Engine control device

Abstract

To enable ignition to be performed at a desirable timing.SOLUTION: An engine control device that performs processing according to a plurality of signals that a sensor generates periodically according to a rotational period of an engine includes: a setting part for setting a timer for performing ignition at an ignition timing in the engine at a timing based on a first timing (T1); and a calculation part for calculating a value of the timer on the basis of a rotation speed of the engine in a first period prior to the T1 at a timing based on the T1. The T1 is a generation timing of the plurality of signals, is a timing before the ignition timing, and is closer to the ignition timing than the generation timing of any signal of the plurality of signals. The first period at least includes a period between the generation timing just before the T1 and the T1.SELECTED DRAWING: Figure 4A

Description

[Technical Field]

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

[0002] Conventional techniques for preventing so-called kickback (i.e., kickback) exist in engine operation. Kickback is a phenomenon in which ignition occurs before the piston reaches top dead center, pushing the piston back and causing the engine (i.e., crankshaft) to rotate in the opposite direction. Kickback can occur not only when the engine is started, but also after it has started.

[0003] For example, Patent Document 1 discloses an ignition timing control system for preventing kickback that occurs after engine start. Specifically, among multiple pulse signals generated in response to the spikes of an alternating current (AC) generator, the amount of drop in engine speed is calculated based on pulse signals from the spikes one spike before (e.g., the fourth spike) and two spikes before (e.g., the third spike) the spike corresponding to the ignition timing (e.g., the fifth spike). If the calculated amount of drop in engine speed is not within a predetermined value (i.e., if kickback is predicted to occur), the ignition timing is switched from the calculated timing (so-called soft ignition) to a fixed timing (so-called hard ignition). The pre-calculated timing is a timing before top dead center. The fixed timing is the timing of top dead center. In this way, by using hard ignition when kickback is predicted to occur, the ignition timing can be delayed. As a result, kickback (i.e., reverse rotation of the engine) is prevented. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-274998 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the technology disclosed in Patent Document 1 may not be able to achieve ignition at the desired timing. Specifically, the technology calculates the amount of drop in engine speed in the section between the projection immediately preceding the projection corresponding to the ignition timing and the projection immediately preceding it. Therefore, if the amount of drop suddenly increases in the section between the projection corresponding to the ignition timing and the projection immediately preceding it, the prediction of kickback may be incorrect. As a result, kickback may occur because the ignition method cannot be switched to hard ignition. Furthermore, even if the ignition method is switched to hard ignition, the desired engine speed may not be achieved. This is because hard ignition is performed at a fixed timing. For example, if the desired ignition timing is earlier than hard ignition, the engine speed at the hard ignition timing may be slower than the engine speed at the desired ignition timing. As a result, the increase in engine speed after ignition (i.e., combustion) may be delayed. This may not be what the user (e.g., the rider) intended.

[0006] An object of the present disclosure is to provide an engine control device that is capable of igniting at a desired timing. [Means for solving the problem]

[0007] An engine control device according to one aspect of the present disclosure includes: a setting unit that performs processing according to a plurality of signals periodically generated by a sensor in accordance with a rotation period of the engine, and sets a timer for igniting the engine at an ignition timing at a timing based on a first timing, and a calculation unit that calculates a value of the timer based on the rotation speed of the engine during a first period before the first timing, the first timing being a generation timing of one of the plurality of signals, which is before the ignition timing and is closer to the ignition timing than the generation timings of any of the plurality of signals, and the first period including at least a period between the generation timing immediately before the first timing and the first timing. [Effects of the Invention]

[0008] According to the present disclosure, it is possible to ignite at a desired timing. Note that the present disclosure may provide other effects instead of or in addition to the above effect. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a block diagram illustrating an example of a schematic functional configuration of an engine control device according to an embodiment of the present disclosure. [Figure 2] 1 is a block diagram illustrating an example of a schematic hardware configuration of an engine control device according to an embodiment of the present disclosure. [Figure 3] 4 is a flowchart for explaining an example of a schematic flow of processing of an engine control device according to an embodiment of the present disclosure. [Figure 4A] 4 is a timing chart for explaining an example of a schematic flow of processing in an EG reverse rotation prevention mode of an engine control device according to an embodiment of the present disclosure. [Figure 4B] 4 is a timing chart for explaining an example of a schematic flow of processing in a normal mode of an engine control device according to an embodiment of the present disclosure. [Figure 5A]4 is a timing chart for explaining an example of engine operation when EG reverse rotation does not occur. [Figure 5B] FIG. 4 is a schematic diagram for explaining an example of engine operation when EG reverse rotation does not occur. [Figure 6A] 10 is a timing chart for explaining an example of engine operation when EG reverse rotation occurs without an EG reverse rotation prevention mode. [Figure 6B] FIG. 10 is a schematic diagram for explaining an example of engine operation when EG reverse rotation occurs without an EG reverse rotation prevention mode. [Figure 7A] 4 is a timing chart for explaining an example of engine operation in an EG reverse rotation prevention mode. [Figure 7B] FIG. 4 is a schematic diagram for explaining an example of engine operation in an EG reverse rotation prevention mode. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. In this specification and drawings, elements that can be similarly described will be designated by the same reference numerals, and redundant description will be omitted.

