Intake air amount control system and saddle-riding type vehicle

Abstract

Provided is an intake air amount control system with which a calculation load is reduced, and which has a flow rate characteristic that takes into consideration a difference between the intake air amount when normal idle control is executed and the intake air amount when catalyst early activation control for activating an exhaust gas purification catalyst is executed. An intake air amount control system (1) executes, in an internal combustion engine, first idle operation control and catalyst early activation control that increases the intake air amount as compared with the first idle operation control, and is provided with: a throttle valve (71); a bypass flow path (12) that bypasses the throttle valve; a bypass valve (13) provided in the bypass flow path; and an actuator (13a). When a region from the fully closed state to the fully open state of the bypass valve is divided into three equal parts, defined as a first region, a second region, and a third region, the first idle operation control is executed in the first region, and the catalyst early activation control is executed in the third region. Under the same internal combustion engine negative pressure, the rate of change of the flow rate in the bypass flow path in the third region is greater than or equal to that in the first region.

Description

Intake volume control system and straddle-type vehicle

[0001] The present invention relates to an intake air amount control system and a straddle-type vehicle.

[0002] Known internal combustion engines include a throttle valve that adjusts the amount of intake air into the engine, as well as a bypass valve that adjusts the amount of intake air during idle operation. The bypass valve is often disposed in a bypass flow path that bypasses the throttle valve. The amount of intake air during idle operation of an internal combustion engine installed in a vehicle as a driving force source is generally smaller than the amount of intake air during driving. However, there are cases where an increase in the amount of intake air during idle operation is required. For example, Patent Documents 1 and 2 disclose control devices for internal combustion engines that quickly activate an exhaust gas purification catalyst. These internal combustion engine control devices increase the amount of intake air compared to normal idle operation when quickly activating the catalyst (i.e., warming up the catalyst).

[0003] Patent Document 1: Japanese Patent Application Laid-Open No. 2000-179439 Patent Document 2: Japanese Patent Application Laid-Open No. 10-030480

[0004] Using an electronically controlled valve to increase the intake volume for early catalyst activation, as in the technology of Patent Document 1, may increase the computational load compared to when an electronically controlled valve is not used. More specifically, electronically controlled valves generally have a shorter control cycle than mechanical valves, which increases the computational load on the ECU (electronic control unit) that controls the valve. Applying an ECU with high processing power to a vehicle (e.g., a saddle-type vehicle equipped with an internal combustion engine) may increase the vehicle weight, etc., and reduce the design flexibility of hardware resources. Patent Document 2 uses a duty-controlled valve and an ON / OFF valve instead of an electronically controlled valve to early catalyst activation.

[0005] The required intake air volume during catalyst early activation control, which increases the intake air volume during idle operation to activate the catalyst early, is larger than that during normal idle control, which is performed during normal idle operation. In other words, the range of values ​​representing the bypass valve opening during catalyst early activation control is different from the range of values ​​representing the bypass valve opening during normal idle control. Therefore, the flow characteristics of the bypass valve may differ when these controls are performed. However, Patent Documents 1 and 2 do not consider this point.

[0006] An object of the present invention is to provide an intake air amount control system that reduces the calculation load and has flow characteristics that take into account the amount of intake air when normal idle control and catalyst early activation control are each executed.

[0007] The present inventors investigated increasing the intake air volume for early catalyst activation without using an electronically controlled valve. The cross-sectional area (flow passage cross-sectional area) of a bypass valve provided in a bypass flow passage is generally 10% or less of the port cross-sectional area. The port cross-sectional area is the flow passage cross-sectional area at the communication portion between the intake port, which is opened and closed by the intake valve, and the combustion chamber. When using a bypass valve to increase the intake air volume during idle operation, the amount of intake air that can be increased generally varies depending on the size (cross-sectional area) of the bypass valve. Therefore, the inventors investigated increasing the size of the bypass valve to satisfy the required intake air volume for early catalyst activation.

