DRIVE ENGINE AND VEHICLE

Abstract

A drive machine (10) with: a prime mover main body (11) having a plurality of cylinders (13, 14), a plurality of exhaust pipes (38, 48) connected to exhaust sides of the plurality of cylinders (13, 14), a plurality of throttle valves (34, 44) arranged on intake sides of the plurality of cylinders (13, 14), a catalyst device (16) connected to the plurality of outlet pipes (38, 48), and a control unit (50) configured to control opening and / or closing operations of the plurality of throttle valves (34, 44), wherein one of the outlet pipes (38, 48) is shorter than another outlet pipe, wherein the control unit (50) opens one of the throttle valves (34, 44) upstream of one of the outlet pipes (38, 48) at a higher speed or a greater degree of opening than the other throttle valve upstream of the other outlet pipe when the prime mover (10) is started, and wherein the control unit (50) opens the plurality of throttle valves (34, 44) upstream of the plurality of outlet pipes (38, 48) at a high speed or a large opening degree in an ascending order of the lengths of the plurality of outlet pipes (38, 48).

Description

Technical field

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

[0002] As an engine mounted on a vehicle such as a straddle-seat type vehicle, an engine in which exhaust ports are separated, such as a V-type engine and a horizontally opposed engine, is known (see, for example, Patent Literature 1). In such an engine, a pair of front and rear cylinders are inclined in opposite directions, and an exhaust pipe extends from a front surface of the front cylinder, and an exhaust pipe extends from a rear surface of the rear cylinder. The front and rear exhaust pipes are joined and connected to a catalyst device; when the engine is started, the catalyst device is warmed up to an activating temperature or operating temperature by flowing exhaust gas through the exhaust pipes. Then, the air pollutants contained in the exhaust gas are purified by the catalyst device.

[0003] Patent Literature 2 discloses that first and second exhaust passages are independently connected to a first cylinder group and a second cylinder group, respectively, and these first / second exhaust passages are merged and expanded as a merged exhaust passage, and a first half catalyst is disposed only on the first exhaust passage, and a final half catalyst is also disposed on the merged exhaust passage. When the temperature of the final half catalyst is increased, first, the first cylinder group is brought into the operating state with a higher degree of exhaust gas temperature increase than the second cylinder group, and temperature increasing means is provided to properly bring the second cylinder group into the operating state with a higher degree of exhaust gas temperature increase than the first cylinder group.

[0004] Patent Literature 3 discloses that when the temperature of a catalyst detected by a sensor is higher than a set temperature, a control circuit does not send a signal, and a three-way valve is in a certain state. Accordingly, the first and second cylinder groups are provided with advance ignition angles compared to the normal ignition timing. On the other hand, when the temperature of the catalyst is lower than the set temperature, the control circuit sends a signal, and the three-way valve actuates a vacuum introduction pipe to communicate with the atmosphere. Therefore, a vacuum advance ignition angle mechanism is not operated, and the first cylinder group is provided with a retarded ignition angle compared to the normal ignition timing. Accordingly, afterburning occurs and the combustion duration is extended, thereby increasing the exhaust gas temperature. Citation listPatent literature Patent literature 1: JP 2009 - 85 112 A Patent literature 2: JP 2000 - 130 155 A Patent literature 3: JP S59 - 200 010 A Summary of the inventionTechnical problem

[0005] For the engine described above, the catalytic converter must be installed taking into account the layout of the individual exhaust pipes extending from the front and rear cylinders. Depending on the installation position of the catalytic converter, it may be necessary to extend the exhaust pipes extending from the front and rear cylinders or sharply bend the exhaust pipes to pass through a complicated path. Therefore, when starting the engine, the warm-up time of the catalytic converter is extended, and sufficient exhaust gas purification performance cannot be achieved.

