Saddle-riding type vehicle

Abstract

To provide a saddle-riding type vehicle hard to be in a wheelie state in circuit traveling or the like.SOLUTION: A saddle-riding type vehicle 1 includes a front wheel 24, a rear wheel 49, and an exhaust device 29 that discharges exhaust gas. The exhaust device 29 includes an exhaust port 73 that jets exhaust gas to cause a reaction force F to act on the front wheel 24. The reaction force F suppresses floating up of the front wheel 24 from a road surface G. By suppressing floating up of the front wheel 24 from the road surface G, a wheelie state of the saddle-riding type vehicle 1 in circuit traveling or the like can be suppressed. By using the reaction force F generated when the exhaust gas is jetted in the exhaust device 29, floating up of the front wheel 24 from the road surface G is suppressed. As a result, the exhaust device 29 can contribute to posture control of the saddle-riding type vehicle 1 by effectively utilizing exhaust gas.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a saddle-ride type vehicle. [Background technology]

[0002] When driving a saddle-riding vehicle, for example, if the driver suddenly opens the accelerator pedal of the saddle-riding vehicle while driving on a circuit, or if the driver suddenly engages the clutch of the saddle-riding vehicle while driving on a circuit, the saddle-riding vehicle will suddenly accelerate. When the saddle-riding vehicle suddenly accelerates, the saddle-riding vehicle is likely to perform a wheelie. When the saddle-riding vehicle performs a wheelie, the front wheel of the saddle-riding vehicle will lift up above the road surface. In other words, when the saddle-riding vehicle performs a wheelie, the front wheel of the saddle-riding vehicle is not in contact with the road surface and is separated from the road surface. In other words, when the saddle-riding vehicle performs a wheelie, the front wheel of the saddle-riding vehicle is positioned above the road surface. Therefore, when the saddle-riding vehicle performs a wheelie, it is difficult to accelerate the saddle-riding vehicle.

[0003] Patent Document 1 discloses a device for controlling the engine of a saddle-riding vehicle when the saddle-riding vehicle is performing a wheelie. The device disclosed in Patent Document 1 includes an acceleration sensor and an ECU. The acceleration sensor detects the inclination of the saddle-riding vehicle. The ECU determines whether the saddle-riding vehicle is performing a wheelie based on the detection result of the acceleration sensor. When the ECU determines that the saddle-riding vehicle is performing a wheelie, the ECU reduces the output of the engine of the saddle-riding vehicle. The ECU reducing the engine output causes the saddle-riding vehicle to decelerate. When a saddle-riding vehicle performing a wheelie decelerates, the front wheel, which was positioned above the road surface, drops down and contacts the road surface again. In other words, when the front wheel contacts the road surface again, the saddle-riding vehicle escapes the wheelie and returns to its normal state. In this application, the state in which the front wheel of the saddle-riding vehicle is in contact with the road surface is referred to as the normal state, and is distinguished from a wheelie. In this way, by using the device disclosed in Patent Document 1, it becomes easy to shorten the period during which the saddle-type vehicle is in a wheelie state.

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2002-70709 DISCLOSURE OF THE INVENTION [Problem to be solved by the invention]

[0005] Even with the conventional technology disclosed in Patent Document 1, if a saddle-riding vehicle is suddenly accelerated while traveling on a circuit, the saddle-riding vehicle will easily enter a wheelie. In other words, even if the device disclosed in Patent Document 1 is used in a saddle-riding vehicle, it is difficult to prevent the vehicle from entering a wheelie from a normal state. Therefore, even with the conventional technology disclosed in Patent Document 1, it is difficult to sufficiently improve the acceleration performance of a saddle-riding vehicle while traveling on a circuit, etc.

[0006] The present invention has been made in view of the above circumstances, and its main object is to provide a saddle-type vehicle that is less likely to perform a wheelie when driving on a circuit or the like. [Means for solving the problem]

[0007] In order to achieve the above object, the present invention has the following configuration. In other words, the saddle-type vehicle of the present invention comprises a front wheel, a rear wheel, and an exhaust device that discharges exhaust gas, and the exhaust device has a first exhaust port that injects the exhaust gas to apply a first force to the front wheel, and the first force acts in a direction that prevents the front wheel from lifting off the road surface.

[0008] (Actions and Effects) According to this configuration, the saddle-riding type vehicle includes a front wheel, a rear wheel, and an exhaust device. The exhaust device discharges exhaust gas. The exhaust device includes a first exhaust port. The first exhaust port injects exhaust gas to apply a first force to the front wheel. The first force acts in a direction that prevents the front wheel from lifting off the road surface. In other words, the first force acts in a direction that presses the front wheel against the road surface. Therefore, the front wheel is prevented from lifting off the road surface. Therefore, the saddle-riding type vehicle is less likely to perform a wheelie when traveling on a circuit, etc. As an example, even when the saddle-riding type vehicle suddenly accelerates when traveling on a circuit, etc., the saddle-riding type vehicle is less likely to perform a wheelie. As a result, the acceleration performance of the saddle-riding type vehicle can be easily improved when traveling on a circuit, etc.

[0009] In the above-described straddle-type vehicle, when the straddle-type vehicle starts moving, it is preferable that the first exhaust port injects the exhaust gas to apply a first force to the front wheel.

[0010] (Action and Effect) In this case, when the saddle-riding type vehicle starts moving, the first force acts in a direction that prevents the front wheel from lifting off the road surface. Therefore, when the saddle-riding type vehicle starts moving on a circuit, etc., the saddle-riding type vehicle is less likely to perform a wheelie. Therefore, it is possible to easily improve the acceleration performance of the saddle-riding type vehicle when starting moving on a circuit, etc.

[0011] In the above-described straddle-type vehicle, when the straddle-type vehicle rapidly accelerates, it is preferable that the first exhaust port injects the exhaust gas to apply a first force to the front wheel.

[0012] (Actions and Effects) In this case, when the saddle-riding vehicle suddenly accelerates while traveling on a circuit, for example, the first force acts in a direction that prevents the front wheel from lifting off the road surface. Therefore, when the saddle-riding vehicle suddenly accelerates while traveling on a circuit, the saddle-riding vehicle is less likely to perform a wheelie. Therefore, the acceleration performance of the saddle-riding vehicle when suddenly accelerating while traveling on a circuit, for example, can be easily improved.

[0013] In the above-described saddle-ride type vehicle, the first force is preferably a reaction force of the jet of exhaust gas ejected from the first exhaust port. In other words, the first force is preferably directed in a direction opposite to the injection direction of the exhaust gas ejected from the first exhaust port.

[0014] (Operation and Effect) In this case, by injecting exhaust gas from the first exhaust port, it becomes easy for the first exhaust port to apply the first force to the front wheel.

[0015] In the above-described straddle-type vehicle, the first exhaust port is preferably configured to eject the exhaust gas rearward.

[0016] (Operation and Effect) In this case, it is easy for the first force to act in a direction that presses the front wheels against the road surface. Therefore, the first force can prevent the front wheels from lifting off the road surface.

[0017] In the above-described straddle-type vehicle, the first exhaust port is preferably disposed above the center of rotation of the rear wheel.

[0018] (Operation and Effect) In this case, it is easier for the first force to act in a direction pressing the front wheels against the road surface. Therefore, the first force can further suppress the front wheels from lifting off the road surface.

[0019] In the above-described straddle-type vehicle, it is preferable that the first exhaust port be disposed above an upper end of the rear wheel.

[0020] (Operation and Effect) In this case, it is easier for the first force to act in a direction pressing the front wheels against the road surface. Therefore, the first force can further suppress the front wheels from lifting off the road surface.

[0021] In the above-described saddle-ride type vehicle, it is preferable that the first force generates a first moment around a rear contact point between the rear wheel and the road surface, and that the first moment acts in a direction pressing the front wheel against the road surface.

[0022] (Action / Effect) In this case, the first force generates a first moment. The first moment is generated around the rear contact point between the rear wheel and the road surface. The first moment acts in a direction that presses the front wheel against the road surface. In other words, the first moment moves the front wheel downward, with the rear contact point as the fulcrum. Therefore, the first moment can prevent the front wheel from lifting off the road surface. Therefore, the first force can prevent the front wheel from lifting off the road surface.

[0023] In the above-described straddle-type vehicle, the first exhaust port is preferably configured to eject the exhaust gas upward.

[0024] (Operation and Effect) In this case, it is easy for the first force to act downward on the front wheels. Therefore, the first force can prevent the front wheels from lifting off the road surface.

[0025] In the above-described straddle-type vehicle, the first force preferably includes a first component that acts downward on the front wheel.

[0026] (Action / Effect) In this case, the first force includes a first component. The first component acts downward on the front wheels. Therefore, the first component acts in a direction that prevents the front wheels from lifting off the road surface. Therefore, the first force can prevent the front wheels from lifting off the road surface.

[0027] In the above-described straddle-type vehicle, it is preferable that the exhaust device includes a main exhaust port that discharges the exhaust gas, and the first exhaust port is smaller than the main exhaust port.

[0028] (Operation and Effect) In this case, it is easy to increase the velocity of the exhaust gas injected from the first exhaust port, and therefore it is easy to increase the first force.

[0029] In the above-described straddle-type vehicle, it is preferable that the first exhaust port has a diameter smaller than a diameter of the main exhaust port.

[0030] (Operation and Effect) In this case, it is easy to increase the velocity of the exhaust gas injected from the first exhaust port. Therefore, it is easy to increase the first force. Therefore, the first force can further suppress lifting of the front wheels from the road surface.

[0031] In the above-described straddle-type vehicle, the first exhaust port is preferably disposed above the main exhaust port.

[0032] (Operation and Effect) In this case, it is easier for the first force to act in a direction pressing the front wheels against the road surface. Therefore, the first force can further suppress the front wheels from lifting off the road surface.

[0033] In the above-described straddle-type vehicle, the exhaust device preferably includes a main valve that opens and closes the main exhaust port.

[0034] (Operation and Effect) In this case, it is easy to control the injection of exhaust gas at the main exhaust port.

[0035] In the above-described straddle-type vehicle, it is preferable that the main valve is configured to open the main exhaust port when the pressure of the exhaust gas in the exhaust device is equal to or greater than a predetermined value.

[0036] (Operation and Effect) In this case, for example, when the pressure of the exhaust gas in the exhaust device is less than a predetermined value, the main valve closes the main exhaust port. Therefore, when the pressure of the exhaust gas in the exhaust system is below a predetermined value, the main exhaust port does not inject the exhaust gas. Therefore, when the pressure of the exhaust gas in the exhaust device is below a predetermined value, it is easy to increase the amount of exhaust gas injected from the first exhaust port. Therefore, when the pressure of the exhaust gas in the exhaust device is less than a predetermined value, it is easy to increase the first force. Therefore, if the exhaust gas pressure in the exhaust system is less than a predetermined value, the straddle-type vehicle is less likely to perform a wheelie when, for example, driving on a circuit. As a result, it is easy to improve the acceleration performance of the saddle-type vehicle when driving on a circuit or the like.

[0037] The above-described straddle-type vehicle preferably includes a detector that detects a state of the straddle-type vehicle, and a main valve controller that controls the main valve based on the detection result of the detector.

[0038] (Operation and Effect) In this case, it is easy to control the injection of exhaust gas from the main exhaust port in accordance with the state of the saddle-ride type vehicle.

[0039] In the above-described saddle-ride type vehicle, the main valve control unit determines whether or not the front wheel is about to lift off the road surface based on the detection result of the detection unit, The main valve control unit is preferably configured to close the main valve when the main valve control unit determines that the front wheels are about to lift off the road surface.

[0040] (Action and Effect) In this case, when the front wheels are about to lift off the road surface, it is easy to increase the amount of exhaust gas injected from the first exhaust port. Therefore, when the front wheels are about to lift off the road surface, it is easy to increase the first force. Therefore, even when the front wheels are about to lift off the road surface, the first force can prevent the front wheels from lifting off the road surface.

[0041] In the above-described saddle-ride type vehicle, it is preferable that the detection unit includes at least one of a first sensor that detects a pitch angle of the saddle-ride type vehicle and a second sensor that detects a stroke amount of a front fork that supports the front wheel.

[0042] (Operation and Effect) In this case, it is easy for the detection unit to detect the posture of the saddle riding type vehicle, and therefore it is easy for the main valve control unit to control the main valve in accordance with the posture of the saddle riding type vehicle.

[0043] In the above-described saddle-ride type vehicle, the detection unit a third sensor that detects the pressure of the exhaust gas in the exhaust system; a fourth sensor for detecting a speed of the saddle-ride type vehicle; a fifth sensor that detects acceleration of the saddle-ride type vehicle; a sixth sensor that detects an operation amount of an accelerator of the saddle riding type vehicle; a seventh sensor that detects an opening degree of a throttle valve of the saddle-ride type vehicle; and an eighth sensor that detects the rotation speed of the engine of the saddle riding type vehicle.

[0044] (Operation and Effect) In this case, it is easy for the detection unit to detect the posture of the saddle riding type vehicle, and therefore it is easy for the main valve control unit to control the main valve in accordance with the posture of the saddle riding type vehicle. [Effects of the Invention]

[0045] According to the present invention, a saddle-type vehicle that is less likely to perform a wheelie when driving on a circuit or the like can be realized. [Brief explanation of the drawings]

[0046] [Figure 1] 1 is a left side view of a saddle-ride type vehicle according to a first embodiment. [Figure 2] 1 is a right side view of a saddle-ride type vehicle according to a first embodiment. [Figure 3] 1 is a vertical cross-sectional view of an exhaust device according to a first embodiment. [Figure 4] 1 is a vertical cross-sectional view of an exhaust device according to a first embodiment. [Figure 5] 1 is a vertical cross-sectional view of an exhaust device according to a first embodiment. [Figure 6] 1 is a functional block diagram showing a control system of a saddle-ride type vehicle according to a first embodiment. [Figure 7] FIG. 2 is a right side view showing a jet of exhaust gas according to the first embodiment. [Figure 8] FIG. 4 is a right side view showing a reaction force and a first component force of exhaust gas according to the first embodiment. [Figure 9] FIG. 4 is a right side view showing the reaction force of exhaust gas and the first moment according to the first embodiment. [Figure 10]FIG. 2 is a right side view showing a jet of exhaust gas according to the first embodiment. [Figure 11] FIG. 4 is a right side view showing the reaction force of exhaust gas and the first moment according to the first embodiment. [Figure 12] FIG. 10 is a functional block diagram showing a control system of a saddle-ride type vehicle according to a second embodiment. [Figure 13] 10 is a flowchart showing steps of an operation in a saddle-ride type vehicle according to a second embodiment. [Figure 14] FIG. 10 is a right side view of a saddle-ride type vehicle according to a third embodiment. [Figure 15] FIG. 10 is a right side view showing a jet of exhaust gas according to the third embodiment. [Figure 16] FIG. 10 is a right side view showing the reaction force of exhaust gas according to the third embodiment. [Figure 17] FIG. 10 is a right side view of a saddle-ride type vehicle according to a fourth embodiment. [Figure 18] FIG. 10 is a right side view showing a jet of exhaust gas according to the fourth embodiment. [Figure 19] FIG. 10 is a right side view showing the reaction force of exhaust gas and the first moment according to the fourth embodiment. [Figure 20] FIG. 10 is a vertical cross-sectional view of an exhaust system according to a modified embodiment. [Figure 21] FIG. 10 is a vertical cross-sectional view of an exhaust system according to a modified embodiment. [Figure 22] 10 is a flowchart showing steps of an operation in a saddle-ride type vehicle according to a modified embodiment. [Figure 23] FIG. 10 is a vertical cross-sectional view of an exhaust system according to a modified embodiment. [Figure 24] FIG. 10 is a vertical cross-sectional view of an exhaust system according to a modified embodiment. [Figure 25] FIG. 10 is a vertical cross-sectional view of an exhaust system according to a modified embodiment. [Figure 26] FIG. 10 is a vertical cross-sectional view of an exhaust system according to a modified embodiment. DETAILED DESCRIPTION OF THE INVENTION [Example]

[0047] A saddle-ride type vehicle 1 according to the present invention will be described below with reference to the drawings.