[0011] The explanation will be given in the following order: 1. Functional configuration of engine control unit 2. Hardware configuration of engine control unit 3. Processing flow of the engine control unit 4. Example of operation 5. Variations

[0012] <1. Functional configuration of engine control unit> An example of the functional configuration of an engine control device 100 according to an embodiment of the present disclosure will be described with reference to FIG. 1. Referring to FIG. 1, the engine control device 100 includes an acquisition unit 101, a storage unit 103, a calculation unit 105, a setting unit 107, and an output unit 109. The engine control device 100 performs processing in accordance with a plurality of signals periodically generated by sensors in accordance with the rotation cycle of the engine. For example, the engine control device 100 uses, as the processing cycle, the timing at which a crank sensor 11 shown in FIG. 2 (described later) generates a pulse signal in accordance with the rotation of the engine. That is, each element of the functional configuration of the engine control device 100 performs processing at a timing based on the generation timing (in other words, output timing) of each of the plurality of signals.

[0013] The acquisition unit 101 acquires engine information. Specifically, the acquisition unit 101 acquires engine information by receiving signals output from various sensors related to the engine. For example, the acquisition unit 101 may acquire the generation timing described above by receiving a signal output from the crank sensor 11. The timing of processing by the engine control device is determined based on the generation timing. Furthermore, for example, the acquisition unit 101 may acquire the opening of a throttle valve (also referred to as a throttle) by receiving a signal output from a throttle opening sensor 13.

[0014] The storage unit 103 stores various information used in the engine control device 100. Specifically, the storage unit 103 stores information acquired by the acquisition unit 101. For example, the above-mentioned throttle opening may be stored. The storage unit 103 also stores information calculated by the calculation unit 105. For example, the value of an ignition timer and an engine rotation speed (also referred to as engine revolutions) calculated by the calculation unit 105 (described later) may be stored. The storage unit 103 also stores parameters used in processing by the engine control device 100. For example, the below-described throttle opening threshold and engine rotation speed threshold may be stored.

[0015] Furthermore, the information stored in the storage unit 103 is provided to each element of the functional configuration of the engine control device 100. Specifically, the information acquired by the acquisition unit 101 and stored in the storage unit 103 is provided to the calculation unit 105 or the setting unit 107. The information calculated by the calculation unit 105 is provided to the setting unit 107. For example, the value of an ignition timer may be provided to the setting unit 107.

[0016] The calculation unit 105 performs various calculations for engine control. Specifically, the calculation unit 105 performs calculations for each operation mode. The calculation unit 105 also selects an operation mode from a plurality of operation modes. The operation modes include an EG (Engine) reverse rotation prevention mode and a normal mode. The EG reverse rotation mode is processed as an interrupt process. The normal mode is processed as a periodic process. The operation modes are not limited to the EG reverse rotation prevention mode and the normal mode, and may include other modes.

[0017] In the EG reverse rotation prevention mode, the calculation unit 105 calculates the value of the ignition timer based on the engine speed during a first period prior to the first timing, at a timing based on the first timing. The ignition timer is a timer for igniting the engine at the ignition timing. For example, the value of the ignition timer may be calculated based on the engine speed during a period corresponding to an ignition angle predicted from the engine speed during the first period (e.g., a period between NNUM: 5 and 6, described below). The first timing is the generation timing of one of the above-mentioned multiple signals, which is before the ignition timing and closer to the ignition timing than any of the multiple signals. In other words, the first timing is the generation timing immediately before the ignition timing. The first period includes at least the period between the generation timing immediately before the first timing and the first timing. For example, the first period may be the period between the generation timing immediately before the first timing and the first timing. The engine speed during the first period may be calculated based on the length of the first period. Furthermore, the timing based on the first timing may be the first timing, a timing a predetermined time after the first timing, or a timing after a predetermined process is performed at the first timing.

[0018] In the normal mode, the calculation unit 105 calculates the value of the ignition timer at a timing based on the second timing based on the engine speed during a second period before the second timing. The second timing is the generation timing immediately before the first timing. The second period includes at least the period between the generation timing immediately before the second timing and the second timing. For example, the second period may be the period between the generation timing immediately before the second timing and the second timing. The engine speed during the second period may be calculated based on the length of the second period. The timing based on the second timing may be the second timing, a predetermined time after the second timing, or a timing after a predetermined process is performed at the second timing.

[0019] The calculation unit 105 also determines the operating mode based on the throttle opening and the engine rotation speed. Specifically, the calculation unit 105 selects the EG reverse rotation prevention mode when the throttle opening is equal to or greater than a threshold and the engine rotation speed at the time of determining the ignition angle (i.e., ignition timing) corresponding to the ignition timing is equal to or less than a threshold. The ignition timing is the timing at which ignition actually occurs. The ignition angle may be, for example, the engine crank angle, which may be an angle corresponding to a point before top dead center (i.e., before top dead center (BTDC)) in the piston compression stroke, where the angle at top dead center (i.e., TDC) is defined as 0 degrees. For example, an ignition angle of 10 degrees may be expressed as 10 degrees BTDC. On the other hand, the calculation unit 105 selects the normal mode when the throttle opening is less than a threshold or the engine rotation speed at the time of determining the ignition angle corresponding to the ignition timing exceeds a threshold. For example, the threshold for the engine rotation speed may be 1500 rpm. However, the threshold for the engine rotation speed is not limited to this. For example, the threshold value of the engine rotation speed may be the rotation speed when the engine is in an idling state (for example, anywhere between 1000 and 1500 rpm).

[0020] The calculation unit 105 determines an ignition angle corresponding to the ignition timing at a generation timing based on a predetermined timing of the engine rotation period. The calculation unit 105 calculates an engine rotation speed based on a specific period before the timing of determining the ignition angle corresponding to the ignition timing, and stores the engine rotation speed in the storage unit 103. For example, the ignition angle corresponding to the ignition timing may be an angle based on a specific position (e.g., top dead center) in the engine rotation. The timing of determining the ignition angle corresponding to the ignition timing may be the first generation timing in the engine rotation period (e.g., the timing of NNUM:0, described later). Note that information about the specific period may be stored in the storage unit 103, and the information about the specific period may be read out when determining the operation mode, and the engine rotation speed at the time of determining the ignition angle corresponding to the ignition timing may be calculated.