[0008] Increasing the size of the bypass valve to accommodate the required intake air volume for early catalyst activation increases the amount of change in intake air volume per step of the stepping motor mounted as an actuator on the bypass valve. On the other hand, precise control of engine speed is generally required during normal idle operation. Therefore, it is desirable to reduce the amount of change in intake air volume per step during normal idle operation. In particular, for internal combustion engines with small loss torque, the required intake air volume during idle operation tends to be small when the engine temperature is relatively high and the engine is operated in a low-altitude area. Even in such situations, it is desirable to ensure controllability of engine speed during idle operation. As described above, the inventors of the present application have realized that simply increasing the size of the bypass valve increases the amount of change in intake air volume per step, making it difficult to achieve the desired flow characteristics.

[0009] Furthermore, the present inventors have investigated a case where an ON / OFF valve is used to meet the required intake air volume during execution of catalyst early activation control, as in Patent Document 2. During execution of catalyst early activation control, a high-flow ON / OFF valve is turned ON, thereby satisfying the required flow volume. However, when the ON / OFF valve is ON, fine adjustment of the intake air volume is required, which requires additional control of the normal bypass valve. As a result, the flow characteristics during execution of catalyst early activation control are similar to those during normal idle operation. Therefore, the present inventors have discovered that improving the responsiveness of the bypass valve is necessary to increase the intake air volume early during execution of catalyst early activation control. To improve the responsiveness of the bypass valve, the flow characteristics of the bypass valve (specifically, the change in intake air volume relative to a change in valve opening) must be increased. In other words, the present inventors have discovered that the required flow characteristics of the bypass valve differ between normal idle operation and execution of catalyst early activation control. In order to achieve the flow characteristics described above, it is necessary to increase the required intake volume using a configuration different from the configuration applied in Patent Document 2, which uses an ON / OFF type valve in addition to a normal bypass valve.

[0010] In light of the above, the inventors of the present application have considered the following configuration: that is, an actuator is capable of varying the state from a fully closed state in which at least one bypass valve is fully closed to a fully open state in which at least one bypass valve is fully opened, and when the time domain when the output of the actuator is changed at a constant speed or a constant angular velocity from the fully closed state to the fully open state is divided into three equal parts and defined as a first region, a second region, and a third region from the fully closed state to the fully open state, in that order, a first idle operation control (i.e., normal idle operation control) is executed in the first region, and catalyst early activation control is executed in the third region, and when the negative pressure of the internal combustion engine is constant, the rate of change of flow rate in the total of all of the at least one bypass flow passage is greater or equal in the third region than in the first region.

[0011] The inventors discovered that controlling the bypass valve using this configuration can adjust the intake air amount of the internal combustion engine to satisfy the required intake air amount during normal idle control and the required intake air amount during catalyst early activation control, while also achieving the flow characteristics required for both normal idle control and catalyst early activation control. The intake air amount control system of this configuration is configured to perform normal idle control over at least a portion of the valve opening within the first range, and to perform catalyst early activation control over at least a portion of the valve opening within the third range. Therefore, electronically controlled valves are not required for normal idle control and catalyst early activation control. This reduces the computational load compared to when electronically controlled valves are used to perform normal idle control and catalyst early activation control.

[0012] Furthermore, since the flow rate change rate in the first region is set to be equal to or less than the flow rate change rate in the third region when the negative pressure of the internal combustion engine is equal, it is possible to achieve finer control (than when early catalyst activation control is performed) during normal idle control and improved responsiveness (compared to when early catalyst activation control is performed) during normal idle control. By adopting the above-described configuration, it is possible to provide an intake air amount control system that has flow rate characteristics that take into account the intake air amounts required for normal idle control and early catalyst activation control, respectively, with a simple configuration while reducing the calculation load.

[0013] Based on the above findings, an intake air amount control system according to each aspect of the present application has the following configuration.