[0048] <Outline of saddle-type vehicle configuration>

[0049] Fig. 1 is a left side view of a saddle-ride type vehicle according to Example 1. Fig. 2 is a right side view of the saddle-ride type vehicle according to Example 1.

[0050] The saddle-type vehicle 1 is a street-type vehicle. A driver (also called a rider) rides on the saddle-type vehicle 1 and operates the saddle-type vehicle 1.

[0051] 1 and 2 show the front-rear direction X, width direction Y, and up-down direction Z of the saddle riding type vehicle 1. The front-rear direction X, width direction Y, and up-down direction Z are defined with respect to a driver riding on the saddle riding type vehicle 1. The front-rear direction X, width direction Y, and up-down direction Z are perpendicular to each other. The front-rear direction X and width direction Y are horizontal. The up-down direction Z is vertical.

[0052] The terms "front," "rear," "up," "down," "right," and "left" respectively refer to the "front," "rear," "up," "down," "right," and "left" of a driver riding in the saddle-riding vehicle 1. Unless otherwise specified in this specification, "front" and "rear" include not only directions parallel to the fore-and-aft direction X but also directions close to the fore-and-aft direction X. A direction close to the fore-and-aft direction X is, for example, a direction that forms an angle of 45 degrees or less with the fore-and-aft direction X. Similarly, unless otherwise specified, "right" and "left" include not only directions parallel to the width direction Y but also directions close to the width direction Y. Unless otherwise specified, "up" and "down" include not only directions parallel to the up-down direction Z but also directions close to the up-down direction Z. In each drawing, the terms "front," "rear," "up," "down," "right," and "left" are indicated as appropriate for reference.

[0053] In this specification, the expressions used to describe the arrangement have the following meanings: In the following description, the width direction Y is taken as an example, but the same applies to the front-rear direction X and the up-down direction Z.

[0054] The expression "member Ma is disposed to the right / left of member Mb" specifies the position of member Ma relative to member Mb in the width direction Y, but does not specify the position of member Ma relative to member Mb in the front-rear direction X or the up-down direction Z. In this expression, member Ma may or may not overlap member Mb in a side view of saddle riding type vehicle 1.

[0055] The expression "member Ma is disposed to the right / left of member Mb" without any reference to the viewing direction defines the position of member Ma relative to member Mb in the width direction Y, the position of member Ma relative to member Mb in the front-rear direction X, and the position of member Ma relative to member Mb in the up-down direction Z. This expression means that member Ma is disposed to the right / left of member Mb, and that at least a portion of member Ma overlaps with at least a portion of member Mb in a side view of saddle riding type vehicle 1.

[0056] The expression "member Ma is disposed to the right / left of member Mb in a plan view of the saddle riding type vehicle 1" specifies the position of member Ma relative to member Mb in the width direction Y and the position of member Ma relative to member Mb in the front-rear direction X, but does not specify the position of member Ma relative to member Mb in the up-down direction Z. This expression means that member Ma is disposed to the right / left of member Mb, the front end of member Ma is located forward of the rear end of member Mb, and the rear end of member Ma is located rearward of the front end of member Mb.

[0057] The expression "member Ma is disposed to the right / left of member Mb in a front view of the saddle riding type vehicle 1" specifies the position of member Ma relative to member Mb in the width direction Y and the position of member Ma relative to member Mb in the up-down direction Z, but does not specify the position of member Ma relative to member Mb in the front-to-rear direction X. This expression means that member Ma is disposed to the right / left of member Mb, the upper end of member Ma is located above the lower end of member Mb, and the lower end of member Ma is located below the upper end of member Mb.

[0058] In this specification, "in a side view of the saddle riding type vehicle 1" will be referred to as "in a side view of the vehicle" where appropriate. Similarly, "in a plan view of the saddle riding type vehicle 1" will be referred to as "in a plan view of the vehicle" where appropriate.

[0059] The saddle-riding type vehicle 1 includes a body frame 3. The body frame 3 includes a head pipe 5 and a main frame 7. The head pipe 5 is disposed at the front of the saddle-riding type vehicle 1. The main frame 7 extends rearward and downward from the head pipe 5 in a side view of the vehicle.

[0060] The saddle-ride type vehicle 1 includes a steering device 9. The steering device 9 is supported by the body frame 3. Specifically, the steering device 9 is supported by the head pipe 5. The steering device 9 is rotatable relative to the body frame 3.

[0061] The steering device 9 includes a top bridge 11, a bottom bridge 13, and a front fork 14. The top bridge 11 is disposed above the head pipe 5. The bottom bridge 13 is disposed below the top bridge 11. The bottom bridge 13 is disposed below the head pipe 5. The front fork 14 is supported by the top bridge 11 and the bottom bridge 13. The front fork 14 extends forward and downward from the top bridge 11 in a side view of the vehicle. The front fork 14 extends to a position lower than the bottom bridge 13.

[0062] The steering device 9 includes a handlebar 15. The handlebar 15 is supported by the top bridge 11. The entire handlebar 15 is, for example, disposed above the top bridge 11. A rider holds the handlebar 15 to steer the steering device 9.

[0063] The handlebars 15 are provided with a clutch lever 17. The clutch lever 17 controls the transmission of driving force. The clutch lever 17 is operated by the rider to control the transmission of driving force. The handlebars 16 are provided with a brake lever 19. The brake lever 19 controls the braking of the front wheel. The brake lever 19 is operated by the rider to decelerate the saddle-type vehicle 1.

[0064] The handlebar 15 includes an accelerator grip 21. The accelerator grip 21 is also called a throttle. The accelerator grip 21 is operated by the driver to accelerate the saddle riding type vehicle 1.

[0065] The steering device 9 includes a front axle 23. The front axle 23 is disposed below the bottom bridge 13. The front axle 23 is supported by the front fork 14.

[0066] The saddle-type vehicle 1 includes a front wheel 24. The front wheel 24 is supported by a steering device 9. Specifically, the front wheel 24 is supported by a front axle 23. The front wheel 24 is rotatable around the front axle 23.

[0067] The saddle-riding type vehicle 1 is equipped with a front wheel braking device 25. The front wheel braking device 25 applies a braking force sufficient to stop the rotation of the front wheel 24. In the saddle-riding type vehicle 1 according to the first embodiment, a configuration in which the front wheel braking device 25 is disposed on both the right and left sides of the front wheel 24 is shown as an example. The front wheel braking device 25 may be disposed on only one of the right and left sides of the front wheel 24.

[0068] The saddle-riding type vehicle 1 includes an engine 31. The engine 31 is supported by the body frame 3. Specifically, the engine 31 is supported by the main frame 5. The engine 31 is fixed to the body frame 3. The engine 31 does not swing relative to the body frame 3. The engine 31 generates driving force for propelling the saddle-riding type vehicle 1. At least a portion of the engine 31 is disposed below the main frame 7 in a side view of the vehicle. The engine 31 is disposed behind the steering device 9 in a side view of the vehicle.

[0069] The engine 31 is equipped with a crankshaft 33 and a transmission 35. The crankshaft 33 outputs driving force. The transmission 35 performs deceleration. The transmission 35 reduces the rotation speed of the crankshaft 33 by reducing the speed in multiple stages. The transmission 35 can switch between multiple gear ratios. The driving force changed by the transmission 35 is transmitted to a drive shaft (not shown). The engine 31 is equipped with a shift pedal 37. The shift pedal 37 is operated by the driver's left foot. The shift pedal 37 operates the gear ratio of the transmission 35.

[0070] The engine 31 is an internal combustion engine. The engine 31 has a combustion chamber (not shown). The engine 31 burns fuel in the combustion chamber. Exhaust gas is generated in the combustion chamber.

[0071] The saddle-type vehicle 1 is equipped with an exhaust device 29. The exhaust device 29 discharges exhaust gas. The exhaust device 29 discharges exhaust gas generated in the engine 31. The exhaust device 29 transports exhaust gas from the engine 31. The exhaust device 29 is connected to the engine 31. The exhaust device 29 may be configured to be directly connected to the engine 31, or may be configured to be indirectly connected to the engine 31. As an example, the exhaust device 29 is connected to the engine 31 via a connecting pipe (not shown). Exhaust gas generated in the combustion chamber of the engine 31 is guided to the exhaust device 29 via the connecting pipe.

[0072] The straddle-type vehicle 1 includes a fuel tank 39. The fuel tank 39 is supported by the body frame 3. Specifically, the fuel tank 39 is supported by the main frame 5. The fuel tank 39 stores fuel.

[0073] The saddle-type vehicle 1 includes a seat 41. The seat 41 is supported by the body frame 3. A driver sits astride the seat 41 and drives the saddle-type vehicle 1.

[0074] The saddle-ride type vehicle 1 includes a pivot shaft 43, a swing arm 45, and a rear axle 47. The pivot shaft 43 is supported by the body frame 3. Specifically, the pivot shaft 43 is supported by the main frame 5. The swing arm 45 is supported by the pivot shaft 43. The swing arm 45 is swingable around the pivot shaft 43 relative to the body frame 3. The swing arm 45 extends rearward from the pivot shaft 43 in a side view of the vehicle. The rear axle 47 is supported at the rear of the swing arm 45.

[0075] The saddle-type vehicle 1 includes a rear wheel 49. The rear wheel 49 is supported by a rear axle 47. The rear wheel 49 is rotatable around the rear axle 47. The swing arm 45 and the rear wheel 49 are disposed behind the engine 31 in a side view of the vehicle. The swing arm 45 and the rear wheel 49 are disposed below the fuel tank 39 and the seat 41.

[0076] The straddle-type vehicle 1 is provided with a rear wheel braking device 51. The rear wheel braking device 51 applies a braking force sufficient to stop the rotation of the rear wheel 49.

[0077] The saddle-riding type vehicle 1 is provided with a brake pedal 53. The brake pedal 53 is operated by the driver's right foot. The brake pedal 53 operates the rear wheel braking device 51. The brake pedal 53 is operated by the driver to decelerate the saddle-riding type vehicle 1.

[0078] The straddle-type vehicle 1 is provided with an accelerator opening sensor 61. The accelerator opening sensor 61 detects the opening of the accelerator grip 21.

[0079] A fuel supply device 63 is disposed behind the engine 31 in the front-rear direction X. The fuel supply device 63 supplies fuel in the fuel tank 39 to the engine 31.

[0080] The straddle-type vehicle 1 is provided with a throttle valve opening sensor 65. The throttle valve opening sensor 65 detects the opening of a throttle valve that adjusts the amount of intake air into the engine 31.

[0081] The engine 31 is provided with a gear position sensor 67 that detects the gear position of the transmission 35. The gear position sensor 67 detects information related to the gear ratio of the transmission 35. The engine 31 is provided with a crankshaft position sensor 69. The crankshaft position sensor 69 detects the angle of the crankshaft 33 and the rotation speed of the engine 31. The crankshaft position sensor 69 detects the phase of the crankshaft 33.

[0082] The saddle-riding type vehicle 1 is provided with an ECU 75 (Electronic Control Unit) at the center in the fore-and-aft direction X. The ECU 75 communicates with various sensors such as an IMU 81 (described later) and other control units via a communication network (not shown). The ECU 75 controls the entire saddle-riding type vehicle 1, including the engine 31, while transmitting and receiving data via this intercommunication.

[0083] <Exhaust system configuration> The configuration of the exhaust device 29 provided in the saddle-riding type vehicle 1 according to the first embodiment will now be described with reference to Fig. 3. Fig. 3 is a vertical cross-sectional view of the exhaust device 29. Fig. 2 also shows a right side view of the exhaust device 29.

[0084] As shown in Fig. 3, the exhaust device 29 includes a junction pipe 55, a first branch pipe 56, and a second branch pipe 57. The junction pipe 55 includes a guide port 59 at one end. The junction pipe 55 includes a branch portion 60 at the other end. The guide port 59 is connected to the engine 31 via a connecting pipe of the engine 31. That is, exhaust gas generated in the engine 31 is guided to the exhaust device 29 through the guide port 59.

[0085] The branching portion 60 of the junction pipe 55 is disposed behind the guide port 59 in a side view of the vehicle. The branching portion 60 of the junction pipe 55 is connected to one end of the first branch pipe 56 and one end of the second branch pipe 57. In other words, the exhaust device 29 has a structure in which the junction pipe 55 branches into the first branch pipe 56 and the second branch pipe 57 at the branching portion 60.

[0086] The first branch pipe 56 extends rearward from the branching portion 60 in a side view of the vehicle. That is, the extending direction of the first branch pipe 56 is the same as the extending direction of the junction pipe 55. An exhaust port 71 is provided at the other end of the first branch pipe 56. The exhaust port 71 injects exhaust gas from the inside of the exhaust device 29 to the outside of the exhaust device 29. In other words, the exhaust port 71 injects exhaust gas from the exhaust device 29 to the outside of the saddle-riding type vehicle 1. Specifically, the exhaust port 71 discharges exhaust gas that has flowed from the junction pipe 55 to the first branch pipe 56 to the outside of the exhaust device 29. The exhaust port 71 according to the first embodiment is configured to discharge exhaust gas rearward in a side view of the vehicle.

[0087] The second branch pipe 57 extends rearward and upward from the branching portion 60 in a side view of the vehicle. In other words, the second branch pipe 57 is disposed higher than the first branch pipe 56. An exhaust port 73 is provided at the other end of the second branch pipe 57. The exhaust port 73 injects exhaust gas from the inside of the exhaust device 29 to the outside of the exhaust device 29. In other words, the exhaust port 73 injects exhaust gas from the exhaust device 29 to the outside of the saddle-riding type vehicle 1. Specifically, the exhaust port 73 discharges exhaust gas that has flowed from the junction pipe 55 to the second branch pipe 57 to the outside of the exhaust device 29. The exhaust port 73 is disposed higher than the exhaust port 71.

[0088] Exhaust port 73 according to the first embodiment is configured to discharge exhaust gases rearward and upward in a side view of the vehicle. Exhaust port 73 according to the first embodiment is disposed higher than exhaust port 71. Exhaust port 73 according to the first embodiment is disposed higher than rear axle 47. That is, exhaust port 73 is disposed higher than the center of rotation of rear wheel 49.

[0089] The diameter of the second branch pipe 57 is configured to be smaller than the diameter of the first branch pipe 56. In other words, the exhaust port 73 of the second branch pipe 57 is configured to be smaller than the exhaust port 71 of the first branch pipe 56. Specifically, the diameter of the exhaust port 73 is configured to be smaller than the diameter of the exhaust port 71.

