DRIVE MACHINE, VEHICLE AND METHOD FOR CONTROLLING A DRIVE MACHINE

Abstract

A drive machine (10) with: a prime mover main body (11) having a plurality of cylinders, a plurality of throttle valves arranged on intake sides of the plurality of cylinders, and a controller (80) configured to control the opening and closing operation of the plurality of throttle valves, wherein an output of a portion of the plurality of cylinders is greater than an output of the remaining portion of the plurality of cylinders, wherein the controller (80) opens a portion of the throttle valves upstream of the portion of the plurality of cylinders at a lower speed than the remaining portion of the throttle valves upstream of the remaining portion of the plurality of cylinders, wherein the controller (80) estimates the output of the plurality of cylinders and determines whether an output deviation of the plurality of cylinders is within a predetermined range, wherein the controller (80) opens the portion of the throttle valves at a lower speed than the remaining portion of the throttle valves until the output deviation of the plurality of cylinders is within the predetermined range, and wherein, after the output deviation of the plurality of cylinders has come into the predetermined range, the controller (80) opens the part of the throttle valves at a higher speed than the remaining part of the throttle valves until the opening degree of the part of the throttle valves agrees with the opening degree of the remaining part of the throttle valves.

Description

Technical area

[0001] The present invention relates to a drive machine, a vehicle and a method for controlling a drive machine. Technical background

[0002] As an engine mounted on a straddle-seat type vehicle or the like, a separate exhaust-port engine, such as a V-engine, an opposed-cylinder engine, or the like, is known (see, for example, Patent Literature 1). In this engine, a pair of front and rear cylinders are inclined in opposite directions, and a throttle valve is provided for each cylinder. Each throttle valve is attached to an intake pipe and opens and closes in response to the operation of a throttle handle to adjust an intake amount of air supplied from the intake pipe to each cylinder. The output of the engine is controlled by changing a combustion efficiency of each cylinder according to the intake amount of each cylinder.

[0003] Patent Literature 2 discloses a vehicle comprising: an engine having a plurality of combustion chambers; a plurality of throttle valves provided in the plurality of combustion chambers corresponding to the plurality of combustion chambers for independently adjusting the flow rates of intake air flowing into the combustion chambers; two or more drive mechanisms for electrically driving the plurality of throttle valves divided into two or more groups in such a manner that each of the drive mechanisms drives the throttle valve in a corresponding group of the groups;and a throttle control device for controlling the drive mechanisms based on a set of throttle operation information input by a driver and a predetermined vehicle condition, wherein the throttle control device provides throttle opening rate commands that differ between the groups to the respective drive mechanisms when a predetermined initial setting condition is met.;

[0004] Patent Literature 3 discloses that an internal combustion engine with cylinders that can selectively rest during engine operation is capable of eliminating gradual increases in engine power when the number of operating cylinders is changed. The internal combustion engine includes a plurality of cylinders divided into two or more groups, with at least some of the cylinders at rest. A throttle valve of each of the cylinders is independently operable based on the group to which the cylinder belongs, and the number of resting cylinders is controlled according to the throttle opening. The throttle opening is different between the groups, except for the fully open state and the fully closed state of the throttle valve. An ECU is provided to open the throttle valve of the next cylinder group before the throttle valve opening of the previous cylinder group reaches the fully open state.

[0005] Patent Literature 4 discloses a multi-cylinder engine having at least a first cylinder group and a second cylinder group. The first cylinder group is connected to a first intake manifold having a first carburetor with a first throttle valve. The second cylinder group is connected to a second intake manifold having a second carburetor with a second throttle valve. A throttle controller is provided to control the opening degrees of the first and second throttle valves in response to the amount of depression of an accelerator pedal, such that the opening degree of the first throttle valve is larger than that of the second throttle valve when the engine is operated under partial load, and the first and second throttle valves are fully open when the engine is operated under high load.

[0006] Patent Literature 5 discloses a multi-throttle valve device comprising a plurality of throttle valves each arranged at each air intake port corresponding to each cylinder of an engine, a plurality of throttle shafts for supporting the plurality of throttle valves for each group, and a plurality of drive members for driving the throttle shafts, respectively. With this structure, the on-off control of one group of throttle valves and the other group of throttle valves can be performed separately.

[0007] Patent Literature 6 discloses a throttle control method for controlling the opening degree of a throttle valve in a multi-cylinder engine including a throttle valve in intake passages provided for each cylinder. The opening degree can be controlled independently for each of the throttle valves. Control of the opening degree of the throttle valve is based on differences between intake air amounts in the respective intake passages.

[0008] Patent Literature 7 discloses that a control device includes an intake air flow controller for individually supplying intake air flow to a plurality of cylinders of the internal combustion engine, a fuel injection valve for individually supplying fuel to each cylinder of the engine, and a controller. In the controller, the required engine torque is calculated for each cylinder, for example, from accelerator pedal position signals. In response to the required torque, an intake air flow for each cylinder and a fuel injection amount corresponding to the intake air flow are separately calculated to operate the intake air flow controller and the fuel injection valve. When the required engine torque increases / decreases, the controller increases / decreases the intake air flow stepwise in the order of the intake strokes in response to the increase / decrease in the required engine torque. Citation listPatent literature Patent literature 1: JP 2010 – 59 942 A Patent literature 2: US 2016 / 0 160 763 A1 Patent literature 3: US 2006 / 0 048 746 A1 Patent Literature 4: US 4,037,571 A Patent literature 5: US 2005 / 0 155 571 A1 Patent literature 6: DE 10 2019 003 691 A1 Patent literature 7: JP 2005 – 16 392 A Summary of the inventionTechnical problem

[0009] In the engine described above, the combustion state of each cylinder may change at the beginning of throttle valve opening, and the output may vary between multiple cylinders. As the output deviation between multiple cylinders increases, throttle shock occurs, indicating excessive acceleration response. To prevent throttle shock, the throttle valve can be prevented from suddenly opening. However, the acceleration sensation may become unnatural.

