before this corresponds to the "first reference pulse signal" in the claims. Calculation of the normal target ignition timing and the calculation of the energization start timing corresponding to this target ignition timing are triggered by the reference pulse signal REF-1 immediately before the reference pulse signal REF0 of the target cylinder. In other words, when the immediately previous reference pulse signal REF-1 is detected, the target ignition timing is set according to the operating conditions (rotation speed and load) of the internal combustion engine 1 at that time, and the energization start timing is set accordingly. The energization start timing is calculated using the battery voltage and engine speed as parameters so as to obtain a target energization time corresponding to the battery voltage. Specifically, when the battery voltage or engine speed is low, the energization start timing becomes relatively early (the crank angle between the energization start timing and the ignition timing becomes relatively long), whereas when the battery voltage or engine speed is high, the energization start timing becomes relatively late (the crank angle between the energization start timing and the ignition timing becomes relatively short). The ignition signal is shown in section (b) of FIG. 3 as a rectangular wave, with its rising edge corresponding to the energization start timing (indicated by the symbol ON) and its falling edge corresponding to the ignition timing (indicated by the symbol ADV). Therefore, in the case of a four-cylinder engine, for example, the engine controller 10 calculates the ignition timing and the energization start timing every 180° CA in response to the reference pulse signal REF-1. Based on the thus-set energization start timing and ignition timing, energization and ignition are performed when the crank angle corresponding to the energization start timing and the ignition timing, respectively, is reached after the reference pulse signal REF-1 for the target cylinder is detected.

[0018] Column (c) of FIG. 3 shows an ignition timing change request that is processed as an interrupt. In the example of FIG. 3, based on knocking detection by the knocking sensor 24, a retard request is output between the reference pulse signal REF0 of the cylinder before the ignition timing and the reference pulse signal REF-1 immediately before that. This retard request is processed as part of normal ignition control for cylinders other than the cylinder in question (for example, the remaining three cylinders in a four-cylinder engine). On the other hand, for the cylinder immediately following that cylinder in the ignition order, a change (retardation) of the ignition timing is processed by interrupt processing.

[0019] 3(b), the current supply start timing ON1 and the ignition timing ADV1 are already scheduled by calculation at the time of the reference pulse signal REF-1. Whether or not to change these in response to a request for retardation is determined based on their relationship with a non-changeable range ΔNG, which is set within a certain crank angle range from the reference pulse signal REF0. The non-changeable range ΔNG is set as a kind of margin that takes into account the time required to calculate the current supply start timing ON, current supply delays, and rotation fluctuations. The engine controller 10 determines, taking into account the engine speed and battery voltage, whether the corresponding current supply start timing ON when the ignition timing ADV is changed in response to a request for ignition timing change will be later than the non-changeable range ΔNG. Specifically, the ignition timing ADV2 corresponding to the change request is calculated on the condition that the already scheduled energization start timing ON1 is delayed relative to the non-changeable range ΔNG. The energization start timing ON2 corresponding to the ignition timing ADV2 is provisionally set based on the engine speed and battery voltage at that time, and it is determined whether the provisionally set energization start timing ON2 is delayed relative to the non-changeable range ΔNG. If the provisionally set energization start timing ON2 is delayed relative to the non-changeable range ΔNG, the energization start timing ON and the ignition timing ADV are changed. In the example of FIG. 3 , the ignition timing ADV1 and the energization start timing ON1 are retarded to the ignition timing ADV2 and the energization start timing ON2, respectively, in response to the retard request. Note that the energization start timing ON2 corresponding to the ignition timing ADV2 is relatively advanced when the battery voltage or the engine speed is low, and is relatively delayed when the battery voltage or the engine speed is high.

[0020] If the provisionally set current distribution start timing ON2 falls within the non-changeable range ΔNG, the current distribution start timing ON is not changed and remains as the already set current distribution start timing ON1, and only the ignition timing ADV1 is retarded to the ignition timing ADV2. Therefore, knocking can also be suppressed for that cylinder.

[0021] Here, if only the ignition timing ADV is retarded in this way, the energization period becomes longer, and if this exceeds the upper limit of a certain predetermined allowable range, the ignition timing ADV2 is limited so that the energization period falls within the allowable range. In other words, ignition is performed with a delay amount slightly smaller than the requested delay amount. This prevents the ignition unit 11 from overheating due to excessive energy.