[0006] The present invention has been made in view of the above, and an object of this invention is to provide an engine and a vehicle which can achieve early activation of a catalyst device and improve the purification efficiency with respect to the exhaust gas. Solution to the problem

[0007] According to the present invention, a prime mover according to independent claim 1 and a vehicle according to independent claim 4 are provided. Advantageous modifications can be found in dependent claims 2 and 3. Brief description of the drawings Fig. 1 is a perspective view of a prime mover according to a 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. 4 is a schematic view of the prime mover according to the present embodiment. Fig. 5 is a perspective view of an exhaust device according to the present embodiment. Fig. 6 is a graph showing a relationship between an opening degree of a throttle valve and a catalyst temperature according to the present embodiment. Fig. 7 is a graph showing a relationship between an opening degree of a throttle valve and a catalyst temperature according to a comparative example. Fig. 8 is a flowchart of a valve control according to the present embodiment. Description of the embodiments

[0008] In an engine according to one aspect of the present invention, a plurality of exhaust pipes are connected to exhaust sides of a plurality of cylinders, and intake amounts of the cylinders are adjusted by a plurality of throttle valves on intake sides of the plurality of respective cylinders. Moreover, one of the exhaust pipes is formed shorter than the other exhaust pipe, and the plurality of exhaust pipes is connected to a catalyst device. When the engine is started, one of the throttle valves upstream of the short exhaust pipe is opened faster or wider than the other throttle valve upstream of the other exhaust pipe, and the intake amount of one of the cylinders connected to the short exhaust pipe is increased to promote combustion.Since a large amount of high-temperature exhaust gas is supplied from one of the cylinders to the catalyst device through the short exhaust pipe, the catalyst device is warmed up early by the exhaust gas to perform better purification performance. Furthermore, since the catalyst device is warmed up early, a degree of freedom in the arrangement of the catalyst device can be improved. [Embodiment]

[0009] Hereinafter, an embodiment will be described in detail with reference to the accompanying drawings. Here, an example in which a prime mover of the present embodiment is mounted on a motorcycle as a straddle-seat type vehicle will be described. However, an application subject is not limited thereto. For example, the prime mover can be applied to other straddle-seat type vehicles such as a buggy-type three-wheeled automatic vehicle. Moreover, in the following drawings, the front of a vehicle is indicated by an arrow FR, the rear of the vehicle by an arrow RE, the left side of the vehicle by an arrow L, and the right side of the vehicle by an arrow R. 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.

[0010] As in the Fig. 1 to 3, an engine 10 is a so-called V-type engine 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 protruding 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 protruding from the crankcase 12.

[0011] An inlet opening 31 (see Fig. 4) is opened in a rear surface of the front cylinder 13, and a first intake pipe 32 is connected to the intake port 31. An intake port 41 (see Fig. 4) is opened in a front surface of the rear cylinder 14, and a second intake pipe 42 is connected to the intake port 41. The first and second intake pipes 32, 42 extend upward from the pair of front and rear cylinders 13, 14, respectively, and are connected to a lower portion of an air cleaner 15 for filtering outside air. A first throttle body 33 for the front cylinder 13 is provided at a middle portion of the first intake pipe 32, and a second throttle body 43 for the rear cylinder 14 is provided at a middle portion of the second intake pipe 42.

[0012] The first throttle body 33 is connected to a first throttle valve 34 (see Fig. 4) for adjusting the intake quantity of the front cylinder 13, and the second throttle body 43 is provided with a second throttle valve 44 for adjusting the intake quantity of the rear cylinder 14 (see Fig. 4). The first and second throttle bodies 33, 43 are electronic throttle bodies and include motors 35, 45 (see Fig. 4) that open and / or close the first and second throttle valves 34, 44, respectively. Since the first and second throttle bodies 33, 43 individually encompass the engines 35, 45, the first and second valves 34, 44 can adjust the intake quantities for the respective cylinders independently of each other.

[0013] An outlet opening 37 (see Fig. 4) is opened in the front surface of the front cylinder 13, and a first exhaust pipe 38 is connected to the exhaust port 37. An exhaust port 47 (see Fig. 4) is opened in the rear surface of the rear cylinder 14, and a second exhaust pipe 48 is connected to the exhaust port 47. The first and second exhaust pipes 38, 48 extend downward from the pair of front and rear cylinders 13, 14 and are connected to a catalyst device 16 that purifies the air pollutants contained in the exhaust gas. The catalyst device 16 is installed at a rear portion of the vehicle below the engine 10 and closer to the rear of the vehicle than the center C of a crankshaft in the crankcase 12.

