Auxiliary system and method for motorcycle engine

Abstract

This invention provides an auxiliary system and method for a motorcycle engine. The auxiliary method for the motorcycle engine includes detecting crankshaft position information via a position sensor of a starter / generator; predicting the stopping position of the crankshaft when the motorcycle engine stops, based on the engine operating parameters and crankshaft operating parameters and position information; and controlling the starter / generator to assist the crankshaft to remain at a designated position when the motorcycle engine stops, based on the crankshaft's stopping position, when the motorcycle engine speed reaches the stopping threshold.

Description

[Technical Field]

[0001] This invention relates to the field of engine control, and more particularly to an auxiliary system and method for a locomotive engine. [Previous Technology]

[0002] Currently, there are integrated starter and generator systems (ISG systems) on the market that are applied to motorcycles, enabling the motorcycle engine (hereinafter referred to as the engine) to have the function of idling shutdown and restart, thereby increasing the fuel efficiency of the motorcycle. When an engine is shut down, it often stops at the compression stroke. At this time, the ISG system needs to provide a large torque to drive the crankshaft to rotate forward in order to overcome the compression pressure of the compression stroke and restart the engine. The engine restart method is generally to repeatedly rotate the crankshaft forward and backward to a predetermined position after the engine is shut down (e.g., the speed returns to zero), or to repeatedly rotate the crankshaft forward and backward to a predetermined position before restarting the engine, to avoid starting the engine at the compression stroke. In this way, the ISG system only needs to provide relatively small torque to complete the engine restart. However, because this method requires the crankshaft to rotate forward and backward repeatedly, it consumes more energy. [Summary of the Invention]

[0003] In view of the above, the present invention provides an auxiliary system and method for a motorcycle engine. The auxiliary system for the motorcycle engine includes a starter / generator and a processor. The starter / generator is connected to a crankshaft and a battery. The starter / generator includes a position sensor. The position sensor detects the position information of the crankshaft. When the motorcycle engine speed is less than a shutdown threshold, the processor predicts the stopping position of the crankshaft when the motorcycle engine stops, based on the engine operating parameters of the motorcycle engine and the crankshaft operating parameters and position information. When the motorcycle engine speed reaches the shutdown threshold, the processor controls the starter / generator to assist the crankshaft to remain at a designated position when the motorcycle engine stops, based on the stopping position of the crankshaft. The designated position corresponds to the intake stroke or exhaust stroke of the motorcycle engine.

[0004] The auxiliary method for the motorcycle engine includes: detecting the position information of the crankshaft via a position sensor of the starter and generator; predicting the stopping position of the crankshaft when the motorcycle engine stops, based on the engine operating parameters of the motorcycle engine and the crankshaft operating parameters and position information of the crankshaft, when the engine speed of the motorcycle engine is less than the shutdown threshold; and controlling the starter and generator to assist the crankshaft to stay at a specified position when the motorcycle engine stops, based on the stopping position of the crankshaft, when the engine speed of the motorcycle engine reaches the shutdown threshold. The specified position corresponds to the intake stroke or exhaust stroke of the motorcycle engine.

[0005] In summary, according to some embodiments, the present invention reduces the engine load by directly stopping the crankshaft at a designated position (such as the position of the crankshaft corresponding to the intake or exhaust stroke of the motorcycle engine) when the motorcycle engine (hereinafter referred to as the engine) stops, without consuming excessive energy, and by restarting the engine with less torque. In some embodiments, the present invention reduces the instantaneous acceleration load of the engine by using a starter-generator to assist the engine's operation when the engine speed is within the acceleration range. In some embodiments, the present invention reduces the engine load by using a starter-generator to assist the engine's operation when the engine speed is within the smooth range and the engine is in the compression stroke, thereby sharing the compression pressure that the engine needs to overcome during the compression stroke.