[0022] FIG. 4 illustrates a case where a sudden advance request is issued as an ignition timing change request between the reference pulse signal REF0 and the immediately preceding reference pulse signal REF-1 for the cylinder in question. In this case, as in the case of the retard request described above, the engine controller 10 determines whether the corresponding current supply start time ON, which would result from changing the ignition timing ADV in response to the ignition timing change request, is delayed relative to the non-changeable range ΔNG, taking into account the engine speed and battery voltage. Specifically, the engine controller 10 determines the ignition timing ADV2 corresponding to the change request, assuming that the previously scheduled current supply start time ON1 is delayed relative to the non-changeable range ΔNG. The engine controller 10 then provisionally sets the current supply start time ON2 corresponding to the ignition timing ADV2 based on the engine speed and battery voltage at that time, and determines whether the provisionally set current supply start time ON2 is delayed relative to the non-changeable range ΔNG. If the provisionally set current supply start time ON2 is delayed relative to the non-changeable range ΔNG, the engine controller 10 changes the current supply start time ON and the ignition timing ADV. 4, in response to the advance request, the ignition timing ADV1 and the current supply start timing ON1 are advanced to the ignition timing ADV2 and the current supply start timing ON2, respectively. Note that the current supply start timing ON2 corresponding to the ignition timing ADV2 becomes relatively earlier when the battery voltage is low or the engine speed is low, and becomes relatively later when the battery voltage is high or the engine speed is high.

[0023] If the provisionally set current distribution start timing ON2 falls within the non-changeable range ΔNG, the current distribution start timing ON is not changed, the already set current distribution start timing ON1 remains unchanged, and only the ignition timing ADV1 is advanced to the ignition timing ADV2. Therefore, an increase in torque, etc., can be achieved for the cylinder in question by advancing the current distribution start timing. Note that in the case of an advance request, even if the already scheduled current distribution start timing ON1 is more retarded than the non-changeable range ΔNG, it is more likely that the current distribution start timing ON2 corresponding to the changed ignition timing ADV2 will fall within the non-changeable range ΔNG than in the case of a retard request.

[0024] If only the ignition timing ADV is advanced in this way, the energization period will be shortened, and if it falls below the lower limit of a certain predetermined allowable range, the ignition timing ADV2 is limited so that the energization period falls within the allowable range. In other words, ignition is performed with an advance amount slightly smaller than the requested advance amount. This ensures reliable ignition.

[0025] FIG. 2 is a flowchart showing the flow of ignition control processing executed by the engine controller 10. In step 1, it is repeatedly determined whether a reference pulse signal REF has been detected. In particular, for a certain cylinder, it is determined whether a reference pulse signal REF-1, which is one signal before the reference pulse signal REF0 corresponding to that cylinder and which precedes the ignition of that cylinder, has been detected. If the reference pulse signal REF-1 is detected, the process proceeds to steps 2 and 3, where the ignition timing ADV (ADV1 in FIGS. 3 and 4) is set according to the engine operating conditions (engine speed and load) at that time, and the energization start timing ON (ON1 in FIGS. 3 and 4) corresponding to this ignition timing ADV is set based on the engine speed and battery voltage.

[0026] Next, proceed to step 4, where it is determined whether there has been a sudden request to change the ignition timing that requires interrupt processing after the ignition timing ADV and energization start timing ON have been set. If there is no request to change the ignition timing, proceed to step 5, where energization and ignition are performed using the set energization start timing ON (ON1) and ignition timing ADV (ADV1).

[0027] If there is an urgent ignition timing change request that requires interrupt processing, the process proceeds from step 4 to step 6, where it is determined whether the current distribution start timing ON can be changed based on its relationship with the non-changeable range ΔNG, as described above. If it is determined that the current distribution start timing ON can be changed, the process proceeds to step 7, where both the ignition timing ADV and the current distribution start timing ON are reset to ignition timing ADV2 and ignition start timing ON2 in Figures 3 and 4 in accordance with the change request. The process then proceeds to step 5, where current distribution and ignition are performed using the changed current distribution start timing ON2 and ignition timing ADV2.

