Vehicle and control method

Abstract

To provide a vehicle or the like that prevents a decrease in the driving feeling of the vehicle while limiting the excessive rotation speed of the drive source of the vehicle. [Solution] A vehicle includes a drive source, a rotation sensor that detects the rotation speed of the drive source, a control circuit that controls the drive source, and an actuator that operates the drive source in response to a command given by the control circuit. When the rotation speed of the drive source exceeds a predetermined upper threshold, the control circuit executes suppression control to suppress the output of the drive source compared to before the rotation speed of the drive source exceeded the upper threshold, and in the suppression control, a command is given to the actuator to suppress the output of the drive source compared to before the suppression control in accordance with an exceedance degree that is set in relation to a period during which the rotation speed of the drive source exceeds the upper threshold.

Description

[Technical Field]

[0001] The present disclosure relates to a vehicle and a control method for controlling the rotation speed of a drive source. [Background technology]

[0002] For example, Patent Document 1 discloses limiting the engine speed to a predetermined overspeed or less. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-26286 Summary of the Invention [Problem to be solved by the invention]

[0004] In the limiting operation of Patent Document 1, if the engine output suppression is started at an engine speed close to the overspeed, the output fluctuation range becomes large, deteriorating the driving feel of the vehicle. Also, if the engine output suppression is started at an engine speed lower than the overspeed, the vehicle acceleration feeling decreases, deteriorating the driving feel of the vehicle.

[0005] Therefore, one aspect of the present disclosure aims to provide a vehicle and a control method that prevent a deterioration in the driving feel of the vehicle while limiting the over-speed of the drive source of the vehicle.

[0006] A vehicle according to one aspect of the present disclosure comprises a drive source, a rotation sensor that detects the rotation speed of the drive source, a control circuit that controls the drive source, and an actuator that operates the drive source in response to commands given by the control circuit, wherein when the rotation speed of the drive source exceeds a predetermined upper threshold, the control circuit executes suppression control to suppress the output of the drive source compared to before the rotation speed of the drive source exceeded the upper threshold, and in the suppression control, a command is given to the actuator to suppress the output of the drive source compared to before the suppression control in accordance with the degree of exceedance set in relation to the period during which the rotation speed of the drive source exceeds the upper threshold. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a side view showing an example of the configuration of a vehicle according to an embodiment as a motorcycle. [Figure 2] FIG. 2 is a schematic diagram showing an example of a power system of the motorcycle of FIG. [Figure 3] FIG. 3 is a flowchart illustrating an example of the operation of the ECU according to the embodiment. [Figure 4] FIG. 4 is a diagram showing a first embodiment of an example of control of the rotation speed of the internal combustion engine by the ECU when the motorcycle is traveling on flat ground. [Figure 5] FIG. 5 is a diagram showing a second embodiment of the control of the rotation speed of the internal combustion engine by the ECU when the motorcycle travels uphill. [Figure 6] FIG. 6 is a diagram showing a third embodiment of the invention, which is an example of control of the rotation speed of the internal combustion engine by the ECU when the motorcycle travels downhill. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, exemplary embodiments of the present disclosure will be described with reference to the drawings. The embodiments described below are all comprehensive or specific examples. Among the components in the following embodiments, components that are not recited in an independent claim showing a top concept will be described as optional components. Each figure in the accompanying drawings is a schematic diagram and is not necessarily an exact drawing. In each figure, substantially identical components are assigned the same reference numerals, and duplicated descriptions may be omitted or simplified.

[0009] A vehicle 1 according to an exemplary embodiment will be described. In this embodiment, the vehicle 1 is a motorcycle, a saddle-ride type vehicle having a foot bar 109 on each side of a seat 107. The vehicle 1 is a lean vehicle that leans when turning. Hereinafter, the "vehicle 1" may be referred to as the "motorcycle 1."

[0010] FIG. 1 is a side view showing an example of the configuration of a vehicle 1 according to an embodiment as a motorcycle. FIG. 2 is a schematic diagram showing an example of a power system of the motorcycle 1 of FIG. 1. As shown in FIGS. 1 and 2, the motorcycle 1 has a drive source 10 and a structure that moves using the drive force generated by the drive source 10. The motorcycle 1 includes a drive structure 20 that moves the vehicle 1 by using the drive force transmitted from the drive source 10, a control circuit 30 that controls the drive source 10, and an actuator 40 that operates the drive source 10 in response to commands given from the control circuit 30. The motorcycle 1 includes one or more status sensors 50 that detect the status of components of the motorcycle 1. The motorcycle 1 includes one or more controls 60 that receive operations by the rider and one or more operation sensors 70 that detect the amount of operation of the controls 60.

[0011] The motorcycle 1 includes a front wheel 21 and a rear wheel 22 as part of a drive structure 20. The motorcycle 1 further includes a body frame 101, a handlebar 102, a steering shaft 103, a pair of left and right front forks 104, a swing arm 105, a rear suspension 106, a seat 107, a fuel tank 108, a pair of left and right foot bars 109, and an electronic control unit 100. The "electronic control unit 100" may be referred to as an "ECU 100." The ECU 100 includes a control circuit 30.

[0012] The upper part of the front fork 104 is connected to a pair of brackets 104a spaced apart in the vertical direction, and the lower part of the front fork 104 rotatably supports the front wheel 21. The bracket 104a is connected to a steering shaft 103 that supports the handlebars 102. The steering shaft 103 is supported by a head pipe 101a, which is part of the body frame 101, so as to be angularly displaceable.

[0013] The swing arm 105 supports the rear wheel 22, extends in the front-to-rear direction, and is pivotally supported by the body frame 101. The rear suspension 106 is connected to the swing arm 105 and the body frame 101. A fuel tank 108 that stores fuel for the drive source 10 is disposed above the body frame 101 and behind the handlebars 102. A seat 107 on which a rider sits is disposed above the body frame 101 and behind the fuel tank 108. A foot bar 109 is attached to the body frame 101 below and to the side of the seat 107.

[0014] Here, in this specification and claims, the upward, downward, forward, backward, leftward, and rightward directions are directions based on the motorcycle 1 placed upright on the horizontal ground. The upward direction refers to the direction from the ground toward the motorcycle 1, and the downward direction refers to the direction from the motorcycle 1 toward the ground. The forward direction refers to the forward direction of the motorcycle 1. The backward, leftward, and rightward directions each refer to a corresponding direction based on the rider straddling the motorcycle 1 standing upright on the ground.

[0015] The motorcycle 1 further includes a front brake 211 arranged on the front wheel 21 and a rear brake 221 arranged on the rear wheel 22. The motorcycle 1 includes, as operating elements 60, a brake lever 212 arranged on the handlebars 102 and a brake pedal 222 arranged on the body frame 101. The motorcycle 1 is structured so that the front brake 211 is actuated by operating the brake lever 212, and so that the rear brake 221 is actuated by operating the brake pedal 222. The motorcycle 1 is provided with brake sensors 213 and 223, which serve as operation sensors 70, on the brake lever 212 and the brake pedal 222, respectively, that detect braking operations. The brake sensors 213 and 223 output detection signals to the ECU 100. The brake pedal 222 may be arranged on the handlebars 102 as a brake lever.

[0016] The motorcycle 1 is equipped with a throttle grip 231 disposed on the handlebar 102 as an operator 60. The throttle grip 231 has a cylindrical shape and is rotatable about a cylindrical axis. The motorcycle 1 is equipped with a throttle position sensor 232 that detects the operating position of the throttle grip 231 as an operation sensor 70. The throttle position sensor 232 outputs a detection signal to the ECU 100. The ECU 100 controls the output of the drive source 10 according to the operating position and amount of operation of the throttle grip 231. Examples of the throttle position sensor 232 include an electromagnetic pickup type rotation sensor, an anisotropic-magneto-resistive (AMR) rotation sensor, a Hall IC type rotation sensor, and a mechanical, optical, magnetic, or electromagnetic induction encoder.

[0017] The motorcycle 1 may be provided with a clutch lever 241 arranged on the handlebar 102 as the operating element 60. The motorcycle 1 has a structure in which the clutch lever 241 is operated to engage or disengage the clutch 24, which will be described later. The motorcycle 1 may be provided with a clutch sensor 242, which detects the engagement and disengagement of the clutch 24, as the operation sensor 70, on the clutch lever 241 or the clutch 24. For example, the clutch sensor 242 may detect both the engagement and disengagement of the clutch 24. The clutch sensor 242 outputs a detection signal to the ECU 100.

[0018] The motorcycle 1 may be equipped with a shift operator 251 as the operator 60. The shift operator 251 may be a shift pedal disposed on the body frame 101 or the like, or a shift button or shift lever disposed on the handlebars 102 or the like. The motorcycle 1 has a structure in which, when the shift operator 251 is operated, the transmission 25 provided in the motorcycle 1 changes the selected reduction ratio. The motorcycle 1 may be equipped with a gear position sensor 252 as the status sensor 50. The gear position sensor 252 detects a command input to the shift operator 251 that specifies the reduction ratio of the transmission 25, and outputs a detection signal to the ECU 100.

[0019] The motorcycle 1 has a drive source 10 for obtaining propulsion force. The drive source 10 is disposed in a space surrounded by a body frame 101 between a front wheel 21 and a rear wheel 22, and is fixed at multiple portions to the body frame 101. In this embodiment, the drive source 10 includes an internal combustion engine 11. The motorcycle 1 may include, as a drive structure 20, a clutch 24, a transmission 25, and a power transmission member 26 that transmit power generated by the internal combustion engine 11 to the rear wheel 22. Examples of the power transmission member 26 may include a chain, a belt, and a gear.

[0020] As shown in FIG. 2, the internal combustion engine 11 includes a crankshaft 11c in a crankcase 11a, and one or more pistons 11d slidably disposed in a cylinder block 11b and connected to the crankshaft 11c so as to transmit driving force.

[0021] The internal combustion engine 11 generates power by repeatedly combusting and exploding a mixture of fuel and air in the cylinders of the cylinder block 11b. The internal combustion engine 11 converts the reciprocating motion of the pistons 11d caused by the combustion and explosion into the rotational motion of the crankshaft 11c, and transmits the rotational power of the crankshaft 11c to the rear wheels 22, which are drive wheels. One end of the crankshaft 11c is connected to a clutch 24 and is further connected to an input shaft of a transmission 25 via the clutch 24 so as to be capable of transmitting power. The clutch 24 has a structure that connects and disconnects the transmission of power between the crankshaft 11c and the transmission 25. In this embodiment, the clutch 24 is mechanically connected to a clutch lever 241 and operates by physically transmitting an operating force applied to the clutch lever 241. The output shaft of the transmission 25 transmits the rotational power of the crankshaft 11c to the rear wheels 22 via a power transmission member 26.

[0022] The motorcycle 1 includes a rotation sensor 261 as the status sensor 50, which detects the rotation speed of the internal combustion engine 11. The rotation speed correlates with the rotational speed. The rotation sensor 261 may be disposed on a flywheel or a crank pulley attached to the end of the crankshaft 11c so as to rotate integrally therewith, or on a camshaft to which the rotational power of the crankshaft 11c is transmitted. The rotation sensor 261 outputs the detection result to the ECU 100. The ECU 100 determines the rotation speed of the crankshaft 11c using the detection result of the rotation sensor 261. An example of the rotation sensor 261 is similar to the example of the throttle position sensor 232. The ECU 100 may function as the rotation sensor 261 and estimate the rotation speed of the internal combustion engine 11 based on a command value that controls the rotation of the internal combustion engine 11.

[0023] The motorcycle 1 is provided with a wheel speed sensor 224 on the rear wheel 22 as a status sensor 50. The wheel speed sensor 224 detects the rotation speed of the rear wheel 22 and outputs a detection signal to the ECU 100. An example of the wheel speed sensor 224 is the same as the example of the throttle position sensor 232. The wheel speed sensor 224 may be disposed on the front wheel 21 and detect the rotation speed of the front wheel 21. The wheel speed sensor 224 or the ECU 100 may detect the speed of the motorcycle 1 from the rotation speed. The motorcycle 1 may be provided with a position detection sensor that uses a Global Navigation Satellite System (GNSS) to detect the position of the motorcycle 1 on the Earth. In this case, the ECU 100 may detect the speed of the motorcycle 1 based on changes over time in position information acquired by the position detection sensor. In this way, it is preferable that the motorcycle 1 is provided with a sensor for detecting the traveling speed.

[0024] As described above, the motorcycle 1 includes the ECU 100, which includes the control circuit 30 that controls the internal combustion engine 11, and the actuator 40, which controls the internal combustion engine 11 in response to commands given by the ECU 100. The motorcycle 1 includes, as the actuator 40, a throttle actuator 41, a fuel injection actuator 42, and an ignition actuator 43. The throttle actuator 41 drives a throttle valve 411 that adjusts the flow rate of air flowing into the cylinder block 11b. The fuel injection actuator 42 includes a fuel injection valve that injects fuel into the cylinder block 11b. The ignition actuator 43 includes a spark plug that ignites the air-fuel mixture in the cylinder block 11b.