[0010] The present invention has been made in view of the circumstances described above, and an object of this invention is to provide an engine, a vehicle, and a method for controlling an engine that can achieve vehicle control suitable for fluctuations in the output generated in a plurality of cylinders. Solution to the problem

[0011] The present invention provides a prime mover according to independent claim 1, a vehicle according to independent claim 7, and a method according to independent claim 8. Advantageous modifications can be found in dependent claims 2 to 6 and 9. Advantageous effects of the invention

[0012] In this engine, according to one aspect of the present invention, the portion of the throttle valves upstream of the large-output portion of the cylinders is opened at a lower speed than the remaining portion of the throttle valves upstream of the remaining cylinders. Therefore, the output deviation of the plurality of cylinders decreases, and throttle shock, which indicates excessive acceleration response at the time of throttle opening, is prevented. The portion of the throttle valves is opened at a low speed, so that a reduction in the acceleration feeling can be prevented and vehicle operation can be improved. Brief description of the drawings Fig. 1 is a perspective view of a prime mover according to the present embodiment. Fig. 2 is a side view of the prime mover according to the present embodiment. Fig. 3 is a bottom view of the prime mover according to the present embodiment. Fig. Figure 4 is a schematic representation of a torque fluctuation of a conventional V-twin engine. Fig. 5 is a schematic diagram of the prime mover according to the present embodiment. Fig. 6 is a perspective view of an exhaust device according to the present embodiment. Fig. 7 is a block diagram of a control of the prime mover according to the present embodiment. Fig. 8 is a map showing map data for determining a throttle shock according to the present embodiment. Fig. 9 is a diagram showing a timing chart when an accelerator is operated in a comparative example. Fig. 10 is a diagram showing a timing chart when an accelerator is operated according to the present embodiment. Fig. 11 is a flowchart of a valve control according to the present embodiment. Description of the embodiments

[0013] In an engine according to one aspect of the present invention, the intake amounts of cylinders are respectively adjusted by a plurality of throttle valves on intake sides of a plurality of cylinders. An output of a portion of the plurality of cylinders is larger than an output of the remaining portion of the plurality of cylinders, and the output varies among the plurality of cylinders. At the beginning of opening of the throttle valves, a portion of the throttle valves upstream of the large output portion of the plurality of cylinders are opened at a slower speed than the remaining portion of the throttle valves upstream of the remaining portion of the plurality of cylinders. Accordingly, the output deviation of the plurality of throttle valves decreases, and throttle shock indicating excessive acceleration response at the time of throttle opening is prevented.The throttle valve part is opened at low speed so that a reduction in the acceleration sensation can be prevented and the operation of the vehicle can be improved. [Embodiment]

[0014] Hereinafter, an embodiment will be described in detail with reference to the accompanying drawings. Here, an example in which a prime mover according to the present embodiment is applied to a motorcycle, which is a straddle-seat type vehicle, will be described. However, an application subject is not limited to this. For example, the prime mover can be applied to other straddle-seat type vehicles, such as an automatic buggy-type three-wheeled vehicle and the like. In the following drawings, a front of the vehicle is indicated by an arrow FR, a rear of the vehicle by an arrow RE, a left side of the vehicle by an arrow L, and a right side of the vehicle by an arrow R. Fig. 1 is a perspective view of the prime mover according to the present embodiment. Fig. 2 is a side view of the prime mover according to the present embodiment. Fig. 3 is a bottom view of the prime mover according to the present embodiment.

[0015] As in Fig. 1 to 3, the engine 10 is a V-type engine in which explosion or combustion occurs at uneven intervals, and includes an engine main body 11 in which a front cylinder 13 and a rear cylinder 14 are arranged in a V-shape on a crankcase 12. The front cylinder 13 is inclined toward the front of the vehicle and is formed by attaching a cylinder head 22 and a head cover 23 to a cylinder block 21 projecting from the crankcase 12. Similarly, the rear cylinder 14 is inclined toward the rear of the vehicle and is formed by attaching a cylinder head 26 and a head cover 27 to a cylinder block 25 projecting from the crankcase 12.

[0016] An inlet opening 31 (see Fig. 5) is opened in a rear surface of the front cylinder 13, and a front intake pipe 32 is connected to the intake port 31. An intake port 41 (see Fig. 5) is opened in a front surface of the rear cylinder 14, and a rear intake pipe 42 is connected to the intake port 41. The front and rear intake pipes 32, 42 extend upward from the front and rear cylinders 13, 14, respectively, and are connected to a lower part of an air cleaner 15 configured to filter the outside air. A front throttle body 33 for the front cylinder 13 is provided at an intermediate part of the front intake pipe 32, and a rear throttle body 43 for the rear cylinder 14 is provided at an intermediate part of the rear intake pipe 42.

[0017] The front throttle body 33 is provided with a front throttle valve 34 (see Fig. 5) configured to adjust an intake amount of the front cylinder 13, and the rear throttle body 43 is provided with a rear throttle valve 44 configured to adjust an intake amount of the rear cylinder 14 (see Fig. 5). The front and rear throttle bodies 33, 43 are electronic throttle bodies and include the motors 35, 45 (see Fig. 5), which are configured to drive the front and rear throttle valves 34, 44 to open and close. The front and rear throttle bodies 33, 43 individually include the motors 35, 45, making it possible to individually control the front and rear throttle valves 34, 44 to adjust the intake quantities for the respective cylinders.

[0018] An outlet opening 37 (see Fig. 5) is opened in a front surface of the front cylinder 13, and a front exhaust pipe 38 is connected to the exhaust port 37. An exhaust port 47 (see Fig. 5) is opened in a rear surface of the rear cylinder 14, and a rear exhaust pipe 48 is connected to the exhaust port 47. The front and rear exhaust pipes 38, 48 extend downward from the front and rear cylinders 13, 14, respectively, and are connected to a catalyst device 16 configured to purify air pollutants in the exhaust gas. The catalyst device 16 is located at a rear part of the vehicle, below the prime mover 10, and closer to the rear of the vehicle than a center point C of a crankshaft in the crankcase 12.

[0019] The rear exhaust pipe 48 is connected to the catalyst device 16 below the engine 10 via a path that is more complicated than that of the front exhaust pipe 38. Therefore, the pipe lengths from the outlets of the exhaust ports 37, 47 to the inlets of the catalyst device 16 are different between the front exhaust pipe 38 and the rear exhaust pipe 48, and the pipe length of the front exhaust pipe 38 connecting to the front cylinder 13 is shorter than the pipe length of the rear exhaust pipe 48 connecting to the rear cylinder 14. The pipe shapes of the front and rear exhaust pipes 38, 48 will be described in detail below. The front and rear exhaust pipes 38, 48 are connected to the catalyst device 16 via a collector pipe 17, and a muffler (an exhaust silencer) 18 configured to attenuate exhaust noise is provided downstream of the catalyst device 16.

[0020] In the engine 10 configured as above, air flows from the air cleaner 15 to the front cylinder 13 and the rear cylinder 14 via the front and rear intake pipes 32, 42. The front and rear throttle valves 34, 44 adjust the intake amounts into the front and rear cylinders 13, 14, and a fuel supply device (not shown) mixes a fuel with the air and introduces an air-fuel mixture into the cylinders 13, 14. The exhaust gas after combustion flows through the front and rear exhaust pipes 38, 48 from the cylinders 13, 14 into the catalyst device 16 and is discharged from the muffler 18 after the air pollutants are purified by the catalyst device 16.