[0021] The setting unit 107 performs various settings for engine control. Specifically, the setting unit 107 sets the ignition timer at a timing based on the first timing. For example, the setting unit 107 sets the ignition timer to a value calculated by the calculation unit 105 immediately before the ignition timing. That is, in the EG reverse rotation prevention mode, the calculation unit 105 calculates the timer value and the setting unit 107 sets the timer based on the same generated timing. In the EG reverse rotation prevention mode, the setting of the ignition timer is performed as an interrupt process. On the other hand, in the normal mode, the calculation unit 105 calculates the timer value and the setting unit 107 sets the timer based on different generated timings. In the normal mode, the setting of the ignition timer is performed as a periodic process.

[0022] The output unit 109 outputs a signal based on the setting. Specifically, the output unit 109 outputs an ignition signal based on a set ignition timer. For example, when the ignition timer expires, the output unit 109 switches the power supply to an IG (Ignition) coil from ON to OFF. The output unit 109 may output signals for fuel injection, motor drive, and the like in addition to ignition. Naturally, the acquisition unit 101, the storage unit 103, the calculation unit 105, and the setting unit 107 handle information related to the control of fuel injection and motor drive. Details will be described later with reference to FIG. 2.

[0023] 2. Hardware configuration of engine control unit An example of a hardware configuration of the engine control device 100 according to the embodiment of the present disclosure will be described with reference to Fig. 2. Referring to Fig. 2, the engine control device 100 includes a waveform shaping circuit 111, an AD (Analog-Digital) converter 113, a power supply circuit 115, a microcomputer 117, an ignition drive circuit 119, an injection drive circuit 121, a motor drive circuit 123, and a nonvolatile memory 125.

[0024] The waveform shaping circuit 111 generates a pulse waveform based on a signal from the crank sensor 11. The pulse waveform indicates the generation timing described above (i.e., the processing timing of the engine control device 100). The microcomputer 117 performs processing at a timing based on the generation timing indicated by the pulse waveform. The waveform shaping circuit 111 can implement part of the functions of the acquisition unit 101 described above. Note that instead of the crank sensor 11, a sensor (e.g., a Hall sensor) that detects the magnetic poles of an electric motor that rotates in accordance with the rotation of the crankshaft and generates a pulse waveform may be used. Furthermore, when such a sensor is used, or when the sensor itself has a waveform shaping function, the waveform shaping circuit 111 may be omitted. The crank sensor 11 or an alternative sensor detects the crank angle of the engine and outputs a signal.

[0025] The AD converter 113 performs AD conversion on signals from the sensors. Specifically, the AD converter 113 converts analog signals output from the throttle opening sensor 13, intake pipe pressure sensor 15, intake air temperature sensor 17, water temperature sensor 19, and O2 sensor 21 into digital signals. The converted digital signals are input to the microcomputer 117. The AD converter 113 can realize part of the functions of the acquisition unit 101 described above.

[0026] The power supply circuit 115 supplies power from the battery power supply 23 to the microcomputer 117 .

[0027] The microcomputer 117 performs processing using the signal input from the AD converter 113 and the data stored in the nonvolatile memory 125. Specifically, the microcomputer 117 includes a processor such as a CPU (Central Processing Unit) and a memory such as a RAM (Random Access Memory). The microcomputer 117 can implement the functions of the calculation unit 105 and the setting unit 107 and part of the functions of the storage unit 103 by executing a program stored in the nonvolatile memory 125.

[0028] The ignition drive circuit 119 energizes the ignition coil 25 based on an ignition signal from the microcomputer 117, causing a spark plug (not shown) to discharge, thereby igniting the air-fuel mixture (i.e., air containing fuel). The injection drive circuit 121 causes the injector 27 to inject fuel based on a fuel injection signal from the microcomputer 117. The motor drive circuit 123 drives the stepping motor 29 based on the motor drive signal from the microcomputer 117. For example, the motor drive circuit 123 and the stepping motor 29 may be used to open and close an idle speed control valve or a throttle valve for adjusting the engine rotation speed during idling. The ignition drive circuit 119, the injection drive circuit 121, and the motor drive circuit 123 may implement the function of the output unit 109 described above.

[0029] The nonvolatile memory 125 stores data used in the processing of the microcomputer 117. For example, the nonvolatile memory 125 may be a ROM (Read Only Memory) or a flash memory. The nonvolatile memory 125 may realize part of the functions of the storage unit 103 described above.

[0030] <3. Processing flow of engine control unit> An example of processing by the engine control device 100 according to an embodiment of the present disclosure will be described with reference to FIG. 3. FIG. 3 and FIG. 4, which will be described later, show an example of processing in the compression stroke. Note that the processing shown in FIG. 3 and FIG. 4 may be performed only in the compression stroke. Specifically, the calculation unit 105 determines the stroke of the engine (i.e., the piston) before step S201. If it is determined that the stroke is the compression stroke, the processing proceeds to step S201. If it is determined that the stroke is not the compression stroke, the processing ends. In this way, by performing processing only in the compression stroke, it is possible to reduce power consumption. Note that FIG. 3 and FIG. 4, which will be described later, do not include stroke determination and only show processing in the compression stroke.

[0031] The engine control device 100 determines an operation mode based on the throttle opening and engine speed (step S201). Specifically, the calculation unit 105 determines whether the throttle opening is equal to or greater than a threshold value and whether the engine speed at the time of determining the ignition angle corresponding to the ignition timing (hereinafter also referred to as the engine speed for determining the operation mode) is equal to or less than a threshold value.