[0025] The throttle actuator 41, the fuel injection actuator 42, and the ignition actuator 43 are controlled by the ECU 100. The ECU 100 adjusts the torque output by the internal combustion engine 11 by controlling the actuator 40 in response to a detection signal from one of the sensors 50 and 70 that detects the vehicle state of the motorcycle 1. For example, the ECU 100 may correct the target value of the torque of the internal combustion engine 11 based on the vehicle state. Examples of the vehicle state may include the rotation speed of the internal combustion engine 11, the reduction ratio selected in the transmission 25, the vehicle speed of the motorcycle 1, the acceleration / deceleration state of the motorcycle 1, the bank angle of the motorcycle 1, the temperature of the internal combustion engine 11, and the air pressure. The bank angle is the lean angle of the motorcycle 1 during cornering. Examples of the temperature of the internal combustion engine 11 may include the temperature of the coolant for the internal combustion engine 11 and the temperature of the lubricating oil for the internal combustion engine 11.

[0026] The ECU 100 may control the actuator 40 based on operation information provided by an operation sensor 70 that detects an operation by the driver. The ECU 100 may also control the actuator 40 based on vehicle information provided by a state sensor 50 that detects the vehicle state. In this embodiment, the ECU 100 controls the actuator 40 based on both the operation information indicating the operation by the driver and the vehicle information indicating the vehicle state.

[0027] For example, the ECU 100 controls the operations of the throttle actuator 41, the fuel injection actuator 42, and the ignition actuator 43 so that the internal combustion engine 11 generates a torque corresponding to the amount of operation of the throttle grip 231 operated by the driver, based on the rotation speed of the internal combustion engine 11, the vehicle speed, the reduction ratio selected in the transmission 25, etc. More specifically, the ECU 100 calculates the torque required for the internal combustion engine 11 based on the amount of operation of the throttle grip 231 detected by the throttle position sensor 232, etc., and determines a target opening of the throttle valve 411, a target fuel injection amount, and a target ignition timing of the spark plug based on the calculated torque, and uses the determination results to control the actuator 40. In this embodiment, the rotation speed of the internal combustion engine 11 is the rotation speed of the crankshaft 11c.

[0028] The motorcycle 1 may include an intake passage 311 that introduces air into the internal combustion engine 11, and an intake air temperature sensor 312 that detects the intake air temperature, which is the temperature of the air passing through the intake passage 311. The intake air temperature sensor 312 is one of the condition sensors 50. The intake air temperature sensor 312 outputs the detection result to the ECU 100. The ECU 100 may control the actuator 40 using the intake air temperature as vehicle information. The intake passage 311 may be formed by an intake duct.

[0029] Motorcycle 1 may include, as condition sensor 50, an intake air amount sensor 313 that detects the flow rate of air passing through intake passage 311. Intake air amount sensor 313 outputs the detection result to ECU 100. ECU 100 may control actuator 40 using the air flow rate as vehicle information. An example of intake air amount sensor 313 includes an air flow sensor. The function of intake air amount sensor 313 may be realized by ECU 100. In this case, ECU 100 may detect the opening degree of throttle valve 411 based on the operating state of throttle actuator 41, and estimate the intake air amount based on the opening degree of throttle valve 411.

[0030] The motorcycle 1 may include an exhaust passage 321 that discharges exhaust gas resulting from combustion of an air-fuel mixture in the internal combustion engine 11 into the outside air, and a catalyst 322 located midway along the exhaust passage 321. The exhaust passage 321 may be formed by an exhaust pipe. The catalyst 322 has a structure in which a catalytic material containing a precious metal such as platinum (Pt), rhodium (Rh), or palladium (Pd) is supported on a substrate such as a honeycomb body, and purifies the exhaust gas passing through the catalyst 322. The motorcycle 1 may also include a catalyst temperature sensor 323 that detects the temperature of the catalyst 322 or a temperature near the downstream side of the catalyst 322 as the condition sensor 50. The catalyst temperature sensor 323 outputs the detection result to the ECU 100. The ECU 100 may control the actuator 40 using the temperature detected by the catalyst temperature sensor 323 as vehicle information.

[0031] The motorcycle 1 may include, as the condition sensor 50, an engine temperature sensor 131 that detects the temperature state of the internal combustion engine 11. One or more engine temperature sensors 131 may be arranged to detect the temperature of the coolant that cools the internal combustion engine 11, the temperature of the lubricating oil that lubricates the internal combustion engine 11, or both. The engine temperature sensor 131 may be arranged in the coolant flow path or the lubricating oil flow path. The engine temperature sensor 131 outputs a detection signal to the ECU 100. The ECU 100 may control the actuator 40 using the temperature of the internal combustion engine 11 as vehicle information.

[0032] Motorcycle 1 may include a transmission actuator 253 that controls the operation of transmission 25. Transmission actuator 253 is controlled by ECU 100. ECU 100 causes transmission actuator 253 to operate transmission 25 in accordance with a detection signal from gear position sensor 252 so that the reduction ratio of transmission 25 becomes a command value. Alternatively, motorcycle 1 may have a structure in which transmission 25 is mechanically connected to shift operator 251 and operates when an operating force applied to shift operator 251 is physically transmitted thereto.

[0033] Motorcycle 1 may include a sensor that detects the attitude of motorcycle 1, such as inertial force sensor 401, as state sensor 50. Inertial force sensor 401 is used to detect the attitude of motorcycle 1 and control the behavior of motorcycle 1, and outputs the detection results to ECU 100. Inertial force sensor 401 includes an acceleration sensor and may further include a gyro sensor. The acceleration sensor detects acceleration in two or three mutually intersecting detection axis directions. The gyro sensor detects angular velocity or angular acceleration around two or three mutually intersecting detection axes. ECU 100 may control actuator 40 using the attitude of motorcycle 1 and the acceleration / deceleration state of motorcycle 1 based on the detection results of inertial force sensor 401 as vehicle information.

[0034] The configuration of the ECU 100 will be described in detail. The ECU 100 may include a microcomputer having one or more processors P, such as a CPU (Central Processing Unit) or a DSP (Digital Signal Processor), and one or more memories M. The control circuit 30 may include the processor P and the memory M. The ECU 100 may include a clock for measuring time. Examples of the memory M may include a semiconductor memory, a hard disk drive (HDD), and a solid state drive (SSD). Examples of the semiconductor memory may include a volatile memory, such as a RAM (Random Access Memory), and a non-volatile memory, such as a ROM (Read-Only Memory). The ECU 100 and the control circuit 30 include processing circuits.

[0035] Some or all of the functions of the ECU 100 may be realized by the CPU using the RAM as a working memory and executing a program stored in the ROM. Some or all of the functions of the ECU 100 may be realized by a dedicated hardware circuit such as an electronic circuit or an integrated circuit. Some or all of the functions of the ECU 100 may be realized by a combination of the above-mentioned software functions and hardware circuits. Communication between the ECU 100 and devices mounted on the motorcycle 1, such as various actuators and various sensors, may be communication via an in-vehicle network such as a CAN (Controller Area Network).

[0036] The ECU 100 stores in advance in the memory M a fuel map used to determine the target fuel injection amount of the fuel injection valve and an ignition map used to determine the target ignition timing of the ignition plug.

[0037] The fuel map is a list of graphs in which a target fuel injection amount of the fuel injector is determined based on the rotation speed and load of the internal combustion engine 11. The fuel map can be set for each reduction ratio of the transmission 25. The ECU 100 determines the load of the internal combustion engine 11 based on the detection signal of the throttle position sensor 232, etc., and determines the target fuel injection amount by inputting the determined load and the rotation speed of the internal combustion engine 11 into the fuel map. The ECU 100 can determine the target fuel injection amount using the detection results of the rotation sensor 261, the throttle position sensor 232, the gear position sensor 252, and the fuel map. The ECU 100 may correct the fuel injection amount by increasing or decreasing it from the target fuel injection amount based on one or more of the detection results of the wheel speed sensor 224, the intake air temperature sensor 312, the catalyst temperature sensor 323, the engine temperature sensor 131, and the clutch sensor 242.

[0038] The ignition map is a list of graphs in which the target ignition timing of the spark plug is determined by the rotation speed of the internal combustion engine 11 and the opening of the throttle valve 411. The ignition map can be set for each reduction ratio of the transmission 25. The ECU 100 determines the target ignition timing by inputting the rotation speed of the internal combustion engine 11 and the opening of the throttle valve 411 into the ignition map. The ignition timing is timing that corresponds to the rotation angle of the crankshaft 11c. The ECU 100 may correct the ignition timing by advancing or retarding it from the target ignition timing based on one or more of the detection results of the wheel speed sensor 224, the intake air temperature sensor 312, the catalyst temperature sensor 323, the engine temperature sensor 131, and the clutch sensor 242.

[0039] Control of the rotation speed of the internal combustion engine 11 by the ECU 100 will be described. The ECU 100 stores an upper limit threshold Th1, which is preset for the rotation speed of the internal combustion engine 11, in the memory M. The upper limit threshold Th1 can be determined based on the structure, durability, etc. of the internal combustion engine 11. The upper limit threshold Th1 can be set to a value lower than a limit threshold Th2 for the rotation speed of the internal combustion engine 11. The limit threshold Th2 can be determined based on the structure of the internal combustion engine 11. For example, the limit threshold Th2 can be determined to a value such that the internal combustion engine 11 will be damaged or its durability will be significantly reduced if it operates at a rotation speed exceeding the limit threshold Th2. The upper limit threshold Th1 can be set as the upper limit of the rotation speed allowed for the internal combustion engine 11 during normal use of the internal combustion engine 11.

[0040] The upper threshold value Th1 may be a rev limit set for the internal combustion engine 11. The range between the upper threshold value Th1 and the limit threshold value Th2 may be defined as a red zone. As the rotation speed of the internal combustion engine 11 exceeds the upper threshold value Th1 and approaches the limit threshold value Th2, the risk of damage to the internal combustion engine 11 and a decrease in durability may increase. As the period during which the rotation speed of the internal combustion engine 11 is maintained within the red zone becomes longer, the risk of damage to the internal combustion engine 11 and a decrease in durability may increase.

[0041] The upper threshold value Th1 may be set to a uniform value regardless of the state of the motorcycle 1, or may be set to a value that varies depending on the vehicle state of the motorcycle 1. In the latter case, examples of the vehicle state of the motorcycle 1 may include the vehicle speed of the motorcycle 1, the reduction ratio selected in the transmission 25, and the temperature of the internal combustion engine 11.

[0042] The ECU 100 detects the rotation speed of the internal combustion engine 11 based on the detection result of the rotation sensor 261. When the ECU 100 determines that the rotation speed of the internal combustion engine 11 has started to exceed the upper limit threshold Th1, the ECU 100 starts executing a suppression algorithm to prevent the rotation speed of the internal combustion engine 11 from reaching the limit threshold Th2. Starting to exceed the upper limit threshold Th1 means that the rotation speed of the internal combustion engine 11 has first exceeded the upper limit threshold Th1 in a state where the suppression algorithm is not being executed.

[0043] In the suppression algorithm, when the ECU 100 determines that the suppression condition is satisfied, it executes suppression control to suppress the output of the internal combustion engine 11. In other words, by executing the suppression control, the ECU 100 suppresses an increase in the rotation speed of the internal combustion engine 11 and reduces the rotation speed. The suppression control is control of the actuator 40 to quickly reduce the rotation speed of the internal combustion engine 11 to equal to or below the upper limit threshold Th1 without allowing it to reach the limit threshold Th2. The suppression condition is a condition based on the degree of excess, which will be described later.

[0044] The output of the internal combustion engine 11 may be defined based on the torque and rotation speed of the internal combustion engine 11. For example, the target output of the internal combustion engine 11 may be determined based on the target torque of the internal combustion engine 11 and the rotation speed of the internal combustion engine 11. The target torque is the torque of the internal combustion engine 11 that is realized by a target fuel injection amount determined using a fuel map and a target ignition timing determined using an ignition map. The ECU 100 may suppress the output of the internal combustion engine 11 by suppressing the output torque of the internal combustion engine 11 to be lower than the target torque. The ECU 100 determines a target opening of the throttle valve 411 and a target fuel injection amount that correspond to the target torque after suppression, and uses the determination result to control the actuator 40.

[0045] When the suppression algorithm is started, the ECU 100 determines an excess E of the rotation speed of the internal combustion engine 11 relative to the upper threshold value Th1. The excess E is set in relation to the period during which the rotation speed of the internal combustion engine 11 exceeds the upper threshold value Th1. The ECU 100 uses the excess E to determine the amount of suppression of the output of the internal combustion engine 11. The output suppression amount is the amount of suppression from the target output of the internal combustion engine 11. The ECU 100 outputs a suppression command corresponding to the output suppression amount.