[0021] A typical motorcycle engine is a high-speed, high-performance machine. The throttle bore diameter of a cylinder is large for the amount of exhaust gas, and throttle shock is likely to occur when the throttle valve begins to open from a fully closed state. In an engine in which explosion or combustion occurs at unequal intervals, the combustion states of the respective cylinders are different when the throttle valves begin to open from a fully closed state, and the output varies between the cylinders. Especially when the exhaust pipes of the cylinders are unequal in length, as in a V-type engine, the output deviation between the cylinders becomes large, and throttle shock is more likely to occur.

[0022] As in Fig. For example, as shown in Figure 4, at a crank angle of 0 degrees, the ignition signal Fr is input to the front cylinder, and the engine torque increases rapidly, and at a crank angle of 270 degrees, the ignition signal Re is input to the rear cylinder, and the engine torque increases rapidly. In this case, due to a V-type engine layout and unequal lengths of the cylinder exhaust pipes, output variation occurs between the front and rear cylinders. The engine torque of the front cylinder fluctuates more than the engine torque of the rear cylinder. As described above, in the V-type engine whose exhaust pipes are unequal lengths, the output variation becomes large, and throttle shock is more likely to occur.

[0023] The engine 10 according to the present embodiment is a V-type engine in which the front exhaust pipe 38 is shorter than the rear exhaust pipe 48. In this case, the output of the front cylinder 13 becomes larger than the output of the rear cylinder 14, and throttle shock may occur in the engine 10 due to the output deviation between the front and rear cylinders 13, 14. Therefore, in the present embodiment, which focuses on the fact that the output of the front cylinder 13 is higher than that of the rear cylinder 14, throttle shock is prevented by opening the front throttle valve 34 at a lower speed than the rear throttle valve 44 when the throttle valve starts to open.

[0024] The following describes a detailed configuration of the prime mover of the present embodiment based on the Fig. 5 and Fig. 6 described. Fig. 5 is a schematic diagram of the prime mover according to the present embodiment. Fig. 6 is a perspective view of the exhaust device according to the present embodiment.

[0025] As in Fig. As shown in Fig. 5, an intake valve 61 is provided on the intake side of the front cylinder 13, which is configured to open and close the intake port 31 to introduce the air-fuel mixture into the cylinder. An exhaust valve 62, which is configured to open and close the exhaust port 37 to discharge the exhaust gas from the inside of the cylinder, is provided on an exhaust side of the front cylinder 13. A piston 63 is housed in a cylinder of the front cylinder 13 so that the piston 63 can reciprocate, and a piston ring 64, which is configured to seal a gap between a piston outer surface and a cylinder inner wall surface, is attached to the piston 63. A spark plug 65, which is configured to ignite the air-fuel mixture in the combustion chamber, protrudes from an upper part of the front cylinder 13.

[0026] The rear cylinder 14 is configured in the same manner as the front cylinder 13. That is, the rear cylinder 14 is provided with an intake valve 71 configured to open and close the intake port 41, an exhaust valve 72 configured to open and close the exhaust port 47, and a piston 73 housed in the cylinder. A spark plug 75 configured to ignite the air-fuel mixture in the combustion chamber protrudes from an upper part of the rear cylinder 14. Explosion or combustion occurs at unequal intervals in the front cylinder 13 and the rear cylinder 14, and the output varies due to a different combustion state (an intake amount) between the front cylinder 13 and the rear cylinder 14 or the like.

[0027] The air cleaner 15 is connected to the intake port 31 of the front cylinder 13 via the front intake pipe 32, and the front throttle body 33 is provided at a center of the front intake pipe 32. The front throttle body 33 is provided with the front throttle valve 34 configured to open and close in response to the operation of an accelerator grip 52. The intake amount of air introduced into the front cylinder 13 is adjusted according to the opening degree of the front throttle valve 34. The front throttle body 33 is provided with the motor 35 connected to the front throttle valve 34 and a throttle sensor 36 configured to detect the opening degree of the front throttle valve 34. An intake pressure sensor 39 configured to detect an intake pressure is provided in the front intake pipe 32.

[0028] Similarly, the air cleaner 15 is connected to the intake port 41 of the rear cylinder 14 via the rear intake pipe 42, and the rear throttle body 43 is provided at a center of the rear intake pipe 42. The rear throttle body 43 is provided with the rear throttle valve 44 configured to open and close in response to operation of the accelerator grip 52. The intake amount of air introduced into the rear cylinder 14 is adjusted according to the opening degree of the rear throttle valve 44. The rear throttle body 43 is provided with the motor 45 connected to the rear throttle valve 44 and a throttle sensor 46 configured to detect the opening degree of the rear throttle valve 44. An intake pressure sensor 49 configured to detect an intake pressure is provided in the rear intake pipe 42.

[0029] The front exhaust pipe 38 is connected to the exhaust port 37 of the front cylinder 13, and the rear exhaust pipe 48 is connected to the exhaust port 47 of the rear cylinder 14. The front and rear exhaust pipes 38, 48 are combined into one by the collector pipe 17 and are connected to the catalyst device 16, and the muffler 18 is connected downstream of the catalyst device 16. In the catalyst device 16, the air pollutants contained in the exhaust gas, i.e., carbon monoxide (CO), hydrocarbons (HC), nitrogen oxides (NOx), and the like, are purified. The catalyst device 16 does not function sufficiently at low temperatures, but may fail and be damaged if it becomes clogged. Therefore, an exhaust gas temperature sensor 51 configured to measure the exhaust gas temperature is provided near the catalyst device 16.

[0030] As described above, in the engine 10, a flow path from the front intake pipe 32 to the front exhaust pipe 38 through the front cylinder 13 and a flow path from the rear intake pipe 42 to the rear exhaust pipe 48 through the rear cylinder 14 are formed independently of each other. The front and rear exhaust pipes 38, 48 join at the collector pipe 17 upstream of the catalyst device 16. However, the collector pipe 17 is located in a region A closer to the vehicle rear than the center C of the crankshaft in the crankcase 12 and closer to the vehicle front than an upstream end 48a of the rear exhaust pipe 48. Therefore, more bends are formed on the rear exhaust pipe 48 extending from the rear cylinder 14 to the catalyst device 16 than on the front exhaust pipe 38 extending from the front cylinder 13 to the catalyst device 16.

[0031] More precisely, as in Fig. As shown in Fig. 6, the front exhaust pipe 38 extends obliquely downward from the front surface of the front cylinder 13 and then bends toward the rear of the vehicle at a slight bending angle at a curved portion 56. After extending downward from the rear surface of the rear cylinder 14, the rear exhaust pipe 48 bends toward the front of the vehicle at a sharp bending angle at a curved portion 57 and further bends toward an inside (a left side) of the vehicle at a sharp bending angle at a curved portion 58. The rear exhaust pipe 48 extends through a path that is more complicated than that of the front exhaust pipe 38, so the rear exhaust pipe 48 has sharper bends than the front exhaust pipe 38 and has a long pipe length.