[0032] If the determination in step S201 is Yes, the engine control device 100 determines whether the timing to set the ignition timer has arrived (step S203). Specifically, the calculation unit 105 selects the EG reverse rotation prevention mode if the throttle opening is equal to or greater than a threshold and the engine speed at the time of determining the ignition angle corresponding to the ignition timing is equal to or less than a threshold. In the EG reverse rotation prevention mode, the calculation unit 105 determines whether the generation timing (i.e., the first timing) to set the ignition timer has arrived. Details will be described later with reference to FIG. 4A.

[0033] If the determination in step S203 is Yes, the engine control device 100 calculates the ignition timer (step S205). Specifically, when the generation timing (i.e., the first timing) for setting the ignition timer arrives, the calculation unit 105 calculates the engine speed during a first period before the first timing, at a timing based on the first timing. Then, the calculation unit 105 calculates the value of the ignition timer based on the calculated engine speed. The processing of step S205 is performed as an interrupt processing.

[0034] Subsequently, the engine control device 100 sets an ignition timer (step S207). Specifically, the setting unit 107 sets the ignition timer to the value calculated by the calculation unit 105. The process of step S207 is performed as an interrupt process.

[0035] If the determination in step S201 is No, the engine control device 100 determines whether the calculation timing of the ignition timer has arrived (step S209). Specifically, the calculation unit 105 selects the normal mode if the throttle opening is less than a threshold value or the engine speed at the time of determining the ignition angle corresponding to the ignition timing exceeds a threshold value. In the normal mode, the calculation unit 105 first determines whether the generation timing (i.e., the second timing) for calculating the ignition timer has arrived.

[0036] If the determination in step S209 is Yes, the engine control device 100 calculates the ignition timer (step S211). Specifically, when the generation timing (i.e., the second timing) for calculating the ignition timer arrives, the calculation unit 105 calculates the engine speed in a second period before the second timing, at a timing based on the second timing. Then, the calculation unit 105 calculates the value of the ignition timer based on the calculated engine speed. The calculated value of the ignition timer is stored in the storage unit 103. The processing of step S211 is performed as periodic processing.

[0037] If the determination in step S209 is No, the engine control device 100 determines whether the timing to set the ignition timer has arrived (step S213). Specifically, if it is determined that the generation timing (i.e., the second timing) for calculating the ignition timer has not arrived, the calculation unit 105 determines whether the generation timing (i.e., the first timing) for setting the ignition timer has arrived.

[0038] If the determination in step S213 is Yes, the engine control device 100 sets the ignition timer (step S215). Specifically, the setting unit 107 acquires the value of the ignition timer calculated by the calculation unit 105 from the storage unit 103, and sets the ignition timer to the acquired value. The processing of step S215 is performed as periodic processing.

[0039] Next, the processing in each operation mode will be described in detail with reference to Figures 4A and 4B. Figures 4A and 4B are timing charts in which the time axis is expressed in NNUM. NNUM corresponds to the generation timing described above.

[0040] Referring to FIG. 4A, the process in the EG reverse rotation prevention mode will be described. First, the engine control device 100 calculates the ignition angle corresponding to the ignition timing at the timing of NNUM:0. Specifically, the calculation unit 105 determines the ignition angle corresponding to the ignition timing at the timing of NNUM:0 to be just before top dead center (for example, an angle slightly before NNUM:6 between NNUM:5 and NNUM:6). The calculation unit 105 also calculates an engine speed for determining an operation mode based on the length between two NNUMs in the period before NNUM:0 (for example, NNUM:9 and NNUM:10 in the previous engine rotation cycle). The calculated engine speed for determining the operation mode is stored in the memory unit 103. The calculation timing of the ignition angle is set so that, even when the ignition angle is advanced (for example, when the ignition angle is advanced by a maximum of 60 degrees from top dead center), the time required to energize the IG coil (i.e., the ignition coil 25) can be ensured and the ignition angle can be calculated periodically. Furthermore, the calculation of the engine speed for determining the operating mode, which is performed simultaneously with the calculation of the ignition angle, is performed based on the periods NNUM:9 and 10. For this reason, NNUM:0 is selected as the calculation timing for the ignition angle in Fig. 4A. However, the calculation of the ignition angle may be performed at any timing as long as the above-described conditions for the calculation timing of the ignition angle and the conditions for the period used to calculate the engine speed for determining the operating mode are satisfied.

[0041] The engine control device 100 determines the operation mode after processing NNUM:0. Specifically, the calculation unit 105 determines the operation mode based on the throttle opening and the engine speed for determining the operation mode at the timing of NNUM:1 or 2. In this case, the operation mode is determined to be the EG reverse rotation prevention mode. Note that the operation mode may also be determined at NNUM:0.

[0042] The engine control device 100 performs timer calculation and timer setting at timing NNUM:5 (i.e., the generation timing one time before top dead center). Specifically, at timing NNUM:5, the calculation unit 105 calculates the engine speed based on the length of the period D1 between NNUM:4 (i.e., the generation timing two times before top dead center) and NNUM:5. The calculation unit 105 calculates the value of the ignition timer based on the calculated engine speed. The setting unit 107 sets the ignition timer to the calculated value. These processes are performed as interrupt processes. Furthermore, these processes are performed as continuous processes without being interrupted by other processes. Because the timer calculation and timer setting cannot be performed in parallel, in order to perform these processes in the shortest time, it is desirable to perform them as a continuous series of interrupt processes as described above. More specifically, the calculation of the engine speed for ignition timer calculation, the ignition timer calculation, and the setting of the ignition timer are performed as a continuous series of processes without any other processes being performed between them. This allows the engine speed during the period immediately prior to the ignition timing to be used in the ignition timer calculation. In other words, ignition can be performed at a more appropriate timing. Note that these processes may be performed slightly after the timing of NNUM:5 during the period between NNUM:5 and NNUM:6.