[0014] (1) An intake air amount control system for an internal combustion engine that, during idle operation, performs first idle operation control and catalyst early activation control, which increases the intake air amount to a level higher than that during the first idle operation control, thereby activating a catalyst for purifying exhaust gas, comprising: a throttle valve whose opening is changed to change the intake air amount of the internal combustion engine; at least one bypass flow path that bypasses the throttle valve; and a bypass intake air amount control device that controls the flow rate of the at least one bypass flow path, wherein the bypass intake air amount control device comprises: at least one bypass valve provided in at least one of the at least one bypass flow paths to change the opening of a corresponding flow path; and an actuator configured to open and close the at least one bypass valve, and the bypass intake air amount control device is variable by the actuator from a fully closed state in which all of the at least one bypass valve are fully closed to a fully open state in which all of the at least one bypass valve are fully opened, When the time domain when the output of the actuator is changed at a constant speed or a constant angular velocity from the fully closed state to the fully open state is divided into three equal parts and defined as a first domain, a second domain, and a third domain from the fully closed state to the fully open state, the first idle operation control is executed in the first domain, and the catalyst early activation control is executed in the third domain, and when the negative pressure of the internal combustion engine is equal, the rate of change of flow rate in the total of all of the at least one bypass flow paths is larger or equal in the third domain than in the first domain.

[0015] In the above configuration, when the actuator output is changed at a constant speed or a constant angular velocity, the position or rotational angle of the valve disc of the bypass valve increases or decreases at a constant speed. In this case, if the position or rotational angle of the valve disc of the bypass valve is expressed as a bypass valve opening, which is a value within the range from 0% to 100%, the bypass valve opening increases or decreases at a constant speed. In other words, the bypass valve opening is a value proportional to the position or rotational angle of the valve disc. Therefore, the range of the bypass valve opening from 0% to 100% can be divided into three equal parts, thereby defining first to third regions.

[0016] In this case, the flow rate change rate is the ratio of the increase in the bypass valve intake air volume to the increase in the bypass valve opening. More specifically, the flow rate change rate is equal to the increase in the bypass valve intake air volume (also referred to as the "bypass intake air volume") when the bypass valve opening increases by a unit amount. The bypass intake air volume can also be said to be the difference between the intake air volume flowing into the internal combustion engine and the intake air volume passing through the throttle.

[0017] When the first idle operation control (i.e., normal idle control) is being performed, the bypass valve opening is likely to be within the first range. The flow rate change rate in the first range is not greater than that in the third range. Therefore, the change in the bypass intake air amount with a change in the bypass valve opening is relatively small. That is, the change in the bypass intake air amount when the actuator provided for the bypass valve is operated by a unit amount is relatively small. Therefore, precise control of the bypass intake air amount with the first idle operation control is relatively easy. On the other hand, when the catalyst early activation control is being performed, the bypass valve opening is likely to be within the third range. The flow rate change rate in the third range is greater than or equal to that in the first range, so the change in the bypass intake air amount with a change in the bypass valve opening is relatively large. That is, the change in the bypass intake air amount when the actuator provided for the bypass valve is operated by a unit amount is relatively large. Therefore, it is relatively easy to improve the responsiveness with the catalyst early activation control. Therefore, the computational load related to the control of the bypass valve with the catalyst early activation control can be reduced. In addition, the improved responsiveness with the catalyst early activation control allows the intake air amount to be increased earlier.

[0018] In addition, it is not necessary to switch the control mode of the bypass valve depending on whether the first idle operation control or the catalyst early activation control is being executed. In other words, the fact that the flow rate change rate in the first region is equal to or less than the flow rate change rate in the third region can be said to take into consideration the difference in the bypass intake air amount (i.e., flow rate characteristics) required in each of the first idle operation control and the catalyst early activation control.

[0019] According to one aspect of the present invention, the intake air amount control system can employ the following configuration: (2) In the intake air amount control system of (1), the flow rate change rate in the first region is smaller than the flow rate change rate in the third region.