[0032] As in Fig. As shown in Figure 5, the engine 10 is equipped with an electrical control unit (ECU) 50 configured to control the engine units based on the output of various sensors. In addition to the throttle sensors 36, 46 and the intake pressure sensors 39, 49, an accelerator position sensor 53, a shift position sensor 54, a crank angle sensor 55, and the like are connected to the ECU 50. The accelerator position sensor 53 is configured to detect the operation of the accelerator grip 52, the shift position sensor 54 is configured to detect a shift position of a transmission, and the crank angle sensor 55 is configured to detect a rotation angle of the crankshaft. A part of the ECU 50 functions as a control unit (controller) 80 (see Fig. 7), which is configured to control the opening and closing operation of the front and rear throttle valves 34, 44.

[0033] As described above, the front exhaust pipe 38 has a less sharp curvature and a short pipe length, so that the exhaust efficiency of the front cylinder 13 is higher than that of the rear cylinder 14 due to the pulsation generated during the intake and exhaust processes. Therefore, when the accelerator handle 52 is opened quickly, the front throttle valve 34 is opened by the ECU 50 at a lower speed than the rear throttle valve 44, so that the output of the front cylinder 13 does not become excessive. Accordingly, throttle shock is prevented when the front and rear throttle valves 34, 44 start to open from a fully closed state, smooth acceleration is achieved, and vehicle operation is improved.

[0034] A control configuration of the prime mover according to the present embodiment will be described with reference to FIG. Fig. 7 and Fig. 8 described. Fig. 7 is a block diagram of the control of the prime mover according to the present embodiment. Fig. 8 is a map showing map data for determining a throttle shock according to the present embodiment.

[0035] As in Fig. As shown in Figure 7, the control unit 80 is provided with a mode switching unit 81, an accelerator operation detection unit 82, a throttle shock determination unit 83, a drive command unit 84, a timing determination unit 85, an output estimation unit 86, and an output deviation determination unit 87. The mode switching unit 81 is configured to switch an operation mode of the control unit 80 to a detection mode and start monitoring the throttle shock. The detection mode switching conditions only need to include that at least the front and rear throttle valves 34, 44 are fully closed. The detection mode switching conditions may further include that the shift position is not neutral and that an engine speed is an idle speed.

[0036] The complete closure of the front and rear throttle valves 34, 44 can be detected when a detected opening degree of the accelerator position sensor 53 is less than a certain opening degree. The complete closure of the front and rear throttle valves 34, 44 can be detected when a detected opening degree of the front and rear throttle sensors 36, 46 is less than a certain opening degree. The complete closure of the front and rear throttle valves 34, 44 can be detected when the detected pressures of the front and rear throttle sensors 39, 49 are less than a certain intake pressure. The plurality of switching conditions can be appropriately combined and adjusted according to a situation in which the throttle shock occurs.

[0037] The accelerator operation detection unit 82 is configured to detect the accelerator operation for increasing the opening degree of the front and rear throttle valves 34, 44. In this case, based on a difference between a previously detected opening degree and a currently detected opening degree of the accelerator position sensor 53, the accelerator operation for opening the front and rear throttle valves 34, 44 from the fully closed state is detected. The throttle shock occurs while the accelerator is being operated, so the throttle shock determination processing is executed using the accelerator operation as a trigger. The accelerator operation detection unit 82 can detect an accelerator operation speed and use the accelerator operation speed equal to or higher than a certain speed as a trigger for the throttle shock determination processing.

[0038] After detecting the accelerator operation, the throttle shock determination unit 83 sets the detection time Tts (Tts ≥ 0) of the throttle shock in a timer (not shown). The timer counts down the detection time Tts according to the elapsed time. For example, when Tts = 10 is satisfied, Tts = 9 is satisfied when 1 [s] has elapsed in real time. The throttle shock determination unit 83 is configured to determine whether the throttle shock indicating excessive acceleration response to an accelerator operation occurs during the elapse of the detection time Tts. Whether the throttle shock occurs is determined based on the accelerator operation speed and a change in the intake pressure of the rear cylinder 14.

[0039] As in Fig. As shown in FIG. 8, the throttle shock determining unit 83 determines the throttle shock based on map data in which a region where the throttle shock occurs and a region where the throttle shock does not occur are divided. A horizontal axis of the map data is the accelerator operation speed, and a vertical axis of the map data is the change in the intake pressure of the rear cylinder 14. The map data indicates that as the accelerator operation speed increases, the change in the intake pressure does not follow the accelerator operation and the output lags sharply, so the throttle shock occurs. The accelerator operation speed is obtained by differentiating the accelerator position per unit time, and the change in the intake pressure is obtained by differentiating the intake pressure of the rear cylinder 14 per unit time.The map data are determined experimentally, empirically or theoretically based on previous data or similar.

[0040] Cross marks on the map data indicate a plot where throttle shock occurs, and circle marks on the map data indicate a plot where throttle shock does not occur. Throttle shock occurs in an area surrounded by a dashed line in the map data. When the change in intake pressure and accelerator operation speed in the region where throttle shock occurs are plotted during the elapse of the detection time Tts, it is determined that throttle shock occurs, and the determination flag is set to 1. When the change in intake pressure and accelerator operation speed are plotted outside the area where throttle shock occurs during the elapse of the detection time Tts, it is determined that throttle shock does not occur, and the determination flag is set to 0.

[0041] One reason why the change in the intake pressure of the rear cylinder 14 is used to determine the throttle shock is that only the rear throttle valve 44 on the side of the rear cylinder 14 follows the accelerator operation during the elapse of the detection time Tts (see Fig. 10). Throttle shock occurs because the change in intake pressure does not catch up with the accelerator operation, so the throttle shock determination unit 83 can determine the throttle shock of the front cylinder 13 based only on the accelerator operation speed. That is, the throttle shock determination unit 83 can determine that throttle shock occurs when the accelerator operation speed exceeds the specified speed.

[0042] The throttle shock determination unit 84 is configured to generate a drive command for the front and rear throttle valves 34, 44 based on the throttle shock determination flag. When the determination flag is set to 1, it is determined that the throttle shock occurs, and a low-speed drive command for the front throttle valve 34 (see Fig. 5) is generated. When the determination flag is set to 0, it is determined that the throttle shock does not occur, and a normal travel command for the front throttle valve 34 is generated. Regardless of a value of the determination flag, a normal travel command for the rear throttle valve 44 (see Fig. 5). The normal drive follows the accelerator position.