Implementation Method

[0007] Referring to Figure 1, it is a schematic diagram of an auxiliary system 10 for a motorcycle engine according to some embodiments of the present invention. The auxiliary system 10 for the motorcycle engine includes an integrated starter and generator (ISG) 20 and a processor 30. The ISG 20 is connected to a crankshaft 40 and a battery 50. The battery 50 is, for example, a car battery, to provide power. The processor 30 is connected to the ISG 20 and the battery 50. The ISG 20 has both motor and generator characteristics to drive the motorcycle engine (hereinafter referred to as the engine) (not shown) through the crankshaft 40 and convert excess energy (e.g., the kinetic energy of the engine) into electrical energy and store it in the battery 50. The ISG 20 includes a position sensor 21. The position sensor 21 is used to detect the position information of the crankshaft 40. For example, the position sensor 21 is disposed on the rotor of the ISG 20, which is connected to the crankshaft 40 and rotates synchronously with the crankshaft 40. The position sensor 21 detects the rotation angle of the rotor. Since the rotor rotates synchronously with the crankshaft 40, the rotation angle of the rotor is the same as the rotation angle of the crankshaft 40, and the position sensor 21 uses the rotation angle of the crankshaft 40 as the position information of the crankshaft. The position sensor 21 is, for example, a Hall sensor. The processor 30 is used to operate and control the operation of the motorcycle engine auxiliary system 10, and is adapted to execute the motorcycle engine auxiliary method of the present invention. The processor 30 is, for example, but not limited to, a central processing unit, a microprocessor, an application-specific integrated circuit (ASIC), or a system on a chip (SOC) and other computing circuits.

[0008] Referring to Figure 2, it is a schematic diagram of an auxiliary system 10 for a motorcycle engine according to some embodiments of the present invention. In some embodiments, the auxiliary system 10 for the motorcycle engine further includes a drive module 60, an engine control unit 70, a main switch 80, and a throttle 90. The engine control unit 70 is connected to the processor 30. The engine control unit 70 is used to control injection electrical components (such as fuel injectors, ignition coils, etc.) so that the engine can start or stop normally, and the engine control unit 70 transmits signals to the processor 30 so that the processor 30 knows whether the engine has started or stopped (for example, the processor 30 only receives the start signal from the engine control unit 70 and drives the drive module 60 to rotate the crankshaft 40, and the processor 30 determines whether the engine is started or stopped through the state of the crankshaft 40). The drive module 60 is connected to the processor 30 and the starter / generator 20. The drive module 60 is controlled by the processor 30 to drive the starter / generator 20. In some embodiments, the drive module 60 includes a drive controller 61 and a drive circuit 63. The drive controller 61 is connected to the processor 30. The drive circuit 63 connects the drive controller 61 and the starter / generator 20. The drive circuit 63 is, for example, a rectifier circuit composed of multiple switching switches. The switching switches are, for example, power transistors. The number of switching switches is, for example, six. The drive controller 61, controlled by the processor 30, sends a switching signal to the control terminal of the switching switches in the drive circuit 63 to control the switching state of the switching switches (e.g., controlling the switching switches to an on or off state). In one example, if the switching switches are implemented with metal-oxide-semiconductor transistors, the control terminal is the gate terminal, and the drive controller 61 is a gate controller. In some embodiments, the switching signal is a sine wave signal to increase the switching frequency of the switching switches and reduce the jitter of the starter / generator 20. For example, the switching frequency of the switching switches is increased to greater than 10 kilohertz (Hz). In some embodiments, the processor 30 controls the starter / generator 20 to be in motor mode or generator mode by adjusting the duty cycle of the switching frequency. For example, the drive controller 61, under the control of the processor 30, can adjust the duty cycle of the switching frequency to be greater than a duty cycle threshold so that the starter and generator 20 is in motor mode, and the drive controller 61, under the control of the processor 30, can adjust the duty cycle of the switching frequency to be no greater than the duty cycle threshold so that the starter and generator 20 is in generator mode.

[0009] The main switch 80 is connected to the processor 30. The switching state of the main switch 80 is determined by the user's operation, either in an on or off state. For example, when the user wants to start the engine to start the motorcycle, the main switch 80 is in the on state, and the engine control unit 70 detects whether the user has pressed the brake and start buttons of the motorcycle when the main switch 80 is in the on state. When the engine control unit 70 detects that the user has pressed the brake and start buttons of the motorcycle, it starts the engine. When the user wants to turn off the engine to stop the motorcycle, the main switch 80 is in the off state, and the engine control unit 70 turns off the engine when the main switch 80 is in the off state. The throttle 90 is connected to the processor 30. The throttle 90 is actuated by the user's operation (e.g., the stepper motor of the throttle 90 is rotated by the user's operation). The processor 30 detects the degree to which the throttle 90 is actuated. Specifically, the processor 30 detects the rotation angle of the stepper motor of the throttle 90 in a single rotation to determine the degree to which the throttle 90 is actuated. In some embodiments, the processor 30 is also connected to the user's electronic device 100 to obtain maintenance information input by the user from the electronic device 100. The processor 30 adjusts some parameters of the components of the motorcycle engine's auxiliary system 10 (such as the engine's operating parameters and the crankshaft operating parameters of the crankshaft 40) according to the maintenance information to complete the motorcycle maintenance.