[0020] According to the above configuration, it is possible to more reliably control the bypass intake air amount precisely when the first idle operation control is executed, and to improve the responsiveness of the bypass intake air amount when the catalyst early activation control is executed.

[0021] According to one aspect of the present invention, the intake air amount control system can employ the following configuration: (3) In the intake air amount control system of (1) or (2), the at least one bypass valve nonlinearly changes the opening degree of the corresponding flow passage in response to the output of the actuator at a constant speed or a constant angular velocity.

[0022] In the above configuration, the opening of the flow path in the bypass valve (i.e., the flow path cross-sectional area in the bypass valve) changes nonlinearly when the position or rotation angle of the valve disc changes by a unit amount. That is, when the bypass valve opening increases at a constant rate, the flow path cross-sectional area in the bypass valve, which is throttled by the valve disc, increases nonlinearly. Alternatively, when the bypass valve opening increases at a constant rate, there is a range in which the flow path cross-sectional area increases nonlinearly. In other words, when the bypass valve changes from a fully closed state to a fully open state, the rate of change of flow rate does not become a fixed value.

[0023] According to one aspect of the present invention, the intake air amount control system can employ the following configuration: (4) In the intake air amount control system of (3), the at least one bypass valve exponentially changes the opening degree of the corresponding flow path in response to the output of the actuator at a constant speed or a constant angular velocity.

[0024] In the above configuration, when the bypass valve opening increases at a constant rate, the flow path cross-sectional area of ​​the bypass valve increases exponentially, i.e., the larger the bypass valve opening, the greater the rate of change of the flow rate.

[0025] According to one aspect of the present invention, the intake air amount control device can employ the following configuration: (5) In the intake air amount control device of (1) or (4), when the value obtained by dividing the total cross-sectional area of ​​all of the bypass valves included in the at least one bypass valve included in the bypass intake air amount control device by the cross-sectional area of ​​the intake port of the internal combustion engine is defined as a valve ratio of the bypass intake air amount control device, the bypass intake air amount control device is configured so that the valve ratio is 20% or more.

[0026] Generally, when the bypass valve is fully open, the larger the valve ratio, the larger the bypass intake air amount. In this configuration, the valve ratio is set to a relatively large value, so it is possible to easily increase the bypass intake air amount when executing catalyst early activation control.

[0027] According to one aspect of the present invention, the intake air amount control system can employ the following configuration: (6) The intake air amount control system according to any one of (1) to (5), further comprising a first intake air flow path in which the throttle valve is provided, and at least one of the at least one bypass flow path is configured to branch off from the first intake air flow path upstream of the throttle valve and merge with the first intake air flow path downstream of the throttle valve.

[0028] In the above configuration, the bypass passage is connected to the first intake passage at a position upstream and a position downstream of the throttle valve, so that the bypass intake air amount control system can be configured relatively easily.

[0029] According to one aspect of the present invention, the intake air amount control system can employ the following configuration: (7) The intake air amount control system according to any one of (1) to (5), further comprising a first intake flow path in which the throttle valve is provided, wherein an upstream end of a first bypass flow path that is at least one of the at least one bypass flow paths is not connected to the first intake flow path, and a downstream end of the first bypass flow path merges with the first intake flow path downstream of the throttle valve.

[0030] In the above configuration, the bypass intake air amount control system includes a bypass passage whose upstream end is not connected to the first intake passage, so that the bypass passage that bypasses the throttle valve can be configured relatively easily.

[0031] According to one aspect of the present invention, the intake air amount control system can employ the following configuration: (8) The intake air amount control system according to any one of (1) to (5), further comprising a first intake flow path in which the throttle valve is provided, wherein a first bypass flow path which is at least one of the at least one bypass flow paths branches off from the first intake flow path upstream of the throttle valve and merges with the first intake flow path downstream of the throttle valve, an upstream end of a second bypass flow path which is at least one of the at least one bypass flow paths is not connected to the first intake flow path, and a downstream end of the second bypass flow path merges with the first intake flow path downstream of the throttle valve.