[0043] Therefore, when the throttle shock determining unit 83 determines that the throttle shock is occurring, the low-speed drive command is output from the drive command unit 84 to the motor 35 of the front throttle valve 34. The front throttle valve 34 opens at a lower speed than the rear throttle valve 44, and the intake amount of the front cylinder 13 is reduced, thus inhibiting the output of the front cylinder 13. Accordingly, the output deviation of the front and rear cylinders 13, 14 decreases, and the throttle shock is inhibited when the front and rear throttle valves 34, 44 start to open from the fully closed state by an accelerator operation.

[0044] The timing determination unit 85 is configured to determine an output timing of the drive command for the front and rear throttle valves 34, 44. The low-speed drive command for the front throttle valve 34 is output from the drive command unit 84 to the motor 35 according to an input timing of the ignition signal of the front cylinder 13 after the detection time Tts has elapsed from a detection timing of the accelerator operation. The normal travel command for the rear throttle valve 44 is output from the travel command unit 84 to the motor 45 according to the detection timing of the accelerator operation (see Fig. 10). Therefore, the front throttle valve 34 begins to open slightly later than the rear throttle valve 44.

[0045] The output estimation unit 86 is configured to estimate the output of the front and rear cylinders 13, 14. The output of the front and rear cylinders 13, 14 is estimated based on the intake pressure and the engine speed. The intake pressures of the front and rear cylinders 13, 14 are detected by the intake pressure sensors 39, 49, respectively. The engine speed is calculated based on a detected value of the crank angle sensor 55. The output deviation determination unit 87 is configured to calculate the output deviation of the front cylinder 13 and the rear cylinder 14 after the detected time Tts has elapsed and determine whether the output deviation is within a predetermined range, that is, whether the throttle shock has been sufficiently prevented.

[0046] A determination result of the output deviation determination unit 87 is input to the drive command unit 84 and used for speed adjustment after the front throttle valve 34 starts moving. As long as the output deviation of the front and rear cylinders 13, 14 is within the predetermined range, the low-speed drive command is output from the drive control unit 84 to the motor 35 of the front throttle valve 34. The front throttle valve 34 is opened at a lower speed than the rear throttle valve 44, and the output deviation between the front and rear cylinders 13, 14 is reduced, thus preventing throttle shock. As described above, the front throttle valve 34 is opened at a low speed until the throttle shock no longer occurs.

[0047] After the output deviation of the front and rear cylinders 13, 14 has reached the predetermined range, a high-speed drive command is output from the drive command unit 84 to the motor 35 of the front throttle valve 34. The front throttle valve 34 is opened at a higher speed than the rear throttle valve 44 until the opening degree of the front throttle valve 34 matches the opening degree of the rear throttle valve 44. As described above, after the front throttle valve 34 is opened at a low speed to prevent throttle shock, the front throttle valve 34 is opened at a high speed to improve acceleration response, thereby improving vehicle operation.

[0048] In the present embodiment, it is assumed that the output of the front cylinder 13 is larger than the output of the rear cylinder 14, and the front throttle valve 34 is opened at a slower speed than the rear throttle valve 44. However, the present invention is not limited to this configuration. A cylinder with a large output may be estimated from a plurality of cylinders, and a throttle valve upstream of this cylinder may be opened at a slower speed than another throttle valve. The cylinder with a large output is estimated based on, for example, an estimation result of the output estimation unit 86 and the determination result of the output deviation determination unit 87.

[0049] In the present embodiment, the output deviation determination unit 87 determines whether output deviation is prevented based on the output deviation of the front and rear cylinders 13, 14. However, the present invention is not limited to this configuration. It may be determined whether throttle surge is prevented based on the output of the engine 10. If the engine output is less than the determined output, it is determined that throttle surge has been prevented, and an opening speed of the front throttle valve 34 is switched from low speed to high speed. It may be determined that throttle surge has been prevented when a sufficiently long time has elapsed from the elapse of the detected time Tts.

[0050] Units of the controller 80 can be implemented by software using a processor or by a logic circuit (hardware) formed in an integrated circuit or the like. When a processor is used, the processor reads and executes a program stored in a data memory, thereby performing various operations. For example, a central processing unit (CPU) is used as the processor. The memory includes one or more data memories, including read-only memory (ROM), random access memory (RAM), and the like, depending on the application. In addition to the program, various parameters, map data, and the like are stored in the memory.

[0051] Operating diagrams of the front and rear throttle valves are shown with reference to Fig. 9 and Fig. 10 described. Fig. 9 is a diagram showing a timing chart when an accelerator is operated in a comparative example. Fig. Fig. 10 is a diagram showing a timing chart when the accelerator according to the present embodiment is operated. Here, the reference numerals in Fig. 5 is used, and the same components as in the present embodiment are denoted by the same reference numerals in the comparative example for description.

[0052] In the comparison example in Fig. 9, when the accelerator is not operated at a time t1, the engine speed is the idle speed, the accelerator position is a fully closed position, the intake pressure is an idle pressure, and the throttle positions of the front and rear throttle valves 34, 44 are fully closed positions. At time t2, the shift position is changed from the neutral position. At time t3, the accelerator is operated, the accelerator position is shifted from the fully closed position, and the throttle positions of the front and rear throttle valves 34, 44 are shifted after the accelerator position from the fully closed position. At this time, the intake pressures of the front cylinder 13 and the rear cylinder 14 rise, and the intake amounts of air into the front cylinder 13 and the rear cylinder 14 increase.

[0053] When the ignition signal is input to the front cylinder 13 at time t4, the engine output increases sharply, and the deviation of the engine output before and after the accelerator operation increases. Specifically, when the front cylinder 13 fires at a time after an accelerator operation, the engine output deviation becomes excessive, and throttle shock occurs. As described above, when the movement of the front and rear throttle valves 34, 44 follows an accelerator operation, throttle shock may occur due to the output deviation of the front and rear cylinders 13, 14.

[0054] In the present embodiment in Fig. 10, when the accelerator is not applied at time t1, the engine speed is idle speed, the accelerator position is fully closed, the intake pressure of the rear cylinder 14 is idle pressure, and the throttle positions of the front and rear throttle valves 34, 44 are fully closed. The throttle shock detection mode is set to OFF, and the throttle shock determination flag is set to 0. When the shift position is changed from the neutral position at time t2, the throttle shock detection mode is switched from OFF to ON.

[0055] The accelerator is operated at time t3, and the detection time Tts of the throttle shock is set in the timer using the accelerator operation as a trigger. Therefore, the detection time Tts is counted down from time t3. At time t3, the accelerator position is moved from the fully closed position while the accelerator is operated, and the throttle position of the rear throttle valve 44 is moved from the fully closed position after the accelerator operation. At this time, the front throttle valve 34 is maintained at a predetermined minute opening degree without following the accelerator position. The throttle shock is determined during the elapsed time Tts of the throttle shock detection.