[0090] The exhaust device 29 includes an on-off valve 58. The on-off valve 58 is disposed inside the first branch pipe 56. The on-off valve 58 opens and closes an exhaust port 71 in the first branch pipe 56. That is, the on-off valve 58 adjusts the opening and closing of the exhaust port 71. The on-off valve 58 is, for example, a spring-loaded valve. Note that FIG. 3 shows a state in which the exhaust port 71 is closed by the on-off valve 58. When the exhaust port 71 is blocked by the on-off valve 58, it is described as "the on-off valve 58 is in a closed state." When the exhaust port 71 is opened by the on-off valve 58, it is described as "the on-off valve 58 is in an open state."

[0091] Here, the relationship between the flow of exhaust gas in the exhaust device 29 and the state of the on-off valve 58 will be described with reference to FIGS.

[0092] 4 shows the direction in which exhaust gas flows when the on-off valve 58 is closed. The direction in which exhaust gas flows when the on-off valve 58 is closed is indicated by the arrow marked R. When the on-off valve 58 is closed, the exhaust port 71 of the first branch pipe 56 is blocked by the on-off valve 58. Therefore, the exhaust gas guided to the junction pipe 55 via the guide port 59 flows to the second branch pipe 57 at the branching portion 60. That is, all of the exhaust gas flows inside the second branch pipe 57 and is discharged from the exhaust port 73. In other words, when the on-off valve 58 is closed, the exhaust device 29 injects all of the exhaust gas from the exhaust port 73.

[0093] In the saddle-riding vehicle 1 according to the first embodiment, the exhaust port 73 injects exhaust gas to apply a first force to the front wheel 24. The first force acts in a direction that inhibits the front wheel 24 from lifting off the road surface. That is, in the first embodiment, exhaust gas is injected from the exhaust port 73 to inhibit the saddle-riding vehicle 1 from performing a wheelie, for example, when traveling on a circuit. The mechanism by which exhaust gas is injected from the exhaust port 73 to generate the first force that inhibits the front wheel 24 from lifting off the road surface will be described later.

[0094] FIG. 5 shows the direction in which exhaust gas flows when the on-off valve 58 is open. When the on-off valve 58 is open, the exhaust port 71 of the first branch pipe 56 is open. The direction in which the first branch pipe 56 extends is the same as the direction in which the junction pipe 55 extends. The first branch pipe 56 has a larger cross-sectional area than the second branch pipe 57. Therefore, most of the exhaust gas guided to the junction pipe 55 via the guide port 59 flows to the first branch pipe 56 at the branching portion 60. The exhaust gas that flows to the first branch pipe 56 is then discharged to the outside of the exhaust device 29 via the exhaust port 71. That is, most of the exhaust gas is discharged from the exhaust port 71, as indicated by the arrow labeled R1 in FIG. 5.

[0095] On the other hand, a small portion of the exhaust gas guided to the junction pipe 55 flows into the second branch pipe 56 at the branching portion 60. The exhaust gas that flows into the second branch pipe 57 is discharged to the outside of the exhaust device 29 via the exhaust port 73. That is, a small portion of the exhaust gas is discharged from the exhaust port 73, as shown by the arrow labeled R2 in FIG. 5 . In other words, when the on-off valve 58 is open, the exhaust device 29 injects most of the exhaust gas from the exhaust port 71 and a small portion of the exhaust gas from the exhaust port 73. In this way, by appropriately switching the state of the on-off valve 58 between the closed state and the open state, it is possible to switch the exhaust port from which exhaust gas is discharged from the exhaust device 29.

[0096] <Control system configuration> Here, a description will be given of a control system of the saddle riding type vehicle 1 according to the embodiment 1. Fig. 6 is a functional block diagram illustrating the control system of the saddle riding type vehicle 1 according to the embodiment 1.

[0097] The ECU 75 includes a CPU 77. The CPU 77 is a so-called central processing unit, and executes various programs to realize various functions.

[0098] The ECU 75 includes a storage unit 79. The storage unit 79 stores programs and data related to the operation of the saddle riding type vehicle 1. An example of a program stored in the storage unit 79 is a control program executed by the ECU 75. The storage unit 79 also stores an opening condition and a closing condition. The opening condition is a condition for switching the on-off valve 58 to an open state. The closing condition is a condition for switching the on-off valve 58 to a closed state. The opening condition and the closing condition will be described in detail later. The storage unit 79 may be rewritable. The various pieces of information stored in the storage unit 79 are read out by the ECU 75 as appropriate.

[0099] The saddle-riding type vehicle 1 includes an IMU 81. The IMU 81 is also called an inertial measurement unit. The IMU 81 detects three-dimensional inertial motion (translational motion and rotational motion in three orthogonal axial directions) of the saddle-riding type vehicle 1. The IMU 81 can detect the attitude of the saddle-riding type vehicle 1. The IMU 81 detects the angle of the saddle-riding type vehicle 1 around an axis in the width direction Y (called a pitch angle), i.e., the tilt in the fore-aft direction X. The IMU 81 detects the angle of the saddle-riding type vehicle 1 around an axis in the fore-aft direction X (called a roll angle), i.e., the tilt in the width direction Y. The IMU 81 detects the angle of the saddle-riding type vehicle 1 around an axis in the up-down direction Z (called a yaw angle). Information detected by the IMU 81 is transmitted to the ECU 75. That is, the ECU 75 can detect the attitude of the saddle-riding type vehicle 1 via the IMU 81.

[0100] As shown in FIG. 6, the saddle-ride type vehicle 1 also includes a stroke sensor 64, a speed sensor 66, an acceleration sensor 68, and a pressure sensor .

[0101] The stroke sensor 64 detects the stroke amount of the front fork 14. In other words, the stroke sensor 64 detects the extension / contraction amount of the front fork 14. The speed sensor 66 detects the traveling speed of the saddle riding type vehicle 1. The acceleration sensor 68 detects the acceleration of the saddle riding type vehicle 1. The pressure sensor 70 detects the pressure of exhaust gas inside the exhaust device 29.

[0102] Information detected by various sensors such as the accelerator opening sensor 61, stroke sensor 64, throttle valve opening sensor 65, speed sensor 66, acceleration sensor 68, crankshaft position sensor 69, and pressure sensor 70 is configured to be transmitted to the ECU 75.

[0103] <Regarding exhaust gas injection> Here, a mechanism for generating a first force that acts in a direction to prevent the front wheels 24 from lifting off the road surface by injecting exhaust gas from the exhaust port 73 will be described.

[0104] Fig. 7 is a schematic diagram of the saddle-ride type vehicle 1 and the exhaust device 29 as seen from the right side. Fig. 7 shows a state in which the on-off valve 58 is closed and exhaust gas is being injected from the exhaust port 73 to the outside of the exhaust device 29. The jet of exhaust gas injected from the exhaust port 73 is indicated by the symbol H. That is, when exhaust gas is injected from the exhaust port 73, a jet H is generated at a starting point Ce which corresponds to the center of the exhaust port 73. Note that in Fig. 7 and other figures, the road surface is indicated by the symbol G. The point of contact between the road surface G and the rear wheel 49 is referred to as a rear contact point T.

[0105] The first force described above is a reaction force F of the jet flow H. When the jet flow H is ejected from the exhaust port 73, a reaction force F is generated as shown in FIG. 8. The reaction force F acts on the saddle-type vehicle 1. The reaction force F also acts on the front wheel 24. The reaction force F acts in a direction that prevents the front wheel 24 from lifting off the road surface G.

[0106] The first mechanism that acts to prevent the front wheel 24 from lifting off the road surface G due to the reaction force F will be described with reference to Figure 8. For ease of explanation, part of the frame that constitutes the saddle riding type vehicle 1 is omitted from Figure 8.

[0107] In the first embodiment, the exhaust port 73 is configured to discharge exhaust gases upward and rearward in a side view of the vehicle, so that the jet flow H flows rearward and upward from the starting point Ce in a side view of the vehicle.

[0108] The reaction force F is directed in the opposite direction to the jet flow H. Therefore, the reaction force F acts forward and downward from the starting point Ce in a side view of the vehicle.

[0109] The reaction force F is a force that acts forward and downward from the starting point Ce in a side view of the vehicle. Therefore, of the components of the reaction force F, a component of force that acts downward from the starting point Ce in the up-down direction Z in a side view of the vehicle is defined as a first component of force F1. Furthermore, a component of force that acts forward from the starting point Ce in the fore-and-aft direction X in a side view of the vehicle is defined as a second component of force F2. In other words, by ejecting exhaust gases rearward and upward from the exhaust port 73 in a side view of the vehicle, the first component of force F1 that acts downward from the starting point Ce in a side view of the vehicle acts on the saddle-riding type vehicle 1.

[0110] The first component force F1 acts on the front wheel 24. The first component force F1 acts downward on the front wheel 24. The downward acting first component force F1 is a force that acts in a direction pressing the front wheel 24 of the saddle riding type vehicle 1 against the road surface G. The first component force F1 acts in a direction pressing the front wheel 24 against the road surface G, thereby preventing the front wheel 24 from lifting up from the road surface G.

[0111] In summary, a first component force F1 acting downward from the starting point Ce is generated by discharging exhaust gas above the exhaust port 73. The generation of the first component force F1 can prevent the saddle riding type vehicle 1 from performing a wheelie.

[0112] When the reaction force F is a downward force in the vertical direction Z, the first component force F1 becomes larger. That is, by positioning the exhaust port 73 so that the direction of the jet flow H is upward in the vertical direction Z, the first component force F1 can be made larger. As a result, the force in the direction pressing the front wheels 24 against the road surface G can be made larger.

[0113] Furthermore, the magnitudes of the reaction force F and the first component force F1 are proportional to the speed of the jet flow H. By making the exhaust port 73 smaller, the speed of the jet flow increases. Therefore, by making the exhaust port 73 smaller, the first component force can be increased. As a result, the force in the direction pressing the front wheels 24 against the road surface G can be increased.

[0114] Next, a second mechanism for preventing the front wheels 24 from lifting off the road surface G due to the reaction force F will be described with reference to FIG.

[0115] When exhaust gas is ejected from the exhaust port 73 and a jet flow H is generated, a reaction force F of the jet flow H acts on the saddle riding type vehicle 1. The point of contact between the rear wheel 49 and the road surface G is defined as rear contact point T. The start point Ce is located above the rear contact point T. The reaction force F acts forward and downward from the start point Ce in a side view of the vehicle. Therefore, the reaction force F generates a first moment M1. The first moment M1 acts around the rear contact point T. More specifically, the first moment M1 acts in a rightward (clockwise) direction with the rear contact point T as a fulcrum in a right side view of the saddle riding type vehicle 1. Therefore, due to the reaction force F, a first moment M1 with the rear contact point T as a fulcrum acts on the saddle riding type vehicle 1.

[0116] The first moment M1 is a force that acts in a clockwise direction with the rear contact point T as a fulcrum when viewed from the right side of the saddle riding type vehicle 1. In other words, the first moment M1 acts forward and downward when viewed from the side of the vehicle. Therefore, the first moment M1 is a force that acts in a direction that presses the front wheel 24 of the saddle riding type vehicle 1 against the road surface G. In other words, the first moment M1 moves the front wheel 24 downward with the rear contact point T as a fulcrum. Therefore, by the first moment M1 acting in a direction that presses the front wheel 24 against the road surface G, it is possible to prevent the front wheel 24 from lifting off the road surface G.

[0117] The reason why the first moment M1 can prevent the saddle riding type vehicle 1 from performing a wheelie will be further explained. As shown in FIG. 9, when the second moment M2 acts on the saddle riding type vehicle 1, the front wheel 24 tends to lift off the road surface G. The second moment M2 is a force that acts counterclockwise with the rear contact point T as a fulcrum when viewed from the right side of the saddle riding type vehicle 1. Because the first moment M1 is a force in the opposite direction to the second moment M2, generating the first moment M1 can offset the second moment M2. Therefore, generating the first moment M1 can prevent the front wheel 24 from lifting off the road surface G.

[0118] In this way, when viewed from the right side of the saddle-riding type vehicle 1, the jet flow H is generated in the counterclockwise direction with the rear contact point T as the fulcrum, thereby generating a first moment M1 that acts in the clockwise direction with the rear contact point T as the fulcrum. By generating the first moment M1, it is possible to prevent the saddle-riding type vehicle 1 from performing a wheelie when traveling on a circuit, for example.

[0119] In FIG. 9, the distance from the rear contact point T to the starting point Ce is indicated by the symbol Ds. The line connecting the rear contact point T and the starting point Ce is indicated by the symbol Lw. The angle between the direction of the reaction force F and the line Lw is indicated by the symbol N. The component of the reaction force F in the direction perpendicular to the line Lw is defined as a third component force F3. Here, the magnitude of the first moment M1 corresponds to the product of the magnitude L3 of the third component force F3 and the distance Ds. The third component force F3 is calculated using the reaction force F and the angle N using the following formula (A). F3=F·(sinN)……(A)

[0120] As shown in the above formula (A), the closer the angle N is to 90°, the greater the third component force F3. In other words, the closer the angle N is to 90°, the stronger the first moment M1. Furthermore, the greater the distance Ds, the stronger the first moment M1. In other words, the first moment M1 can be increased by positioning the exhaust port 73 farther from the road surface G. In other words, in order to increase the first moment M1, it is preferable to position the exhaust port 73 higher than the rear axle 47, and it is more preferable to position the exhaust port 73 higher than the upper end of the rear wheel 49. By increasing the first moment M1, it is possible to further prevent the saddle-riding type vehicle 1 from performing a wheelie when riding on a circuit, for example.

[0121] Furthermore, the magnitude of the reaction force F is proportional to the speed of the jet H. By making the exhaust port 73 smaller, the speed of the jet H increases. Therefore, by making the exhaust port 73 smaller, the reaction force F can be increased. In other words, by making the exhaust port 73 smaller, the third component force F3 increases. Therefore, by making the exhaust port 73 smaller, the force in the direction pressing the front wheels 24 against the road surface G can be increased.

[0122] 10 shows a state in which the on-off valve 58 is open and exhaust gas is being injected from the exhaust port 71 to the outside of the exhaust device 29. The jet of exhaust gas injected from the exhaust port 71 is indicated by the symbol Hc. When exhaust gas is injected from the exhaust port 71, a jet Hc is generated at a starting point Cf corresponding to the center of the exhaust port 71. The exhaust port 71 is configured to discharge exhaust gas rearward in the longitudinal direction X as viewed from the side of the vehicle. Therefore, the jet Hc flows rearward in the longitudinal direction X from the starting point Cf as viewed from the side of the vehicle.

[0123] FIG. 11 shows a reaction force Fc generated by a jet flow Hc ejected from a starting point Cf corresponding to the exhaust port 71. For ease of explanation, the exhaust device 29 is not shown in FIG. 11. The reaction force Fc has a direction opposite to that of the jet flow Hc. The jet flow Hc flows rearward in the longitudinal direction X from the starting point Cf in a side view of the vehicle. Therefore, the reaction force Fc is a force that acts forward in the longitudinal direction X from the starting point Cf in a side view of the vehicle. In other words, the reaction force Fc acts horizontally or in a direction substantially the same as the horizontal direction. Therefore, the first component of the reaction force Fc is zero or very small. The first component of the reaction force Fc is a downward component in the vertical direction Z from the starting point Cf in a side view of the vehicle.