[0014] The second exhaust pipe 48 is connected to the catalyst device 16 below the engine 10 via a more complicated route than the first 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 first exhaust pipe 38 and the second exhaust pipe 48, and the pipe length of the first exhaust pipe 38 connected to the front cylinder 13 is shorter than the pipe length of the second exhaust pipe 48 connected to the rear cylinder 14. Incidentally, the pipe shapes of the first and second exhaust pipes 38, 48 will be described in detail later. The first and second exhaust pipes 38, 48 are connected to the catalyst device 16 via a manifold 17, and a muffler (exhaust muffler) 18 for attenuating an exhaust noise is provided on a downstream side of the catalyst device 16.

[0015] In the engine 10 configured as above, the air flows from the air cleaner 15 to the front cylinder 13 and the rear cylinder 14 via the first and second intake pipes 32, 42. The first and second throttle valves 34, 44 adjust the intake amounts to the front cylinder 13 and the rear cylinder 14. The fuel is mixed with the air by a fuel supply device (not shown), and the air-fuel mixture is supplied to the combustion chambers of the cylinders 13, 14. The exhaust gas after combustion flows through the first and second 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.

[0016] Immediately after the engine 10 is started, the catalyst device 16 has a low temperature, and the exhaust gas purification performance is not sufficiently performed until the catalyst device 16 reaches an activating temperature or operating temperature. Since the catalyst device can be installed relatively upstream of an exhaust system, in a parallel engine used in an automatic four-wheel vehicle or the like, the catalyst device can be warmed up early to maintain the exhaust gas purification performance. However, in the V-type engine used in the motorcycle or the like, since the front cylinder 13 and the rear cylinder 14 are separated in a vehicle front-rear direction as described above, the catalyst device 16 must be installed below the engine 10 or on the muffler 18 downstream of the exhaust system.

[0017] Therefore, the distances between the cylinders 13, 14 and the catalyst device 16 are increased, and the catalyst device 16 cannot be warmed up early when the engine 10 starts. Therefore, in the present embodiment, the first throttle valve 34 upstream of the first exhaust pipe 38 is opened earlier than the second throttle valve 44 upstream of the second exhaust pipe 48, focusing on the fact that the pipe length of the first exhaust pipe 38 is shorter than the pipe length of the second exhaust pipe 48. Accordingly, a large amount of high-temperature exhaust gas is guided from the front cylinder 13 to the catalyst device 16 through the short first exhaust pipe 38, and the purification performance of the exhaust gas is improved by the early warm-up of the catalyst device 16.

[0018] In the following, a detailed configuration of the prime mover of the present embodiment will be described with reference to Fig. 4 and Fig. 5 described. Fig. 4 is a schematic diagram of the prime mover according to the present embodiment. Fig. 5 is a perspective view of the exhaust device according to the present embodiment.

[0019] As in Fig. As shown in Fig. 4, the air cleaner 15 is connected to the intake port 31 of the front cylinder 13 via the first intake pipe 32, and the first throttle body 33 is provided in the center of the first intake pipe 32. The first throttle body 33 is provided with the first throttle valve 34 that opens and / or closes in response to operation of a throttle grip. The intake amount sent into the combustion chamber in the front cylinder 13 is adjusted according to an opening degree of the first throttle valve 34. Furthermore, the first throttle body 33 is provided with the motor 35 connected to the first throttle valve 34 and a throttle valve sensor 36 for detecting the opening degree of the first throttle valve 34.

[0020] Similarly, the air cleaner 15 is connected to the intake port 41 of the rear cylinder 14 via the second intake pipe 42, and the second throttle body 43 is provided in the center of the second intake pipe 42. The second throttle body 43 is provided with the second throttle valve 44, which opens and / or closes in response to the operation of the throttle handle. The intake amount sent into the combustion chamber in the rear cylinder 14 is adjusted according to an opening degree of the second throttle valve 44. In addition, the second throttle body 43 is provided with the motor 45 connected to the second throttle valve 44 and a throttle valve sensor 46 for detecting the opening degree of the second throttle valve 44.