[0046] The process of determining the degree of excess E by the ECU 100 will be described. The degree of excess E is an index related to the occurrence state of an excess event, which is an event in which the rotation speed of the internal combustion engine 11 exceeds the upper threshold value Th1. Examples of the occurrence state of the excess event may include the period during which the excess event occurred, the number of times the excess event occurred, and the frequency with which the excess event occurred.

[0047] In this embodiment, the occurrence state of an exceedance event is a period during which the exceedance event occurs. In other words, the degree of exceedance E is related to an exceedance period, which is a period during which the rotational speed of the internal combustion engine 11 exceeds the upper threshold value Th1. The exceedance period may be a single period during which the rotational speed of the internal combustion engine 11 continuously exceeds the upper threshold value Th1, or may be the total period of multiple periods during which the rotational speed of the internal combustion engine 11 continuously exceeds the upper threshold value Th1. In this embodiment, the exceedance period is the total period during which the rotational speed of the internal combustion engine 11 continuously exceeds the upper threshold value Th1 within a determination period from the start timing of the suppression algorithm to the timing when the degree of exceedance E is calculated.

[0048] The degree of excess E may be an index that changes in response to the length of the excess period. In this case, the value of the degree of excess E increases as the excess period becomes longer, and is a value that corresponds to the length of the excess period. The degree of excess E may be an index that changes in response to a change in the combination of the excess period and other factors. Examples of the other factors may include the rotation speed of the internal combustion engine 11, the length of the non-exceeding period, and the reduction ratio selected in the transmission 25. In this embodiment, the other factors include the rotation speed of the internal combustion engine 11, the length of the non-exceeding period, and the reduction ratio selected in the transmission 25.

[0049] The non-exceeding period is a period during which the rotation speed of the internal combustion engine 11 is equal to or less than the upper limit threshold Th1. The non-exceeding period may be one period during which the rotation speed of the internal combustion engine 11 is continuously equal to or less than the upper limit threshold Th1, or may be the total period of multiple periods during which the rotation speed of the internal combustion engine 11 is continuously equal to or less than the upper limit threshold Th1. In this embodiment, the non-exceeding period is the total period during which the rotation speed of the internal combustion engine 11 is continuously equal to or less than the upper limit threshold Th1 within the determination period from the start timing of the suppression algorithm to the timing at which the degree of exceedance E is calculated.

[0050] The value of the excess degree E changes in response to changes in the combination of the excess period and the amount by which the rotation speed of the internal combustion engine 11 exceeds the upper threshold value Th1. The value of the excess degree E changes in response to the length of the excess period and the change in the rotation speed of the internal combustion engine 11 within the excess period. For example, the value of the excess degree E increases as the excess period increases and as the amount by which the rotation speed of the internal combustion engine 11 exceeds the upper threshold value Th1. In this embodiment, the value of the excess degree E is increased in accordance with the amount by which the rotation speed of the internal combustion engine 11 exceeds the upper threshold value Th1. Specifically, the value of the excess degree E is increased at predetermined intervals in accordance with the amount by which the rotation speed of the internal combustion engine 11 exceeds the upper threshold value Th1, which is acquired at each predetermined interval.

[0051] Furthermore, the value of the excess degree E changes in response to changes in the combination of the non-exceeding period and the amount by which the rotation speed of the internal combustion engine 11 is below the upper limit threshold Th1. The value of the excess degree E changes in response to the length of the non-exceeding period and the change in the rotation speed of the internal combustion engine 11 within the non-exceeding period. For example, the value of the excess degree E becomes smaller as the non-exceeding period becomes longer, and becomes smaller as the amount by which the rotation speed of the internal combustion engine 11 is below the upper limit threshold Th1 increases. In this embodiment, the value of the excess degree E is discounted in accordance with the amount by which the rotation speed of the internal combustion engine 11 is below the upper limit threshold Th1, which is acquired in each predetermined period.

[0052] Furthermore, the value of the excess degree E varies depending on the reduction ratio selected in the transmission 25. For example, the value of the excess degree E when a high reduction ratio, i.e., a reduction ratio for low-speed driving, is selected may be changed to be larger than the value of the excess degree E when a low reduction ratio, i.e., a reduction ratio for high-speed driving, is selected. The higher the reduction ratio, the larger the excess degree E may be changed to. In this embodiment, the value of the excess degree E is increased or decreased depending on the reduction ratio selected in the transmission 25.

[0053] Although not limited thereto, in this embodiment, the excess degree E is expressed using a count value counted for each predetermined sampling period Ps. For each sampling period Ps, the ECU 100 determines a count value corresponding to the rotation speed difference, which is the difference obtained by subtracting the upper threshold value Th1 from the rotation speed of the internal combustion engine 11. The count value corresponds to the excess amount and the under amount. The ECU 100 adds, or counts up, the determined count value for each sampling period Ps. The sum of the count values ​​corresponds to the excess degree E. In this embodiment, the excess degree E is the sum of the count values. The count value is an excess degree element that constitutes the excess degree. For example, the sampling period Ps may be set to a period of less than one second.

[0054] In this embodiment, multiple ranges are set for the rotation speed difference, and a different count value is set for each range of the rotation speed difference. The larger the range of the rotation speed difference, the larger the count value is set. When the rotation speed difference is a positive value, the count value is a positive value and increases the excess E by counting up. Such a count value is used in the excess period. When the rotation speed difference is a negative value, the count value is a negative value and decreases the excess E by counting up. Such a count value can be used in the non-excess period. When the rotation speed difference is 0, the count value is 0 or a negative value, and in this embodiment, it is a negative value. Such a count value is used in the non-excess period. In this embodiment, ECU 100 counts not only positive count values ​​but also negative count values ​​as excess.

[0055] For example, the count value may be increased by a predetermined number, such as 1, for each 100 rpm increase in the rotation speed difference when the rotation speed difference is within a range of greater than 0 and not greater than 100 rpm (revolutions per minute), and the count value may be 2 when the rotation speed difference is within a range of greater than 100 rpm and not greater than 200 rpm. For example, the count value may be decreased by a predetermined number, such as 1, for each 100 rpm decrease in the rotation speed difference when the rotation speed difference is within a range of greater than -100 rpm and less than 0, and the count value may be -1 when the rotation speed difference is within a range of greater than -200 rpm and not greater than -100 rpm. In this embodiment, when the absolute values ​​of the ranges of positive and negative rotation speed differences are the same, the absolute values ​​of the count values ​​are the same. When the rotation speed difference is 0, the count value may be 0 or -1, and in this embodiment, it is -1.

[0056] In this embodiment, the count values ​​corresponding to the same range of rotation speed difference are set to differ depending on the reduction ratio selected in the transmission 25. The count values ​​corresponding to the same range of rotation speed difference may be the same between two or more reduction ratios. For example, the change in the count value per 100 rpm of rotation speed difference at a high reduction ratio, i.e., a reduction ratio for low-speed driving, may be greater than the change in the count value per 100 rpm of rotation speed difference at a low reduction ratio, i.e., a reduction ratio for high-speed driving. Thus, even for the same rotation speed difference, the change in the count value per 100 rpm of rotation speed difference increases as the reduction ratio increases. Specifically, the count values ​​corresponding to the same range of rotation speed difference are increased as the reduction ratio increases. For example, the relationship between the reduction ratio, the range of rotation speed difference, and the rate of change in the count value within the range of rotation speed difference can be set as shown in Tables 1 and 2 below. In the examples of Tables 1 and 2, six reduction ratios are selectable in the transmission 25.

[0057] [Table 1]

[0058] [Table 2]

[0059] The ECU 100 stores in advance in the memory M the relationship between the range of the rotation speed difference and the count value, or the relationship between the range of the rotation speed difference, the reduction ratio of the transmission 25, and the count value.

[0060] When the ECU 100 determines that the rotation speed of the internal combustion engine 11 has started to exceed the upper threshold value Th1, it executes a suppression algorithm and starts calculating the degree of excess E. The ECU 100 detects a rotation speed difference obtained by subtracting the upper threshold value Th1 from the rotation speed of the internal combustion engine 11 every time a sampling period Ps elapses, counts up a count value corresponding to the rotation speed difference, and determines a total value of the count values. The ECU 100 determines a value of the degree of excess E corresponding to the total value of the count values. The ECU 100 may add the count value to a preset initial value. The initial value may be 0 or a value greater than 0. In this embodiment, the initial value is set to differ depending on the reduction ratio selected in the transmission 25. The initial value may be the same for two or more reduction ratios. The initial value may be larger as the reduction ratio selected in the transmission 25 is higher.

[0061] The ECU 100 continues to calculate the excess degree E until a predetermined stop condition is satisfied. When the ECU 100 determines that the stop condition is satisfied, it cancels the execution of the suppression algorithm and resets the value of the excess degree E to an initial value. The stop condition will be described later.

[0062] When the ECU 100 determines that the suppression condition is satisfied in the process of calculating the excess degree E, the ECU 100 executes suppression control to suppress the output of the internal combustion engine 11. The suppression condition is that the value of the excess degree E exceeds an initial value.

[0063] In suppression control, the ECU 100 outputs a suppression command to the actuator 40 to suppress the output of the internal combustion engine 11 compared to before the suppression control. Examples of control before the suppression control include normal control. The normal control is control that applies to the actuator 40 a target fuel injection amount according to a fuel map or a corrected target fuel injection amount based on the detection results of various sensors, and an ignition timing according to an ignition map or a corrected ignition timing based on the detection results of various sensors. The suppression command is a command to suppress the output of the internal combustion engine 11 below the target output of the internal combustion engine 11. Furthermore, when the ECU 100 determines that the stop condition is satisfied, it stops the suppression control and transitions to normal control, etc.

[0064] The process of determining the output suppression amount of the internal combustion engine 11 by the ECU 100 will be described. In the suppression control, the ECU 100 controls the actuator 40 so that the output suppression amount increases as the excess degree E increases. When a positive count value is counted up, the excess degree E increases, and therefore the output suppression amount increases. When a negative count value is counted up, the excess degree E decreases, and therefore the output suppression amount decreases.

[0065] The ECU 100 determines the output suppression amount PS of the internal combustion engine 11 based on the excess E and the target output PT. The target output PT is the target output of the internal combustion engine 11 under normal control. The output suppression amount PS is obtained by PS=PT×αE, where α is a coefficient.

[0066] In this embodiment, the coefficient α is the reciprocal of the maximum excess degree Emax, which is the maximum allowable value set for the excess degree. For example, the ECU 100 stores the maximum excess degree Emax in the memory M in advance. The maximum excess degree Emax is set according to the vehicle state of the motorcycle 1. Examples of the vehicle state may include the reduction ratio set in the transmission 25, the vehicle speed of the motorcycle 1, the intake pressure of the internal combustion engine 11, the intake temperature of the internal combustion engine 11, and the attitude of the motorcycle 1.

[0067] The ECU 100 determines the output suppression amount PS of the internal combustion engine 11 based on the ratio R of the excess degree E to the maximum excess degree Emax. That is, PS = PT × R. In this embodiment, the ECU 100 determines the target suppressed output PST, which is the target output after output suppression, by multiplying the target output PT by (1 - ratio R). That is, PST = PT × (1 - R). The ECU 100 determines the ratio R of the excess degree E to the maximum excess degree Emax and the target output PT of the internal combustion engine 11 for each sampling period Ps, and determines the target suppressed output PST based on these.

[0068] The degree of excess E increases as the excess period becomes longer. Therefore, the above-described output suppression amount PS increases as the excess period becomes longer. The amount of increase in the output suppression amount PS per sampling period Ps during the excess period depends on the rotation speed difference and the sampling period Ps. Therefore, the change over time of the output suppression amount PS is gentler than, for example, when it fluctuates sequentially in accordance with fluctuations in the rotation speed of the internal combustion engine 11. Furthermore, the output suppression amount PS decreases as the non-excess period becomes longer. The amount of decrease in the output suppression amount PS per sampling period Ps during the non-excess period depends on the rotation speed difference and the sampling period Ps. Therefore, the change over time of the output suppression amount PS is gentler than, for example, when it fluctuates sequentially in accordance with fluctuations in the rotation speed of the internal combustion engine 11. Therefore, the behavior of the internal combustion engine 11 is gentle in both the excess period and the non-excess period.

[0069] Furthermore, in this embodiment, the ECU 100 determines the maximum excess degree Emax corresponding to any one of the vehicle conditions of the motorcycle 1, for example, the reduction ratio set in the transmission 25, the vehicle speed of the motorcycle 1, the intake pressure of the internal combustion engine 11, the intake temperature of the internal combustion engine 11, and the attitude of the motorcycle 1. Furthermore, the ECU 100 can correct the determined maximum excess degree Emax using a vehicle condition different from the vehicle condition used to determine the maximum excess degree Emax.