[0124] Furthermore, exhaust port 71 is disposed below exhaust port 73. In other words, start point Cf, which corresponds to the position of exhaust port 71, is located below start point Ce, which corresponds to the position of exhaust port 73. Therefore, distance Dk from start point Cf to rear contact point T is shorter than distance Ds from start point Ce to rear contact point T. Therefore, moment Mc generated due to reaction force Fc of jet Hc shown in FIG. 11 is weaker than first moment M1 generated due to reaction force F of jet H shown in FIG. 9.

[0125] The exhaust port 73 is configured to discharge the exhaust gas upward. Therefore, the first component F1 of the reaction force F is greater than the first component Fc of the reaction force F. Therefore, the reaction force F is more effective than the reaction force Fc in preventing the front wheels 24 from lifting off the road surface G.

[0126] The exhaust port 73 is disposed higher than the exhaust port 71. That is, as shown in FIGS. 9 and 11, the distance Ds from the rear contact point T to the exhaust port 73 is longer than the distance Dk from the rear contact point T to the exhaust port 71. Therefore, the first moment M1 generated by the reaction force F is greater than the moment Mc generated by the reaction force Fc. Therefore, the reaction force F is more effective than the reaction force Fc in preventing the front wheel 24 from lifting off the road surface G.

[0127] In this way, when exhaust gas is ejected from exhaust port 73, a greater force acts in the direction of pressing the front wheel 24 against the road surface than when exhaust gas is ejected from exhaust port 71. Therefore, when exhaust gas is ejected from exhaust port 73, it is possible to more effectively prevent the saddle-riding type vehicle 1 from doing a wheelie when driving on a circuit, for example, than when exhaust gas is ejected from exhaust port 71.

[0128] <Control of on-off valve according to embodiment 1> Next, a configuration for switching the on-off valve 58 from a closed state to an open state in the first embodiment will be described. In the first embodiment, a spring-type valve is used as the on-off valve 58. That is, in the first embodiment, the on-off valve 58 is switched from a closed state to an open state according to the magnitude of the exhaust gas pressure acting on the on-off valve 58. The exhaust gas pressure inside the exhaust device 29 is also called the "back pressure of the engine 31" or the "exhaust gas back pressure."

[0129] When the pressure of the exhaust gas inside the exhaust device 29 is less than a predetermined value K1, the on-off valve 58 is configured to be in a closed state.

[0130] The predetermined value K1 is a value that is set in advance depending on various conditions, such as the weight and performance of the saddle riding type vehicle 1. The predetermined value K1 may be changed by the driver using an input unit (not shown). Information on the predetermined value K1 is stored in the storage unit 79. In this way, in the first embodiment, the blocking condition corresponds to the exhaust gas pressure inside the exhaust device 29 being less than the predetermined value K1.

[0131] When the saddle riding type vehicle 1 is in operation, if the traveling speed of the saddle riding type vehicle 1 is low, the exhaust gas pressure inside the exhaust device 29 is low. In other words, if the traveling speed of the saddle riding type vehicle 1 is low, the exhaust gas pressure acting on the on-off valve 58 is low. In other words, if the traveling speed of the saddle riding type vehicle 1 is low and the exhaust gas pressure is lower than the predetermined value K1, the on-off valve 58 remains closed.

[0132] Examples of situations in which a wheelie is likely to occur when driving the saddle-riding vehicle 1 include sudden acceleration while driving on a circuit or sudden engagement of the clutch while driving on a circuit. Generally, sudden acceleration and sudden engagement of the clutch occur when the saddle-riding vehicle 1 is traveling at a low speed while driving on a circuit. In other words, when the saddle-riding vehicle 1 is traveling at a low speed while driving on a circuit, the saddle-riding vehicle 1 is more likely to perform a wheelie.

[0133] Therefore, in the saddle-riding vehicle 1 according to the first embodiment, when the traveling speed of the saddle-riding vehicle 1 is low and the exhaust gas pressure is low, the on-off valve 58 is switched to a closed state. In other words, when the traveling speed of the saddle-riding vehicle 1 is low, the exhaust port from which exhaust gas is injected from the exhaust device 29 is switched from exhaust port 71 to exhaust port 73. By injecting exhaust gas from exhaust port 73, a greater force acts in the direction of pressing the front wheel 24 against the road surface G than when exhaust gas is injected from exhaust port 71. As a result, by injecting exhaust gas from exhaust port 73 when the traveling speed of the saddle-riding vehicle 1 is low, it is possible to further prevent the saddle-riding vehicle 1 from performing a wheelie when, for example, driving on a circuit.

[0134] When the pressure of the exhaust gas acting on the on-off valve 58 is equal to or greater than a predetermined value K1, the on-off valve 58 is switched to an open state. The condition for opening is that the pressure of the exhaust gas inside the exhaust device 29 is equal to or greater than the predetermined value K1.

[0135] When the traveling speed of the saddle riding type vehicle 1 is high, the amount of exhaust gas generated increases. Therefore, when the traveling speed of the saddle riding type vehicle 1 is high, the pressure of the exhaust gas inside the exhaust device 29 is high. In other words, when the traveling speed of the saddle riding type vehicle 1 is high, the pressure of the exhaust gas acting on the on-off valve 58 increases. That is, when the traveling speed of the saddle riding type vehicle 1 increases and the pressure of the exhaust gas becomes equal to or greater than a predetermined value K1, the on-off valve 58 opens due to the pressure of the exhaust gas that has increased to or greater than the predetermined value K1. That is, in the first embodiment, when the traveling speed of the saddle riding type vehicle 1 increases above a certain value, the on-off valve 58 switches from a closed state to an open state.

[0136] As shown in FIG. 5, when the on-off valve 58 is open, exhaust gas can flow into the first branch pipe 56. That is, when the on-off valve 58 is open, exhaust gas can be discharged from the exhaust port 71. The first branch pipe 56 has a larger diameter than the second branch pipe 57. Therefore, most of the exhaust gas guided from the engine 31 to the exhaust device 29 flows into the second branch pipe 56 and is discharged to the outside through the exhaust port 71. That is, when the saddle-riding type vehicle 1 is traveling at a high speed, the exhaust gas is ejected from the exhaust port 71, generating a jet flow Hc, as shown in FIG. 10. The exhaust port 71 is configured to be larger than the exhaust port 73. Therefore, even when the saddle-riding type vehicle 1 is traveling at a high speed and a large amount of exhaust gas is generated, the exhaust gas can be efficiently discharged from the large exhaust port 71.

[0137] When exhaust gas is ejected from the exhaust port 71, the force acting in the direction of pressing the front wheel 24 against the road surface G is smaller than when exhaust gas is ejected from the exhaust port 73. However, if the saddle-riding vehicle 1 is already traveling at a high speed, the frequency of sudden clutch engagement or rapid acceleration is low when traveling on a circuit, for example. Therefore, when the saddle-riding vehicle 1 is traveling at a high speed, the saddle-riding vehicle 1 is unlikely to perform a wheelie even if the force acting in the direction of pressing the front wheel 24 against the road surface G decreases. Therefore, when the saddle-riding vehicle 1 is traveling at a high speed, the on-off valve 58 is switched to an open state to discharge exhaust gas from the exhaust port 71. By discharging exhaust gas from the exhaust port 71 when the saddle-riding vehicle 1 is traveling at a high speed when traveling on a circuit, for example, it is possible to efficiently discharge exhaust gas while preventing the saddle-riding vehicle 1 from performing a wheelie.

[0138] The saddle-ride type vehicle 1 includes a front wheel 24, a rear wheel 49, and an exhaust device 29. The exhaust device 29 discharges exhaust gas. The exhaust device 29 includes an exhaust port 73. The exhaust port 73 injects exhaust gas, causing a reaction force F to act on the front wheel 24. The reaction force F prevents the front wheel 24 from lifting up from the road surface G. In other words, the reaction force F acts in a direction that presses the front wheel 24 against the road surface G. Therefore, the front wheel 24 is prevented from lifting up from the road surface G.

[0139] Generally, when a driver of a saddle-type vehicle suddenly opens the accelerator or suddenly engages the clutch, for example, while driving on a circuit, the saddle-type vehicle will suddenly accelerate. When a conventional saddle-type vehicle suddenly accelerates, the front wheel tends to lift off the road surface, causing the saddle-type vehicle to easily perform a wheelie. Therefore, when driving a conventional saddle-type vehicle, the driver is required to carefully operate the accelerator and clutch of the saddle-type vehicle.

[0140] On the other hand, in the saddle-riding vehicle 1 according to the first embodiment, the exhaust device 29 generates a reaction force F by injecting exhaust gas from the exhaust port 73. The reaction force F acts on the front wheel 24. The reaction force F acts in a direction that prevents the front wheel 24 from lifting off the road surface G. Therefore, in the saddle-riding vehicle 1 according to the first embodiment, it is difficult for the saddle-riding vehicle to perform a wheelie even when suddenly accelerating while driving on a circuit, for example. For this reason, the saddle-riding vehicle 1 according to the first embodiment provides assistance in operating the accelerator and clutch of the saddle-riding vehicle 1. Therefore, the driver can easily operate the saddle-riding vehicle 1 according to the first embodiment.

[0141] When the saddle-riding vehicle 1 starts moving, the exhaust port 73 injects exhaust gas, causing a reaction force F to act on the front wheel 24. When the saddle-riding vehicle 1 starts moving, the reaction force F acts in a direction that prevents the front wheel 24 from lifting off the road surface G. Therefore, when the saddle-riding vehicle 1 starts moving while traveling on a circuit, for example, the saddle-riding vehicle 1 is less likely to perform a wheelie. Therefore, the acceleration performance of the saddle-riding vehicle 1 when starting moving while traveling on a circuit, for example, can be easily improved.

[0142] As an example, when the saddle-riding vehicle 1 suddenly accelerates while traveling on a circuit, the exhaust port 73 injects exhaust gas, causing a reaction force F to act on the front wheel 24. When the saddle-riding vehicle 1 suddenly accelerates while traveling on a circuit, the reaction force F acts in a direction that prevents the front wheel 24 from lifting off the road surface G. Therefore, when the saddle-riding vehicle 1 suddenly accelerates while traveling on a circuit, the saddle-riding vehicle 1 is less likely to perform a wheelie. Therefore, the acceleration performance of the saddle-riding vehicle 1 when the saddle-riding vehicle 1 suddenly accelerates while traveling on a circuit can be easily improved.

[0143] The first force acting in a direction that prevents the front wheel 24 from lifting off the road surface G is a reaction force F of the jet flow H of exhaust gas ejected from the exhaust port 73. Therefore, by ejecting exhaust gas from the exhaust port 73, it becomes easy to apply the first force to the front wheel 24.

[0144] The exhaust port 73 is configured to eject exhaust gas rearward. Therefore, it is easy for the reaction force F to act in a direction that presses the front wheel 24 against the road surface F. Therefore, the reaction force F acts in a direction that prevents the front wheel 24 from lifting up from the road surface G.

[0145] The exhaust port 73 is positioned above the center of rotation of the rear wheel 49. Therefore, it is even easier for the reaction force F to act in a direction pressing the front wheel 24 against the road surface G. Therefore, the reaction force F acts in a direction that further prevents the front wheel 24 from lifting off the road surface G.

[0146] The exhaust port 73 is disposed above the upper end of the rear wheel 49. Therefore, it is even easier for the reaction force F to act in a direction pressing the front wheel 24 against the road surface G. Therefore, the reaction force F acts in a direction that further prevents the front wheel 24 from lifting off the road surface G.

[0147] The reaction force F generates a first moment M1. The first moment M1 acts around the rear contact point T. The first moment M1 acts in a direction pressing the front wheel 24 against the road surface G. In other words, the first moment M1 moves the front wheel 24 downward, with the rear contact point T as a fulcrum. Therefore, the first moment M1 acts in a direction that prevents the front wheel 24 from lifting up from the road surface G. Therefore, the reaction force F acts in a direction that prevents the front wheel 24 from lifting up from the road surface G.

[0148] The exhaust port 73 is configured to eject exhaust gas upward. Therefore, it is easy for the reaction force F to act downward on the front wheel 24. Therefore, the reaction force F acts in a direction that prevents the front wheel 24 from lifting off the road surface G.

[0149] The reaction force F includes a first component F1. The first component F1 acts downward on the front wheel 24. Therefore, the first component F1 acts in a direction that suppresses the front wheel 24 from lifting up from the road surface G. Therefore, the reaction force F acts in a direction that suppresses the front wheel 24 from lifting up from the road surface G.

[0150] The exhaust device 29 has an exhaust port 71 that discharges exhaust gas. The exhaust port 73 is smaller than the exhaust port 71. Therefore, it is easy to increase the velocity of the exhaust gas injected from the exhaust port 73. Therefore, it is easy to increase the reaction force F.

[0151] The exhaust port 73 has a diameter smaller than the diameter of the exhaust port 71. Therefore, it is easy to increase the velocity of the exhaust gas injected from the exhaust port 73. Therefore, it is easy to increase the reaction force F. Therefore, the reaction force F acts in a direction that further suppresses the lifting of the front wheel 24 from the road surface G.

[0152] The exhaust port 73 is disposed higher than the exhaust port 71. Therefore, it is even easier for the reaction force F to act in a direction that presses the front wheel 24 against the road surface G. Therefore, the reaction force F acts in a direction that further prevents the front wheel 24 from lifting up from the road surface G.

[0153] The exhaust device 29 includes an on-off valve 58 that opens and closes the exhaust port 71. Therefore, it is easy to control the injection of exhaust gas at the exhaust port 71.

[0154] The on-off valve 58 is configured to close the exhaust port 71 when the exhaust gas pressure in the exhaust device 29 is less than a predetermined value K1. Therefore, when the exhaust gas pressure in the exhaust device 29 is less than the predetermined value K1, the exhaust port 71 does not inject exhaust gas. Therefore, when the exhaust gas pressure in the exhaust device 29 is less than the predetermined value K1, it is easy to increase the amount of exhaust gas injected from the exhaust port 73. Therefore, when the exhaust gas pressure in the exhaust device 29 is less than the predetermined value K1, it is easy to increase the reaction force F. Therefore, when the exhaust gas pressure in the exhaust device 29 is less than the predetermined value K1, the saddle-type vehicle 1 is less likely to perform a wheelie when traveling on a circuit, etc. As a result, it is easy to improve the acceleration performance of the saddle-type vehicle 1 when traveling on a circuit, etc.

[0155] For example, when the pressure of the exhaust gas inside the exhaust device 29 is less than the predetermined value K1, the saddle-riding type vehicle 1 travels at a low speed. Therefore, when the saddle-riding type vehicle 1 travels at a low speed on a circuit or the like, the saddle-riding type vehicle 1 is less likely to perform a wheelie.

[0156] For example, the saddle-riding type vehicle 1 starts moving when the pressure of the exhaust gas inside the exhaust device 29 is less than a predetermined value K1. Therefore, when the saddle-riding type vehicle 1 starts moving while traveling on a circuit, the saddle-riding type vehicle 1 is less likely to perform a wheelie.

[0157] For example, when the pressure of the exhaust gas inside the exhaust device 29 is less than the predetermined value K1, the saddle-riding type vehicle 1 may suddenly accelerate while traveling on a circuit, for example. Therefore, when the saddle-riding type vehicle 1 suddenly accelerates while traveling on a circuit, the saddle-riding type vehicle 1 is less likely to perform a wheelie.