[0032] The bypass intake air amount control device in the above configuration includes multiple bypass flow paths. Therefore, it is possible to selectively use the bypass valve that is preferentially opened when the first idle operation control is being executed and the bypass valve that is preferentially opened when the catalyst early activation control is being executed. Therefore, it is possible to quickly increase the intake air amount when the catalyst early activation control is being executed.

[0033] According to one aspect of the present invention, the intake air amount control system can employ the following configuration: (9) The intake air amount control system according to any one of (1) to (5), further comprising a first intake flow path in which the throttle valve is provided, wherein a first bypass flow path which is at least one of the at least one bypass flow paths branches off from the first intake flow path upstream of the throttle valve and merges with the first intake flow path downstream of the throttle valve, and a second bypass flow path which is at least one of the at least one bypass flow paths branches off from the first bypass flow path upstream of the at least one bypass valve and merges with the first intake flow path downstream of the throttle valve.

[0034] The bypass intake air amount control device in the above configuration also includes multiple bypass flow paths. Therefore, it is possible to selectively use the bypass valve that is preferentially opened when the first idle operation control is being executed and the bypass valve that is preferentially opened when the catalyst early activation control is being executed. Therefore, it is possible to quickly increase the intake air amount when the catalyst early activation control is being executed, thereby quickly increasing the rotation speed of the internal combustion engine.

[0035] According to one aspect of the present invention, a saddle-ride type vehicle can employ the following configuration: (10) A saddle-ride type vehicle including the intake amount control system according to any one of (1) to (9).

[0036] Generally, the body of a saddle-riding vehicle is often smaller than that of a four-wheeled vehicle. Therefore, greater flexibility in the design of hardware resources is required in the design of a saddle-riding vehicle. Furthermore, the location of an exhaust gas purification catalyst in a saddle-riding vehicle is generally more susceptible to the influence of wind when the vehicle is running than in a four-wheeled vehicle. According to the above configuration, when performing catalyst early activation control for an exhaust gas purification catalyst of an internal combustion engine mounted on a saddle-riding vehicle, the intake volume can be increased with better responsiveness while suppressing an increase in the computational load of a control device provided in the saddle-riding vehicle. Therefore, catalyst early activation can be achieved more quickly while suppressing an increase in the volume of an ECU mounted on the saddle-riding vehicle.

[0037] Idle operation is an operating state in which the internal combustion engine rotates but the rotation of the internal combustion engine is not transmitted to a power transmission mechanism connected to the internal combustion engine. Idle operation control is a control for realizing the above-mentioned idle operation in which the throttle valve is fully closed and the internal combustion engine is rotated by intake air from a bypass flow path. For example, in an internal combustion engine mounted on an automobile, idle operation control means control for operating the internal combustion engine while the vehicle is stopped. Generally, the intake air volume during idle operation control is smaller than the intake air volume while the vehicle is running.

[0038] The first idle operation control is, for example, a control executed when the vehicle is temporarily stopped in an internal combustion engine mounted on an automobile. Even when the internal combustion engine is used in, for example, a generator, an agricultural machine, a construction machine, or a ship, the first idle operation control may be executed when transmission of torque generated by the internal combustion engine is not required.

[0039] The catalyst early activation control is executed to increase the temperature of a catalyst used in an exhaust gas purification device provided in an exhaust path of an internal combustion engine in order to activate the catalyst. Therefore, the intake air volume during the execution of the catalyst early activation control is greater than the intake air volume during the execution of the first idle operation control. The catalyst early activation control is executed, for example, during a cold start of the internal combustion engine, but the execution timing of the control is not limited thereto. For example, the average intake air volume during the execution of the first idle operation control is measured, and if the intake air volume is greater than the average intake air volume by a predetermined percentage or more, it can be determined that the catalyst early activation control is being executed. This determination may be made based on the bypass valve opening amount during the idle operation control or the rotational speed of the internal combustion engine. This determination may be made based on both the bypass valve opening amount during the idle operation control and the rotational speed of the internal combustion engine.