[0021] The first exhaust pipe 38 is connected to the exhaust port 37 of the front cylinder 13, and the second exhaust pipe 48 is connected to the exhaust port 47 of the rear cylinder 14. The first and second exhaust pipes 38, 48 are combined into one and connected to the catalyst device 16 through the manifold 17, and the muffler 18 is connected to the downstream side of the catalyst device 16. In the catalyst device 16, air pollutants such as carbon monoxide (CO), hydrocarbons (HC), and nitrogen oxides (NOx) contained in the exhaust gas are purified. The catalyst device 16 does not function well at low temperatures, but may fail and be damaged if the temperature of the catalyst device 16 is too high. Therefore, an exhaust gas temperature sensor 51 for measuring the exhaust gas temperature is mounted near the catalyst device 16.

[0022] As described above, in the engine 10, a flow path from the first intake pipe 32 to the first exhaust pipe 38 through the front cylinder 13 and a flow path from the second intake pipe 42 to the second exhaust pipe 48 through the rear cylinder 14 are independently formed. The first and second exhaust pipes 38, 48 are connected at the manifold 17 upstream of the catalyst device 16. However, the manifold 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 49 of the second exhaust pipe 48. Therefore, the second exhaust pipe 48 extending from the rear cylinder 14 to the catalyst device 16 is more curved than the first exhaust pipe 38 extending from the front cylinder 13 to the catalyst device 16.

[0023] More precisely, as in Fig. 5, the first exhaust pipe 38 extends obliquely downward from the front surface of the front cylinder 13 toward the rear, and then is bent at a slight bending angle toward the rear of the vehicle at a bent portion 56. The second exhaust pipe 48 extends downward from the rear surface of the rear cylinder 14, and then is bent at a sharp bending angle toward the front of the vehicle at a bent portion 57, and is further bent at a sharp bending angle toward an inside of the vehicle (a left side) at a bent portion 58. Since the second exhaust pipe 48 traverses a more complicated path than the first exhaust pipe 38, the second exhaust pipe 48 has sharper bends than the first exhaust pipe 38 and has a long pipe length.

[0024] As in Fig. As shown in Figure 4, the engine 10 is provided with an electric control unit (ECU) 50 as a control unit that controls the opening and / or closing operations of the first and second throttle valves 34, 44. Immediately after the engine 10 is started, the motors 35, 45 of the first and second throttle bodies 33, 43 are driven by the ECU 50 until the opening degrees of the first and second throttle valves 34, 44 become the target opening degrees. At this time, the first throttle valve 34 upstream of the first exhaust pipe 38 opens at a higher speed than the second throttle valve 44 upstream of the second exhaust pipe 48. The intake amount of the front cylinder 13 increases, and the combustion of the front cylinder 13 is promoted more than that of the rear cylinder 14.

[0025] Therefore, the exhaust amount of the front cylinder 13 is larger than the exhaust amount of the rear cylinder 14, and more exhaust gas flows into the first exhaust pipe 38 than into the second exhaust pipe 48. Since the first exhaust pipe 38 has a small number of sharp bends and the pipe length is short, the exhaust temperature of the exhaust gas is less likely to decrease. A large amount of high-temperature exhaust gas is guided from the front cylinder 13 through the first exhaust pipe 38 to the catalyst device 16. Therefore, compared with a configuration in which the first and second throttle valves 34, 44 are opened simultaneously at low speed, the large amount of high-temperature exhaust gas can be guided to the catalyst device 16, and the catalyst device 16 can be warmed up early.

[0026] The ECU 50 has a processor and a memory mounted thereon. The processor reads and executes a program stored in the data memory, thereby performing a throttle valve control operation described later. A central processing unit (CPU) or the like is used as the processor. The data memory is configured using one or more storage media, such as read-only memory (ROM) and random access memory (RAM), depending on the application. In addition to the program, various parameters used for the control operation are stored in the memory. Furthermore, an ignition switch 52, which receives a start operation of the engine 10, is connected to the ECU 50.