[0158] The on-off valve 58 is configured to open the exhaust port 71 when the pressure of the exhaust gas in the exhaust device 29 is equal to or higher than the predetermined value K1. Therefore, when the pressure of the exhaust gas in the exhaust device 29 is equal to or higher than the predetermined value K1, the on-off valve 58 is switched to an open state to discharge the exhaust gas from the exhaust port 71. Discharging the exhaust gas from the exhaust port 71 greatly improves the exhaust efficiency of the exhaust gas. As a result, by controlling the opening and closing of the on-off valve 58 in accordance with the level of the exhaust gas pressure, it is possible to improve the exhaust efficiency of the exhaust gas in the saddle-riding type vehicle 1 and prevent the saddle-riding type vehicle 1 from doing a wheelie when riding on a circuit, for example.

[0159] For example, when the pressure of the exhaust gas inside the exhaust device 29 is equal to or greater than a predetermined value K1, the saddle riding type vehicle 1 travels at high speed. Therefore, when the saddle riding type vehicle 1 travels at high speed, the exhaust gas discharge efficiency of the saddle riding type vehicle 1 can be improved.

[0160] Furthermore, in the saddle-riding vehicle 1 according to the first embodiment, exhaust gas is ejected from the exhaust port 73 of the exhaust device 29, thereby generating a force that acts in a direction that presses the front wheel 24 downward. In other words, ejecting exhaust gas from the exhaust port 73 prevents the saddle-riding vehicle 1 from performing a wheelie, for example, when driving on a circuit. A device that discharges exhaust gas is a configuration that is generally provided in the saddle-riding vehicle 1. Therefore, there is no need to install a new device, in addition to the exhaust device 29, in the saddle-riding vehicle 1 for generating a force that acts in a direction that presses the front wheel 24 downward. This eliminates the need to add a new device to the saddle-riding vehicle 1 for generating a force that acts in a direction that presses the front wheel 24 downward. This makes it possible to prevent the saddle-riding vehicle 1 from performing a wheelie, for example, when driving on a circuit, while avoiding an increase in the complexity of the saddle-riding vehicle 1. In other words, a saddle-riding vehicle 1 that can prevent the saddle-riding vehicle 1 from performing a wheelie, for example, when driving on a circuit, can be realized at a lower cost. Furthermore, by effectively utilizing the exhaust gas that is inevitably generated when driving the saddle-riding vehicle 1, it is possible to prevent the saddle-riding vehicle 1 from performing a wheelie, for example, when driving on a circuit. That is, the exhaust device 29 can effectively utilize exhaust gas to contribute to posture control of the saddle-riding type vehicle 1. Therefore, it is possible to realize a saddle-riding type vehicle 1 that is environmentally friendly and can prevent wheelies from occurring when driving on a circuit, for example. [Example]

[0161] Next, a second embodiment of the present invention will be described. Note that the same components as those in the saddle-riding vehicle 1 according to the first embodiment are assigned the same reference numerals, and only different components will be described in detail. The configuration of the exhaust device 29 according to the second embodiment is the same as that of the first embodiment. Furthermore, the positions at which the exhaust port 71 and the exhaust port 73 are disposed in the second embodiment are also the same as those of the first embodiment.

[0162] <Configuration of on-off valve and control system> The second embodiment differs from the first embodiment in the configuration of the on-off valve 58. In the first embodiment, a spring-type valve is used as the on-off valve 58. When exhaust gas having a pressure equal to or greater than a predetermined value K1 acts on the on-off valve 58, the on-off valve 58 is pushed open by the pressure of the exhaust gas. That is, in the first embodiment, the opening and closing operation of the on-off valve 58 is adjusted according to the level of the exhaust gas pressure. On the other hand, in the saddle-riding type vehicle 1A according to the second embodiment, an electrically operated valve is used as the on-off valve 58. In the second embodiment, the ECU 75 is configured to control the opening and closing operation of the on-off valve 58. That is, under the control of the ECU 75, the on-off valve 58 is reversibly switched from the closed state shown in FIG. 4 to the open state shown in FIG. 5.

[0163] 12 is a functional block diagram illustrating a control system in a saddle-riding type vehicle 1A according to a second embodiment. In the second embodiment, as in the first embodiment, the ECU 75 includes a CPU 77 and a storage unit 79. The saddle-riding type vehicle 1A includes an IMU 81. The IMU 81 detects the posture of the saddle-riding type vehicle 1A. Information detected by the IMU 81 is transmitted to the ECU 75. Information detected by various sensors, such as the accelerator opening sensor 61, stroke sensor 64, throttle valve opening sensor 65, speed sensor 66, acceleration sensor 68, crankshaft position sensor 69, and pressure sensor 70, is transmitted to the ECU 75.

[0164] However, in the second embodiment, unlike the first embodiment, the on-off valve 58 is electrically connected to the ECU 75 as shown in Fig. 12. The ECU 75 controls the opening and closing operation of the on-off valve 58.

[0165] The ECU 75 determines whether a predetermined closing condition or an opening condition is satisfied. If the ECU 75 determines that the closing condition is satisfied, the ECU 75 performs control to switch the on-off valve 58 to a closed state. On the other hand, if the ECU 75 determines that the opening condition is satisfied, the ECU 75 performs control to switch the on-off valve 58 to an open state. The closing condition is a condition for switching the on-off valve 58 to a closed state and controlling the exhaust gas to be injected from the exhaust port 73. The opening condition is a condition for switching the on-off valve 58 to an open state and controlling the exhaust gas to be injected from the exhaust port 71.

[0166] In the second embodiment, the ECU 75 determines whether the closing condition or the opening condition is met based on information detected by the IMU 81 and the stroke sensor 64. In the second embodiment, if the pitch angle of the saddle riding type vehicle 1A is equal to or greater than a predetermined value K2, or if the stroke amount of the front forks 14 is equal to or greater than a predetermined value K3, the ECU 75 determines that the closing condition is met. On the other hand, if the pitch angle of the saddle riding type vehicle 1A is less than the predetermined value K2 and the stroke amount of the front forks 14 is less than the predetermined value K3, the ECU 75 determines that the opening condition is met.

[0167] In other words, in the second embodiment, the closing conditions for the on-off valve 58 include the following two. The first closing condition is that the pitch angle of the saddle riding type vehicle 1A is equal to or greater than a predetermined value K2. The second closing condition is that the stroke amount of the front fork 14 is equal to or greater than a predetermined value K3. In the second embodiment, if either of the two closing conditions is satisfied, the ECU 75 determines that the closing condition for the on-off valve 58 is satisfied. On the other hand, if the closing condition for the on-off valve 58 is not satisfied, the ECU 75 determines that the opening condition for the on-off valve 58 is satisfied.

[0168] The IMU 81 detects the pitch angle of the saddle riding type vehicle 1A. That is, the IMU 81 can detect the inclination of the saddle riding type vehicle 1A in the fore-and-aft direction X. As shown in FIG. 12 , information detected by the IMU 81 is transmitted to the ECU 75. When driving on a circuit, for example, the front of the saddle riding type vehicle 1A moves upward relative to the rear of the saddle riding type vehicle 1A, which is a precursor to the saddle riding type vehicle 1A performing a wheelie. Therefore, if the pitch angle of the saddle riding type vehicle 1A is equal to or greater than a predetermined value K2, the ECU 75 can determine that there is a high possibility that the saddle riding type vehicle 1A will perform a wheelie in the near future. In other words, if the IMU 81 detects that the front of the saddle riding type vehicle 1A has moved upward relative to the rear of the saddle riding type vehicle 1A by more than the predetermined value K2, the ECU 75 determines that a blocking condition has been satisfied. The blocking condition is also a condition under which it is determined that there is a high possibility that the saddle riding type vehicle 1A will perform a wheelie in the near future.

[0169] The stroke sensor 64 detects the stroke amount of the front fork 14. As shown in FIG. 12 , information detected by the stroke sensor 64 is transmitted to the ECU 75. When riding on a circuit, for example, the front wheel 24 lifts off the road surface G, which is a sign that a wheelie will occur, and the front fork 14 extends. In other words, when riding on a circuit, for example, the stroke amount of the front fork 14 increases, which is a sign that the saddle-riding type vehicle 1 will perform a wheelie. Therefore, if the stroke sensor 64 detects that the stroke amount of the front fork 14 is equal to or greater than the predetermined value K3, the ECU 75 can determine that there is a high possibility that the saddle-riding type vehicle 1 will perform a wheelie in the near future. In other words, if the stroke sensor 64 detects that the stroke amount of the front fork 14 is equal to or greater than the predetermined value K3, the ECU 75 determines that the blocking condition is satisfied.

[0170] <Control of on-off valve according to embodiment 2> Here, the operation of the saddle riding type vehicle 1A according to the second embodiment will be described, and details of the control for switching the on-off valve 58 according to the second embodiment from a closed state to an open state will be described. Fig. 13 is a flowchart showing the operation of the saddle riding type vehicle 1A according to the second embodiment.

[0171] Step S1 When starting to drive the saddle riding type vehicle 1A, the driver starts the engine 31. After starting the engine 31, the driver drives the saddle riding type vehicle 1A.

[0172] Step S2 When the saddle riding type vehicle 1A starts traveling, the ECU 75 constantly monitors whether the closing condition of the on-off valve 58 or the opening condition of the on-off valve 58 is satisfied. First, in step S2, the ECU 75 determines whether the closing condition of the on-off valve 58 is satisfied based on information transmitted from the IMU 81. The IMU 81 constantly detects the pitch angle of the saddle riding type vehicle 1A. The IMU 81 then transmits information about the detected pitch angle to the ECU 75 as needed.

[0173] The ECU 75 reads information about a predetermined value K2 stored in advance in the storage unit 79. The ECU 75 compares the pitch angle of the saddle riding type vehicle 1A with the predetermined value K2. The ECU 75 branches the processing depending on the value of the pitch angle of the saddle riding type vehicle 1A. If the pitch angle of the saddle riding type vehicle 1A is equal to or greater than the predetermined value K2, the ECU 75 determines that the closing condition of the on-off valve 58 is satisfied (see symbol J2 in FIG. 13). In the second embodiment, the pitch angle of the saddle riding type vehicle 1A being equal to or greater than the predetermined value K2 corresponds to the first closing condition. If it is determined that the closing condition of the on-off valve 58 is satisfied, the ECU 75 shifts the processing to step S6. The process of step S6 will be described later.

[0174] On the other hand, if the pitch angle of the saddle riding type vehicle 1A is less than the predetermined value K2, the ECU 75 causes the process to proceed to step S3.

[0175] Step S3 When the pitch angle of the saddle riding type vehicle 1A is less than the predetermined value K2, the ECU 75 determines whether or not a closing condition for the on-off valve 58 is satisfied based on information transmitted from the stroke sensor 64. The stroke sensor 64 constantly detects the stroke amount of the front fork 14. The stroke sensor 64 then transmits information on the detected stroke amount to the ECU 75 as needed.

[0176] The ECU 75 reads information about a predetermined value K3 stored in advance in the storage unit 79. The ECU 75 compares the stroke amount of the front forks 14 with the predetermined value K3. The ECU 75 branches the process depending on the value of the stroke amount of the front forks 14. If the stroke amount of the front forks 14 is equal to or greater than the predetermined value K3, the ECU 75 determines that the closing condition of the on-off valve 58 is satisfied (see symbol J2 in FIG. 13). In the second embodiment, the stroke amount of the front forks 14 being the predetermined value K3 corresponds to the second closing condition. If it is determined that the closing condition of the on-off valve 58 is satisfied, the ECU 75 shifts the process to step S6. The process of step S6 will be described later.

[0177] On the other hand, if the stroke amount of the front forks 14 is less than the predetermined value K3, the ECU 75 determines that neither of the closing conditions of the on-off valve 58 is satisfied. That is, the ECU 75 determines that the closing conditions of the on-off valve 58 are satisfied for both the pitch angle of the saddle riding type vehicle 1A and the stroke amount of the front forks 14. If it is determined that the closing conditions of the on-off valve 58 are not satisfied for both the pitch angle of the saddle riding type vehicle 1A and the stroke amount of the front forks 14, the ECU 75 determines that the opening condition of the on-off valve 58 is satisfied (see symbol J1 in FIG. 13). If it is determined that the opening condition of the on-off valve 58 is satisfied, the ECU 75 causes the process to proceed to step S4.

[0178] Step S4 If it is determined in step S3 that the opening condition of the on-off valve 58 is satisfied, the process of step S4 is started. In step S4, the ECU 75 performs control to open the on-off valve 58. That is, the on-off valve 58, which is an electrically operated valve, is controlled by the ECU 75 and switched to an open state.

[0179] Step S5 When the on-off valve 58 is switched to an open state, as shown in Figure 5, exhaust gas guided to the exhaust device 29 via the guide port 59 can flow to the first branch pipe 56. In other words, when the on-off valve 58 is in an open state, exhaust gas can be discharged from the exhaust port 71. The first branch pipe 56 has a larger diameter than the second branch pipe 57. Therefore, most of the exhaust gas guided from the engine 31 to the exhaust device 29 flows into the second branch pipe 56 and is discharged to the outside from the exhaust port 71.

[0180] That is, when the opening condition of the on-off valve 58 is satisfied, the exhaust gas is injected from the exhaust port 71 to generate a jet flow Hc, as shown in Figure 10. In other words, when it is determined that the saddle riding type vehicle 1A is unlikely to perform a wheelie while driving on a circuit, for example, the ECU 75 switches the on-off valve 58 to an open state, causing the exhaust gas to be discharged from the exhaust port 71. The exhaust port 71 is configured to be larger than the exhaust port 73. Therefore, the exhaust gas can be efficiently discharged from the large exhaust port 71.

[0181] In this way, when the opening condition of the on-off valve 58 is satisfied, the processes of steps S4 and S5 are carried out. As a result, as shown in Figures 5 and 10, the on-off valve 58 is switched to an open state, and exhaust gas is efficiently discharged from the exhaust port 71. The exhaust gas discharged from the exhaust port 71 is sprayed rearward in the fore-and-aft direction X when viewed from the side of the vehicle, generating a jet flow Hc. Thereafter, the process proceeds to step S9.

[0182] Step S6 On the other hand, if it is determined in step S2 or step S3 that the closing condition of the on-off valve 58 is satisfied, the process of step S6 is started. In step S6, the ECU 75 performs control to close the on-off valve 58. That is, the on-off valve 58, which is an electrically operated valve, is controlled by the ECU 75 and switched to a closed state.

[0183] Step S7 When the on-off valve 58 is switched to the closed state, as shown in Fig. 4, the exhaust gas guided to the exhaust device 29 via the guide port 59 cannot flow to the first branch pipe 56. Therefore, all of the exhaust gas guided from the engine 31 to the exhaust device 29 is sent to the second branch pipe 57 and discharged to the outside from the exhaust port 73. When the exhaust gas is discharged from the exhaust port 73, a jet flow H is generated at the starting point Ce corresponding to the exhaust port 73, as shown in Fig. 7.

[0184] Step S8 The exhaust port 73 is configured to discharge the exhaust gas rearward and upward in a side view of the vehicle. In other words, the jet flow H is a flow that flows rearward and upward in a side view of the vehicle. Therefore, when the exhaust gas is ejected from the exhaust port 73, the reaction force F generated by the jet flow H includes a downward first component force F1. Therefore, by ejecting the exhaust gas from the exhaust port 73, the first component force F1 of the reaction force F acts in a direction that presses the front wheels 24 against the road surface G, as shown in FIG. 8 .