[0040] The bypass flow passage refers to a part of the intake flow passage of an internal combustion engine that bypasses the throttle valve. The bypass flow passage can be realized in any form. For example, the downstream end (downstream end) of the bypass flow passage is connected to a position downstream of the throttle valve in the first intake flow passage (i.e., the intake flow passage in which the throttle valve is disposed). The downstream end of the bypass flow passage may be connected to an intake port or an intake manifold. The downstream end of the bypass flow passage may be connected to a position upstream of the intake manifold in the first intake flow passage. The upstream end of the bypass flow passage does not have to be connected to the first intake flow passage. For example, the upstream end of the bypass flow passage may be connected to an air cleaner different from the air cleaner provided at the upstream end of the first intake flow passage. The number of bypass flow passages may be one or more. The upstream end of one bypass flow passage may be connected to another of the bypass flow passages. The downstream end of one bypass flow passage may be connected to another of the bypass flow passages.

[0041] At least one bypass valve is provided in at least one bypass flow path provided in the intake air quantity control system. The type of bypass valve is not limited. The bypass valve may be, for example, a butterfly valve, a poppet valve, or a linear valve. When the intake air quantity control system is provided with multiple bypass valves, the bypass valves may be different from each other. When the intake air quantity control system is provided with multiple bypass valves, the bypass valve may include one that is not provided with a bypass valve. When the bypass flow path branches (i.e., when another bypass valve is connected midway through the bypass flow path), bypass valves may be provided in all of the sections upstream and downstream of the branch in these bypass flow paths. Alternatively, bypass valves may be provided in parts of the upstream and downstream sections.

[0042] The first to third ranges related to the bypass valve are hypothetical ranges introduced for the purpose of explaining the present technology, and do not mean that the control is changed depending on whether the bypass valve opening is in the first, second, or third range when the first idle operation control or the catalyst early activation control is executed.

[0043] The bypass intake air amount is the amount of intake air flowing through a bypass passage included in the bypass intake air amount control device. In other words, the bypass intake air amount is the amount of intake air bypassing the throttle valve and flowing into the internal combustion engine. That is, the bypass intake air amount is equal to the difference between the amount of intake air flowing into the combustion chamber of the internal combustion engine and the amount of intake air flowing through the throttle valve. The bypass intake air amount can be obtained by various methods. For example, the bypass intake air amount can be detected by an airflow sensor provided in the bypass passage. Alternatively, the bypass intake air amount can be estimated based on the detection value of an airflow sensor provided upstream of the branch point of the first intake passage with the bypass passage and the detection values ​​of pressure sensors provided near the throttle valve in the first intake passage and in the bypass passage. The bypass intake air amount can be estimated based on the detection values ​​of a flow velocity sensor and a pressure sensor provided in the bypass passage. Furthermore, the bypass intake air amount can be estimated based on the bypass valve opening and / or the rotational speed of the internal combustion engine.

[0044] The flow rate change rate is the amount of change in the bypass intake air amount relative to a change in the bypass valve opening, i.e., the flow rate change rate is the amount of change in the bypass intake air amount when the bypass valve opening changes by a unit amount.

[0045] "The first idle operation control is executed with at least a portion of the bypass valve opening falling within the first range" means that the bypass valve opening may fall within all or part of the first range when the first idle operation control is executed. Therefore, it is not excluded that there may be a period when the bypass valve opening is not within the first range when the first idle operation control is executed. Similarly, "The catalyst early activation control is executed with at least a portion of the bypass valve opening falling within the third range" does not exclude that there may be a period when the catalyst early activation control is executed with the bypass valve opening not within the third range when the catalyst early activation control is executed.