[0056] At the detection time Tts of the throttle shock, an accelerator operating speed ΔAP is calculated from a time differentiation of the accelerator position and the change of an intake pressure ΔPb is calculated from a time differentiation of the intake pressure of the rear cylinder 14. Referring to the map data (see Fig. 8) When the accelerator operation speed ΔAP and the change in intake pressure ΔPb are plotted in the range where the throttle shock occurs, it is determined that the throttle shock occurs, and the determination flag is set to 1. At time t4 after the elapse of the detection time Tts, the front throttle valve 34 is opened at a lower speed than the rear throttle valve 44. That is, the slope of a speed V1 of the front throttle valve 34 is lower than the speed V2 of the rear throttle valve 44 indicated by the dashed line.

[0057] When the ignition signal is input to the front cylinder 13 at time t4, the output deviation of the front and rear cylinders 13, 14 is reduced, and throttle shock is prevented. When the output deviation of the front and rear cylinders 13, 14 is within the predetermined range at time t5, the front throttle valve 34 is opened at a higher speed than the rear throttle valve 44. That is, the slope of a speed V3 of the front throttle valve 34 is greater than the speed V2 of the rear throttle valve 44 indicated by the dashed line. After the throttle shock is prevented, the acceleration response is enhanced, and the acceleration feeling is improved. When the accelerator position is maintained at a constant opening degree, the throttle shock detection mode is switched from ON to OFF at time t6, and the determination flag is set to 0.

[0058] The throttle shock reduction process is described with reference to Fig. 11 described. Fig. 11 is a flowchart of a valve control system according to the present embodiment. Here, the reference numerals in Fig. 5 and Fig. 7 used accordingly for description.

[0059] As in Fig. As shown in FIG. 11, the controller 80 determines whether the detection mode switching condition is satisfied (step S01). Here, it is determined that the detection mode switching condition is satisfied when the shift position is not neutral, the engine speed is idle speed, and the front and rear throttle valves 34, 44 are fully closed. If the detection mode switching condition is not satisfied (No in step S01), the throttle shock reduction process ends. If the detection mode switching condition is satisfied (Yes in step S01), the detection mode is set to ON, and the throttle shock monitoring is started (step S02).

[0060] Next, the control unit 80 determines whether the accelerator has been operated based on the output of the accelerator position sensor 53 (step S03). If it is determined that the accelerator has not been operated (No in step S03), the process in step S03 is repeated until the accelerator grip 52 is moved from the fully closed position. If it is determined that the accelerator has been operated (Yes in step S03), the control unit 80 controls the detection time Tts of the throttle surge in the timer (step S04). The detection time Tts is counted down, and opening control of the front and rear throttle valves 34, 44 is executed in parallel.

[0061] During the opening control of the front throttle valve 34, the control unit 80 determines whether throttle shock occurs (step S05). Whether throttle shock occurs can be determined based on the accelerator operation speed and the change in intake pressure, or based only on the accelerator operation speed. If it is determined that throttle shock occurs (Yes in step S05), the control unit 80 sets the throttle shock determination flag to 1 (step S06). Conversely, if it is determined that throttle shock does not occur (No in step S05), the control unit 80 sets the throttle shock determination flag to 0 (step S07).

[0062] Next, the control unit 80 determines whether the detection time Tts = 0 is satisfied (step S08). If the detection time Tts = 0 is not satisfied (No in step S08), the process in steps S05 to S08 is repeated until the detection time Tts has elapsed. If the detection time Tts = 0 is satisfied (Yes in step S08), the control unit 80 determines whether the determination flag is 1 (step S09). If the determination flag is 0 (No in step S09), the throttle shock does not occur, so the throttle shock reduction process is ended. If the determination flag is 1 (Yes in step S09), the throttle shock occurs, so the front throttle valve 34 drives to open at a lower speed than the rear throttle valve 44 (step S10).

[0063] Next, the control unit 80 estimates the output of the front and rear cylinders 13, 14 (step S11) and determines whether an output deviation between the front and rear cylinders 13, 14 is within the predetermined range (step S12). If the output deviation is not within the predetermined range (No in step S12), the process in steps S10 to S12 is repeated until the output deviation is within the predetermined range. If the output deviation is within the predetermined range (Yes in step S12), the front throttle valve 34 is driven to open at a higher speed than the rear throttle valve 44 (step S13).

[0064] In the opening control of the rear throttle valve 44, the rear throttle valve 44 is opened at a normal speed after an accelerator operation (step S14). Then, the control unit 80 determines whether a reset condition of the detection mode is satisfied (step S15). When a predetermined time has elapsed in a state where the opening degrees of the front and rear throttle valves 34, 44 match, it is determined that the reset condition is satisfied (step S15). If the reset condition is satisfied (Yes in step S15), the detection mode is switched from ON to OFF, the determination flag is set to 0, and the throttle shock reduction process ends. When the operation is performed in response to an accelerator operation in a direction in which the front and rear throttle valves 34, 44 are closed in steps S10 to S13, the throttle shock reduction process ends.

[0065] As described above, according to the present embodiment, the front throttle valve 34 upstream of the front cylinder 13 is opened at a lower speed than the rear throttle valve 44 upstream of the rear cylinder 14. This reduces the output deviation between the front and rear cylinders 13, 14, and prevents throttle shock, which indicates excessive acceleration response at the time of throttle valve opening. The front throttle valve 34 is opened at a low speed, so that the deterioration of the acceleration feeling can be prevented and vehicle operation can be improved.

[0066] An example has been described in which the throttle valve control according to the present embodiment is applied to a two-cylinder V-type engine. However, the present invention is not limited to this configuration. The throttle valve control according to the present embodiment may be applied to an engine with three or more cylinders, or it may be applied not only to the V-type engine but also to an inline engine or a horizontally opposed engine. For example, in an engine with three or more cylinders, the throttle valve upstream of the largest output cylinder is opened at a lower speed than the remaining throttle valves.

[0067] In the present embodiment, throttle shock is prevented when the front and rear throttle valves are opened from the fully closed state. However, the present invention is not limited to this configuration. Throttle shock can be prevented when the front and rear throttle valves are opened from a predetermined opening degree.

[0068] In the present embodiment, it is determined whether the throttle shock occurs, and when the throttle shock occurs, the front throttle valve is opened at a slower speed than the rear throttle valve. However, the present invention is not limited to this configuration. The front throttle valve may be opened at a slower speed than the rear throttle valve without determining whether the throttle shock occurs. Therefore, the process in steps S04 to S09 may be Fig. 11 should be omitted.

[0069] In the present embodiment, the output of the front cylinder is greater than the output of the rear cylinder. However, the present invention is not limited to this configuration. The output of the rear cylinder may be greater than the output of the front cylinder. In this case, the rear exhaust pipe may be shorter than the front exhaust pipe.