[0010] Referring to Figure 3, which is a flowchart of an auxiliary method for a motorcycle engine according to some embodiments of the present invention. First, when the processor 30 detects that the main switch 80 is in the on state (step S301), it determines whether a start signal has been received from the engine control unit 70 (step S303). For example, when the engine control unit 70 detects that the user has pressed the brake and start buttons of the motorcycle while the main switch 80 is in the on state, it sends a start signal to the processor 30 to notify the processor 30 that the user wants to start the engine. If the processor 30 does not receive a start signal from the engine control unit 70, step S303 is repeated until the processor 30 receives a start signal. When the processor 30 receives a start signal from the engine control unit 70, the processor 30 controls the starter generator 20 to enter motor mode to drive the engine (step S305). Next, the processor 30 determines whether the rotor of the starter generator 20 has successfully rotated forward after entering motor mode (step S307). If the rotor of the starter / generator 20 fails to rotate forward, it indicates that the engine has failed to start. At this time, the processor 30 returns to step S303 and its subsequent steps to restart the engine. If the rotor of the starter / generator 20 rotates forward successfully, it indicates that the engine has been successfully started. At this time, the processor 30 controls the starter / generator 20 to enter the power generation mode to recover and convert the kinetic energy of the engine into electrical energy and store it in the battery 50 (step S309).

[0011] Next, the processor 30 determines whether the engine speed is less than the shutdown threshold (step S311). For example, when the throttle 90 is not applied, the engine speed is within the idle range. The idle range is, for example, 1400 rpm to 1700 rpm (revolutions per minute). Suppose the engine control unit 70 detects that the user presses the motorcycle brake and does not apply the throttle 90 to stop at a traffic light, the engine control unit 70 shuts off the engine. At this time, the engine speed will gradually decrease and fall below the lower limit of the idle range. The shutdown threshold can be set to a speed value below the lower limit of the idle range, such as 900 rpm. Therefore, by determining whether the engine speed is less than the shutdown threshold, the processor 30 can determine whether the engine has been shut off. If the engine speed is not less than the shutdown threshold, it means that the engine may not have been shut off yet, and the processor 30 can execute step S313. If the engine speed is less than the shutdown threshold, it means that the engine has been shut off, and the processor 30 executes step S315. In some embodiments, when the processor 30 detects that the throttle 90 is not activated, it generates a throttle-not-activated signal to the engine control unit 70 so that the engine control unit knows that the user has not activated the throttle 90.

[0012] In step S315, the processor 30 predicts the stopping position of the crankshaft 40 when the engine stops (e.g., the engine speed returns to zero) based on the engine operating parameters and the crankshaft operating parameters and position information of the crankshaft 40. For example, after the engine starts and has undergone at least one stroke cycle, the processor 30 can define the absolute position of the crankshaft 40's rotation angle (hereinafter referred to as the absolute crankshaft angle) and the range of absolute crankshaft angles corresponding to each stroke based on the stroke time of each stroke in a single stroke cycle of the engine. In this way, the processor 30 can convert the position information of the crankshaft 40 into an absolute crankshaft angle based on the stroke time of each stroke in a single stroke cycle of the engine, and can determine which stroke of the engine it corresponds to. In some embodiments, a single stroke cycle includes an intake stroke, a compression stroke, a power stroke, and an exhaust stroke. In some embodiments, the stroke time of each stroke in a single stroke cycle is not the same. For example, the stroke time of the intake stroke is 3 seconds, the stroke time of the compression stroke is 3.8 seconds, the stroke time of the power stroke is 2.5 seconds, and the stroke time of the exhaust stroke is 2.8 seconds. In some embodiments, the absolute crankshaft angle range corresponding to the intake stroke is 0 degrees to 180 degrees, the absolute crankshaft angle range corresponding to the compression stroke is 181 degrees to 360 degrees, the absolute crankshaft angle range corresponding to the power stroke is 361 degrees to 540 degrees, and the absolute crankshaft angle range corresponding to the exhaust stroke is 541 degrees to 720 degrees. The processor 30 calculates the engine's inertia parameters based on the engine's operating parameters (e.g., engine speed, operating friction resistance, and oil viscous resistance) and the crankshaft 40's operating parameters (e.g., crankshaft 40 damping parameters) and the absolute crankshaft angle converted from position information. It then uses a known crankshaft stop position prediction algorithm (e.g., a crankshaft angle prediction algorithm using a Kalman filter) or a self-developed crankshaft stop position prediction algorithm to predict the engine's inertia parameters and predict the crankshaft 40's stopping position when the engine stops. Specifically, the processor 30 predicts the crankshaft 40's stopping position when the engine stops without additional interference from the starter / generator 20. In some embodiments, the processor 30 calculates the engine's rotational speed (R) based on Newton's laws and the engine's speed, and subtracts the engine's operating friction resistance (F) and oil viscous resistance (S) from the rotational speed (R) to calculate the engine's inertia parameter (I) (as shown in Equation 1).