[0027] The speeds of the first and second throttle valves 34, 44 are determined by values ​​obtained experimentally, empirically, or theoretically from past data or the like. For example, the speeds of the first and second throttle valves 34, 44 can be adjusted based on the pipe lengths of the first and second outlet pipes 38, 48. Furthermore, the speeds of the first and second throttle valves 34, 44 can be varied according to a catalyst temperature of the catalyst device 16 in addition to the pipe lengths of the first and second outlet pipes 38, 48.

[0028] A relationship between the degree of opening of the throttle valve and the catalyst temperature is determined using the Fig. 6 and Fig. 7 described. Fig. 6 is a graph showing the relationship between the opening degree of the throttle valve and the catalyst temperature according to the present embodiment. Fig. 7 is a graph showing a relationship between a throttle valve opening degree and a catalyst temperature according to a comparative example. Fig. 6 and Fig. 7, a solid line W1 indicates the speed of the first throttle valve, a dashed line W2 indicates the speed of the second throttle valve, and a solid line W3 indicates a temperature change of the catalyst device. Here, the reference numerals in Fig. 4 used.

[0029] In the present embodiment of Fig. 6, the first throttle valve 34 is opened at a high speed, indicated by the solid line W1, and the second throttle valve 44 is opened at a low speed, indicated by the dashed line W2. After the lapse of time t1 from the start of the engine 10, the first throttle valve 34 is opened to the target opening degree, and the second throttle valve 44 is opened to a low opening degree. From time t1 to time t2, the first throttle valve 34 is maintained at the target opening degree, and the second throttle valve 44 continues to open to the target opening degree. After the lapse of time t2, the second throttle valve 44 is opened to the target opening degree, and thereafter, the first and second throttle valves 34, 44 are maintained at the target opening degrees.

[0030] As indicated by the solid line W3, from the start of the engine 10 to time t2, the temperature of the catalyst device 16 increases with increasing opening degrees of the first and second throttle valves 34, 44. In particular, since the first throttle valve 34 is opened to the target opening degree in a short time, the large amount of high-temperature exhaust gas flows from the first exhaust pipe 38 into the catalyst device 16, and the temperature of the catalyst device 16 increases in a short time. When the catalyst device 16 reaches the activation temperature or operating temperature after the lapse of time t2, the first and second throttle valves 34, 44 are maintained at the target opening degrees, and the temperature of the catalyst device 16 progressively increases with time.

[0031] In the comparison example of Fig. 7, on the other hand, as shown by the solid line W1 and the dashed line W2, the first throttle valve 34 and the second throttle valve 44 are opened simultaneously at a low speed. After the lapse of time t2 from the start of the engine 10, the first and second throttle valves 34, 44 are opened to the target opening degree, and thereafter, the first and second throttle valves 34, 44 are maintained at the target opening degree. Since the first and second throttle valves 34, 44 are opened at a low speed, less high-temperature exhaust gas flows into the catalyst device 16 compared to the present embodiment. Therefore, as shown by the solid line W3, after the lapse of time t3, the catalyst device 16 reaches the activation temperature or operating temperature, and the time until the catalyst device 16 is warmed up is longer.

[0032] With reference to Fig. 8 describes the control process of the throttle valve when starting the engine. Fig. Fig. 8 is a flowchart of a valve control system according to the present embodiment. Here, the reference numerals from Fig. 4 used.

[0033] As in Fig.As shown in Fig. 8, when the ignition switch 52 is turned on (step S01), a cell motor (not shown) rotates, and the engine 10 is started. When the engine 10 is started, the ECU 50 determines whether or not the temperature of the catalyst device 16 is equal to or higher than the activation temperature or operating temperature (step S02). The temperature of the catalyst device 16 is estimated based on, for example, a detection result of the exhaust gas temperature sensor 51 or the elapsed time since the engine was started. If it is determined that the temperature of the catalyst device 16 is equal to or higher than the activation temperature or operating temperature (Yes in step S02), the ECU 50 switches an operation of the engine 10 from a start mode to a normal mode (step S11).