[0070] In this embodiment, the ECU 100 determines the maximum excess degree Emax1 corresponding to the reduction ratio selected in the transmission 25. For example, the ECU 100 determines the maximum excess degree Emax1 based on the detection result of the gear position sensor 252. The maximum excess degree Emax1 is set in advance for each reduction ratio set in the transmission 25 and stored in the memory M of the ECU 100. The maximum excess degree Emax1 when the reduction ratio is high is smaller than the maximum excess degree Emax1 when the reduction ratio is low. For example, the maximum excess degree Emax1 is set to decrease as the reduction ratio shifts from that for high-speed driving to that for low-speed driving.

[0071] The larger the maximum excess degree Emax1, the smaller the output suppression amount PS and the larger the target suppressed output PST. Therefore, as the reduction ratio selected in the transmission 25 shifts from that for low-speed driving to that for high-speed driving, that is, as the reduction ratio becomes smaller, the output suppression amount PS becomes smaller.

[0072] In addition, in this embodiment, the ECU 100 corrects the maximum excess degree Emax1 corresponding to the reduction ratio based on one or more of the vehicle speed of the motorcycle 1, the intake pressure of the internal combustion engine 11, the intake temperature of the internal combustion engine 11, and the attitude of the motorcycle 1.

[0073] The ECU 100 may correct the maximum excess degree Emax1 to the maximum excess degree Emax2 based on the detection result of the wheel speed sensor 224. The corrected maximum excess degree Emax2 when the vehicle speed is high may be larger than the corrected maximum excess degree Emax2 when the vehicle speed is low. For example, the ECU 100 may correct the maximum excess degree Emax1 so that the maximum excess degree Emax2 decreases as the vehicle speed transitions from high to low. This reduces the output suppression amount PS as the vehicle speed transitions from low to high.

[0074] The ECU 100 may correct the maximum excess degree Emax1 to the maximum excess degree Emax3 based on the detection result of the intake air amount sensor 313. The ECU 100 may estimate the intake pressure of the internal combustion engine 11 based on the intake air amount detected by the intake air amount sensor 313. The ECU 100 may estimate the intake air amount based on the opening degree of the throttle valve 411. The corrected maximum excess degree Emax3 when the intake pressure is high may be larger than the corrected maximum excess degree Emax3 when the intake pressure is low. For example, the ECU 100 may correct the maximum excess degree Emax1 so that the maximum excess degree Emax3 becomes smaller as the intake pressure transitions from a high state to a low state. As a result, the output suppression amount PS becomes smaller as the intake pressure transitions from a low state to a high state.

[0075] The ECU 100 may correct the maximum excess degree Emax1 to the maximum excess degree Emax4 based on the detection result of the intake air temperature sensor 312. The corrected maximum excess degree Emax4 when the intake air temperature is low may be larger than the corrected maximum excess degree Emax4 when the intake air temperature is high. For example, the ECU 100 may correct the maximum excess degree Emax1 so that the maximum excess degree Emax4 decreases as the intake air temperature transitions from a low state to a high state. This reduces the output suppression amount PS as the intake air temperature transitions from a high state to a low state.

[0076] ECU 100 may correct maximum excess degree Emax1 to maximum excess degree Emax5 based on the detection result of inertial force sensor 401. ECU 100 detects the attitude of motorcycle 1 based on the detection result of inertial force sensor 401. The corrected maximum excess degree Emax5 when the lateral lean amount of motorcycle 1 is small may be greater than the corrected maximum excess degree Emax5 when the lateral lean amount of motorcycle 1 is large. For example, ECU 100 may correct maximum excess degree Emax1 so that maximum excess degree Emax5 decreases as the lateral lean amount of motorcycle 1 transitions from a small state to a large state. As a result, output suppression amount PS decreases as the lateral lean amount of motorcycle 1 transitions from a large state to a small state.

[0077] The ECU 100 may correct the maximum excess degree Emax1 by combining two or more of the correction processes for the maximum excess degrees Emax2 to Emax5.

[0078] Based on the target suppressed output PST calculated as described above, the ECU 100 outputs a suppression command to the actuator 40 to change the target output of the internal combustion engine 11 to the target suppressed output PST. The suppression command includes one or more of the following: an ignition cut command, a fuel cut command, a fuel reduction command, a retard command, and an intake reduction command.

[0079] The ignition cut command is a command to stop ignition of the spark plug at the target ignition timing, and is output by the ECU 100 to the ignition actuator 43. The internal combustion engine 11 temporarily suspends output by stopping ignition, so that the output torque can be suppressed.

[0080] The fuel cut command is a command to stop fuel injection from the fuel injection valve, and is output by the ECU 100 to the fuel injection actuator 42. The internal combustion engine 11 temporarily suspends output by stopping fuel injection, and therefore the output torque can be suppressed.

[0081] The fuel reduction command is a command to reduce the fuel injection amount of the fuel injection valve below the target fuel injection amount, and is output by the ECU 100 to the fuel injection actuator 42. The internal combustion engine 11 can suppress the output torque by reducing the fuel injection amount.

[0082] The retard command is a command to delay the ignition timing of the spark plug from the target ignition timing, that is, to retard the ignition timing, and is output by the ECU 100 to the ignition actuator 43. The internal combustion engine 11 cannot obtain efficient combustion and explosion due to the retarded ignition timing, so the output torque can be suppressed.

[0083] The intake air amount reduction command is a command to reduce the opening of the throttle valve 411 below the opening corresponding to the detection signal of the throttle position sensor 412, and is output by the ECU 100 to the throttle actuator 41. The internal combustion engine 11 can suppress the output torque by reducing the intake air amount.

[0084] The stop conditions will be described. The stop conditions are set in advance to include multiple conditions. The ECU 100 stops the suppression control or the suppression algorithm when any one of the multiple stop conditions is satisfied. This makes it easier to reduce the number of times the suppression control is performed, and reduces the number of times the rider of the motorcycle 1 experiences a deterioration in driving comfort due to the suppression control. For example, the stop conditions include first to sixth conditions, and the ECU 100 stores the stop conditions, including the first to sixth conditions, in advance in the memory M. When the ECU 100 determines that one or more of the first to sixth conditions are satisfied, it determines that the stop conditions are satisfied and stops the suppression control or the suppression algorithm. Stopping the suppression control may mean ending the suppression control without ending the suppression algorithm, or may mean ending both the suppression algorithm and the suppression control, or may mean temporarily stopping the suppression control without ending the suppression algorithm. Stopping the suppression algorithm means ending the suppression algorithm, which in turn ends the suppression control. In this embodiment, stopping the suppression control means ending the suppression algorithm, and the excess degree is reset to an initial value.

[0085] The first condition is that the total count value converges to an initial value after the start of the suppression control. When the first condition is satisfied, the influence of the overspeed of the internal combustion engine 11 is reduced, so it is preferable to stop the suppression control.

[0086] The second condition is a condition that the period during which the rotation speed of the internal combustion engine 11 exceeds the upper threshold value Th1 and then the period during which the rotation speed is less than the upper threshold value Th1 is equal to or longer than a preset threshold value period. When the second condition is satisfied, similar to the first condition, the influence of the over-speed of the internal combustion engine 11 is reduced, and therefore it is preferable to stop the suppression control.

[0087] The third condition is that the rotation speed of the internal combustion engine 11 is equal to or less than a predetermined lower threshold. The lower threshold is less than the upper threshold Th1. The lower threshold can be set to a rotation speed that will take a long time to reach the upper threshold Th1 again under suppression control. For this reason, it is preferable to stop the suppression control. For example, the lower threshold is preferably equal to or less than 70% of the upper threshold Th1, more preferably equal to or less than 60% of the upper threshold Th1, and even more preferably equal to or less than 50% of the upper threshold Th1. The lower threshold is preferably equal to or more than 40% of the upper threshold Th1. In this embodiment, the lower threshold is set within a range of 45% to 55% of the upper threshold Th1.

[0088] The fourth condition is that the detection result of the clutch sensor 242 indicates a transition from an engaged state to a disengaged state of the clutch 24. When the fourth condition is satisfied, it is preferable to stop the suppression control that is being executed in order to prioritize the driver's driving feeling and because the load acting on the internal combustion engine 11 is significantly reduced.

[0089] The fifth condition is that the detection result of the gear position sensor 252 indicates a change in the reduction ratio selected in the transmission 25. For example, if the motorcycle 1 is equipped with a sensor that detects a gear shift operation, the ECU 100 may detect a change in the reduction ratio based on the detection result of the sensor. Specifically, the sensor may detect an upshift operation that lowers the reduction ratio or a downshift operation that increases the reduction ratio. When the fifth condition is satisfied, it is preferable to stop the ongoing suppression control in order to prioritize the driver's driving feel and to allow for fluctuations in the load acting on the internal combustion engine 11 during a gear shift transition. Furthermore, when the reduction ratio is changed, the maximum excess degree changes. Therefore, in order to determine the output suppression amount of the internal combustion engine 11, it is necessary to reset the current excess degree and generate a new excess degree. For these reasons, it is also preferable to stop the ongoing suppression control.

[0090] The sixth condition is that the temperature of the catalyst 322 is equal to or higher than the upper limit temperature. During the suppression control, the air-fuel ratio of the amount of fuel and air supplied to the internal combustion engine 11 fluctuates, which may cause the catalyst temperature to rise. If the catalyst temperature is equal to or higher than the upper limit temperature, the purification function may be reduced, the catalyst 322 may be deteriorated, etc. When the sixth condition is satisfied, the suppression control being executed must be stopped, and another control must be performed to rapidly reduce the catalyst temperature. The ECU 100 may estimate the temperature of the catalyst 322 using the detection result of the catalyst temperature sensor 323. Alternatively, the ECU 100 may estimate the temperature of the catalyst 322 using information on the intake air amount of the internal combustion engine 11, the vehicle speed of the internal combustion engine 11, the rotation speed of the internal combustion engine 11, and the ignition timing of the internal combustion engine 11.

[0091] The first condition, the second condition, the third condition, and the sixth condition are rotation conditions related to the rotation state of the internal combustion engine 11. The rotation condition is a condition that the influence of over-rotation of the internal combustion engine 11 exceeding the upper threshold value Th1 becomes smaller, so that the suppression control currently being performed becomes unnecessary. The fourth condition is a load condition related to the load state imposed on the internal combustion engine 11. The load condition is a condition that the load imposed on the internal combustion engine 11 decreases, so that the suppression control currently being performed becomes unnecessary. The sixth condition is an excess degree condition related to the excess degree. The excess degree condition is a condition that the suppression control currently being performed becomes unnecessary because a new excess degree needs to be generated due to fluctuations in the maximum excess degree, etc.

[0092] An operation of the ECU 100 for controlling the rotation speed of the internal combustion engine 11 will be described. Fig. 3 is a flowchart showing an example of the operation of the ECU 100 according to the embodiment. As shown in Fig. 3, in step S101, the ECU 100 executes normal control of the internal combustion engine 11.

[0093] In step S102, the ECU 100 acquires the detection result of the rotation sensor 261 and determines, based on the detection result, whether or not the rotation speed of the internal combustion engine 11 exceeds the upper limit threshold Th1. If the rotation speed of the internal combustion engine 11 exceeds the upper limit threshold Th1 (Yes in step S102), the ECU 100 proceeds to step S103, and if the rotation speed of the internal combustion engine 11 is equal to or less than the upper limit threshold Th1 (No in step S102), the ECU 100 returns to step S101.

[0094] In step S103, the ECU 100 executes the suppression algorithm for the internal combustion engine 11.

[0095] In step S104, ECU 100 determines whether or not the sampling period Ps has elapsed. If the sampling period Ps has elapsed (Yes in step S104), ECU 100 proceeds to step S105, and if the sampling period Ps has not yet elapsed (No in step S104), ECU 100 repeats step S104.

[0096] In step S105, the ECU 100 detects the difference between the rotation speed of the internal combustion engine 11 in the most recent sampling period Ps and the upper limit threshold value Th1. The ECU 100 determines a count value, which is a component of the excess degree E, using the sampling period Ps and the rotation speed difference.

[0097] In step S106, the ECU 100 determines the excess degree E by adding the count value to the total value of the count values ​​that have been added up to that point. If the count value has not yet been added up, the ECU 100 determines the excess degree E by adding the count value to an initial value. If the count value has not yet been added up, a positive count value is added to the initial value, and the suppression condition is satisfied, so the ECU 100 switches control from normal control to suppression control.

[0098] In step S107, the ECU 100 determines the target output of the internal combustion engine 11. The ECU 100 may determine the target output at any timing after step S104, or may execute the determination of the target output in parallel with one or more of steps S105 and S106.

[0099] In step S108, the ECU 100 determines the target suppressed output PST using the excess E and the target output of the internal combustion engine 11.