[0013] …………………………………………(Equation 1)

[0014] Next, after the processor 30 predicts the stop position of the crankshaft 40, the processor 30 determines whether the engine speed has reached the stop threshold (step S317). If the engine speed has not yet dropped to the stop threshold, it means that the engine is not about to stop. At this time, the processor 30 repeats step S317 until it determines that the engine speed has reached the stop threshold. The stop threshold can be set to the speed at which the crankshaft 40 will stop after one more revolution, for example, 50 rpm. If the engine speed reaches the stop threshold, it means that the engine may be about to stop. Therefore, the processor 30 controls the starter and generator 20 to assist the crankshaft 40 to stay at a specified position when the engine stops, based on the stop position of the crankshaft 40 (step S319). The specified position corresponds to the intake stroke or exhaust stroke of the engine. For example, the specified position can be any absolute crankshaft angle between 0 degrees and 180 degrees and between 541 degrees and 720 degrees. In this way, when the engine stops, the crankshaft 40 can directly remain in the designated position without consuming too much extra energy, and can restart the engine with less torque (for example, it can avoid restarting the engine during the compression stroke), thereby reducing the burden on the engine.

[0015] In some embodiments, the designated position may be the absolute crankshaft angle corresponding to the crankshaft 40 before the fuel injector injects fuel, so as to optimize the reduction of the burden of engine restart (specifically, to minimize the resistance required for engine restart). For example, assuming that the absolute crankshaft angle corresponding to the crankshaft 40 when the fuel injector injects fuel is 150 degrees, the designated position may be an absolute crankshaft angle set to 100 degrees.

[0016] In some embodiments of step S319, the processor 30 determines whether the specified position is greater than the stop position of the crankshaft 40. When the specified position is greater than the stop position of the crankshaft 40, the processor 30 controls the starter / generator 20 to output torque in a first direction to the crankshaft 40, so that the crankshaft 40 remains at the specified position when the engine stops. When the specified position is less than the stop position of the crankshaft 40, the processor 30 controls the starter / generator 20 to output torque in a second direction to the crankshaft 40, so that the crankshaft 40 remains at the specified position when the engine stops. The first direction and the second direction are opposite to each other. For example, the torque in the first direction is a positive torque, and the torque in the second direction is a negative torque. Specifically, when the specified position is greater than the stop position of the crankshaft 40, the processor 30 controls the starter / generator 20 to be in motor mode and increases the current supplied by the battery 50 to the starter / generator 20, so that the starter / generator 20 outputs positive torque to the crankshaft 40, thereby allowing the crankshaft 40 to be pushed from the stop position to the specified position when the engine stops. When the specified position is less than the stop position of the crankshaft 40, the processor 30 controls the starter-generator 20 to be in power generation mode and causes the starter-generator 20 to increase its power generation (e.g., increase its power generation current) to enhance its magnetic force, thereby using the magnetic force to output reverse torque to the crankshaft 40, so that the crankshaft 40 can be locked to the specified position when the engine stops and will not remain in the stop position.