[0070] In the present embodiment, the front cylinder and the rear cylinder, which are separated from each other in the vehicle's front-rear direction, are exemplified as the plurality of cylinders. However, the present invention is not limited to this configuration. The plurality of cylinders may be arranged side by side in a vehicle in the left-right direction without being divided into front and rear.

[0071] The engine according to the present embodiment includes the front cylinder and the rear cylinder. However, the present invention is not limited to this configuration. The engine may include a plurality of cylinders, and the output of a part of the plurality of cylinders may be larger than the output of the remaining part of the plurality of cylinders. For example, the output of two cylinders among three or more cylinders may be larger than the output of the remaining part of the cylinders. In this case, the throttle valves upstream of the two cylinders with large output are opened at a lower speed than the throttle valves of the remaining part of the cylinders. When the engine includes three or more cylinders with different outputs, the throttle valves upstream of a plurality of throttle valves may be opened at a low speed in descending order of the output of the cylinders.

[0072] The throttle valve control according to the present embodiment is applied to the motorcycle. However, the present invention is not limited to this configuration. The throttle valve control according to the present embodiment can be applied to other vehicles in which the throttle valve is provided, for example, to special machines, including a personal watercraft, a lawnmower, and an outboard motor, in addition to a four-wheeled automatic vehicle and a three-wheeled buggy-type automatic vehicle.

[0073] The throttle valve control operation program according to the present embodiment can be stored in a storage medium. The storage medium is not particularly limited and may be a non-transitory storage medium such as an optical disk, a magneto-optical disk, a flash memory, or the like.

[0074] As described above, an engine (10) according to the present embodiment includes: an engine main body (11) having a plurality of cylinders (13, 14), a plurality of throttle valves (34, 44) arranged on intake sides of the plurality of cylinders, and a controller (80) configured to control an opening and closing operation of the plurality of throttle valves. The output of a portion (the front cylinder 13) of the plurality of cylinders is greater than the output of the remaining portion (the rear cylinder 14) of the plurality of cylinders. And the controller opens a portion (the front throttle valve 34) of the throttle valves upstream of the portion of the plurality of cylinders at a lower speed than the remaining portion (the rear throttle valve 44) of the throttle valves upstream of the remaining portion of the plurality of cylinders.According to this configuration, the portion of the throttle valves upstream of the high-output portion of the cylinders opens at a lower speed than the remaining portion of the throttle valves upstream of the remaining portion of the cylinders. Therefore, the output deviation of the plurality of cylinders decreases, and throttle shock, which indicates excessive acceleration response at the time of throttle valve opening, is prevented. The portion of the throttle valves opens at a low speed, preventing a reduction in the acceleration feel and improving vehicle operation.

[0075] In the engine according to the present embodiment, the controller determines whether excessive acceleration response to an accelerator operation is indicated, and if it determines that excessive acceleration response is indicated, opens the portion of the throttle valves at a lower speed than the remaining portion of the throttle valves. According to this configuration, the portion of the throttle valves that does not experience throttle shock is not opened at a low speed. Therefore, the acceleration response and operation of the vehicle can be further improved.

[0076] In the engine according to the present embodiment, the controller determines whether excessive acceleration response is indicated upon accelerator operation based on an accelerator operation speed and a change in intake pressure. According to this configuration, the throttle shock can be accurately determined.

[0077] In the engine according to the present embodiment, the controller estimates the output of the plurality of cylinders and determines whether an output deviation of the plurality of cylinders is within a predetermined range. The controller controls the part of the throttle valves at a lower speed than the remaining part of the throttle valves until the output deviation of the plurality of throttle valves is within the predetermined range. And after the output deviation of the plurality of cylinders comes within the predetermined range, the controller opens the part of the throttle valves at a higher speed than the remaining part of the throttle valves until the opening degree of the part of the throttle valves matches the opening degree of the remaining part of the throttle valves.According to this configuration, after the part of the throttle valves is opened at a low speed and the throttle shock is prevented, the part of the throttle valves can be opened at a high speed to improve the acceleration feeling and operation of the vehicle.

[0078] In the engine according to the present embodiment, the controller opens a plurality of throttle valves upstream of the throttle valves at a low speed in descending order of the output of the plurality of cylinders. According to this configuration, the opening speed of the throttle valves can be adjusted according to the output size of the plurality of cylinders, improving vehicle operation while simultaneously preventing throttle shock.

[0079] The engine according to the present embodiment further includes: a plurality of exhaust pipes (38, 48) connected to the exhaust sides of the plurality of cylinders. A portion (a front exhaust pipe 38) of the plurality of exhaust pipes connected to the exhaust side of the portion of the cylinders is shorter than the remaining portion (a rear exhaust pipe 48) of the plurality of exhaust pipes connected to the exhaust side of the remaining portion of the cylinders. According to this configuration, the output of the portion of the cylinders connected to the short exhaust pipe tends to be larger than the output of the remaining portion of the cylinders. Therefore, the portion of the throttle valves upstream of the portion of the cylinders is opened at a lower speed than the remaining portion of the throttle valves, so that throttle shock in the portion of the cylinders can be prevented.

[0080] In the engine according to the present embodiment, a plurality of cylinders are a front cylinder and a rear cylinder separated from each other in a vehicle front-rear direction. The exhaust pipe portion is a front exhaust pipe connected to an exhaust side of the front cylinder. The remaining exhaust pipe portion is a rear exhaust pipe connected to an exhaust side of the rear cylinder. The throttle valve portion is a front throttle valve disposed on an intake side of the front cylinder. The remaining throttle valve portion is a rear throttle valve disposed on an intake side of the rear cylinder. According to this configuration, the operation of the vehicle can be improved while preventing throttle shock in this engine in which the plurality of cylinders are provided in the vehicle front-rear direction.

[0081] The vehicle according to the present embodiment is equipped with the engine described above. According to this configuration, vehicle operation can be improved while simultaneously preventing throttle shock by controlling the opening and closing of the throttle valves according to the output of the plurality of cylinders.

[0082] According to the present embodiment, there is provided a method for controlling an engine including an engine main body having a plurality of cylinders, a plurality of throttle valves arranged on intake sides of the plurality of cylinders, and a controller configured to control an opening and closing operation of the plurality of throttle valves, wherein the output of a part of the plurality of cylinders is greater than the output of the remaining part of the plurality of cylinders.The method includes: a determining step of determining whether an excessive acceleration response to a throttle operation is indicated by the controller; and an opening step of opening a portion of the throttle valves upstream of the portion of the plurality of cylinders at a lower speed than the remaining portion of the throttle valves upstream of the remaining portion of the plurality of cylinders when it is determined that the excessive acceleration response is indicated by the controller. According to this configuration, when the throttle shock occurs at the start of opening the throttle valves, the portion of the throttle valves upstream of the large output portion of the cylinders is opened at a lower speed than the remaining portion of the throttle valves upstream of the remaining portion of the cylinders.Therefore, the output deviation of the plurality of cylinders is reduced, and throttle shock at the time of throttle opening is prevented. The throttle valves are opened at a low speed, preventing a reduction in the acceleration sensation and improving vehicle operation.