[0034] On the other hand, if it is determined that the temperature of the catalyst device 16 is lower than the activation temperature or operating temperature (No in step S02), the ECU 50 adjusts the speeds of the first throttle valve 34 and the second throttle valve 44 (step S03). Since the first exhaust pipe 38 is shorter than the second exhaust pipe 48, the speed of the first throttle valve 34 upstream of the first exhaust pipe 38 is set higher than the speed of the second throttle valve 44 upstream of the second exhaust pipe 48, so that more exhaust gas flows through the first exhaust pipe 38. Next, the motors 35, 45 are simultaneously driven by the ECU 50, and valve opening control of the first and second throttle valves 34, 44 is performed in parallel.

[0035] In the valve opening control of the first throttle valve 34, the ECU 50 controls the first throttle valve 34 at high speed (step S04) and determines whether the first throttle valve 34 is opened to the target opening degree or not (step S05). If the first throttle valve 34 is not opened to the target opening degree (No in step S05), the ECU 50 executes operations of steps S04, S05 until the opening degree of the first throttle valve 34 reaches the target opening degree (step S05). If the first throttle valve 34 is opened to the target opening degree (Yes in step S05), the ECU 50 stops the opening of the first throttle valve 34 (step S06).

[0036] In the valve opening control of the second throttle valve 44, the ECU 50 controls the second throttle valve 44 at low speed (step S07) and determines whether the second throttle valve 44 has been opened to the target opening degree (step S08). If the second throttle valve 44 is not opened to the target opening degree (No in step S08), the ECU 50 executes the processes of steps S07, S08 until the opening degree of the second throttle valve 44 reaches the target opening degree. If the second throttle valve 44 is opened to the target opening degree (Yes in step S08), the ECU 50 stops the opening of the second throttle valve 44 (step S09).

[0037] The first and second throttle valves 34, 44 are controlled independently of each other, and the first throttle valve 34 is opened to the target opening degree before the second throttle valve 44. The exhaust gas from the front cylinder 13 to the catalyst device 16 through the short exhaust pipe 38 rises, and the catalyst device 16 is warmed up early by the high-temperature exhaust gas. When the first and second throttle valves 34, 44 stop at the target opening degree, the ECU 50 determines whether or not the temperature of the catalyst device 16 is equal to or higher than the activation temperature or operating temperature (step S10). If it is determined that the temperature of the catalyst device 16 is equal to or higher than the activation temperature or operating temperature (Yes in step S10), the ECU 50 switches the operation mode of the engine 10 from the start mode to the normal mode (step S11).

[0038] As described above, according to the present embodiment, when the engine is started, the first throttle valve 34 opens faster than the second throttle valve 44, and the intake amount of the front cylinder 13 connected to the first exhaust pipe 38 with the short pipe length is increased to promote combustion. Therefore, since the large amount of high-temperature exhaust gas from the front cylinder 13 is guided through the first exhaust pipe 38 to the catalyst device 16, the catalyst device 16 can be warmed up by the exhaust gas early, and the purification performance of the exhaust gas can be improved. In addition, since the catalyst device 16 is warmed up early, a degree of freedom in the arrangement of the catalyst device 16 can be improved.

[0039] Although an example in which the throttle valve control according to the present embodiment is applied to a V-type two-cylinder engine has been described, 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 the engine with three or more cylinders, a throttle valve upstream of a cylinder to which the shortest exhaust pipe is connected is opened at a higher speed or a larger opening degree than the other throttle valves.

[0040] In the present embodiment, the first exhaust pipe connected to the front cylinder is formed shorter than the second exhaust pipe connected to the rear cylinder, but the present embodiment is not limited to this configuration. The second exhaust pipe may be formed shorter than the first exhaust pipe.

[0041] In the present embodiment, the front cylinder and the rear cylinder, which are separated from each other in the vehicle front-rear direction, are exemplified as a plurality of cylinders, but the present invention is not limited to this configuration. The plurality of cylinders may be formed side by side in a vehicle in the left-right direction without being divided into front and rear.