[0028] On the other hand, if it is determined in step 6 that the energization start timing ON cannot be changed, the process proceeds to step 8, where only the ignition timing ADV is changed in accordance with the change request. In other words, the energization start timing ON1 shown in Figures 3 and 4 is not changed, and only the ignition timing ADV is changed from ignition timing ADV1 to ignition timing ADV2. Next, the process proceeds to step 9, where it is determined whether the energization time when the ignition timing ADV is changed to ignition timing ADV2 is within a predetermined allowable range. If the energization time is within the allowable range, the process proceeds from step 9 to step 5, and energization and ignition are performed using the originally set energization start timing ON1 and the re-set ignition timing ADV2.

[0029] If the energization time is not within the predetermined tolerance in step 9, the process proceeds to step 10, where the ignition timing ADV2 is restricted and reset so that the energization time is within the predetermined tolerance.Then the process proceeds to step 5, where energization and ignition are performed using the initially set energization start timing ON1 and the reset ignition timing ADV2 after the restriction.

[0030] Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment and various modifications are possible. For example, while a four-cylinder engine has been described as an example, the present invention can be similarly applied to internal combustion engines with other numbers of cylinders, such as three-cylinder engines or six-cylinder engines. The specific crank angle position of the reference pulse signal is arbitrary and is not limited to the above example. In addition, while the above example determines whether the power supply start timing can be changed based on both the engine rotation speed and the battery voltage, the determination may be made based on only one of these. In addition, in the above embodiment, the timing retard request is output based on knocking detection by the knock sensor. However, this is not limited to this, and the timing retard request may also be output based on changes in operating conditions (e.g., sudden acceleration from idling). [Explanation of symbols]

[0031] 1...Internal combustion engine 9...Spark plug 10...Engine controller 11...Ignition unit 12...Battery 24...Knocking sensor 25...Voltage sensor

Claims

1. 1. An ignition control method for an internal combustion engine, comprising: setting a start time for energizing an ignition coil when a first reference pulse signal that is one pulse earlier than a second reference pulse signal that is before an ignition timing is detected as a reference pulse signal indicating a reference crank angle position of each cylinder in a multi-cylinder internal combustion engine; and energizing the ignition coil when a corresponding crank angle is reached, when a request for changing the ignition timing is made between the first reference pulse signal and the second reference pulse signal, determining whether the corresponding current supply start timing when the ignition timing is changed in response to the request will be delayed from a predetermined non-changeable range from the second reference pulse signal, taking into consideration at least one of the engine rotation speed and the battery voltage; If the timing is delayed beyond the predetermined non-changeable range, the energization start timing is reset in response to the ignition timing change request and energization is performed. A method for controlling ignition in an internal combustion engine.

2. an ignition timing is set when the first reference pulse signal is detected, and ignition is performed when a corresponding crank angle is reached, and if the current supply start timing according to the ignition timing change request is within a predetermined non-changeable range, only the ignition timing is reset according to the ignition timing change request and ignition is performed; 2. The ignition control method for an internal combustion engine according to claim 1.

3. Limiting the reset ignition timing so that the energization time is within a predetermined tolerance range.

3. The ignition control method for an internal combustion engine according to claim 2.

4. When a request to change the ignition timing is made, it is determined whether the preset current application start timing is delayed relative to a predetermined non-changeable range, The ignition timing is determined in accordance with the ignition timing change request, with the condition that the ignition timing is on the delayed side. The timing for starting energization is provisionally set for this ignition timing, taking into consideration the engine rotation speed and battery voltage. It is determined whether the temporarily set energization start time is later than a predetermined unchangeable range. The ignition control method for an internal combustion engine according to any one of claims 1 to 3.

5. The ignition timing change request is a retard request based on knocking detection. The ignition control method for an internal combustion engine according to any one of claims 1 to 4.

6. an internal combustion engine having an ignition coil and an igniter for each cylinder; a crank angle sensor for obtaining a reference pulse signal indicating a reference crank angle position of each cylinder; a controller that sets a timing for starting energization of the ignition coil when detecting a first reference pulse signal that is immediately before a second reference pulse signal that is immediately before the ignition timing, and energizes the igniter when a corresponding crank angle is reached; An ignition control device for an internal combustion engine comprising: The above controller is when a request for changing the ignition timing is made between the first reference pulse signal and the second reference pulse signal, determining whether the corresponding current supply start timing when the ignition timing is changed in response to the request will be delayed from a predetermined non-changeable range from the second reference pulse signal, taking into consideration at least one of the engine rotation speed and the battery voltage; If the timing is delayed beyond the predetermined non-changeable range, the energization start timing is reset in response to the ignition timing change request and energization is performed. Ignition control device for internal combustion engines.

Images