[0100] In step S109, the ECU 100 outputs to the actuator 40 a suppression command corresponding to the target suppression output PST.

[0101] In step S110, ECU 100 determines whether or not a stop condition for the suppression control is satisfied based on the detection results of various sensors. If the stop condition is satisfied (Yes in step S110), ECU 100 proceeds to step S111, and if the stop condition is not satisfied (No in step S110), ECU 100 returns to step S104. In step S104, ECU 100 determines whether or not the next sampling period Ps has elapsed. Note that ECU 100 may execute step S110 at any timing after step S104, or may execute step S110 in parallel with one or more of steps S105 to S109.

[0102] In step S111, the ECU 100 switches the control of the internal combustion engine 11 from suppression control to normal control. The ECU 100 resets the degree of excess, the excess period, etc. to initial values ​​or 0, and ends the suppression algorithm. After step S111, the ECU 100 repeats step S101 and subsequent steps.

[0103] According to steps S101 to S111, during suppression control, the ECU 100 determines the target suppressed output PST of the internal combustion engine 11 using the excess degree E, which increases as the exceedance period becomes longer. Because the output suppression amount PS of the internal combustion engine 11 increases as the exceedance period becomes longer, the target suppressed output PST decreases as the exceedance period becomes longer. The target suppressed output PST does not fluctuate abruptly because it fluctuates in relation to the length of the exceedance period. Therefore, the ECU 100 can reduce the rotation speed of the internal combustion engine 11 while suppressing abrupt fluctuations in the behavior of the internal combustion engine 11 when the rotation speed exceeds the upper threshold value Th1.

[0104] An example of control of the rotation speed of the internal combustion engine 11 by the ECU 100 according to the embodiment will be described below. Fig. 4 shows a first example of control of the rotation speed of the internal combustion engine 11 by the ECU 100 when the motorcycle 1 is traveling on flat ground. In the following example, the ECU 100 suppresses the output of the internal combustion engine 11 by adjusting the opening of the throttle valve 411 as output suppression in the suppression control.

[0105] 4, the rotation speed of the internal combustion engine 11 reaches the upper threshold value Th1 at time t1 and exceeds the upper threshold value Th1 immediately after time t1. The ECU 100 starts the suppression control at time t1, specifically, when a sampling period Ps has elapsed since time t1. In other words, the ECU 100 does not start suppressing the opening of the throttle valve 411 until the rotation speed of the internal combustion engine 11 reaches the upper threshold value Th1. Therefore, the ECU 100 can easily maintain the acceleration state of the motorcycle 1 until time t1 is reached, thereby preventing any adverse effects on the driver's driving experience.

[0106] The ECU 100 starts suppressing the output of the internal combustion engine 11 when time t1 is exceeded. After time t1, the period during which the rotation speed of the internal combustion engine 11 exceeds the upper threshold value Th1 is short, and therefore the amount of output suppression is small. Therefore, the rotation speed of the internal combustion engine 11 may continue to exceed the upper threshold value Th1 from time t1 onward. The rotation speed of the internal combustion engine 11 may also increase slightly after time t1. After time t1, the ECU 100 continues to add a positive count value at each sampling period Ps to calculate the degree of excess. The ECU 100 reduces the opening of the throttle valve 411 based on the calculated degree of excess. Therefore, even after time t1 has passed, the rotation speed of the internal combustion engine 11 continues to exceed the upper threshold value Th1, and the degree of excess gradually increases over time. The ECU 100 then gradually reduces the opening of the throttle valve 411 in response to the gradually increasing degree of excess.

[0107] Therefore, the rotation speed of the internal combustion engine 11 fluctuates in a range relatively close to the upper threshold value Th1, which prevents the fluctuation in the rotation speed of the internal combustion engine 11 before and after time t1 from adversely affecting the driving feeling of the driver.

[0108] As the ECU 100 continues to suppress the output by gradually increasing the output suppression amount, the rotation speed of the internal combustion engine 11 decreases over time, reaches the upper limit threshold Th1 at time t2, after time t1, and becomes less than the upper limit threshold Th1 immediately after time t2. After time t2, the rotation speed of the internal combustion engine 11 remains at or below the upper limit threshold Th1. Therefore, the ECU 100 continues to add a negative count value to the excess degree at each sampling period Ps, and the excess degree gradually decreases over time. After time t2, as the excess degree decreases, the ECU 100 gradually increases the opening of the throttle valve 411 while maintaining the output suppression state.

[0109] The excessive fluctuation rate after time t2 is significantly smaller than the excessive fluctuation rate between time t1 and time t2, and the fluctuation amount of the opening of the throttle valve 411 after time t2 is significantly smaller than the fluctuation amount of the opening of the throttle valve 411 between time t1 and time t2. Therefore, the rotation speed of the internal combustion engine 11 fluctuates near the upper limit threshold Th1 without abrupt fluctuations. This prevents the fluctuation in the rotation speed of the internal combustion engine 11 before and after time t2 from adversely affecting the driving feeling of the driver.

[0110] As time passes from time t2, the degree of excess decreases and the amount of output suppression becomes smaller, so the rotation speed of the internal combustion engine 11 increases and reaches the upper limit threshold Th1 again at time t3, and may exceed the upper limit threshold Th1 immediately after time t3. After time t3, the ECU 100 adds a positive count value to the degree of excess for each sampling period Ps, so the degree of excess begins to increase. After time t3, the rotation speed of the internal combustion engine 11 continues to exceed the upper limit threshold Th1, and the degree of excess gradually increases over time. Then, the ECU 100 gradually reduces the opening of the throttle valve 411 in response to the gradually increasing degree of excess.

[0111] The excessive fluctuation rate after time t3 is greater than the excessive fluctuation rate between time t2 and time t3, but is significantly smaller than the excessive fluctuation rate between time t1 and time t2. The fluctuation amount of the opening of the throttle valve 411 after time t3 is greater than the fluctuation amount of the opening of the throttle valve 411 between time t2 and time t3, but is significantly smaller than the fluctuation amount of the opening of the throttle valve 411 between time t1 and time t2. Therefore, the rotation speed of the internal combustion engine 11 fluctuates in a range relatively close to the upper limit threshold Th1. This prevents the fluctuation in the rotation speed of the internal combustion engine 11 around time t3 from adversely affecting the driving feeling of the driver.

[0112] As time passes from time t3, the degree of excess increases and the amount of output suppression becomes larger, so the rotation speed of the internal combustion engine 11 decreases and reaches the upper limit threshold Th1 again at time t4, and may become less than the upper limit threshold Th1 immediately after time t4. After time t4, the ECU 100 adds a negative count value to the degree of excess for each sampling period Ps, so the degree of excess begins to decrease. After time t4, the rotation speed of the internal combustion engine 11 remains at or below the upper limit threshold Th1, and the degree of excess decreases over time. Then, the ECU 100 gradually increases the opening of the throttle valve 411 in response to the gradually decreasing degree of excess.

[0113] The excessive fluctuation rate after time t4, like the excessive fluctuation rate between time t2 and time t3, is significantly smaller than the excessive fluctuation rate between time t1 and time t2. The excessive fluctuation rate after time t4, like the excessive fluctuation rate between time t2 and time t3, is significantly smaller than the excessive fluctuation rate between time t1 and time t2. After time t4, the rotation speed of the internal combustion engine 11 remains below the upper limit threshold Th1 and fluctuates near the upper limit threshold Th1 without any sudden fluctuations. This prevents fluctuations in the rotation speed of the internal combustion engine 11 before and after time t4 from adversely affecting the driver's driving feeling.

[0114] In this way, the ECU 100 reflects not only the difference between the rotation speed of the internal combustion engine 11 and the upper limit threshold Th1, but also the exceeding and non-exceeding periods of the rotation speed with respect to the upper limit threshold Th1 in the output suppression amount of the internal combustion engine 11, thereby preventing sudden fluctuations in the output suppression amount, making it easier to maintain the rotation speed of the internal combustion engine 11 close to the upper limit threshold Th1, and preventing the rotation speed from exceeding the limit threshold Th2.

[0115] Fig. 5 shows a second embodiment, which is an example of control of the rotation speed of the internal combustion engine 11 by the ECU 100 when the motorcycle 1 travels uphill. Fig. 5 shows the second embodiment drawn with a solid line and the first embodiment drawn with a dashed line.

[0116] As shown in Fig. 5, in this embodiment, the rotation speed of the internal combustion engine 11 reaches the upper threshold value Th1 at time t1 and exceeds the upper threshold value Th1 immediately after time t1. The ECU 100 starts the suppression control when a sampling period Ps has elapsed since time t1. As in the first embodiment, after time t1, the ECU 100 calculates the degree of excess by adding a positive count value every sampling period Ps. The ECU 100 gradually reduces the opening of the throttle valve 411 in response to the gradually increasing degree of excess.

[0117] On the other hand, when the internal combustion engine 11 is traveling uphill, gravity acting on the motorcycle 1 places a greater load on the engine 11 that inhibits rotation than when the internal combustion engine 11 is traveling on flat ground, and this load suppresses an increase in the engine speed. Therefore, after time t1, the amount by which the engine speed of the internal combustion engine 11 exceeds the upper limit threshold Th1 may be smaller than in the first embodiment. Therefore, the degree of exceedance may be smaller than in the first embodiment, and the amount of output suppression may also be smaller than in the first embodiment.

[0118] After time t1, the rotation speed of the internal combustion engine 11 fluctuates in a range relatively close to the upper limit threshold Th1 due to the above-described output suppression amount and the load during uphill driving. Therefore, the influence of the rotation speed fluctuation of the internal combustion engine 11 before and after time t1 on the driving feeling of the driver can be reduced.

[0119] The rotation speed of the internal combustion engine 11 decreases over time due to the output suppression and the load caused by uphill driving, reaches the upper limit threshold Th1 at time t12, and falls below the upper limit threshold Th1 immediately after time t12. The period from time t1 to time t12 is shorter than the period from time t1 to time t2 in the first embodiment. Furthermore, the excess value at time t12 is smaller than the excess value at time t2 in the first embodiment. Therefore, the ECU 100 reduces the rotation speed of the internal combustion engine 11 to the upper limit threshold Th1 by an output suppression amount that is smaller than that in the first embodiment.

[0120] After time t12, the ECU 100 calculates the degree of excess by adding a negative count value at each sampling period Ps. The ECU 100 gradually increases the opening of the throttle valve 411 in response to the gradually decreasing degree of excess. The rotation speed of the internal combustion engine 11 fluctuates near the upper limit threshold Th1 without any sudden fluctuations.

[0121] As time passes from time t12, the degree of excess decreases and the amount of output suppression becomes smaller, so the rotation speed of the internal combustion engine 11 increases and reaches the upper limit threshold Th1 again at time t13, exceeding the upper limit threshold Th1 immediately after time t13. After time t13, the ECU 100 calculates the degree of excess by adding a positive count value every sampling period Ps. The ECU 100 gradually reduces the opening of the throttle valve 411 in response to the gradually increasing degree of excess.

[0122] The excessive fluctuation rate after time t13 is similar to the excessive fluctuation rate between time t1 and time t12. The fluctuation rate of the opening of the throttle valve 411 after time t13 is similar to the fluctuation rate of the opening of the throttle valve 411 between time t1 and time t12. After time t13, the rotation speed of the internal combustion engine 11 fluctuates in a range relatively close to the upper limit threshold Th1.

[0123] The rotation speed of the internal combustion engine 11 decreases over time due to the output suppression and the load caused by uphill driving, reaches the upper limit threshold Th1 at time t14, and becomes less than the upper limit threshold Th1 immediately after time t14. The excess value at time t14 is smaller than the excess values ​​at times t2 and t4 in the first embodiment. Therefore, the ECU 100 reduces the rotation speed of the internal combustion engine 11 to the upper limit threshold Th1 by an output suppression amount that is smaller than that in the first embodiment. Therefore, the influence of fluctuations in the rotation speed of the internal combustion engine 11 around time t13 on the driving feeling of the driver can be reduced.

[0124] After time t14, the ECU 100 calculates the degree of excess by adding a negative count value at each sampling period Ps. The ECU 100 gradually increases the opening of the throttle valve 411 in response to the gradually decreasing degree of excess. The rotation speed of the internal combustion engine 11 remains equal to or less than the upper limit threshold Th1 and fluctuates in a range relatively close to the upper limit threshold Th1 without any sudden fluctuations.

[0125] Fig. 6 shows a third embodiment, which is an example of control of the rotation speed of the internal combustion engine 11 by the ECU 100 when the motorcycle 1 travels downhill. Fig. 6 shows the third embodiment drawn with a solid line and the first embodiment drawn with a dashed line.