[0017] Referring to Figure 4, it is a flowchart of a motorcycle engine assistance method according to some embodiments of the present invention. In step S313, the processor 30 detects and determines whether the charge level of the battery 50 (hereinafter also referred to as the remaining charge level) is greater than the charge level threshold. If the charge level of the battery 50 is not greater than the charge level threshold, it means that the remaining charge level of the battery 50 is insufficient to support the operation of the starter-generator 20 to assist the engine (for example, if the remaining charge level is provided to the starter-generator 20 to assist the engine, it may cause the battery 50 to run out of power and the motorcycle to break down). Then the processor 30 returns to execute step S309 and subsequent steps so that the starter-generator 20 continues to store electrical energy in the battery 50 to increase the remaining charge level of the battery 50. If the charge level of the battery 50 is greater than the charge level threshold, it means that the remaining charge level of the battery 50 is sufficient to support the operation of the starter-generator 20 to assist the engine. Then the processor 30 determines whether to generate an acceleration signal (step S401). For example, when processor 30 detects that the rotation angle of the stepper motor of throttle 90 in a single rotation exceeds a rotation threshold, it indicates that the user is significantly stimulating throttle 90 to accelerate the motorcycle. At this time, processor 30 generates and sends an acceleration signal to engine control unit 70 to increase engine speed and enable the motorcycle to accelerate. Processor 30 executes step S403 when it determines that an acceleration signal has been generated. If processor 30 does not determine that an acceleration signal has been generated, it means that the user only needs the motorcycle to move smoothly without acceleration, and processor 30 executes step S405.

[0018] In step S403, the processor 30 responds to the acceleration signal and determines whether the engine speed is within the acceleration range. The acceleration range is, for example, 3000 rpm to 6000 rpm. If the engine speed is not within the acceleration range, it means that the engine cannot accelerate yet, and the processor 30 returns to execute step S309 and subsequent steps to wait for the engine to be in an accelerable state. If the engine speed is within the acceleration range, it means that the engine is in an accelerable state, and the processor 30 controls the starter / generator 20 to enter motor mode to assist the engine operation (step S407). Thus, since the starter / generator 20 in motor mode can drive the engine through the crankshaft 40, the instantaneous acceleration burden of all engine strokes can be reduced. In other words, by using the starter / generator 20 in motor mode to assist the operation of each stroke of the engine, the stroke time of each stroke can be shortened, and the engine's fuel consumption can be reduced.

[0019] Referring to Figure 5, it is a flowchart of a motorcycle engine assistance method according to some embodiments of the present invention. In some embodiments, the processor 30 accumulates the time during which the starter-generator 20 in motor mode assists the engine in operation. After the starter-generator 20 in motor mode assists the engine in operation (step S407), the processor 30 accumulates and determines whether the time during which the starter-generator 20 in motor mode assists the engine in operation reaches a time threshold (step S501). If the time during which the starter-generator 20 in motor mode assists the engine in operation reaches the time threshold, it indicates that the engine assistance acceleration has been completed. The processor 30 then returns to execute step S309 and subsequent steps to control the starter-generator 20 to enter the power generation mode and stop the engine operation.

[0020] If the time for which the starter / generator 20 assists the engine in motor mode does not reach the time threshold, the processor 30 continues to detect and determine whether the battery 50's charge level is still greater than the charge threshold (step S503) to ensure that the remaining charge level of the battery 50 is sufficient to support the operation of the starter / generator 20 assisting the engine. If the processor 30 determines that the battery 50's charge level is not greater than the charge threshold, it means that the remaining charge level of the battery 50 can no longer support the operation of the starter / generator 20 assisting the engine. The processor 30 then returns to step S309 and subsequent steps to allow the starter / generator 20 to store electrical energy in the battery 50 to increase the remaining charge level of the battery 50. If the processor 30 determines that the battery 50's charge level is still greater than the charge threshold, it means that the remaining charge level of the battery 50 is still sufficient to support the operation of the starter / generator 20 assisting the engine. The processor 30 then returns to step S407 and subsequent steps to allow the starter / generator 20 in motor mode to continue assisting the engine in operation.

[0021] Referring to Figure 6, it is a flowchart of a motorcycle engine assistance method according to some embodiments of the present invention. In some embodiments, the processor 30 accumulates the number of stroke cycles in which the starter / generator 20 in motor mode assists the engine operation. In some embodiments, the engine completes one stroke cycle after experiencing the intake stroke, compression stroke, power stroke, and exhaust stroke. After the starter / generator 20 in motor mode assists the engine operation (step S407), the processor 30 accumulates and determines whether the number of stroke cycles in which the starter / generator 20 in motor mode assists the engine operation reaches a cycle threshold (step S601). The cycle threshold is, for example, five times. If the number of stroke cycles in which the starter / generator 20 in motor mode assists the engine operation reaches the cycle threshold, it indicates that the engine assistance acceleration has been completed, and the processor 30 returns to execute step S309 and subsequent steps to control the starter / generator 20 to enter the generator mode and stop the engine operation.