[0043] The engine control device 100 performs ignition when the set ignition timer expires. Specifically, when the set ignition timer expires, the output unit 109 switches the power supply to the IG coil (i.e., the ignition coil 25) from ON to OFF. This causes ignition.

[0044] Next, the processing in the normal mode will be described with reference to Fig. 4B. Note that detailed description of the content that is substantially the same as that in the EG reverse rotation prevention mode will be omitted.

[0045] First, the engine control device 100 calculates the ignition angle corresponding to the ignition timing at the timing of NNUM:0.

[0046] After processing NNUM:0, the engine control device 100 determines the operating mode. Here, the operating mode is determined to be normal mode. In normal mode, there is more time for processing than in EG reverse rotation prevention mode. Specifically, in EG reverse rotation prevention mode, multiple processes are performed within the same NNUM, but in normal mode, processes are performed sequentially across multiple NNUMs.

[0047] The engine control device 100 performs timer calculation at the timing of NNUM:4. Specifically, the calculation unit 105 calculates the engine speed at the timing of NNUM:4 based on the length of the period D2 between NNUM:3 and NNUM:4. The calculation unit 105 calculates the value of the ignition timer based on the calculated engine speed. The calculated ignition timer value is stored in the storage unit 103. The above processing is performed as a periodic process. The above processing is performed slightly after the timing of NNUM:4 in the period between NNUM:4 and NNUM:5.

[0048] The engine control device 100 sets the timer at the timing of NNUM: 5. Specifically, the setting unit 107 acquires the value of the ignition timer calculated by the calculation unit 105 from the storage unit 103, and sets the ignition timer to the acquired value.

[0049] The engine control device 100 performs ignition when the set ignition timer expires.

[0050] <4. Example of operation> 5 to 7, an example of the operation of an engine controlled by the engine control device 100 according to an embodiment of the present disclosure will be described. Figures 5A, 6A, and 7A are timing charts of the compression stroke. Figures 5B, 6B, and 7B are schematic diagrams showing four strokes of the engine.

[0051] First, an example of engine operation when EG reverse rotation does not occur will be described with reference to Figures 5A and 5B. In the example of Figure 5A, the value of the ignition timer is calculated based on the engine speed during the period between NNUM:3 and NNUM:4. With the ignition timer set to the calculated value, ignition occurs just before NNUM:6 (i.e., top dead center).

[0052] Referring to FIG. 5B, during the intake stroke, the piston 33 moves downward, causing the crankshaft 37 to rotate via the connecting rod 35. Furthermore, as the piston 33 moves downward, the air-fuel mixture flows into the cylinder 31. During the compression stroke, the piston 33 moves upward, compressing the air-fuel mixture in the cylinder 31. Furthermore, just before the piston 33 reaches top dead center, ignition is performed based on the ignition timer described above. During the combustion stroke, when the piston 33 reaches top dead center (or immediately after reaching top dead center), ignition burns the air-fuel mixture, and the piston 33 is pushed down. During the exhaust stroke, the pushed-down piston 33 moves upward again, expelling the air from the cylinder 31.

[0053] As described above, in the examples of Figures 5A and 5B, combustion occurs after reaching top dead center. This is because the calculated ignition timer value roughly matches the ignition timing corresponding to the ignition angle. As a result, the rotation direction of the crankshaft 37 does not change. In other words, EG reverse rotation does not occur. Note that the engine operation of Figures 5A and 5B may be achieved by the normal mode of the engine control device 100.

[0054] Next, an example of engine operation when EG reverse rotation occurs without the EG reverse rotation prevention mode will be described with reference to Figures 6A and 6B. Note that a description of the content that is substantially the same as Figure 5 will be omitted.

[0055] In the example of Fig. 6A, similar to Fig. 5A, the value of the ignition timer is calculated based on the engine speed in the period between NNUM: 3 and 4. However, ignition occurs at a timing midway between NNUM: 5 and 6. In other words, ignition occurs at a timing with a larger advance angle from top dead center than in the case of Fig. 5A (i.e., at an angle earlier than in the case of Fig. 5A).

[0056] 6B, during the intake stroke, the piston 33 moves downward, causing the air-fuel mixture to flow into the cylinder 31. During the compression stroke, the piston 33 moves upward, compressing the air-fuel mixture in the cylinder 31. The intake amount in FIG. 6B is greater than the intake amount in FIG. 5B.

[0057] Here, if sudden acceleration (i.e., full throttle) occurs, the amount of intake air increases during the intake stroke, preventing the piston 33 from ascending during the compression stroke. In particular, when the engine rotation speed is low, the rotational inertia of the crankshaft 37 is weak, so the influence of the intake air pushing back against the ascending piston 33 during the compression stroke is significant. That is, the ascending speed of the piston 33 further gradually decreases. Furthermore, in the case of a single-cylinder engine, ignition occurs only once every two engine rotation cycles, so engine output is likely to decrease. That is, the rotational inertia of the crankshaft 37 is even weaker. Therefore, as shown in FIG. 6A, the distance between NNUM:4 and NNUM:5 and the distance between NNUM:5 and NNUM:6 are wider than in FIG. 5A. That is, the engine rotation speed is lower at NNUM:4 to NNUM:6 than in FIG. 5A.