[0185] The position and orientation of the exhaust port 73 are determined so that the jet flow H flows rearward and upward in a side view of the vehicle, with the rear contact point T as its center. Therefore, the reaction force F generated by the jet flow H is a force that flows forward and downward in a side view of the vehicle, with the rear contact point T as its center. Therefore, as shown in Figure 9, when exhaust gas is ejected from the exhaust port 73, a first moment M1 that flows forward and downward with the rear contact point T as a fulcrum is generated by the reaction force F. The first moment M1 then acts in a direction that presses the front wheel 24 against the road surface G.

[0186] The exhaust port 73 is disposed higher than the exhaust port 71. That is, as shown in FIGS. 9 and 11, the distance Ds from the rear contact point T to the exhaust port 73 is longer than the distance Dk from the rear contact point T to the exhaust port 71. Therefore, when exhaust gas is ejected from the exhaust port 73, the magnitude of the first moment M1 that acts forward and downward with the rear contact point T as the fulcrum becomes stronger. Therefore, the first moment M1 is generated by the reaction force F of the jet flow H, and the force in the direction pressing the front wheel 24 against the road surface G further increases.

[0187] In this way, when the closing condition of the on-off valve 58 is satisfied, the processes of steps S6 and S7 are performed. As a result, as shown in FIGS. 4 and 8, the on-off valve 58 is switched to a closed state and exhaust gas is discharged from the exhaust port 73. The exhaust gas discharged from the exhaust port 73 is sprayed rearward and upward in a side view of the vehicle, generating a jet flow H. A first component force F1 included in the reaction force F of the jet flow H and a first moment M1 generated by the reaction force F of the jet flow H each act in a direction pressing the front wheel 24 against the road surface G. In other words, discharging exhaust gas from the exhaust port 73 increases the force in the direction pressing the front wheel 24 against the road surface G. As a result, the first component force F1 and the first moment M1 prevent the front wheel 24 of the saddle riding type vehicle 1A from lifting off the road surface G and performing a wheelie when driving on a circuit, for example. After exhaust gas is ejected from exhaust port 73 to generate a force in a direction that presses front wheels 24 against road surface G, the process proceeds to step S9.

[0188] Step S9 After the ECU 75 controls the on-off valve 58 to switch between a closed state and an open state, the process branches depending on the operating state of the engine 31. If the engine 31 is stopped, the ECU 75 stops monitoring the closing and opening conditions. On the other hand, if the operation of the engine 31 continues, the process branches to step S2. That is, the ECU 75 continues monitoring the closing and opening conditions. Then, the process from step S2 to step S9 is repeated as appropriate. The series of processes ends when the engine 31 is stopped.

[0189] <Effects of Example 2> The saddle riding type vehicle 1A includes an ECU 75, a stroke sensor 64, and an IMU 81. The stroke sensor 64 and the IMU 81 detect the state of the saddle riding type vehicle 1A. The ECU 75 controls the on-off valve 58 based on the detection results of the stroke sensor 64 and the IMU 81. This makes it easy to control the injection of exhaust gas from the exhaust port 71 in accordance with the state of the saddle riding type vehicle 1A.

[0190] The ECU 75 determines whether the front wheels 24 are about to lift off the road surface G based on the detection results of the stroke sensor 64 and the IMU 81. If the ECU 75 determines that the front wheels 24 are about to lift off the road surface G, the ECU 75 is configured to close the on-off valve 58. Therefore, if the front wheels 24 are about to lift off the road surface G, it is easy to increase the amount of exhaust gas injected from the exhaust port 73. Therefore, if the front wheels 24 are about to lift off the road surface G, it is easy to increase the reaction force F. Therefore, even if the front wheels 24 are about to lift off the road surface G, the reaction force F acts in a direction that prevents the front wheels 24 from lifting off the road surface G.

[0191] The IMU 81 detects the pitch angle of the saddle riding type vehicle 1A. The stroke sensor 64 detects the stroke amount of the front fork 14 that supports the front wheel 24. In this case, it is easy for the stroke sensor 64 and IMU 81 to detect the posture of the saddle riding type vehicle 1A. Therefore, it is easy for the ECU 75 to control the on-off valve 58 in accordance with the posture of the saddle riding type vehicle 1A.

[0192] Specifically, the ECU 75 controls the opening and closing of the on-off valve 58 based on the stroke amount of the front forks 14 and the pitch angle of the saddle riding type vehicle 1A. If the stroke amount of the front forks 14 or the pitch angle of the saddle riding type vehicle 1A exceeds a predetermined value, the front wheel 24 may lift off the road surface G, increasing the possibility that the saddle riding type vehicle 1A may perform a wheelie, for example, when driving on a circuit.

[0193] Therefore, the ECU 75 is configured to determine that the closing condition for the on-off valve 58 is satisfied when the stroke amount of the front fork 14 or the value of the pitch angle of the saddle riding type vehicle 1A becomes equal to or greater than a predetermined value. When it is determined that the closing condition for the on-off valve 58 is satisfied, the ECU 75 switches the on-off valve 58 to a closed state. By switching the on-off valve 58 to a closed state, the location from which exhaust gas is discharged from the exhaust device 29 is switched from the exhaust port 71 to the exhaust port 73.

[0194] When exhaust gas is discharged from the exhaust port 73, a first component force F1 and a first moment M1 are generated due to a reaction force F of the jet flow H. The first component force F1 and the first moment M1 act as forces pressing the front wheel 24 against the road surface G. As a result, the first component force F1 and the first moment M1 can prevent the saddle riding type vehicle 1A from performing a wheelie when traveling on a circuit, etc. In this way, in the second embodiment, when a situation occurs in which it is determined that the saddle riding type vehicle 1A is likely to perform a wheelie when traveling on a circuit, etc., the ECU 75 automatically switches the on-off valve 58 to a closed state, and quickly generates a force that acts in a direction pressing the front wheel 24 against the road surface G. As a result, even when a situation occurs in which the saddle riding type vehicle 1A is likely to perform a wheelie when traveling on a circuit, etc., the control executed by the ECU 75 can further prevent the saddle riding type vehicle 1A from performing a wheelie. [Example]

[0195] Next, a saddle-ride type vehicle 1B according to a third embodiment of the present invention will be described. In the first and second embodiments, a configuration is used as an example in which two types of forces, a first component force F1 and a first moment M1, are generated as forces acting in a direction pressing the front wheel 24 against the road surface G. In the third embodiment, a configuration is used as an example in which only the first component force F1 is generated as a force acting in a direction pressing the front wheel 24 against the road surface G. Note that the control for switching the open / closed state of the on-off valve 58 in the third embodiment is the same as in the first or second embodiment, and therefore description thereof will be omitted.

[0196] As shown in Fig. 14 , an exhaust device 29B according to the third embodiment includes an exhaust port 71 provided in the first branch pipe 56 and an exhaust port 73B provided in the second branch pipe 57. The exhaust port 73B according to the third embodiment differs from the exhaust port 73 according to the first embodiment in the direction in which the exhaust gas is discharged. The exhaust port 73B is configured to discharge the exhaust gas upward in the vertical direction Z. In other words, the exhaust port 73B is configured to face upward in the vertical direction Z. The exhaust device 29B is attached to the frame of the saddle-riding type vehicle 1B so that the exhaust port 73B is located above the rear axle 47 in the vertical direction Z. In other words, the exhaust device 29B is attached to the frame of the saddle-riding type vehicle 1B so that the exhaust port 73B is located on an extension line between the rear contact point T and the rear axle 47.

[0197] The exhaust port 73B is configured to discharge the exhaust gas upward in the vertical direction Z. That is, when the exhaust gas is discharged from the exhaust port 73B to the outside of the exhaust device 29B, the jet flow H of the exhaust gas becomes a flow that heads upward in the vertical direction Z, as shown in Fig. 15. In other words, in the third embodiment, the jet flow H of the exhaust gas becomes a flow that heads upward in the vertical direction.

[0198] When exhaust gas is ejected from the exhaust port 73B to generate a jet H, a reaction force F of the jet H acts on the saddle-ride type vehicle 1B, as shown in FIG. 16. For ease of explanation, the exhaust device 29B is omitted from FIG. 16. The reaction force F is directed in the opposite direction to the jet H. Therefore, the reaction force F generated in the third embodiment acts downward from the start point Ce in the up-down direction Z. Therefore, the first component force F1 acting downward from the start point Ce is equal to the reaction force F. In the third embodiment, the component force of the reaction force F that acts in the fore-aft direction X (second component force F2) is zero.

[0199] In other words, when the direction of the reaction force F is downward from the start point Ce in the vertical direction Z, the first component force F1, which is a force acting in a direction pressing the front wheel 24 against the road surface G, is at its maximum. In this way, by arranging the exhaust port 73B so that the exhaust gas jet H flows upward in the vertical direction, the first component force F1 can be made larger. Increasing the first component force F1 can prevent the saddle-riding type vehicle 1B from performing a wheelie when driving on a circuit, for example.

[0200] Unlike Example 1, Example 3 does not generate a first moment M1 when exhaust gas is discharged from exhaust port 73B. Exhaust port 73B is disposed above rear axle 47 in the vertical direction Z. The rear axle 47 is disposed above rear contact point T in the vertical direction Z. Therefore, reaction force F is a force directed from start point Ce toward rear contact point T. Therefore, the angle N formed by the direction of reaction force F and straight line Lw is zero. Therefore, the component of reaction force F in the direction perpendicular to straight line Lw (third component force F3) is zero. Since the third component force F3 is zero in Example 3, the magnitude of first moment M1 is also zero.

[0201] In this way, in the third embodiment, exhaust gas is ejected from the exhaust port 73B to generate a first component force F1 that acts downward in the vertical direction Z. Generating the first component force F1 increases the force that acts in a direction pressing the front wheel 24 against the road surface G. Therefore, ejecting exhaust gas from the exhaust port 73B can prevent the saddle riding type vehicle 1B from performing a wheelie when traveling on a circuit, for example.

[0202] Furthermore, in the third embodiment, by arranging the exhaust port 73B facing upward in the vertical direction Z, it is possible to further increase the first component force F1 that is generated when exhaust gas is ejected from the exhaust port 73B, thereby making it possible to prevent the saddle riding type vehicle 1B from performing a wheelie when traveling on a circuit, for example. [Example]

[0203] Next, a saddle-ride type vehicle 1C according to a fourth embodiment of the present invention will be described. In the first and second embodiments, a configuration is used to generate two types of forces, a first component force F1 and a first moment M1, as forces acting in a direction pressing the front wheel 24 against the road surface G. In the fourth embodiment, a configuration is used to generate only the first moment M1 as a force acting in a direction pressing the front wheel 24 against the road surface G. Note that the control for switching the open / closed state of the on-off valve 58 in the fourth embodiment is the same as in the first or second embodiment, and therefore description thereof will be omitted.

[0204] As shown in Fig. 17 , an exhaust device 29C according to the fourth embodiment includes an exhaust port 71 provided in the first branch pipe 56 and an exhaust port 73C provided in the second branch pipe 57. The exhaust port 73C according to the fourth embodiment differs from the exhaust port 73 according to the first embodiment in the direction in which the exhaust gas is discharged. The exhaust port 73C is configured to discharge the exhaust gas rearward in the front-rear direction X. In other words, the exhaust port 73C is configured to face rearward in the front-rear direction X. The exhaust device 29C is attached to the frame of the saddle-riding type vehicle 1C so that the exhaust port 73C is located above the rear axle 47 in the up-down direction Z. In other words, the exhaust device 29C is attached to the frame of the saddle-riding type vehicle 1C so that the exhaust port 73C is located on an extension line between the rear contact point T and the rear axle 47.

[0205] The exhaust port 73C is configured to discharge the exhaust gas rearward in the front-rear direction X. That is, when the exhaust gas is discharged from the exhaust port 73C to the outside of the exhaust device 29C, a jet flow H of the exhaust gas flows rearward in the front-rear direction X, as shown in Fig. 18. In other words, in the fourth embodiment, the jet flow H of the exhaust gas flows rearward in the horizontal direction.

[0206] When exhaust gas is ejected from the exhaust port 73C to generate a jet H, a reaction force F of the jet H acts on the saddle-ride type vehicle 1C, as shown in Fig. 19. For ease of explanation, the exhaust device 29C is omitted from Fig. 19. The reaction force F has a direction opposite to that of the jet H. Therefore, the reaction force F generated in the fourth embodiment is a force that acts forward from the starting point Ce in the fore-and-aft direction X. Therefore, in the fourth embodiment, the component of the reaction force F that acts downward in the up-and-down direction Z (first component force F1) is zero.

[0207] On the other hand, in the fourth embodiment, as shown in Fig. 19, a first moment M1 is generated by the reaction force F. In the fourth embodiment, the exhaust port 73C is disposed above the rear axle 47 in the vertical direction Z. That is, in the fourth embodiment, the start point Ce is located above the rear axle 47 in the vertical direction Z. The rear axle 47 is disposed above the rear contact point T in the vertical direction Z. That is, the straight line Lw connecting the start point Ce and the rear contact point T is in the same direction as the vertical direction Z.

[0208] In the fourth embodiment, the reaction force F is a force that acts forward from the starting point Ce in the fore-and-aft direction X. Therefore, the reaction force F and the line Lw are perpendicular to each other. In other words, the angle N formed by the direction of the reaction force F and the line Lw is 90°. When the angle N is 90°, the reaction force F and the third component force F3 are equal. In other words, when the angle N is 90°, the magnitude of the third component force F3 is maximized. Therefore, by positioning the exhaust device 29C so that the line Lw connecting the starting point Ce and the rear contact point T is perpendicular to the reaction force F, the first moment M1 can be made stronger. This makes it possible to prevent the saddle-riding type vehicle 1C from performing a wheelie when driving on a circuit, for example.

[0209] The correspondence between the above-described Examples 1 to 4 and the configuration of the present invention is as follows.

[0210] The exhaust port 73 corresponds to the first exhaust port in the present invention. The exhaust port 71 corresponds to the main exhaust port in the present invention. The on-off valve 58 corresponds to the main valve in the present invention. The reaction force F corresponds to the first force in the present invention. The first component force F1 corresponds to the first component in the present invention. The IMU 81 corresponds to the first sensor in the present invention. The stroke sensor 64 corresponds to the second sensor in the present invention. The accelerator opening sensor 61, the stroke sensor 64, the throttle valve opening sensor 65, the speed sensor 66, the acceleration sensor 68, the crankshaft position sensor 69, the pressure sensor 70, and the IMU 81 correspond to the detection unit in the present invention. The ECU 75 corresponds to the main valve control unit in the present invention.

[0211] The present invention is not limited to the above-described embodiment, but can be modified as follows.

[0212] (1) In each of the first to fourth embodiments, as shown in Figures 1 and 2, the exhaust device 29 is disposed to the right of the rear wheel 49. However, this is not limited to this. For example, the exhaust device 29 may be disposed to the left of the rear wheel 49. Furthermore, the exhaust device 29 may be disposed in a position overlapping with the rear wheel 49 in a front view of the vehicle. One example of a configuration in which the exhaust device 29 is disposed in a position overlapping with the rear wheel 49 in a front view of the vehicle is a configuration in which the exhaust device 29 is disposed in front of the rear wheel 49.