[0126] As shown in Fig. 6, in this embodiment, the rotation speed of the internal combustion engine 11 reaches the upper limit threshold Th1 at time t1 and exceeds the upper limit threshold Th1 immediately after time t1. The ECU 100 starts the suppression control when a sampling period Ps has elapsed since time t1. As in the first embodiment, after time t1, the ECU 100 calculates the degree of excess by adding a positive count value every sampling period Ps. The ECU 100 gradually reduces the opening of the throttle valve 411 in response to the gradually increasing degree of excess.

[0127] On the other hand, when the internal combustion engine 11 is traveling downhill, gravity acting on the motorcycle 1 applies an assist force that promotes the rotation of the internal combustion engine 11. Therefore, after time t1, the amount by which the rotation speed of the internal combustion engine 11 exceeds the upper limit threshold Th1 may be greater than in the first embodiment. Therefore, the degree of exceedance may be greater than in the first embodiment, and the amount of output suppression may also be greater than in the first embodiment.

[0128] After time t1, the rotation speed of the internal combustion engine 11 fluctuates in a range relatively close to the upper limit threshold Th1 due to the above-described output suppression amount and assist force. Therefore, the influence of the rotation speed fluctuation of the internal combustion engine 11 before and after time t1 on the driving feeling of the driver can be reduced.

[0129] The rotation speed of the internal combustion engine 11 decreases over time due to the output suppression against the assist force when traveling downhill, reaches the upper limit threshold Th1 at time t22, and becomes less than the upper limit threshold Th1 immediately after time t22. The period from time t1 to time t22 is longer than the period from time t1 to time t2 in the first embodiment. Furthermore, the excess value at time t22 is greater than the excess value at time t2 in the first embodiment. Therefore, the ECU 100 reduces the rotation speed of the internal combustion engine 11 to the upper limit threshold Th1 by a larger output suppression amount than in the first embodiment.

[0130] After time t22, the ECU 100 calculates the degree of excess by adding a negative count value at each sampling period Ps. The ECU 100 gradually increases the opening of the throttle valve 411 in response to the gradually decreasing degree of excess. The rotation speed of the internal combustion engine 11 remains equal to or less than the upper limit threshold Th1 and fluctuates in a range relatively close to the upper limit threshold Th1 without any sudden fluctuations.

[0131] [others] Although exemplary embodiments and modifications of the present disclosure have been described above, the present disclosure is not limited to the above-described embodiments and modifications. In other words, various modifications and improvements are possible within the scope of the present disclosure. For example, various modifications made to the embodiments or modifications, and forms constructed by combining components of different embodiments and modifications, are also included within the scope of the present disclosure.

[0132] For example, in the embodiment, the ECU 100 suppresses the output of the internal combustion engine 11 using the degree of excess when the occurrence state of the excess event is the occurrence period of the excess event, but is not limited to this. For example, the occurrence state of the excess event related to the degree of excess may be the number of times the excess event has occurred or the frequency at which the excess event has occurred.

[0133] For example, if the occurrence state of an exceedance event is the number of occurrences of the exceedance event, the degree of exceedance may be related to the number of occurrences of the exceedance event. The exceedance event is an event in which the rotation speed of the internal combustion engine 11 exceeds the upper threshold value for a predetermined unit period. The value of the degree of exceedance increases as the value of the number of consecutive occurrences of the exceedance event increases.

[0134] For example, if the occurrence state of an exceedance event is the frequency of the exceedance event, the degree of exceedance may be related to the frequency of the exceedance event. The exceedance event is an event in which the rotational speed of the internal combustion engine 11 exceeds an upper threshold value for a predetermined unit period. As the number of occurrences of the exceedance event increases within a predetermined frequency calculation period, the value of the degree of exceedance increases.

[0135] In either case, the ECU 100 may determine whether the rotation speed of the internal combustion engine 11 exceeds the upper threshold at each predetermined period, and may increment a count value of the number of times of exceedance or the frequency of exceedance if the rotation speed of the internal combustion engine 11 exceeds the upper threshold. The number of times of exceedance is the number of times that the rotation speed of the internal combustion engine 11 exceeds the upper threshold over a unit period, and the frequency of exceedance is the number of times that the rotation speed of the internal combustion engine 11 exceeds the upper threshold over a unit period within a frequency calculation period. The ECU 100 may determine the degree of exceedance based on the count value. Alternatively, the ECU 100 may detect the number of times that the rotation speed of the internal combustion engine 11 exceeds the upper threshold over a predetermined period by scanning fluctuations in the rotation speed of the internal combustion engine 11 over the predetermined period. The ECU 100 may determine the number of times of exceedance or the frequency of exceedance based on the number of times detected over the predetermined period, and then determine the degree of exceedance based on the number of times of exceedance or the frequency of exceedance.

[0136] In the embodiment, the ECU 100 determines the degree of excess based on the total value obtained by counting up the count value for each sampling period, but this is not limited to this. For example, the ECU 100 may time-integrate the rotation speed or the rotation speed difference of the internal combustion engine 11 and determine the degree of excess based on the integration result. For example, the degree of excess may be the time integration result or a result obtained by adding a calculation process to the time integration result. Even when using such an excess, the ECU 100 can suppress the output while gently suppressing fluctuations in the internal combustion engine 11.

[0137] In the embodiment, the initial value of the excess is set to a different value corresponding to the multiple reduction ratios set in the transmission 25, but it may also be set to the same value for all of the multiple reduction ratios.

[0138] In the embodiment, the absolute value of the count value for determining the degree of excess is the same when the absolute value of the rotation speed difference, which is the difference obtained by subtracting the upper threshold value Th1 from the rotation speed of the internal combustion engine 11, is the same. However, the relationship between the rotation speed difference and the count value is not limited to the above relationship. For example, even if the absolute values ​​of the positive and negative rotation speed differences are the same, the absolute value of the count value may be different between the positive rotation speed difference and the negative rotation speed difference, or even if the absolute values ​​of the ranges of the positive and negative rotation speed differences are the same, the absolute value of the count value may be different between the ranges of the positive rotation speed difference and the ranges of the negative rotation speed difference.

[0139] In the embodiment, when the rotation speed difference is 0, the count value is a negative value, but it may also be 0. As a result, the degree of excess does not change when the rotation speed difference is 0, so that the ECU 100 can maintain the ratio of the output suppression amount to the target output of the internal combustion engine 11.

[0140] In the embodiment, the ECU 100 counts a negative count value as the excess degree, but this does not have to be the case. As a result, the excess degree does not change when the count value is a negative value, so the ECU 100 can maintain the ratio of the output suppression amount to the target output of the internal combustion engine 11.

[0141] In the embodiment, the count values ​​corresponding to the same range of the rotation speed difference differ depending on the reduction ratio set in the transmission 25, but this is not limiting. For example, the count values ​​corresponding to the same range of the rotation speed difference may be the same value regardless of the reduction ratio set in the transmission 25.

[0142] The ECU 100 according to the embodiment determines or corrects the maximum excess amount depending on the vehicle state of the motorcycle 1. Examples of such vehicle states include, but are not limited to, the reduction ratio set in the transmission 25, the vehicle speed of the motorcycle 1, the intake pressure of the internal combustion engine 11, the intake temperature of the internal combustion engine 11, and the attitude of the motorcycle 1.

[0143] For example, the vehicle state may include the amount of tilt of motorcycle 1 in the vertical direction. ECU 100 may use the amount of tilt in the vertical direction to determine or correct the maximum excess degree. In this case, ECU 100 may detect the amount of tilt of motorcycle 1 in the vertical direction using the detection results of inertial force sensor 401, the detection results of the front stroke sensor, the detection results of the rear stroke sensor, or two or more of these. For this reason, motorcycle 1 may include a front stroke sensor, a rear stroke sensor, or both. These stroke sensors output their detection results to ECU 100. The front stroke sensor detects the stroke amount due to the extension and contraction of front fork 104, which is the front suspension. The rear stroke sensor detects the stroke amount due to the extension and contraction of rear suspension 106.

[0144] The ECU 100 may determine or correct the maximum excess degree so that the maximum excess degree when the vertical lean amount is small is greater than the maximum excess degree when the vertical lean amount is large. For example, the ECU 100 may determine or correct the maximum excess degree so that the maximum excess degree becomes smaller as the vertical lean amount transitions from a small state to a large state. This allows the output suppression amount of the internal combustion engine 11 to become smaller and the target suppressed output to become larger as the vertical lean amount of the motorcycle 1 transitions from a large state to a small state, that is, as the vertical posture of the motorcycle 1 transitions to a stable state.

[0145] Alternatively, the ECU 100 may determine or correct the maximum excess degree by distinguishing the amount of tilt of the motorcycle 1 in the up-down direction between the amount of tilt in the forward tilt direction and the amount of tilt in the backward tilt direction. For example, the ECU 100 may determine or correct the maximum excess degree so that the maximum excess degree when the amount of tilt in the forward tilt direction is small is larger than the maximum excess degree when the amount of tilt in the forward tilt direction is large. For example, the ECU 100 may determine or correct the maximum excess degree so that the maximum excess degree becomes smaller as the amount of tilt in the forward tilt direction transitions from a small state to a large state. This may reduce the output suppression amount of the internal combustion engine 11 and increase the target suppressed output as the amount of tilt in the forward tilt direction of the motorcycle 1 transitions from a large state to a small state.

[0146] For example, the ECU 100 may determine or correct the maximum excess degree so that the maximum excess degree when the lean amount in the backward tilt direction is large is greater than the maximum excess degree when the lean amount in the backward tilt direction is small. For example, the ECU 100 may determine or correct the maximum excess degree so that the maximum excess degree becomes smaller as the lean amount in the backward tilt direction transitions from a large state to a small state. This may reduce the output suppression amount of the internal combustion engine 11 and increase the target suppressed output as the lean amount in the backward tilt direction of the motorcycle 1 transitions from a small state to a large state.

[0147] In the embodiment, the ECU 100 determines the output suppression amount of the internal combustion engine 11 based on the ratio of the excess amount to the maximum excess amount, but this is not limited to this. For example, the ECU 100 may store in the memory M a map that lists a graph in which the output suppression amount corresponding to the excess amount is determined based on the excess amount. The ECU 100 may store in the memory M a map that lists a graph in which the output suppression amount corresponding to the excess amount and the vehicle state of the motorcycle 1 is determined based on the excess amount and the vehicle state of the motorcycle 1. The ECU 100 may obtain the output suppression amount by inputting the excess amount, or the excess amount and the vehicle state of the motorcycle 1, into the map.

[0148] In the embodiment, the ECU 100 adjusts the output suppression amount of the internal combustion engine 11 according to the vehicle state of the motorcycle 1 by determining or correcting the maximum excess amount according to the vehicle state of the motorcycle 1. The method for adjusting the output suppression amount is not limited to the above. For example, the ECU 100 may determine or correct the count value used to determine the excess amount according to the vehicle state of the motorcycle 1. For example, the ECU 100 may determine or correct the count value so that the count value determined or corrected corresponding to a vehicle state that increases the maximum excess amount is smaller than the count value determined or corrected corresponding to a vehicle state that decreases the maximum excess amount. For example, the ECU 100 may determine or correct the count value so that the count value increases as the vehicle transitions from a vehicle state that increases the maximum excess amount to a vehicle state that decreases the maximum excess amount. The count value may be determined or corrected so that fluctuations in the count value in response to changes in the vehicle state behave inversely to fluctuations in the maximum excess amount in response to changes in the vehicle state.

[0149] In the embodiment, the ECU 100 is configured to determine a target torque of the internal combustion engine 11 and suppress the target torque in order to suppress the output of the internal combustion engine 11. Furthermore, the ECU 100 determines a target opening of the throttle valve 411 and a target fuel injection amount corresponding to the suppressed target torque. The method of suppressing the output of the internal combustion engine 11 is not limited to the above. For example, the ECU 100 may store in the memory M a map that lists graphs in which the opening of the throttle valve 411 and the fuel injection amount that achieve the output are determined based on the output and the rotation speed of the internal combustion engine 11. The ECU 100 may obtain the target opening of the throttle valve 411 and the target fuel injection amount by applying the target suppressed output of the internal combustion engine 11 and the rotation speed of the internal combustion engine 11 to the map. The ECU 100 may obtain the target ignition timing of the spark plug that achieves the target suppressed output by applying the target opening and the rotation speed of the internal combustion engine 11 to an ignition map.

[0150] In the embodiment, the ECU 100 stores stop conditions including, but not limited to, the first to sixth conditions in the memory M. The stop conditions may include one or more of the first to sixth conditions. The stop conditions may include one or more of the seventh to tenth conditions below in addition to one or more of the first to sixth conditions. The ECU 100 may be configured to stop the suppression algorithm or the suppression control when one or more of the conditions included in the stop conditions are satisfied.

[0151] The seventh condition is a condition that the detection result of the throttle position sensor 412 indicates a decrease in the opening of the throttle valve 411. The decrease in the opening of the throttle valve 411 that satisfies the seventh condition may be set to any amount. When the seventh condition is satisfied, the internal combustion engine 11 behaves in a manner that reduces the rotation speed, so it is preferable to stop the suppression control that is being executed, with an emphasis on the driver's driving feeling. The seventh condition is a load condition.