[0022] If the number of stroke cycles of the starter / generator 20 assisting the engine in motor mode has not reached the cycle threshold, the processor 30 continues to detect and determine whether the battery 50's charge level is still greater than the charge threshold (step S603) to ensure that the remaining charge level of the battery 50 can still support the operation of the starter / generator 20 assisting the engine. Since step S603 is the same as step S503, it will not be described again.

[0023] As shown in Figure 4, in step S405, the processor 30 determines whether the engine speed is within a smooth range. The smooth range is, for example, 3000 rpm to 6000 rpm. If the engine speed is not within the smooth range, it indicates that the engine is in an unassistable state, and the processor 30 returns to step S309 and subsequent steps to wait for the engine to be in an assistable state. If the engine speed is within the smooth range, it indicates that the engine is in an assistable state, and the processor 30 determines whether the engine is in the compression stroke (step S409). When the engine is in the compression stroke, the processor 30 controls the starter / generator 20 to enter motor mode to assist the engine's operation (step S411). For example, since the engine faces greater compression pressure and a greater burden when in the compression stroke, in order to reduce the engine's burden, the starter / generator 20 in motor mode can drive the engine through the crankshaft 40 to share the compression pressure faced by the engine during the compression stroke (that is, by using the starter / generator 20 in motor mode to assist the engine's compression stroke operation, the compression stroke duration can be shortened). If the engine is not in the compression stroke (e.g., the engine is in the intake, power, or exhaust stroke), the processor 30 returns to step S309 and subsequent steps because the engine is not under significant load at this time, thus saving energy. In other words, when the engine is in the intake, power, or exhaust stroke, the starter / generator 20 is in generator mode. Furthermore, each stroke of the engine has a different speed. Compared to other strokes, the engine speed is slower during the compression stroke. By using the starter / generator 20 in motor mode to assist the engine's operation during the compression stroke, the speed difference between the compression stroke and other strokes can be reduced, thereby reducing engine vibration.

[0024] After the starter-generator 20 assists the engine in motor mode (step S411), the processor 30 continuously detects and determines whether the battery 50's charge level is still greater than the charge threshold (step S413) to ensure that the remaining charge level of the battery 50 is sufficient to support the starter-generator 20's engine operation. If the processor 30 determines that the battery 50's charge level is not greater than the charge threshold, it means that the remaining charge level of the battery 50 can no longer support the starter-generator 20's engine operation. In this case, the processor 30 returns to step S309 and its subsequent steps to allow the starter-generator 20 to store electrical energy in the battery 50 to increase the remaining charge level of the battery 50. If the processor 30 determines that the battery 50's charge level is still greater than the charge threshold, it means that the remaining charge level of the battery 50 is still sufficient to support the starter-generator 20's engine operation. In this case, the processor 30 returns to step S409 and its subsequent steps to re-determine whether the engine is in the compression stroke, and when the engine is in the compression stroke, the starter-generator 20 re-enters motor mode to continue assisting the engine operation.

[0025] In summary, according to some embodiments, the present invention reduces the engine load by directly stopping the crankshaft at a designated position (such as the position of the crankshaft corresponding to the intake or exhaust stroke of the motorcycle engine) when the motorcycle engine (hereinafter referred to as the engine) stops, without consuming excessive energy, and by restarting the engine with less torque. In some embodiments, the present invention reduces the instantaneous acceleration load of the engine by using a starter-generator to assist the engine's operation when the engine speed is within the acceleration range. In some embodiments, the present invention reduces the engine load by using a starter-generator to assist the engine's operation when the engine speed is within the smooth range and the engine is in the compression stroke, thereby sharing the compression pressure that the engine needs to overcome during the compression stroke. [Simplified Explanation of the Diagram]

[0006] Figure 1 is a schematic diagram of an auxiliary system for a locomotive engine according to some embodiments of the present invention. Figure 2 is a schematic diagram of an auxiliary system for a locomotive engine according to some embodiments of the present invention. Figure 3 is a flowchart of an auxiliary method for a locomotive engine according to some embodiments of the present invention. Figure 4 is a flowchart of an auxiliary method for a locomotive engine according to some embodiments of the present invention. Figure 5 is a flowchart of an auxiliary method for a locomotive engine according to some embodiments of the present invention. Figure 6 is a flowchart of an auxiliary method for a locomotive engine according to some embodiments of the present invention.