[0042] Although the prime mover in the present embodiment includes two exhaust pipes of the first exhaust pipe and the second exhaust pipe, the present invention is not limited to this configuration. The prime mover may include a plurality of exhaust pipes, and some exhaust pipes of the plurality of exhaust pipes may be formed shorter than other exhaust pipes. For example, two of the three or more exhaust pipes may be formed shorter than the other exhaust pipes. In this case, throttle valves upstream of the two short exhaust pipes are opened at a higher speed or to a larger opening degree than throttle valves upstream of the other exhaust pipes.In addition, in a case where the prime mover includes three or more exhaust pipes having different lengths, the throttle valves upstream of the plurality of exhaust pipes may be opened at a high speed or a large opening degree in ascending order of the lengths of the plurality of exhaust pipes.

[0043] In the present embodiment, the flow rate of exhaust gas from the cylinder to the catalyst device is increased by rapidly opening the throttle valve, but the present invention is not limited to this configuration. By increasing the opening degree of the throttle valve, the flow rate of exhaust gas from the cylinder to the catalyst device can also be increased.

[0044] Although the throttle valve control according to the present embodiment is applied to the motorcycle, the present invention is not limited to this configuration. The throttle valve control according to the present embodiment can be suitably applied to other vehicles in which the throttle valve is installed, such as a personal watercraft, a lawnmower, an outboard motor, or the like, in addition to a four-wheeled automatic vehicle and a three-wheeled buggy-type automatic vehicle.

[0045] 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, or a flash memory.

[0046] As described above, an engine (10) of the present embodiment includes: an engine main body (11) having a plurality of cylinders (the front cylinder 13, the rear cylinder 14), a plurality of exhaust pipes (the first exhaust pipe 38, the second exhaust pipe 48) connected to exhaust sides of the plurality of cylinders, a plurality of throttle valves (the first throttle valve 34, the second throttle valve 44) arranged on intake sides of the plurality of cylinders, a catalyst device (16) connected to the plurality of exhaust pipes, and a control unit (ECU 50) configured to control the opening and / or closing operations of the plurality of throttle valves. One of the exhaust pipes (the first exhaust pipe 38) is formed shorter than the other exhaust pipe (the second exhaust pipe 48).The control unit controls one of the throttle valves (first throttle valve 34) upstream of one of the exhaust pipes at a higher speed or a larger opening degree than the other throttle valve (second throttle valves 44) upstream of the other exhaust pipe when the engine is started. According to this configuration, when the engine is started, one of the throttle valves upstream of the short exhaust pipe opens faster or to a larger opening degree than the other throttle valve, and the intake amount of the one of the cylinders connected to the short exhaust pipe is increased to promote combustion. Since the large amount of high-temperature exhaust gas from the one of the cylinders is guided to the catalyst device through the short exhaust pipe, the catalyst device can be warmed up by the exhaust gas early, and the exhaust gas purification performance can be improved.In addition, since the catalyst device is warmed up early by controlling the throttle valve regardless of an arrangement position of the catalyst device, a degree of freedom in the arrangement of the catalyst device can be improved.

[0047] In the engine according to the present embodiment, the control unit opens the plurality of throttle valves upstream of the plurality of exhaust pipes at high speed or with a large opening degree in ascending order of the lengths of the plurality of exhaust pipes. According to this configuration, the intake amount through the throttle valve is adjusted according to the length of the exhaust pipe, so that the catalyst device can be warmed up in a shorter time and the exhaust gas purification performance can be further improved.

[0048] In the engine according to the present embodiment, a plurality of exhaust pipes are front and rear cylinders separated from each other in a vehicle front-rear direction. One of the exhaust pipes is a first exhaust pipe connected to an exhaust side of the front cylinder, the other exhaust pipe is a second exhaust pipe connected to an exhaust side of the rear cylinder. One of the throttle valves is a first throttle valve arranged on an intake side of the front cylinder, and the other throttle valve is a second throttle valve arranged on an intake side of the rear cylinder. According to this configuration, in the engine in which the plurality of cylinders are arranged in the front-rear direction, the catalyst device can be warmed up early and the exhaust gas purification performance can be improved.