[0058] On the other hand, the difference between the interval between NNUM:3 and NNUM:4 in FIG. 6A is small compared to the case of FIG. 5A. That is, the value of the ignition timer based on the engine speed during the period between NNUM:3 and NNUM:4 (i.e., ignition timing) is approximately the same as in the case of FIG. 5A. Therefore, in the case of FIG. 6, ignition occurs at a timing corresponding to an advance angle greater than the ignition angle suitable for combustion. That is, ignition occurs before the ignition timing suitable for combustion. As a result, combustion occurs during the combustion stroke before reaching top dead center, and the piston 33 is pushed down. That is, EG reverse occurs.

[0059] Finally, an example of engine operation in the EG reverse rotation prevention mode will be described with reference to Figures 7A and 7B. Note that a description of the content that is substantially the same as Figures 5 and 6 will be omitted.

[0060] In the example of EG reverse rotation prevention mode in Fig. 7A, the value of the ignition timer is calculated based on the engine speed during the period between NNUM: 4 and 5. With the ignition timer set to the calculated value, ignition occurs just before NNUM: 6 (i.e., top dead center).

[0061] 7B, similar to Fig. 6B, the intake air amount in Fig. 7B is greater than the intake air amount in Fig. 5B. Therefore, as shown in Fig. 7A, the intervals between NNUM:4 and 5 and between NNUM:5 and 6 are wider than in Fig. 5A. That is, similar to Fig. 6A, the engine rotation speed at NNUM:4 to 6 is lower than in Fig. 5A.

[0062] On the other hand, the interval between NNUM:4 and NNUM:5 in FIG. 7A is wider than in FIG. 5A. That is, the value of the ignition timer based on the engine speed during the period between NNUM:4 and NNUM:5 is larger than in FIG. 5A. That is, the ignition timing is later than in FIG. 5A. Therefore, in FIG. 7, ignition occurs at a timing corresponding to an angle closer to the above-mentioned ignition angle than in FIG. 6. That is, ignition occurs at a timing closer to the ignition timing suitable for combustion than in FIG. 6. As a result, combustion occurs after reaching top dead center during the combustion stroke, and the piston 33 is pushed down. That is, EG reverse rotation does not occur.

[0063] As described above, the engine control device 100 according to the embodiment of the present disclosure performs processing in accordance with a plurality of signals periodically generated by the crank sensor 11 in accordance with the rotation period of the engine. The engine control device 100 includes a setting unit 107 that sets a timer for igniting the engine at an ignition timing based on a first timing, and a calculation unit 105 that calculates the value of the timer based on the engine rotation speed during a period D1 prior to the first timing, at a timing based on the first timing. The first timing is the generation timing of one of the plurality of signals, is prior to the ignition timing, and is closer to the ignition timing than any of the generation timings of the plurality of signals, and the period D1 includes at least the period between the generation timing immediately prior to the first timing and the first timing.

[0064] As a result, the ignition timer value is calculated based on the engine speed during the period between the generation timings closest to the ignition timing. In other words, the ignition timer value is calculated based on the most recent available engine speed. Therefore, the ignition timing based on the calculated ignition timer value can be adjusted to approach the timing corresponding to the ignition angle suitable for combustion. For example, as shown in FIG. 7A, even if the engine speed during the period between NNUM:4 and NNUM:5 is lower than the engine speed during the period between NNUM:3 and NNUM:4, the ignition coil 25 can be ignited at a timing just before top dead center corresponding to the ignition angle suitable for combustion. Therefore, ignition can be performed at the desired timing. For example, even if the engine speed decreases more rapidly over time, kickback can be prevented.

[0065] Furthermore, the calculated ignition timer value is used to determine ignition timing close to the timing corresponding to the ignition angle suitable for combustion. That is, soft ignition is used. This allows kickback to be prevented without using a fixed ignition timing (i.e., hard ignition). For example, as in conventional technology, when soft ignition is switched to hard ignition because kickback is predicted to occur, the ignition angle is retarded compared to soft ignition. As a result, the expected power output may not be achieved, and the behavior (i.e., acceleration) of the vehicle equipped with the engine may not be in line with the driver's (e.g., the rider in the case of a motorcycle) intention. In other words, drivability may be impaired. However, the engine control device 100 according to an embodiment of the present disclosure does not use hard ignition, so ignition can be performed at the desired timing. For example, behavior that is not in line with the driver's intention can be prevented. Naturally, kickback can also be prevented. In particular, in the case of a single-cylinder engine, engine output is likely to decrease as described above. Therefore, the engine control device 100 according to an embodiment of the present disclosure is suitable for single-cylinder engines.

[0066] In addition, the calculation unit 105 acquires the throttle opening during the intake stroke of the engine and the engine rotation speed at the time of determining the ignition angle corresponding to the ignition timing, and if the throttle opening is equal to or greater than a threshold value and the engine rotation speed at the time of determining the ignition angle corresponding to the ignition timing is equal to or less than the threshold value, calculates the value of the ignition timer based on the engine rotation speed during period D1.

[0067] As described above, when sudden acceleration (i.e., full throttle) occurs, the amount of intake air increases during the intake stroke, preventing the piston 33 from ascending during the compression stroke. When the engine speed is low, the intake air exerts a significant force on the piston 33 as it ascends during the compression stroke. On the other hand, when the engine speed is high, engine control-related processes, including the calculation of the ignition timer value and the setting of the ignition timer, must also be performed at high speed. Therefore, when the engine speed is high, the processing load on the engine control device 100 increases. Alternatively, the engine control device 100 is more likely to fail to complete its processing within the required time. Therefore, the engine control device 100 according to an embodiment of the present disclosure limits the use of the EG reverse prevention mode to situations in which its use is preferable. That is, the engine control device 100 uses the EG reverse prevention mode only when it is determined that there is a possibility of EG reverse rotation occurring based on the throttle opening and engine speed. This reduces the processing load on the engine control device 100 while preventing kickback.