[0213] (2) In each embodiment, the exhaust port 71 is configured to discharge exhaust gas rearward in the fore-and-aft direction X. That is, the exhaust port 71 is configured to discharge exhaust gas in a direction parallel to the fore-and-aft direction X, which is a horizontal direction. However, this is not limited to this. As an example, the exhaust port 71 may be configured to discharge exhaust gas rearward and upward in a side view of the vehicle. The exhaust port 71 may also be configured to discharge exhaust gas rearward and downward in a side view of the vehicle. Furthermore, the exhaust port 71 may discharge exhaust gas downward in the up-down direction Z. The exhaust port 71 may also discharge exhaust gas to the left or right in the width direction Y.

[0214] (3) In each embodiment, the exhaust device 29 branches into a first branch pipe 56 and a second branch pipe 57 at a branching portion 60. However, this is not limited to this. For example, as shown in FIGS. 20 and 21 , the first branch pipe 56 may be omitted from the exhaust device 29. In the modified embodiment shown in FIGS. 20 and 21 , a junction pipe 55 extending in the longitudinal direction X and a second branch pipe 57 extending rearward and upward in a side view of the vehicle are connected at a connection portion 60A. An exhaust port 71 and an on-off valve 58 are disposed at the connection portion 60A. As an example, the exhaust port 71 is configured to discharge exhaust gas rearward in the longitudinal direction X. FIG. 20 illustrates a state in which the on-off valve 58 is closed because a closing condition for the on-off valve 58 is satisfied. FIG. 21 illustrates a state in which the on-off valve 58 is open because an opening condition for the on-off valve 58 is satisfied.

[0215] When the closing condition of the on-off valve 58 is satisfied, the exhaust port 71 is closed by the on-off valve 58, as shown in Figure 20. When the exhaust port 71 is closed, the exhaust gas guided to the exhaust device 29 is guided to the second branch pipe 57. The exhaust gas is then discharged from an exhaust port 73 disposed in the second branch pipe 57. When the opening condition of the on-off valve 58 is satisfied, the exhaust port 71 is in an open state, as shown in Figure 21. When the exhaust port 71 is in an open state, the exhaust gas guided to the exhaust device 29 is discharged from the exhaust port 71.

[0216] (4) In the first embodiment, the closing condition for the on-off valve 58 is that the pressure of the exhaust gas in the exhaust device 29 is less than a predetermined value K1. In the second embodiment, the closing condition for the on-off valve 58 is that the pitch angle of the saddle riding type vehicle 1A is equal to or greater than a predetermined value K2, or the stroke amount of the front fork 14 is equal to a predetermined value K3. However, the closing condition for the on-off valve 58 is not limited to this. In other words, the configuration for determining the closing condition for the on-off valve 58 is not limited to a configuration that determines the closing condition based on the pressure of the exhaust gas, the pitch angle of the saddle riding type vehicle 1A, or the stroke amount of the front fork 14. The following configurations can be given as other configurations for determining the closing condition for the on-off valve 58.

[0217] First, there is a configuration in which a closing condition of the on-off valve 58 is determined based on the amount of operation of the accelerator grip 21. The accelerator opening sensor 61 detects the amount of operation of the accelerator grip 21. As shown in FIGS. 6 and 12, information detected by the accelerator opening sensor 61 is transmitted to the ECU 75. For example, when driving on a circuit, if the driver operates the accelerator grip 21 by a large amount, the saddle-riding type vehicle 1 will accelerate suddenly. When the saddle-riding type vehicle 1 accelerates suddenly, the saddle-riding type vehicle 1 is likely to perform a wheelie. Therefore, if the accelerator opening sensor 61 detects that the amount of operation of the accelerator grip 21 is equal to or greater than a predetermined value K4, the ECU 75 can determine that there is a high possibility that the saddle-riding type vehicle 1 will perform a wheelie in the near future. In other words, if the amount of operation of the accelerator grip 21 is equal to or greater than the predetermined value K4, the ECU 75 can determine that the closing condition of the on-off valve 58 is satisfied.

[0218] A second example is a configuration in which the closing condition of the on-off valve 58 is determined based on the opening of the throttle valve. The throttle valve opening sensor 65 detects the opening of the throttle valve. As shown in FIGS. 6 and 12, information detected by the throttle valve opening sensor 65 is transmitted to the ECU 75. An acceleration operation also increases the opening of the throttle valve. For example, when driving on a circuit, if the opening of the throttle valve is large, the saddle-riding vehicle 1 will rapidly accelerate. Rapid acceleration of the saddle-riding vehicle 1 makes the saddle-riding vehicle 1 prone to performing a wheelie. Therefore, when the throttle valve opening sensor 65 detects that the opening of the throttle valve is equal to or greater than a predetermined value K5, the ECU 75 can determine that there is a high possibility that the saddle-riding vehicle 1 will perform a wheelie in the near future. In other words, when the opening of the throttle valve is equal to or greater than the predetermined value K5, the ECU 75 can determine that the closing condition of the on-off valve 58 is satisfied.

[0219] A third example is a configuration in which the closing condition of the on-off valve 58 is determined based on the rotational speed of the engine 31. The crankshaft position sensor 69 detects the rotational speed of the engine 31. As shown in FIGS. 6 and 12, information detected by the crankshaft position sensor 69 is transmitted to the ECU 75. For example, when driving on a circuit, if the rotational speed of the engine 31 is high, the saddle-riding vehicle 1 will rapidly accelerate. If the saddle-riding vehicle 1 rapidly accelerates, the saddle-riding vehicle 1 is likely to perform a wheelie. Therefore, if the crankshaft position sensor 69 detects that the rotational speed of the engine 31 is equal to or greater than a predetermined value K6, the ECU 75 can determine that there is a high possibility that the saddle-riding vehicle 1 will perform a wheelie in the near future. In other words, if the rotational speed of the engine 31 is equal to or greater than the predetermined value K6, the ECU 75 can determine that the closing condition of the on-off valve 58 is satisfied.

[0220] A fourth example is a configuration in which the closing condition of the on-off valve 58 is determined based on the traveling speed of the saddle riding type vehicle 1. The speed sensor 66 detects the traveling speed of the saddle riding type vehicle 1. As shown in FIGS. 6 and 12, information detected by the speed sensor 66 is sent to the ECU 75. For example, when traveling on a circuit, if the traveling speed of the saddle riding type vehicle 1 suddenly increases, the saddle riding type vehicle 1 will suddenly accelerate. Therefore, by using the speed sensor 66, it is possible to determine whether the saddle riding type vehicle 1 is suddenly accelerating. In other words, if the speed sensor 66 detects that the traveling speed of the saddle riding type vehicle 1 is equal to or greater than a predetermined value K7, the ECU 75 can determine that there is a high possibility that the saddle riding type vehicle 1 will perform a wheelie in the near future. In other words, if the traveling speed of the saddle riding type vehicle 1 is equal to or greater than the predetermined value K7, the ECU 75 can determine that the closing condition of the on-off valve 58 is satisfied.

[0221] A fifth example is a configuration in which a closing condition for the on-off valve 58 is determined based on the acceleration of the saddle-riding vehicle 1. The acceleration sensor 68 detects the acceleration of the saddle-riding vehicle 1. As shown in FIGS. 6 and 12, information detected by the acceleration sensor 68 is sent to the ECU 75. For example, when driving on a circuit, if the acceleration of the saddle-riding vehicle 1 increases suddenly, the saddle-riding vehicle 1 will accelerate suddenly. If the saddle-riding vehicle 1 accelerates suddenly, the saddle-riding vehicle 1 is likely to perform a wheelie. Therefore, if the acceleration sensor 68 detects that the acceleration of the saddle-riding vehicle 1 is equal to or greater than a predetermined value K8, the ECU 75 can determine that there is a high possibility that the saddle-riding vehicle 1 will perform a wheelie in the near future. In other words, if the acceleration of the saddle-riding vehicle 1 is equal to or greater than the predetermined value K8, the ECU 75 can determine that a closing condition for the on-off valve 58 is satisfied.

[0222] A sixth example is a configuration in which a closing condition for the on-off valve 58 is determined based on the pressure of exhaust gas inside the exhaust device 29. The pressure sensor 70 detects the pressure of exhaust gas inside the exhaust device 29. As shown in FIGS. 6 and 12, information detected by the pressure sensor 70 is sent to the ECU 75. For example, when the saddle-riding vehicle 1 suddenly accelerates while driving on a circuit, the amount of exhaust gas generated by the engine 31 and guided into the exhaust device 29 increases. Therefore, by using the pressure sensor 70, it is possible to determine whether the saddle-riding vehicle 1 is suddenly accelerating. In other words, if the pressure sensor 70 detects that the pressure of exhaust gas inside the exhaust device 29 is equal to or greater than a predetermined value K9, the ECU 75 can determine that there is a high possibility that the saddle-riding vehicle 1 will perform a wheelie in the near future. In other words, if the pressure of exhaust gas inside the exhaust device 29 is equal to or greater than the predetermined value K9, the ECU 75 can determine that a closing condition for the on-off valve 58 is satisfied.

[0223] Here, a modified embodiment will be described in which the opening and closing operation of the on-off valve 58 is controlled using an accelerator opening sensor 61, a throttle valve opening sensor 65, a crankshaft position sensor 69, a speed sensor 66, an acceleration sensor 68, a pressure sensor 70, and an ECU 75. The functional block diagram of this modified embodiment is common to that of the second embodiment shown in Fig. 12. Fig. 22 is a flowchart showing the operation of the saddle riding type vehicle 1 according to the modified embodiment.

[0224] An overview of the operation of the saddle riding type vehicle 1 according to the modified embodiment is as follows. When starting to drive the saddle riding type vehicle 1, the driver starts the engine 31 and drives the saddle riding type vehicle 1A (step S11). Once the saddle riding type vehicle 1 starts to drive, the ECU 75 constantly monitors whether the closing condition of the on-off valve 58 or the opening condition of the on-off valve 58 is satisfied (steps S12 to S17). If the ECU 75 determines that the opening condition of the on-off valve 58 is satisfied (reference J1), the ECU 75 switches the on-off valve 58 to an open state, causing exhaust gas to be discharged from the exhaust port 71 (steps S18 to S19). If the ECU 75 determines that the closing condition of the on-off valve 58 is satisfied (reference J2), the ECU 75 switches the on-off valve 58 to a closed state, causing exhaust gas to be discharged from the exhaust port 73 (steps S20 to S22). When the driver wishes to end driving the saddle riding type vehicle 1, the driver stops the engine 31 (step S23).

[0225] In steps S12 to S17 according to the modified embodiment, the ECU 75 monitors the closing condition and the opening condition of the on-off valve 58 in detail as follows.

[0226] Step S12 First, in step S12, the ECU 75 determines whether or not a closing condition for the on-off valve 58 is satisfied based on information transmitted from the accelerator pedal position sensor 61. The accelerator pedal position sensor 61 constantly detects the amount of operation of the accelerator grip 21. The accelerator pedal position sensor 61 then transmits information about the detected amount of operation of the accelerator grip 21 to the ECU 75 as needed.

[0227] The ECU 75 reads information about a predetermined value K4 stored in advance in the memory unit 79. The ECU 75 compares the amount of operation of the accelerator grip 21 with the predetermined value K4. If the amount of operation of the accelerator grip 21 is equal to or greater than the predetermined value K4, the ECU 75 determines that the closing condition of the on-off valve 58 is satisfied (see symbol J2). On the other hand, if the amount of operation of the accelerator grip 21 is less than the predetermined value K4, the ECU 75 shifts the process to step S13.

[0228] Step S13 In step S13, the ECU 75 determines whether or not the closing condition of the on-off valve 58 is satisfied based on information transmitted from the throttle valve opening sensor 65. The throttle valve opening sensor 65 constantly detects the opening of the throttle valve. The throttle valve opening sensor 65 transmits information on the detected opening of the throttle valve to the ECU 75 as needed.

[0229] The ECU 75 reads information about a predetermined value K5 stored in advance in the storage unit 79. The ECU 75 compares the opening of the throttle valve with the predetermined value K5. If the opening of the throttle valve is equal to or greater than the predetermined value K5, the ECU 75 determines that the closing condition of the on-off valve 58 is satisfied (see symbol J2). On the other hand, if the opening of the throttle valve is less than the predetermined value K5, the ECU 75 shifts the process to step S14.

[0230] Step S14 In step S14, the ECU 75 determines whether or not the closing condition of the on-off valve 58 is satisfied based on the information transmitted from the crankshaft position sensor 69. The crankshaft position sensor 69 constantly detects the rotation speed of the engine 31. The crankshaft position sensor 69 transmits information on the detected rotation speed of the engine 31 to the ECU 75 as needed.

[0231] The ECU 75 reads information about a predetermined value K6 stored in advance in the storage unit 79. The ECU 75 compares the rotation speed of the engine 31 with the predetermined value K6. If the rotation speed of the engine 31 is equal to or greater than the predetermined value K6, the ECU 75 determines that the closing condition of the on-off valve 58 is satisfied (see symbol J2). On the other hand, if the rotation speed of the engine 31 is less than the predetermined value K6, the ECU 75 shifts the process to step S15.

[0232] Step S15 In step S15, the ECU 75 determines whether or not the closing condition for the on-off valve 58 is satisfied based on the information transmitted from the speed sensor 66. The speed sensor 66 constantly detects the traveling speed of the saddle riding type vehicle 1. The speed sensor 66 then transmits information on the detected traveling speed to the ECU 75 as needed.

[0233] The ECU 75 reads out information about a predetermined value K7 that is stored in advance in the storage unit 79. The ECU 75 compares the traveling speed of the saddle riding type vehicle 1 with the predetermined value K7. If the traveling speed of the saddle riding type vehicle 1 is equal to or greater than the predetermined value K7, the ECU 75 determines that the closing condition of the on-off valve 58 is satisfied (see symbol J2). On the other hand, if the traveling speed of the saddle riding type vehicle 1 is less than the predetermined value K7, the ECU 75 shifts the process to step S16.

[0234] Step S16 In step S16, the ECU 75 determines whether or not the closing condition for the on-off valve 58 is satisfied based on the information transmitted from the acceleration sensor 68. The acceleration sensor 68 constantly detects the acceleration of the saddle riding type vehicle 1. The acceleration sensor 68 then transmits information on the detected acceleration to the ECU 75 as needed.

[0235] The ECU 75 reads out information about a predetermined value K8 that is stored in advance in the storage unit 79. The ECU 75 compares the acceleration of the saddle riding type vehicle 1 with the predetermined value K8. If the acceleration of the saddle riding type vehicle 1 is equal to or greater than the predetermined value K8, the ECU 75 determines that the closing condition of the on-off valve 58 is satisfied (see symbol J2). On the other hand, if the acceleration of the saddle riding type vehicle 1 is less than the predetermined value K8, the ECU 75 shifts the process to step S17.

[0236] Step S17 In step S17, the ECU 75 determines whether or not the closing condition of the on-off valve 58 is satisfied based on the information transmitted from the pressure sensor 70. The pressure sensor 70 constantly detects the pressure of the exhaust gas inside the exhaust device 29. The pressure sensor 70 then transmits information on the detected pressure to the ECU 75 as needed.