[0046] The measurement of the rate of change of flow rate when the negative pressures are equal can be performed, for example, using an airflow bench that can maintain the downstream end of the bypass flow passage and / or the intake port at a specific pressure (specifically, a pressure lower than atmospheric pressure (outside air pressure)). The expression "when the negative pressures are equal" is not intended to limit the first idle operation control and catalyst early activation control according to the present invention to those performed under conditions where the negative pressure does not change. The results of the measurement performed using the above-mentioned method of "measuring the rate of change of flow rate when the negative pressures are equal" merely describe the characteristics of the intake air amount control system of the present application.

[0047] The "rate of flow rate change in the first region" in "the rate of flow rate change in the first region is equal to or less than the rate of flow rate change in the third region" refers to the average value of the rate of flow rate change when the bypass valve opening is within the first region and continues to change. In other words, the "rate of flow rate change in the first region" does not refer to a value (i.e., an instantaneous value) obtained only once when the bypass valve opening is within the first region. Similarly, the "rate of flow rate change in the third region" refers to the average value of the rate of flow rate change when the bypass valve opening is within the third region and continues to change.

[0048] The bypass valve includes an actuator and a valve element whose position or rotational speed is changed by the actuator. The actuator may be, for example, a stepping motor, but the type of motor is not limited thereto. The actuator may be, for example, a direct-acting actuator such as a linear solenoid.

[0049] When "the output of the actuator is changed at a constant speed or a constant angular velocity from the fully closed state of the bypass valve to the fully open state," the position or rotational angle of the valve disc of the bypass valve increases or decreases at a constant speed. The region obtained by "dividing into three equal parts the time region when the output of the actuator is changed at a constant speed or a constant angular velocity from the fully closed state of the bypass valve to the fully open state of the bypass valve" means that the range of the bypass valve opening (bypass valve opening) from 0% to 100% is divided into three equal parts. Note that the expression "changed at a constant speed or a constant angular velocity" is an expression used to define first to third regions related to the bypass valve. Therefore, the present invention is not limited to cases where the output of the actuator is changed at a constant speed or a constant angular velocity.

[0050] The valve ratio is a value obtained by dividing the overall cross-sectional area (flow path cross-sectional area) of the bypass valve included in the bypass intake air amount control device by the cross-sectional area (flow path cross-sectional area) of the intake port of the internal combustion engine. For example, if the bypass intake air amount control device includes one combination of a bypass flow path and a bypass valve, the overall cross-sectional area of ​​the bypass valve may be the flow path cross-sectional area of ​​the bypass flow path when the bypass valve is fully open. Alternatively, if the bypass intake air amount control device includes multiple combinations of a bypass flow path and a bypass valve, the overall cross-sectional area of ​​the bypass valve may be the flow path cross-sectional area of ​​all of the bypass flow paths when all of the bypass valves are fully open. In this case, the overall cross-sectional area of ​​the bypass valve may be the minimum value of the flow path cross-sectional area of ​​the path of intake air that bypasses the throttle valve.

[0051] The first intake passage includes an upstream intake passage provided with a throttle valve and an intake port, and constitutes at least a part of an intake path of the internal combustion engine. The first intake passage may include an intake manifold interposed between the upstream intake passage and the intake port.

[0052] "Upstream" and "downstream" are defined based on the direction of intake air flow. Therefore, the side of the intake passage closer to the internal combustion engine is the downstream side. "Joining the first intake passage downstream of the throttle valve" includes cases where the downstream end of the bypass passage is connected to a position downstream of the throttle valve in the upstream intake passage. In addition, "joining the first intake passage downstream of the throttle valve" includes cases where the downstream end of the bypass passage is connected to an intake port or an intake manifold.