[0068] Furthermore, when the throttle opening is less than a threshold value or the engine rotation speed at the time of determining the ignition angle corresponding to the ignition timing exceeds a threshold value, the calculation unit 105 calculates the value of the ignition timer at a timing based on the second timing based on the engine rotation speed in a period D2 before the second timing. The second timing is a generation timing immediately before the first timing, and the period D2 includes at least the period between the generation timing immediately before the second timing and the second timing.

[0069] As described above, when the engine rotation speed is high, the engine control processing is also required to be performed at high speed. Therefore, when the engine rotation speed is high, the processing load of the engine control device 100 is high. Furthermore, even when the engine rotation speed is high, if the throttle opening is small, the possibility of kickback occurring is low. Therefore, when the engine rotation speed is high or the throttle opening is small, the engine control device 100 according to an embodiment of the present disclosure calculates the value of the ignition timer using the engine rotation speed in the period D2 before the engine rotation speed period D1 used in the EG reverse rotation prevention mode. In other words, when the engine rotation speed is high, the normal mode is selected. This makes it possible to reduce the processing load when the possibility of kickback occurring is low.

[0070] Furthermore, the calculation of the value of the ignition timer based on the engine rotation speed during the period D1 is performed as an interrupt process.

[0071] This allows the engine control device 100 to prioritize the calculation of the ignition timer value in the EG reverse rotation prevention mode. In the EG reverse rotation prevention mode, the ignition timer value is calculated just before the ignition timing, so the time from the calculation of the ignition timer value to the ignition timing is short. By performing the processing in the EG reverse rotation prevention mode as an interrupt processing, the ignition timer value can be calculated and the ignition timer can be set before the ignition timing.

[0072] The first timing is the generation timing immediately preceding the generation timing corresponding to the top dead center of the engine, and the ignition timing is between the generation timing corresponding to the top dead center and the first timing.

[0073] This allows the timer calculation and timer setting to be performed based on the engine speed during the period between the generation timings immediately before the top dead center, thereby enabling the ignition timing triggered by the ignition timer to be closer to the timing suitable for combustion.

[0074] Furthermore, the calculation of the engine rotation speed, the calculation of the timer value, and the setting of the timer during the first period are performed as a continuous series of processes.

[0075] This prevents other processes from interrupting the calculation of the engine rotation speed, the calculation of the timer value, and the setting of the timer, thereby shortening the time required to complete this series of processes and enabling the processes to be completed in time for the ignition timing.

[0076] <5. Variations> Next, first to third modified examples according to the embodiment of the present disclosure will be described.

[0077] (1) First Modification In the above-described example of the embodiment of the present disclosure, the calculation unit 105 determines the operation mode based on the throttle opening and the engine rotation speed. However, the determination of the operation mode according to the embodiment of the present disclosure is not limited to this example.

[0078] In a first modified example of the embodiment of the present disclosure, the calculation unit 105 may determine the operation mode based on the amount of change in the throttle opening and the engine rotation speed. Specifically, the calculation unit 105 selects the EG reverse rotation prevention mode when the amount of change in the throttle opening is equal to or greater than a threshold and the engine rotation speed at the time of determining the ignition angle corresponding to the ignition timing is equal to or less than a threshold. Furthermore, the calculation unit 105 selects the normal mode when the amount of change in the throttle opening is less than a threshold or the engine rotation speed at the time of determining the ignition angle corresponding to the ignition timing exceeds a threshold. For example, the comparison of the throttle opening with the threshold in the determination of step S201 in FIG. 3 may be replaced with a comparison of the amount of change in the throttle opening with the threshold.

[0079] Thus, according to the first modified example of the embodiment of the present disclosure, the calculation unit 105 determines the operation mode based on the amount of change in the throttle opening and the engine rotation speed. As described above, when sudden acceleration (i.e., the throttle is fully open) occurs, the amount of intake air increases during the intake stroke, preventing the piston 33 from moving upward during the compression stroke. In the case of sudden acceleration, the amount of increase in the throttle opening is large. Therefore, the amount of change in the throttle opening can be used to determine sudden acceleration, just like the magnitude of the throttle opening.

[0080] (2) Second Modification In the above-described example of the embodiment of the present disclosure, the first period is the period between the generation timing immediately preceding the first timing and the first timing. However, the first period according to the embodiment of the present disclosure is not limited to this example.

[0081] In a second modified example of the embodiment of the present disclosure, the first period may include a period between the first timing and the generation timing immediately preceding the first timing, as well as another period preceding the first timing. For example, the first period may include both period D1 in FIG. 4A and period D2 in FIG. 5A. Furthermore, the calculation unit 105 may calculate the value of the ignition timer based on the engine rotation speed during period D1 and the engine rotation speed during period D2. For example, the amount of change in the engine rotation speed between period D1 and period D2 may be additionally used in the timer calculation. Note that the other period may be a period other than period D2.

[0082] Thus, according to the second modified example of the embodiment of the present disclosure, the first period includes period D1 between the generation timing immediately before the first timing and the first timing, and another period before the first timing. Calculation unit 105 calculates the value of the ignition timer based on the engine rotation speed during period D1 and the engine rotation speed during the other period. This improves the accuracy of the ignition timer value relative to the ignition angle.

[0083] (3) Third Modification In the above-described example of the embodiment of the present disclosure, the engine (i.e., the crankshaft) is rotated by the driving force of the engine. However, the power source for rotating the engine according to the embodiment of the present disclosure is not limited to this example.