[0083] In the determination step of the engine control method according to the present embodiment, the controller determines whether excessive acceleration response to an accelerator operation is indicated based on an accelerator operation speed and a change in intake pressure. According to this configuration, the throttle shock can be accurately determined.

[0084] The method for controlling the engine according to the present embodiment further includes a step of determining the output of the plurality of cylinders and determining whether the output deviation of the plurality of cylinders is within a predetermined range by the controller. In the opening step, the part of the throttle valves is opened at a lower speed than the remaining part of the throttle valves by the controller until the output deviation of the plurality of throttle valves comes within the predetermined range. And after the output deviation of the plurality of cylinders comes within the predetermined range, the part of the throttle valves is opened at a higher speed than the remaining part of the throttle valves by the controller until the opening degree of the part of the throttle valves matches the opening degree of the remaining part of the throttle valves.According to this configuration, after the part of the throttle valves is opened at a low speed and the throttle shock is prevented, the part of the throttle valves can be opened at a high speed to improve the acceleration feeling and operation of the vehicle.

[0085] Although the present embodiment has been described, the above-described embodiment and the modification may be combined in whole or in part as another embodiment.

[0086] The technique of the present embodiment is not limited to the above-described embodiment, and various changes, substitutions, and modifications can be made without departing from the spirit of the technical idea of ​​the present embodiment. Furthermore, the present invention can be implemented using other methods as long as the technical ideas of the present invention can be implemented by the methods through technological advancement or other derivative technologies. Accordingly, the claims encompass all embodiments that can fall within the scope of the technical idea. List of reference symbols 10 drive machine 11 Main body of the drive machine 13 Front cylinder (part of the multitude of cylinders) 14 Rear cylinder (remaining part of the plurality of cylinders) 34 Front throttle valve (part of the throttle valves) 38 Front exhaust pipe (part of the variety of exhaust pipes) 44 Rear throttle valve (remaining part of the throttle valves) 48 Rear exhaust pipe (remaining part of the plurality of exhaust pipes) 80 Control unit (control) 83 Throttle shock determination unit 84 Drive command unit 86 Output estimation unit 87 Output deviation determination unit

Claims

[1] A drive machine (10) with: a prime mover main body (11) having a plurality of cylinders, a plurality of throttle valves arranged on intake sides of the plurality of cylinders, and a controller (80) configured to control the opening and closing operation of the plurality of throttle valves, wherein an output of a portion of the plurality of cylinders is greater than an output of the remaining portion of the plurality of cylinders, wherein the controller (80) opens a portion of the throttle valves upstream of the portion of the plurality of cylinders at a lower speed than the remaining portion of the throttle valves upstream of the remaining portion of the plurality of cylinders, wherein the controller (80) estimates the output of the plurality of cylinders and determines whether an output deviation of the plurality of cylinders is within a predetermined range, wherein the controller (80) opens the portion of the throttle valves at a lower speed than the remaining portion of the throttle valves until the output deviation of the plurality of cylinders is within the predetermined range, and wherein, after the output deviation of the plurality of cylinders has come into the predetermined range, the controller (80) opens the part of the throttle valves at a higher speed than the remaining part of the throttle valves until the opening degree of the part of the throttle valves agrees with the opening degree of the remaining part of the throttle valves. [2] The prime mover (10) of claim 1, wherein the controller (80) determines whether an excessive acceleration response to an accelerator operation is indicated and opens the portion of the throttle valves at a lower speed than the remaining portion of the throttle valves when it is determined that the excessive acceleration response is indicated. [3] The prime mover (10) of claim 2, wherein the controller (80) determines whether the excessive acceleration response is indicated upon an accelerator operation based on an accelerator operation speed and a change in intake pressure. [4] The prime mover (10) according to any one of claims 1 to 3, wherein the controller (80) opens throttle valves upstream of the plurality of cylinders at a low speed in a descending order of output of the plurality of cylinders. [5] The drive machine (10) according to one of claims 1 to 4, further comprising: a plurality of exhaust pipes connected to exhaust sides of the plurality of cylinders, wherein a portion of the plurality of exhaust pipes connected to an exhaust side of the portion of the cylinders is shorter than the remaining portion of the plurality of exhaust pipes connected to the exhaust side of the remaining portion of the cylinders. [6] The engine (10) according to claim 5, wherein the plurality of cylinders are a front cylinder (13) and a rear cylinder (14) separated from each other in a vehicle front-rear direction, wherein the part of the exhaust pipes is a front exhaust pipe (38) connected to an exhaust side of the front cylinder (13), wherein the remaining part of the exhaust pipes is a rear exhaust pipe (48) connected to an exhaust side of the rear cylinder (14), wherein the part of the throttle valves is a front throttle valve (34) arranged on an intake side of the front cylinder (13), and wherein the remaining part of the throttle valves is a rear throttle valve (44) arranged on an intake side of the rear cylinder (14). [7] A vehicle to which the prime mover (10) according to any one of claims 1 to 6 is mounted. [8] A method for controlling an engine (10) having an engine main body (11) having a plurality of cylinders, a plurality of throttle valves arranged on intake sides of the plurality of cylinders, and a controller (80) configured to control the opening and closing operation of the plurality of throttle valves, wherein an output of a part of the plurality of cylinders is greater than an output of a remaining part of the plurality of cylinders, the method comprising: a determining step of determining whether an excessive acceleration response to an accelerator operation by the controller (80) is indicated, an opening step of opening a portion of the throttle valves upstream of the portion of the plurality of cylinders at a lower speed than the remaining portion of the throttle valves upstream of the remaining portion of the plurality of cylinders when it is determined that the excessive acceleration response is indicated by the controller (80), and a step of estimating by the controller (80) an output of the plurality of cylinders and determining whether an output deviation of the plurality of cylinders is within a predetermined range, wherein in the opening step, the part of the throttle valves is opened by the controller (80) at a lower speed than the remaining part of the throttle valves until the output deviation of the plurality of cylinders is within the predetermined range, and wherein, after the output deviation of the plurality of cylinders has come into the predetermined range, the part of the throttle valves is opened at a higher speed than the remaining part of the throttle valves by the controller (80) until the opening degree of the part of the throttle valves agrees with the opening degree of the remaining part of the throttle valves. [9] The method of controlling the prime mover (10) according to claim 8, wherein in the determining step, it is determined by the controller (80) whether the excessive acceleration response is indicated to an accelerator operation based on an accelerator operation speed and a change in an intake pressure.

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