Claims

1. An auxiliary system for a motorcycle engine, comprising: a starter-generator connected to a crankshaft and a battery, the starter-generator including a position sensor for detecting position information of the crankshaft; and a processor, wherein when the starter-generator is in a power generation mode, it determines whether a rotational speed of the motorcycle engine has decreased from above a shutdown threshold to the shutdown threshold; when it is determined that the rotational speed of the motorcycle engine has decreased from above the shutdown threshold to the shutdown threshold, based on an engine operating parameter of the motorcycle engine, a crankshaft operating parameter of the crankshaft, and the position information, it predicts a stopping position of the crankshaft when the motorcycle engine subsequently stops; and when the rotational speed of the motorcycle engine further decreases to a stopping threshold, based on the stopping position of the crankshaft, it controls the starter-generator to assist the crankshaft to remain at a designated position when the motorcycle engine subsequently stops, wherein the designated position corresponds to an intake stroke or an exhaust stroke of the motorcycle engine, and the stopping threshold is lower than the shutdown threshold.

2. The auxiliary system for a motorcycle engine as described in claim 1, wherein the step of controlling the starter-generator to assist the crankshaft in remaining at the designated position when the motorcycle engine stops comprises, when the designated position is greater than the stop position, the processor controls the starter-generator to output a torque in a first direction to the crankshaft so that the crankshaft remains at the designated position when the motorcycle engine stops, and when the designated position is less than the stop position, the processor controls the starter-generator to output a torque in a second direction to the crankshaft so that the crankshaft remains at the designated position when the motorcycle engine stops, wherein the first direction and the second direction are opposite to each other.

3. The auxiliary system for a motorcycle engine as described in claim 1, wherein when the battery charge is greater than a charge threshold, the processor responds to an acceleration signal to determine whether the engine speed is within an acceleration range, and when the engine speed is within the acceleration range, the processor controls the starter and generator to enter a motor mode to assist the operation of the motorcycle engine.

4. The auxiliary system for a motorcycle engine as described in claim 3, wherein when the starter-generator is in the motor mode to assist the operation of the motorcycle engine for a period of time reaching a time threshold, the processor controls the starter-generator to enter the generator mode to stop assisting the operation of the motorcycle engine.

5. The auxiliary system for a motorcycle engine as described in claim 4, wherein when the time during which the starter and generator is in the motor mode to assist the operation of the motorcycle engine has not reached the time threshold, the processor determines whether the battery charge is still greater than the charge threshold, and when the battery charge is not greater than the charge threshold, the processor controls the starter and generator to enter the generator mode to stop assisting the operation of the motorcycle engine.

6. The auxiliary system for a motorcycle engine as described in claim 5, wherein when the battery charge is still greater than the charge threshold, the processor controls the starter and generator to remain in the motor mode to continue assisting the operation of the motorcycle engine.

7. The auxiliary system for a motorcycle engine as described in claim 3, wherein when the number of stroke cycles in which the starter and generator is in the motor mode to assist the operation of the motorcycle engine reaches a cycle threshold, the processor controls the starter and generator to enter the generator mode to stop assisting the operation of the motorcycle engine.

8. The auxiliary system for a motorcycle engine as described in claim 7, wherein when the number of stroke cycles in which the starter and generator is in the motor mode to assist the operation of the motorcycle engine has not reached the cycle threshold, the processor determines whether the battery charge is still greater than the charge threshold, and when the battery charge is not greater than the charge threshold, the processor controls the starter and generator to enter the generator mode to stop assisting the operation of the motorcycle engine.

9. The auxiliary system for a motorcycle engine as described in claim 8, wherein when the battery charge is still greater than the charge threshold, the processor controls the starter and generator to remain in the motor mode to continue assisting the operation of the motorcycle engine.