[0152] The eighth condition is a condition in which the detection result of one or more of the brake sensors 213 and 223 indicates the operation of one or more of the front brake 211 and the rear brake 221. When the eighth condition is satisfied, the rotation of the internal combustion engine 11 is forcibly suppressed by one or more of the front brake 211 and the rear brake 221, so that the suppression control being executed becomes unnecessary. The eighth condition is a rotation condition.

[0153] The ninth condition is that the rearward lean angle of motorcycle 1 is equal to or greater than a threshold value. ECU 100 may detect the rearward lean angle of motorcycle 1 based on one or more of the detection results of inertial force sensor 401, the detection results of a front stroke sensor provided in motorcycle 1, and the detection results of a rear stroke sensor. When motorcycle 1 is in a rearward lean position in which front wheel 21 is higher than rear wheel 22, there is a possibility that motorcycle 1 is traveling uphill. If suppression control is executed while traveling uphill, the rotation of internal combustion engine 11 may be suppressed more excessively than the driver expects. When the ninth condition is satisfied, the rotation of internal combustion engine 11 may be suppressed excessively, so it is preferable to stop the suppression control that is currently being executed, with an emphasis on the driver's driving feeling. The ninth condition is a rotation condition.

[0154] The tenth condition is that the temperature of the catalyst 322 is equal to or lower than a lower limit temperature. During suppression control, the air-fuel ratio of the amount of fuel and air supplied to the internal combustion engine 11 may fluctuate, causing the catalyst temperature to drop. If the catalyst temperature falls below the lower limit temperature, the catalyst 322 may not be able to perform a sufficient purification function. When the tenth condition is satisfied, the suppression control being executed is no longer necessary to raise the catalyst temperature.

[0155] The stop condition may include a condition that a value representing the state of motorcycle 1 detected based on the detection result of inertial force sensor 401 is equal to or greater than a threshold value. Examples of the value representing the state of motorcycle 1 may include the attitude angle and inertial force of motorcycle 1. For example, when a state such as the start of turning of motorcycle 1 or the shifting of the rider's weight to turn motorcycle 1 is detected, suppression of rotation of internal combustion engine 11 may cause the behavior of motorcycle 1 to become unstable, and therefore, the suppression control that is being executed may be stopped in order to prioritize the driver's driving feeling.

[0156] The suppression algorithm according to the embodiment may be combined with proportional-integral-differential (PID) control in a case where the internal combustion engine 11 is subjected to PID control. For example, when the rotation speed of the internal combustion engine 11 exceeds an upper threshold value Th1 and the ECU 100 starts suppression control, the ECU 100 may change the coefficient values ​​of the P term, I term, and D term in the PID control to coefficient values ​​that stabilize the response of the internal combustion engine 11 more than before the suppression control. The P term is a term corresponding to proportional control, and the coefficient of the P term is a proportional gain. The I term is a term corresponding to integral control, and the coefficient of the I term is an integral gain. The D term is a term corresponding to differential control, and the coefficient of the D term is a differential gain. The values ​​of the proportional gain, integral gain, and differential gain when suppression control is being executed and when suppression control is not being executed may be set in advance and stored in the memory M of the ECU 100. The ECU 100 may switch the values ​​of the proportional gain, integral gain, and differential gain depending on whether suppression control is being executed or not, and may further change them during suppression control. For example, the ECU 100 may be configured to increase or decrease the values ​​of the proportional gain, the integral gain, and the derivative gain according to the output suppression amount of the internal combustion engine 11.

[0157] In the embodiment, the motorcycle 1 is a saddle-ride type vehicle, but it may also be a scooter type vehicle having a footrest in front of the seat 107.

[0158] In the motorcycle 1 according to this embodiment, the clutch 24 is mechanically connected to the clutch lever 241, and is operated by the physical transmission of an operating force applied to the clutch lever 241. However, the structure for driving the clutch 24 is not limited to the above. For example, the motorcycle 1 may include a clutch actuator that controls the driving of the clutch 24. The clutch actuator is controlled by the ECU 100. The ECU 100 may cause the clutch actuator 243 to operate the clutch 24 to an engaged state or a disengaged state based on a detection signal from the clutch sensor 242.

[0159] In the embodiment, the vehicle 1 is a motorcycle, but is not limited to this. The ECU 100 and its functions, the control circuit 30 and its functions, and the control method according to the present disclosure can be applied to various vehicles 1 other than motorcycles. The vehicle 1 may be any vehicle equipped with a drive source 10. The vehicle 1 may have a structure for carrying one or more people. Examples of the vehicle 1 may include cars, ships, and various other forms of mobility.

[0160] Examples of vehicles may include motorcycles, mopeds, and automobiles. A vehicle may include three or more wheels. Examples of vehicles may include passenger cars, trucks, public transport vehicles, all-terrain vehicles, and utility vehicles. An all-terrain vehicle may be a vehicle capable of off-road driving. Examples of watercraft may include cargo ships, passenger ships, work boats, fishing boats, pleasure boats, and personal watercraft. A watercraft may include one or more propulsors.

[0161] In the embodiment, the vehicle 1 includes an internal combustion engine 11 as the driving source 10, but is not limited to this. For example, the driving source 10 may have a structure that generates rotational power to rotate a shaft. Examples of the driving source 10 include a heat engine that converts thermal energy into mechanical energy and a rotating electric machine that converts electrical energy into mechanical energy. The vehicle 1 may include one or more driving sources 10. For example, the multiple driving sources 10 may drive the same part of the vehicle 1, or may drive two or more different parts of the vehicle 1. For example, the multiple driving sources 10 may individually drive multiple wheels included in the drive structure 20. One driving source 10 of the two or more driving sources 10 may drive another driving source 10. For example, the driving source 10 as an internal combustion engine may transmit rotational power to the drive structure 20, the driving source 10 as a rotating electric machine, or both. The internal combustion engine may drive the rotating electric machine and generate electric energy in the rotating electric machine.

[0162] The internal combustion engine serving as the driving source 10 may have any known structure. The internal combustion engine operates by receiving a supply of fuel. The fuel used by the internal combustion engine may be any fuel, such as fuels containing hydrocarbon compounds such as gasoline, ethanol, propane gas, and methane, fuels derived from animals and plants such as biofuels, or non-carbon fuels such as hydrogen.

[0163] For example, the cylinder structure of the internal combustion engine may be either a single-cylinder or a multi-cylinder structure, and the internal combustion engine may be either a four-stroke engine or a two-stroke engine.

[0164] The structure of the rotating electric machine serving as the drive source 10 may be any existing structure. For example, the rotating electric machine may have an inner rotor structure in which the rotor is located inside the stator and includes a rotor that rotates integrally with the drive shaft, or an outer rotor structure in which the rotor is located outside the stator. The rotating electric machine may generate electric power by rotating the rotor when supplied with electric power and forcibly rotating the rotor via the drive shaft. The rotating electric machine may transmit the rotational driving force of the drive shaft to the drive wheels of the drive structure 20. The rotating electric machine may generate electric power by rotating the drive shaft by the drive structure 20, an internal combustion engine, or both that operate while the vehicle 1 is moving, and supply the electric power to a battery provided in the vehicle 1.

[0165] The vehicle 1 may be a vehicle including only an internal combustion engine 11 as the drive source 10, an EV vehicle having only a rotating electric machine as the drive source 10, or a hybrid vehicle having an internal combustion engine 11 and a rotating electric machine as the drive source 10.

[0166] Examples of various aspects of the technology of the present disclosure are listed below. In this specification and claims, the expressions "in the case of A" and "when A" include the meaning "in response to A being the case" and can be replaced with the expression "in response to A being the case."

[0167] A vehicle according to a first aspect of the present disclosure comprises a drive source, a rotation sensor that detects the rotation speed of the drive source, a control circuit that controls the drive source, and an actuator that operates the drive source in response to commands given by the control circuit, wherein when the rotation speed of the drive source exceeds a predetermined upper threshold, the control circuit executes suppression control to suppress the output of the drive source compared to before the rotation speed of the drive source exceeded the upper threshold, and in the suppression control, a command is given to the actuator to suppress the output of the drive source compared to before the suppression control in accordance with an exceedance degree set in relation to the exceedance period during which the rotation speed of the drive source exceeds the upper threshold.

[0168] According to the first aspect, when the control circuit determines that the rotation speed of the drive source has reached the upper threshold, it reduces the output of the drive source compared to before the suppression control in accordance with the degree of exceedance. The change over time of the period in which the upper threshold is exceeded is more gradual than the change over time of the deviation of the rotation speed from the upper threshold. This makes it possible to suppress output fluctuations of the drive source caused by output suppression. For example, compared to when the control circuit suppresses output in accordance with the deviation of the rotation speed from the upper threshold, the control circuit can suppress a so-called hunting state, in which output suppression control and non-output suppression control are repeated near the upper threshold.

[0169] In the first aspect above, in a vehicle according to a second aspect of the present disclosure, the control circuit may cancel the execution of the suppression control based on a period of time during which the rotation speed of the drive source is below the upper threshold.

[0170] According to the second aspect, the control circuit cancels the suppression control state when the rotation speed of the drive source continues to be below the upper threshold, thereby preventing the suppression control state from continuing undesirably and preventing a deterioration in the driving feel of the vehicle.

[0171] In the first or second aspect described above, in a vehicle according to a third aspect of the present disclosure, the control circuit may, in the suppression control, increase the amount of output suppression of the drive source as the exceeding period increases, and decrease the amount of output suppression of the drive source as the period during which the rotation speed of the drive source is below the upper threshold increases.

[0172] According to the third aspect, the output suppression amount of the drive source in the suppression control is set based on the exceeding period and the under-period, which makes it possible to set the output suppression amount according to the time history of the state in which the rotation speed exceeds the upper threshold, and to prevent a sudden change in the operation of the drive source due to the output suppression while preventing the exceeding state in which the rotation speed exceeds the upper threshold from continuing.

[0173] In any of the first to third aspects above, in a vehicle according to a fourth aspect of the present disclosure, the control circuit may, in the suppression control, reduce the amount of output suppression of the drive source as the rotation speed of the drive source decreases.

[0174] According to the fourth aspect described above, even during suppression control, the control circuit can reduce the amount of suppression of the output of the drive source when the rotation speed of the drive source is low and the possibility of reaching the upper threshold is low, thereby preventing a deterioration in the driving feel of the vehicle.

[0175] In any of the first to fourth aspects above, in a vehicle according to a fifth aspect of the present disclosure, the control circuit may, in the suppression control, reduce the amount of output suppression of the drive source as the reduction ratio selected in the transmission of the vehicle becomes smaller.

[0176] According to the fifth aspect described above, even during suppression control, if the reduction ratio selected in the transmission is small and the rotation speed of the drive source is unlikely to reach the upper threshold, the control circuit can reduce the amount of output suppression of the drive source, thereby preventing a deterioration in the driving feel of the vehicle.

[0177] In any of the first to fifth aspects above, in a vehicle according to a sixth aspect of the present disclosure, the control circuit may, in the suppression control, reduce the amount of output suppression of the drive source as the rotation speed of the drive source decreases, and may reduce the amount of output suppression of the drive source as the reduction ratio selected in the transmission provided in the vehicle decreases.

[0178] According to the sixth aspect, even during suppression control, the control circuit can reduce the amount of suppression of the output of the drive source when the rotation speed of the drive source is low and unlikely to reach the upper threshold, and can also reduce the amount of suppression of the output of the drive source when the reduction ratio selected in the transmission is low and unlikely to reach the upper threshold. Thus, the control circuit can prevent a deterioration in the driving feel of the vehicle during suppression control.

[0179] In any of the above first to sixth aspects, in a vehicle according to a seventh aspect of the present disclosure, the control circuit may cancel the execution of the suppression control when it determines that a state other than the state of the rotation speed of the drive source satisfies a predetermined condition during the suppression control.

[0180] According to the seventh aspect described above, by setting the release condition separately from the state of the rotation speed of the drive source, the control circuit can prevent the output suppression state from continuing undesirably, and can prevent a deterioration in the driving feel of the vehicle.

[0181] In the seventh aspect above, in a vehicle according to an eighth aspect of the present disclosure, the control circuit may release the suppression control when it determines that the reduction ratio selected in the transmission provided in the vehicle has been changed during the suppression control.

[0182] According to the eighth aspect, the control circuit can cancel the suppression control when it determines that the reduction ratio has been changed, thereby canceling the output suppression after the reduction ratio has been changed. This prevents the output suppression state from being undesirably continued, and prevents a deterioration in the driving feel of the vehicle.