[0049] In the engine according to the present embodiment, the engine main body includes a crankcase (12) in which a crankshaft is housed, the first exhaust pipe and the second exhaust pipe are connected at a manifold (17) upstream of the catalyst device, and the manifold is arranged closer to a vehicle rear side than a center (C) of the crankshaft and closer to a vehicle front side than an upstream end (49) of the second exhaust pipe. According to this configuration, the second exhaust pipe extending from the rear cylinder to the catalyst device is bent more than the first exhaust pipe extending from the front cylinder to the catalyst device. The rapid or large opening of the first throttle valve promotes combustion of the front cylinder.Since a large amount of exhaust gas flows smoothly into the catalyst device of one chamber from the front cylinder through the first exhaust pipe with less sharp bend in a short time, the catalyst device can be warmed up early by the exhaust gas and the purification performance of the exhaust gas can be improved.

[0050] The vehicle according to the present embodiment is equipped with the engine described above. According to this configuration, the opening and / or closing operation of the throttle valve can be controlled according to the length of the exhaust pipe, and the purification performance of the vehicle's exhaust gas can be improved.

[0051] Although the present embodiment has been described as another embodiment, the above embodiment and the modification may be combined in whole or in part.

[0052] The technique of the present embodiment is not limited to the above embodiment, and various changes, substitutions, and modifications can be made without departing from the spirit of the technical idea. Furthermore, the present invention can be implemented using other methods as long as the technical idea can be realized by the methods through advancement of technology or other derived technology. Accordingly, the claims encompass all embodiments that can fall within the scope of the technical ideas. List of reference symbols 10 drive machine 11 Main body of the engine 12 Crankcase 13 Front cylinder 14 Rear cylinder 16 Catalyst device 17 Collector pipe 34 First throttle valve 38 First outlet pipe 44 Second throttle valve 48 Second outlet pipe 49 Upstream end of the second outlet pipe 50 ECU (control unit)

Claims

[1] A drive machine (10) with: a prime mover main body (11) having a plurality of cylinders (13, 14), a plurality of exhaust pipes (38, 48) connected to exhaust sides of the plurality of cylinders (13, 14), a plurality of throttle valves (34, 44) arranged on intake sides of the plurality of cylinders (13, 14), a catalyst device (16) connected to the plurality of outlet pipes (38, 48), and a control unit (50) configured to control opening and / or closing operations of the plurality of throttle valves (34, 44), wherein one of the outlet pipes (38, 48) is shorter than another outlet pipe, wherein the control unit (50) opens one of the throttle valves (34, 44) upstream of one of the outlet pipes (38, 48) at a higher speed or a greater degree of opening than the other throttle valve upstream of the other outlet pipe when the prime mover (10) is started, and wherein the control unit (50) opens the plurality of throttle valves (34, 44) upstream of the plurality of outlet pipes (38, 48) at a high speed or a large opening degree in an ascending order of the lengths of the plurality of outlet pipes (38, 48). [2] The engine (10) according to claim 1, wherein the plurality of cylinders (13, 14) are a front cylinder (13) and a rear cylinder (14) separated from each other in a vehicle front-rear direction, wherein one of the exhaust pipes (38, 48) is a first exhaust pipe (38) connected to an exhaust side of the front cylinder (13), wherein the other exhaust pipe is a second exhaust pipe (48) connected to an exhaust side of the rear cylinder (14), wherein one of the throttle valves (34, 44) is a first throttle valve (34) arranged on an intake side of the front cylinder (13), and wherein the other throttle valve is a second throttle valve (44) arranged on an intake side of the rear cylinder (14). [3] The drive machine (10) according to claim 2, wherein the engine main body (11) comprises a crankcase (12) in which a crankshaft is accommodated, and wherein the first outlet pipe (38) and the second outlet pipe (48) are joined at a manifold (17) upstream of the catalyst device (16), and the manifold (17) is arranged closer to a vehicle rear than a center of the crankshaft and closer to a vehicle front than an upstream end (49) of the second outlet pipe (48). [4] A vehicle equipped with the prime mover (10) according to any one of claims 1 to 3.

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