10. The auxiliary system for a motorcycle engine as described in claim 1, wherein when the battery charge is greater than a charge threshold and the motorcycle engine speed is within a smooth range, the processor determines whether the motorcycle engine is in a compression stroke; when the motorcycle engine is in the compression stroke, the processor controls the starter-generator to enter a motor mode to assist the operation of the motorcycle engine; and when the battery charge is not greater than the charge threshold, the processor controls the starter-generator to enter the generator mode to stop assisting the operation of the motorcycle engine.

11. A method for assisting a motorcycle engine, comprising: detecting position information of a crankshaft via a position sensor of a starter-generator; when the starter-generator is in a generator mode, determining whether a rotational speed of the motorcycle engine has decreased from above a shutdown threshold to the shutdown threshold; when determining that the rotational speed of the motorcycle engine has decreased from above the shutdown threshold to the shutdown threshold, predicting a stopping position of the crankshaft when the motorcycle engine subsequently stops, based on an engine operating parameter of the motorcycle engine, a crankshaft operating parameter of the crankshaft, and the position information; and when the rotational speed of the motorcycle engine further decreases to a stopping threshold, controlling the starter-generator to assist the crankshaft to remain at a designated position when the motorcycle engine subsequently stops, based on the stopping position of the crankshaft, wherein the designated position corresponds to an intake stroke or an exhaust stroke of the motorcycle engine, and the stopping threshold is lower than the shutdown threshold.

12. The auxiliary method for a motorcycle engine as described in claim 11, wherein when the designated position is greater than the stop position, the starting and generating device is controlled to output a torque in a first direction to the crankshaft so that the crankshaft remains at the designated position when the motorcycle engine stops, and when the designated position is less than the stop position, the starting and generating device is controlled to output a torque in a second direction to the crankshaft so that the crankshaft remains at the designated position when the motorcycle engine stops, wherein the first direction and the second direction are opposite to each other.

13. The method for assisting a motorcycle engine as described in claim 11 further includes: when a battery charge is greater than a charge threshold, in response to an acceleration signal, determining whether the rotational speed of the motorcycle engine is within an acceleration range; and when the rotational speed of the motorcycle engine is within the acceleration range, controlling the starter and generator to enter a motor mode to assist the operation of the motorcycle engine.

14. The method for assisting a motorcycle engine as described in claim 13 further includes: when the time during which the starting and generating device is in the motor mode to assist the operation of the motorcycle engine reaches a time threshold, controlling the starting and generating device to enter the generating mode to stop assisting the operation of the motorcycle engine.

15. The method for assisting a motorcycle engine as described in claim 14 further includes: when the time during which the starting and generating device is in the motor mode to assist the operation of the motorcycle engine has not reached the time threshold, determining whether the charge of the battery is still greater than the charge threshold; and when the charge of the battery is not greater than the charge threshold, controlling the starting and generating device to enter the generating mode to stop assisting the operation of the motorcycle engine.

16. The method for assisting a motorcycle engine as described in claim 15 further includes: when the battery charge is still greater than the charge threshold, controlling the starter and generator to continue in the motor mode to continue assisting the operation of the motorcycle engine.

17. The method for assisting a motorcycle engine as described in claim 13 further comprises: when the number of stroke cycles in which the starting and generating device is in the motor mode to assist the operation of the motorcycle engine reaches a cycle threshold, controlling the starting and generating device to enter the generating mode to stop assisting the operation of the motorcycle engine.

18. The method for assisting a motorcycle engine as described in claim 17 further comprises: when the number of stroke cycles in which the starter and generator is in the motor mode to assist the operation of the motorcycle engine has not reached the cycle threshold, determining whether the charge of the battery is still greater than the charge threshold; and when the charge of the battery is not greater than the charge threshold, controlling the starter and generator to enter the generator mode to stop assisting the operation of the motorcycle engine.

19. The method for assisting a motorcycle engine as described in claim 18 further includes: when the battery charge is still greater than the charge threshold, controlling the starter and generator to continue in the motor mode to continue assisting the operation of the motorcycle engine.

20. The method for assisting a motorcycle engine as described in claim 11 further comprises: determining whether the motorcycle engine is in a compression stroke when a battery charge is greater than a charge threshold and the motorcycle engine speed is within a smooth range; controlling the starter-generator to enter a motor mode to assist the operation of the motorcycle engine when the motorcycle engine is in the compression stroke; and controlling the starter-generator to enter the generator mode to stop assisting the operation of the motorcycle engine when the battery charge is not greater than the charge threshold.

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