[0183] In any of the above first to eighth aspects, in a vehicle according to a ninth aspect of the present disclosure, the actuator includes a throttle actuator that drives a throttle valve that adjusts the flow rate of air flowing into the driving source, and the control circuit sets a target throttle opening of the throttle valve based on a torque command required of the driving source in response to a command for operation of the driving source input by a driver of the vehicle, and the suppression control may correct the target throttle opening to be smaller in accordance with an output suppression amount of the driving source.

[0184] According to the ninth aspect, the control circuit can suppress deterioration of the power feel of the drive source experienced by the driver, compared to when the output of the drive source is suppressed by cutting ignition or controlling fuel injection for the drive source.

[0185] In any of the above first to ninth aspects, in a vehicle according to a tenth aspect of the present disclosure, the control circuit may, in the suppression control, determine the excess degree so that it increases as the reduction ratio selected in the transmission equipped in the vehicle increases, and may determine the output suppression amount of the drive source so that it increases as the excess degree increases.

[0186] According to the tenth aspect, the control circuit increases the degree of excess when a high low-speed reduction ratio is selected compared to when a low high-speed reduction ratio is selected. Furthermore, when a low-speed reduction ratio is selected, output fluctuations of the internal combustion engine can have a greater impact on the vehicle, such as vibrations, than when a high-speed reduction ratio is selected. When a low-speed reduction ratio is selected, the control circuit suppresses the output of the internal combustion engine by a larger output suppression amount than when a high-speed reduction ratio is selected, thereby effectively suppressing output fluctuations of the internal combustion engine.

[0187] In any of the above first to tenth aspects, in a vehicle according to an eleventh aspect of the present disclosure, the control circuit may release the suppression control when it determines that the rotation speed of the internal combustion engine has fallen below a predetermined lower threshold value that is lower than the upper threshold value.

[0188] According to the eleventh aspect, the control circuit cancels the suppression control when the rotation speed of the internal combustion engine falls to or below a lower threshold that is lower than the upper threshold. Therefore, since neither the start nor the end of the suppression control is based on the upper threshold, it is possible to suppress output fluctuations of the internal combustion engine near the upper threshold.

[0189] In any of the above first to eleventh aspects, in a vehicle according to a twelfth aspect of the present disclosure, the control circuit may acquire temperature information of a catalyst provided in the vehicle in an exhaust path for exhaust gas emitted from the internal combustion engine, and release the suppression control when it determines that the temperature of the catalyst has dropped below a first temperature.

[0190] According to the twelfth aspect, when the temperature of the catalyst drops below the first temperature, the catalyst may not be able to fully demonstrate its purification ability. In such a case, the control circuit can prevent the catalyst from decreasing in purification ability by terminating the suppression control.

[0191] In any of the above first to twelfth aspects, in a vehicle according to a thirteenth aspect of the present disclosure, the control circuit may suppress the output of the internal combustion engine from the target output with a suppression degree corresponding to the ratio of the excess degree to a maximum excess degree, which is a maximum value set for the excess degree.

[0192] According to the thirteenth aspect, the control circuit increases the amount of output suppression as the degree of excess increases. For example, when the degree of excess is the maximum degree of excess, the control circuit may set the output of the internal combustion engine to zero. This more effectively prevents damage to the internal combustion engine due to over-revving.

[0193] In the above-mentioned 13th aspect, in a vehicle according to a 14th aspect of the present disclosure, a plurality of maximum excess degrees are set for the excess degree, and the plurality of maximum excess degrees correspond to a plurality of reduction ratios set in a transmission equipped in the vehicle, and are set to become larger as the reduction ratio becomes smaller, and the control circuit may acquire detection results from a gear position sensor that detects the reduction ratio selected in the transmission, and determine the output suppression amount using the maximum excess degree corresponding to the reduction ratio selected in the transmission.

[0194] According to the above fourteenth aspect, the reduction ratio selected by the transmission is related to the load on the internal combustion engine. The output suppression amount can be higher when the reduction ratio is on the low speed side, i.e., when the load is low, than when the load is high. The control circuit suppresses the output of the internal combustion engine by a larger output suppression amount when the load is low than when the load is high, thereby effectively suppressing output fluctuations of the internal combustion engine.

[0195] In the above 13th or 14th aspect, in a vehicle according to a 15th aspect of the present disclosure, a plurality of maximum excess degrees are set for the excess degree, and the plurality of maximum excess degrees are set to change in response to factors related to the load received by the internal combustion engine, including one or more of the attitude of the vehicle, the speed of the vehicle, the intake temperature of the internal combustion engine, and the intake pressure of the internal combustion engine, and the control circuit may acquire information related to the load received by the internal combustion engine, including one or more of information on the attitude of the vehicle, information on the speed of the vehicle, information on the intake temperature of the internal combustion engine, and information on the intake pressure of the internal combustion engine, and determine the amount of output suppression using the maximum excess degree corresponding to the acquired information.

[0196] According to the fifteenth aspect, the plurality of maximum excess degrees are set in accordance with the load on the internal combustion engine. The control circuit suppresses the output of the internal combustion engine by an output suppression amount corresponding to the load on the internal combustion engine. Therefore, output fluctuations of the internal combustion engine can be effectively suppressed.

[0197] A control method according to a sixteenth aspect of the present disclosure is a method for controlling the rotation speed of a driving source of a vehicle, and includes acquiring information on the rotation speed of the driving source, determining whether the rotation speed of the driving source exceeds a predetermined upper threshold, and, if it is determined that the rotation speed of the driving source exceeds the upper threshold, executing suppression control to suppress the output of the driving source compared to before the rotation speed of the driving source exceeded the upper threshold, wherein the suppression control increases the amount of suppression of the output of the driving source the longer the period during which the rotation speed of the driving source exceeds the upper threshold after it exceeds the upper threshold.

[0198] According to the sixteenth aspect, before the upper threshold is exceeded, the amount of suppression of the output of the drive source is small or not suppressed compared to after the upper threshold is exceeded, and the intention of the driver of the vehicle can be reflected in the operation of the drive source, which makes it easy to improve the driving feeling. After the upper threshold is exceeded, by setting the amount of output suppression based on the exceeding period, it is possible to reduce the occurrence of hunting by the drive source compared to when the output of the drive source is suppressed based on the deviation of the rotation speed from the upper threshold.

[0199] A processing circuit according to a seventeenth aspect of the present disclosure includes a processor and a memory, wherein the memory stores information on a predetermined upper threshold for the rotation speed of a vehicle's driving source, and the processor acquires information on the rotation speed of the driving source, determines whether the rotation speed of the driving source exceeds the upper threshold, and, if it is determined that the rotation speed of the driving source exceeds the upper threshold, executes suppression control to suppress the output of the driving source compared to before the rotation speed of the driving source exceeded the upper threshold, wherein, in the suppression control, the processor determines a degree of exceedance related to the time during which the rotation speed of the driving source exceeds the upper threshold, and outputs a command to suppress the output of the driving source according to the determined degree of exceedance compared to before the suppression control.

[0200] According to the seventeenth aspect, the processing circuit can achieve the same effects as the vehicle according to each aspect of the present disclosure.

[0201] The present disclosure may also be a computer program that causes a computer to execute the control method or processing circuit according to each aspect of the present disclosure. For example, a computer program according to an eighteenth aspect of the present disclosure causes a computer to acquire information on the rotation speed of a driving source of a vehicle, determine whether the rotation speed of the driving source exceeds a predetermined upper threshold, and, if it is determined that the rotation speed of the driving source exceeds the upper threshold, execute suppression control to suppress the output of the driving source compared to before the rotation speed of the driving source exceeded the upper threshold. In the suppression control, the computer determines an excess degree related to an excess time during which the rotation speed of the driving source exceeds the upper threshold, and outputs a command to suppress the output of the driving source according to the determined excess degree compared to before the suppression control.

[0202] Such a computer program can achieve the same effects as the vehicle, control method, or processing circuit according to each aspect of the present disclosure. The computer program may be, for example, a program recorded on a non-transitory, tangible computer-readable recording medium, and may be configured to be read from the recording medium using a recording medium drive device and installed on a computer. The computer program may be, for example, a program that can be distributed via a transmission medium such as the Internet, and may be configured to be downloaded and installed on a computer.

[0203] The functions of the elements disclosed herein can be performed using circuits or processing circuitry, including general-purpose processors, special-purpose processors, integrated circuits, ASICs, conventional circuits, and / or combinations thereof, configured or programmed to perform the disclosed functions. A processor is considered a processing circuit or circuitry because it includes transistors and other circuitry. In this disclosure, a circuit, unit, or means is hardware that performs the recited functions or hardware that is programmed to perform the recited functions. The hardware may be hardware disclosed herein or other known hardware that is programmed or configured to perform the recited functions. Where the hardware is a processor, which is considered a type of circuit, the circuit, means, or unit is a combination of hardware and software, and the software is used to configure the hardware and / or processor.

[0204] All numbers such as ordinal numbers and quantities used in this specification are provided as examples to specifically explain the technology of the present disclosure, and the present disclosure is not limited to the illustrated numbers. The connection relationships between components are provided as examples to specifically explain the technology of the present disclosure, and the connection relationships that realize the functions of the present disclosure are not limited to these.

[0205] Because the present disclosure may be embodied in various forms without departing from the scope of its essential characteristics, the scope of the present disclosure is defined by the appended claims rather than the description in the specification, and therefore the exemplary embodiments and modifications are intended to be illustrative and not limiting. All modifications that are within the scope of the claims, or equivalents thereof, are intended to be embraced by the claims. [Explanation of symbols]

[0206] 1 Vehicles, motorcycles 10. Drive source 25 gearbox 30 Control circuit 40 Actuator 41 Throttle actuator 411 Throttle valve 261 Rotation Sensor

Claims

1. A driving source; a rotation sensor for detecting the number of rotations of the drive source; a control circuit for controlling the drive source; an actuator that operates the drive source in response to a command given from the control circuit, The control circuit When the rotation speed of the driving source exceeds a predetermined upper threshold, suppression control is executed to suppress the output of the driving source compared to before the rotation speed of the driving source exceeded the upper threshold; In the suppression control, a command is given to the actuator to suppress the output of the drive source compared to before the suppression control, in accordance with an excess degree set in relation to an excess period during which the rotation speed of the drive source exceeds the upper limit threshold. vehicle.

2. the control circuit cancels the execution of the suppression control based on a period of time during which the rotation speed of the drive source is below the upper limit threshold.

10. The vehicle of claim 1.

3. the control circuit, in the suppression control, increases the output suppression amount of the drive source as the exceeding period increases, and decreases the output suppression amount of the drive source as the under-period during which the rotation speed of the drive source is below the upper limit threshold increases.

3. A vehicle according to claim 1 or 2.

4. the control circuit, in the suppression control, reduces the amount of output suppression of the drive source as the rotation speed of the drive source decreases; 3. A vehicle according to claim 1 or 2.

5. the control circuit, in the suppression control, reduces the amount of suppression of the output of the drive source as the reduction ratio selected in the transmission of the vehicle decreases; 3. A vehicle according to claim 1 or 2.

6. In the suppression control, the control circuit reduces the output suppression amount of the drive source as the rotation speed of the drive source decreases, and reduces the output suppression amount of the drive source as the reduction ratio selected in the transmission provided in the vehicle decreases.

3. A vehicle according to claim 1 or 2.

7. When the control circuit determines that a state different from the state of the rotation speed of the drive source satisfies a predetermined condition during the suppression control, the control circuit cancels the execution of the suppression control.

3. A vehicle according to claim 1 or 2.

8. When the control circuit determines that a reduction ratio selected in a transmission provided in the vehicle has been changed during the suppression control, the control circuit cancels the suppression control.

8. The vehicle of claim 7.

9. the actuator includes a throttle actuator that drives a throttle valve that adjusts the flow rate of air flowing into the drive source, The control circuit setting a target throttle opening of the throttle valve based on a torque command required of the drive source in accordance with a command for operation of the drive source input by a driver of the vehicle; In the suppression control, the target throttle opening is corrected so as to become smaller in accordance with the output suppression amount of the drive source.

3. A vehicle according to claim 1 or 2.

10. A method for controlling the rotation speed of a drive source of a vehicle, comprising: acquiring information about the rotation speed of the drive source; determining whether or not a rotation speed of the drive source exceeds a predetermined upper threshold; when it is determined that the rotation speed of the driving source will exceed the upper limit threshold, executing suppression control to suppress the output of the driving source compared to before the rotation speed of the driving source exceeded the upper limit threshold, In the suppression control, the amount of suppression of the output of the drive source is increased as the period during which the rotation speed of the drive source exceeds the upper limit threshold becomes longer after the rotation speed of the drive source exceeds the upper limit threshold. Control Method

11. In the suppression control, it is determined whether a reduction ratio selected in a transmission provided in the vehicle has been changed; resetting the excess period used to determine the output suppression amount of the drive source when it is determined that the reduction ratio selected in the transmission has been changed; The control method according to claim 10

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