[0237] The ECU 75 reads information about a predetermined value K9 stored in advance in the memory unit 79. The ECU 75 compares the pressure of the exhaust gas inside the exhaust device 29 with the predetermined value K9. If the pressure of the exhaust gas inside the exhaust device 29 is equal to or greater than the predetermined value K9, the ECU 75 determines that the closing condition of the on-off valve 58 is satisfied (see symbol J2).

[0238] On the other hand, when the pressure of the exhaust gas inside the exhaust device 29 is less than the predetermined value K9, the ECU 75 determines that none of the closing conditions of the on-off valves 58 are satisfied. When it is determined that none of the closing conditions of the on-off valves 58 are satisfied, the ECU 75 determines that the opening condition of the on-off valves 58 is satisfied (see symbol J1). When it is determined that the opening condition of the on-off valves 58 is satisfied, the ECU 75 shifts the processing to step S18.

[0239] In the modified embodiment, steps S18 and S19 are performed when it is determined that the opening condition of the on-off valve 58 is satisfied. Steps S18 to S19 according to the modified embodiment will be described.

[0240] Step S18 If it is determined in step S17 that the opening condition for the on-off valve 58 is satisfied, the process of step S18 is started. In step S18, the ECU 75 performs control to open the on-off valve 58. That is, the on-off valve 58, which is an electrically operated valve, is controlled by the ECU 75 and switched to an open state.

[0241] Step S19 When the on-off valve 58 is switched to an open state, the exhaust gas guided to the exhaust device 29 via the guide port 59 can flow to the first branch pipe 56. That is, when the on-off valve 58 is in an open state, the exhaust gas can be discharged from the exhaust port 71 (see FIG. 5). The first branch pipe 56 has a larger diameter than the second branch pipe 57. Therefore, most of the exhaust gas guided from the engine 31 to the exhaust device 29 flows to the second branch pipe 56 and is discharged to the outside from the exhaust port 71. That is, when the opening condition of the on-off valve 58 is satisfied, the exhaust gas is injected from the exhaust port 71 and a jet flow Hc is generated (see FIG. 10). The exhaust port 71 is configured to be larger than the exhaust port 73. Therefore, the exhaust gas can be efficiently discharged from the large exhaust port 71. Thereafter, the process proceeds to step S23.

[0242] In the modified embodiment, steps S20, S21, and S22 are performed when it is determined that the closing condition of the on-off valve 58 is satisfied. Steps S20 to S22 according to the modified embodiment will be described.

[0243] Step S20 If it is determined in steps S12 to S17 that the closing condition of the on-off valve 58 is satisfied, the process of step S20 is started. In step S20, the ECU 75 performs control to close the on-off valve 58. That is, the on-off valve 58, which is an electrically operated valve, is controlled by the ECU 75 and switched to a closed state.

[0244] Step S21 When the on-off valve 58 is switched to the closed state, the exhaust gas guided to the exhaust device 29 via the guide port 59 cannot flow to the first branch pipe 56 (see FIG. 4). Therefore, all of the exhaust gas guided from the engine 31 to the exhaust device 29 is sent to the second branch pipe 57 and discharged to the outside from the exhaust port 73. When the exhaust gas is discharged from the exhaust port 73, a jet flow H is generated at the starting point Ce corresponding to the exhaust port 73 (see FIG. 7).

[0245] Step S22 When the jet H is generated at the starting point Ce, a reaction force F of the jet H is generated. The reaction force F acts on the front wheel 24. The reaction force F acts in a direction that prevents the front wheel 24 from lifting off the road surface G. For example, the reaction force F includes a first component force F1. The first component force F1 acts downward in the up-down direction Z on the front wheel 24 (see FIG. 8). For example, the reaction force F generates a first moment M1, and the first moment M1 acts in a direction that presses the front wheel 24 against the road surface G (see FIG. 9). After the exhaust gas is injected from the exhaust port 73, the process proceeds to step S23.

[0246] Step S23 After the ECU 75 performs control to switch the on-off valve 58 between a closed state and an open state, the process branches depending on the operating state of the engine 31. If the engine 31 is stopped, the ECU 75 stops monitoring the closing condition and the opening condition. On the other hand, if the operation of the engine 31 continues, the process branches to step S2. That is, the ECU 75 continues monitoring the closing condition and the opening condition.

[0247] In the modified embodiment related to (4) above, the saddle riding type vehicle 1 is equipped with a pressure sensor 70, a speed sensor 66, an acceleration sensor 68, an accelerator opening sensor 61, a throttle valve opening sensor 65, and a crankshaft position sensor 69. This makes it easy to detect the posture of the saddle riding type vehicle 1. This makes it easy for the ECU 75 to control the on-off valve 58 in accordance with the posture of the saddle riding type vehicle 1.

[0248] The modified embodiment according to (4) above may be further modified as follows.

[0249] In the modified embodiment according to (4) above, the sensors of the saddle riding type vehicle 1 may be changed as appropriate. For example, the saddle riding type vehicle 1 may be provided with at least one of the pressure sensor 70, the speed sensor 66, the acceleration sensor 68, the accelerator opening sensor 61, the throttle valve opening sensor 65, and the crankshaft position sensor 69.

[0250] The IMU 81 may be used instead of the acceleration sensor 68. For example, the IMU 81 may detect the acceleration of the saddle riding type vehicle 1 in step S16.

[0251] In the modified embodiment according to (4) above, six conditions are used as the closing conditions for the on-off valve 58, but the number of closing conditions may be increased or decreased as appropriate. As an example, in the flowchart shown in Fig. 22, one or more of steps S2 to S7 may be omitted.

[0252] In the modified embodiment according to (4) above, the pressure sensor 70 corresponds to the third sensor of the present invention. The speed sensor 66 corresponds to the fourth sensor of the present invention. The acceleration sensor 68 corresponds to the fifth sensor of the present invention. The IMU 81 may also correspond to the fifth sensor of the present invention. The accelerator opening sensor 61 corresponds to the sixth sensor of the present invention. The throttle valve opening sensor 65 corresponds to the seventh sensor of the present invention. The crankshaft position sensor 69 corresponds to the eighth sensor of the present invention.

[0253] (5) In the second embodiment, the saddle riding type vehicle 1A is equipped with a stroke sensor 64 and an IMU 81. However, the sensors of the saddle riding type vehicle 1A may be changed as appropriate. For example, the saddle riding type vehicle 1A may be equipped with at least one of the stroke sensor 64 and the IMU 81. For example, the saddle riding type vehicle 1A may be equipped with a gyro sensor. The gyro sensor detects the pitch angle of the saddle riding type vehicle 1A.

[0254] (6) In each embodiment, the second branch pipe 57 is disposed so as to extend rearward and upward in a side view of the vehicle. However, this is not limited to this. The direction in which the second branch pipe 57 extends may be changed as appropriate depending on the position and orientation of the exhaust port 73. As an example, the second branch pipe 57 may be disposed so as to extend horizontally or vertically.

[0255] (7) In each embodiment, the on-off valve 58 switches the flow path of the exhaust gas in the exhaust device 29. However, the configuration for switching the flow path of the exhaust gas in the exhaust device 29 is not limited to this. Two modified embodiments will be described below.

[0256] (7-1) First modified embodiment 23, the exhaust device 29 includes an on-off valve 83 in addition to the on-off valve 58. The on-off valve 83 is disposed in the second branch pipe 57. The on-off valve 83 opens and closes the exhaust port 73.

[0257] In the first modified embodiment, when a specific condition is met that indicates that there is a high possibility that the front wheels 24 will lift off the road surface G, the on-off valve 58 is switched to a closed state and the on-off valve 83 is switched to an open state, as shown in FIG. 23 . That is, the on-off valve 58 closes the exhaust port 71, while the on-off valve 83 is switched to a state that does not close the exhaust port 73. The specific condition that indicates there is a high possibility that the front wheels 24 will lift off the road surface G corresponds to the closing condition described in the first embodiment and the like. By switching the open / closed states of the on-off valve 58 and the on-off valve 83 as shown in FIG. 23 , the exhaust gas guided to the exhaust device 29 reliably flows into the second branch pipe 57 and is discharged from the exhaust port 73.

[0258] On the other hand, when a specific condition for determining that there is a high possibility that the front wheels 24 will lift off the road surface G is not met, the on-off valve 58 is switched to an open state, and the on-off valve 83 is switched to a closed state, as shown in Fig. 24. That is, the on-off valve 83 closes the exhaust port 73, while the on-off valve 58 is switched to a state that does not close the exhaust port 71. By switching the open / close states of the on-off valves 58 and 83 as shown in Fig. 24, the exhaust gas guided to the exhaust device 29 reliably flows into the first branch pipe 56 and is discharged from the exhaust port 71.

[0259] As described above, in the first modified embodiment, the exhaust device 29 includes the on-off valve 58 and the on-off valve 83. Therefore, it is possible to reliably discharge the exhaust gas guided to the exhaust device 29 from only one of the exhaust port 71 and the exhaust port 73.

[0260] (7-2) Second modified embodiment 25, the exhaust device 29 includes an on-off valve 85 instead of the on-off valve 58. The on-off valve 85 selectively closes the first branch pipe 56 and the second branch pipe 57. The on-off valve 85 opens and closes the exhaust port 71, and also opens and closes the exhaust port 73. When the on-off valve 85 opens the exhaust port 71, the on-off valve 85 closes the exhaust port 73. When the on-off valve 85 opens the exhaust port 73, the on-off valve 85 closes the exhaust port 71. The on-off valve 85 is also called a three-way valve.

[0261] In the second modified embodiment, when a specific condition is met that indicates that there is a high possibility that the front wheels 24 will lift off the road surface G, the on-off valve 85 closes the first branch pipe 56, as shown in Fig. 25. By closing the first branch pipe 56 with the on-off valve 85, exhaust gas is reliably discharged from the exhaust port 73.

[0262] On the other hand, if a specific condition that indicates a high possibility of the front wheels 24 lifting off the road surface G is not met, the on-off valve 85 closes the second branch pipe 57, as shown in Figure 26. By closing the second branch pipe 57 with the on-off valve 85, exhaust gas is reliably discharged from the exhaust port 71.

[0263] As described above, in the second modified embodiment, the exhaust device 29 is provided with the on-off valve 85. This makes it possible to reliably discharge the exhaust gas guided to the exhaust device 29 from only one of the exhaust ports 71 and 73.

[0264] In the second modified embodiment of (7-2) above, the on-off valve 85 corresponds to the main valve in the present invention.

[0265] (8) In each embodiment, the number of front wheels 24 is one. However, this is not limited to this. The number of front wheels 24 may be two or more. In each embodiment, the number of rear wheels 49 is one. However, this is not limited to this. The number of rear wheels 49 may be two or more.

[0266] (9) Each of the first to fourth embodiments and the modified embodiments described above in (1) to (8) may be further modified as appropriate by replacing or combining each configuration with the configuration of another modified embodiment. [Explanation of symbols]

[0267] 1. Saddle-type vehicle 3... Body frame 5... Head pipe 7...Mainframe 9... Steering device 11 ... Top bridge 13... Bottom Bridge 14...Front fork 15...Handle 17 ... Clutch lever 19...Brake lever 21... Accelerator Grip 23 … Front axle 24... Front wheel 25... Front wheel brake device 29...Exhaust system 31... Engine 33... crankshaft 35 ... Transmission 37 ... Shift pedal 39... fuel tank 41 ... seats 43... Pivot axis 45 ... swing arm 47... Rear axle (center of rotation of rear wheels) 49 ... rear wheel 51 ... Rear wheel brake device 53...Brake pedal 55 … Merging pipe 56 ... First branch pipe 57 ... Second branch pipe 58...Shut-off valve (main valve) 59 … Information entrance 60 ... Branch 61 ... Accelerator opening sensor (sixth sensor) 63…Fuel supply device 64 ... Stroke sensor (second sensor) 65 ... Throttle valve opening sensor (7th sensor) 66 ... Speed ​​sensor (4th sensor) 67 ... Gear position sensor 68...Acceleration sensor (5th sensor) 69 ... Crankshaft position sensor (8th sensor) 70... Pressure sensor (third sensor) 71... Exhaust port (main exhaust port) 73 ... Exhaust port (first exhaust port) 75 ... ECU (main valve control unit) 77...CPU 79 … Storage section 81 ... IMU (first sensor) H... Jet F... reaction force (first force) F1 … 1st component force (1st component) F2 … 2nd component force F3 … 3rd component force M1 ... first moment

Claims

1. The front wheel and The rear wheel and an exhaust device that discharges exhaust gas; Equipped with the exhaust device includes a first exhaust port that injects the exhaust gas to apply a first force to the front wheel; The first force acts in a direction that prevents the front wheel from lifting off the road surface.

2. The saddle-type vehicle according to claim 1, The first force is a reaction force of the jet of exhaust gas injected from the first exhaust port. Saddle-type vehicle.

3. The saddle-type vehicle according to claim 1, The first exhaust port is configured to eject the exhaust gas rearward. Saddle-type vehicle.

4. The saddle-type vehicle according to claim 1, The first exhaust port is disposed above the rotation center of the rear wheel. Saddle-type vehicle.

5. The saddle-type vehicle according to claim 1, the first force generates a first moment about a rear contact point between the rear wheel and the road surface; The first moment acts in a direction pressing the front wheels against the road surface. Saddle-type vehicle.

6. The saddle-type vehicle according to claim 1, The first exhaust port is configured to eject the exhaust gas upward. Saddle-type vehicle.

7. The saddle-type vehicle according to claim 1, The first force includes a first component acting downward on the front wheel. Saddle-type vehicle.

8. The saddle-type vehicle according to claim 1, The exhaust device is a main exhaust port for discharging the exhaust gas; The first exhaust port is Smaller than the main exhaust port Saddle-type vehicle.

9. The saddle-type vehicle according to claim 8, The first exhaust port is disposed above the main exhaust port. Saddle-type vehicle.

10. 9. The saddle-type vehicle according to claim 8, The exhaust device is A main valve is provided to open and close the main exhaust port. Saddle-type vehicle.

11. The saddle-type vehicle according to claim 10, The main valve is configured to open the main exhaust port when the pressure of the exhaust gas in the exhaust device is equal to or greater than a predetermined value. Saddle-type vehicle.

12. The saddle-type vehicle according to claim 10, a detection unit that detects a state of the saddle riding type vehicle; a main valve control unit that controls the main valve based on the detection result of the detection unit; Equipped with Saddle-type vehicle.

13. The saddle-type vehicle according to claim 12, The main valve control unit is determining whether the front wheels are about to lift off the road surface based on the detection result of the detection unit; The main valve control unit is configured to close the main valve when the main valve control unit determines that the front wheels are about to lift off the road surface. Saddle-type vehicle.

14. The saddle-type vehicle according to claim 12, The detection unit a first sensor for detecting a pitch angle of the saddle-ride type vehicle and a second sensor for detecting a stroke amount of a front fork that supports the front wheel; Saddle-type vehicle.

15. The saddle-type vehicle according to claim 12, The detection unit a third sensor for detecting the pressure of the exhaust gas in the exhaust system; a fourth sensor for detecting a speed of the saddle-ride type vehicle; a fifth sensor for detecting acceleration of the saddle-ride type vehicle; a sixth sensor for detecting an operation amount of an accelerator of the saddle riding type vehicle; a seventh sensor that detects the opening degree of a throttle valve of the saddle-ride type vehicle; and an eighth sensor for detecting the rotation speed of the engine of the saddle riding type vehicle. Saddle-type vehicle.

Images