[0084] In a third modified example of the embodiment of the present disclosure, the engine may be rotated by the driving force of the engine and the driving force of the electric motor. Specifically, the above-described engine control device 100 is applied to a hybrid of an engine and an electric motor. The driving force of the engine and the driving force of the electric motor rotate the crankshaft. The calculation unit 105 calculates the value of the ignition timer based on the rotation speed of the crankshaft (i.e., the engine) on which these driving forces act.

[0085] As described above, according to the third modified example of the embodiment of the present disclosure, the calculation unit 105 calculates the value of the ignition timer based on the driving force of the engine and the rotational speed of the engine rotated by the driving force of the electric motor. Here, when the crankshaft is rotated by the driving force of the engine, the engine rotational speed is predicted taking into account the rotational inertia of the crankshaft. However, when the driving force of the electric motor is added as a power source for rotating the engine, prediction of the engine rotational speed requires consideration of the driving force of the electric motor in addition to the rotational inertia of the crankshaft. According to this modified example, the value of the ignition timer is calculated based on the engine rotational speed taking into account the driving force of the electric motor. The driving force of the electric motor may be affected by the remaining charge of the battery, which is the power source of the electric motor. When the remaining charge of the battery is low, the output torque of the electric motor may decrease. Furthermore, when the remaining charge of the battery is low, the engine output may be used to charge the battery. In this way, the engine rotational speed may fluctuate depending on the remaining charge of the battery. As a result, predicting the engine rotational speed may be difficult. Therefore, it is desirable to use an engine rotation speed predicted from a period as close as possible to the ignition timing (i.e., the ignition angle) for calculating the ignition timer. According to this modification, the ignition timer is calculated using the engine rotation speed based on the period immediately before the ignition timing. Therefore, even when the driving force of the engine and the driving force of the electric motor are used, the engine rotation speed can be accurately predicted. In other words, the ignition timing can be brought closer to the ignition angle.

[0086] Although the embodiments of the present disclosure have been described above, the present disclosure is not limited to these embodiments. It will be understood by those skilled in the art that these embodiments are merely examples and that various modifications are possible without departing from the scope and spirit of the present disclosure.

[0087] For example, the steps in the processes described herein do not necessarily have to be performed in chronological order according to the order depicted in the flowcharts or sequence diagrams. For example, the steps in the processes may be performed in an order different from that depicted in the flowcharts or sequence diagrams, or may be performed in parallel. Furthermore, some of the steps in the processes may be deleted, and additional steps may be added to the processes.

[0088] For example, a method including the operation of one or more components of the apparatus described herein may be provided, or a program for causing a computer to execute the operation of the components may be provided. Also, a non-transitory tangible computer-readable storage medium having the program recorded thereon may be provided. Naturally, such methods, programs, and non-transitory tangible computer-readable storage media are also included in the present disclosure.

[0089] For example, in this disclosure, "obtain / acquire" may mean obtaining information from stored information, obtaining information from information received from another device, or obtaining information by generating the information.

[0090] For example, in this disclosure, "include" and "comprise" do not mean including only the listed items, but may mean including only the listed items or may include additional items in addition to the listed items.

[0091] For example, in this disclosure, "or" does not mean an exclusive or, but rather a logical or. [Explanation of symbols]

[0092] 11 Crank sensor 13 Throttle opening sensor 25 Ignition coil 100 control device 101 Acquisition Department 103 Storage section 105 Arithmetic section 107 Setting section 109 Output section 117 Microcomputer 119 Ignition drive circuit 125 Non-volatile memory

Claims

1. An engine control device that performs processing according to a plurality of signals that are periodically generated by a sensor according to the rotation period of an engine, a setting unit that sets a timer for igniting the engine at an ignition timing based on a first timing; a calculation unit that calculates, at a timing based on the first timing, a value of the timer based on a rotation speed of the engine during a first period before the first timing, the first timing is a generation timing of one of the plurality of signals, is earlier than the ignition timing, and is closer to the ignition timing than the generation timing of any of the plurality of signals; The first period includes at least a period between the generation timing immediately preceding the first timing and the first timing. Engine control device.

2. The calculation unit acquiring a throttle opening or a change in the throttle opening during an intake stroke of the engine, and a rotational speed of the engine at a time when an ignition angle corresponding to the ignition timing is determined; When the throttle opening or the amount of change in the throttle opening is equal to or greater than a threshold value and the engine rotation speed at the time of determining the ignition angle corresponding to the ignition timing is equal to or less than a threshold value, the value of the timer is calculated based on the engine rotation speed during the first period. The engine control device according to claim 1 .

3. the calculation unit calculates the value of the timer at a timing based on a second timing based on the engine rotation speed during a second period before the second timing when the throttle opening or a change in the throttle opening is less than a threshold value, or when the engine rotation speed at the time of determining the ignition angle corresponding to the ignition timing exceeds a threshold value; the second timing is the generation timing immediately preceding the first timing, The second period includes at least a period between the generation timing immediately preceding the second timing and the second timing. The engine control device according to claim 2.

4. The calculation of the timer value based on the rotation speed of the engine during the first period is performed as an interrupt process. The engine control device according to any one of claims 1 to 3.

5. the first timing is the generation timing immediately before the generation timing corresponding to the top dead center of the engine, The ignition timing is between the generation timing corresponding to the top dead center and the first timing. The engine control device according to any one of claims 1 to 3.

6. The calculation of the engine rotation speed during the first period, the calculation of the timer value, and the setting of the timer are performed as a continuous series of processes. The engine control device according to any one of claims 1 to 3.

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