[0053] A saddle-type vehicle is a vehicle that is ridden in a horseback riding style. A driver sits astride the saddle of the saddle-type vehicle. An example of a saddle-type vehicle is a lean-type vehicle. Examples of saddle-type vehicles include scooter-type, moped-type, off-road-type, and on-road-type motorcycles. In addition, the saddle-type vehicle is not limited to motorcycles, and may be, for example, an ATV (All-Terrain Vehicle) or a motor tricycle. A motor tricycle may have two front wheels and one rear wheel, or one front wheel and two rear wheels.

[0054] The terminology used herein is for the purpose of defining particular embodiments only and is not intended to limit the invention. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed components. As used herein, the use of the terms "including," "comprising," or "having," and variations thereof, identifies the presence of stated features, steps, operations, elements, components, and / or equivalents thereof, but may include one or more of the steps, operations, elements, components, and / or groups thereof. As used herein, the terms "attached," "connected," "coupled," and / or equivalents thereof are used broadly and encompass both direct and indirect attachments, connections, and couplings. Furthermore, "connected" and "coupled" are not limited to physical or mechanical connections or couplings, but can include direct or indirect electrical connections or couplings. Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Terms, such as those defined in commonly used dictionaries, should be interpreted to have a meaning consistent with the relevant technology and the context of this disclosure, and should not be interpreted in an idealized or overly formal sense unless explicitly defined herein. In describing the present invention, it is understood that a number of techniques and steps are disclosed. Each of these has distinct advantages, and each can be used with one or more, or in some cases all, of the other disclosed techniques. Therefore, for clarity, this description will refrain from unnecessarily repeating all possible combinations of individual steps. Nevertheless, the specification and claims should be read with the understanding that all such combinations are within the scope of the present invention and claims. This specification describes a novel intake air flow control system and a straddle-type vehicle. In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the present invention.However, it will be apparent to one skilled in the art that the present invention may be practiced without these specific details. The present disclosure is to be considered as an example of the present invention and is not intended to limit the invention to the specific embodiments illustrated by the following drawings or description.

[0055] According to the present invention, it is possible to reduce the computational load and to realize an intake air amount control system having flow characteristics that take into account the difference in intake air amount when normal idle control and catalyst early activation control are executed.

[0056] FIG. 1 is a diagram schematically showing an intake air amount control system according to a first embodiment. FIG. 2 is a diagram showing the relationship between a bypass valve opening and an intake air amount. FIG. 3 is a diagram schematically showing an intake air amount control system according to a second embodiment. FIG. 4 is a diagram schematically showing a cross section of a bypass valve provided in the intake air amount control system according to the second embodiment. FIG. 5 is a diagram schematically showing a side view of a bypass valve provided in the intake air amount control system according to the second embodiment. FIG. 6 is a diagram schematically showing an intake air amount control system according to a third embodiment. FIG. 7 is a diagram schematically showing an intake air amount control system according to a fourth embodiment. FIG. 8 is a diagram schematically showing an intake air amount control system according to a fifth embodiment. FIG. 9 is a diagram schematically showing a cross section of a bypass valve according to a first modified example of the bypass valve. FIG. 10 is a diagram schematically showing a side view of a bypass valve according to the first modified example of the bypass valve. FIG. 11 is a diagram schematically showing a cross section of a bypass valve according to a second modified example of the bypass valve. FIG. 12 is a diagram schematically showing a side view of a bypass valve according to the second modified example of the bypass valve. FIG. 13 is a diagram schematically showing a cross section of a bypass valve according to a third modified example of the bypass valve. FIG. 10 is a diagram schematically showing a cross section of a bypass valve according to a fourth modified example of the bypass valve. FIG. 11 is a diagram schematically showing a side view of a bypass valve according to the fourth modified example of the bypass valve. FIG. 12 is a diagram schematically showing a cross section of a bypass valve according to a fifth modified example of the bypass valve. FIG. 13 is a diagram schematically showing a side view of a bypass valve according to the fifth modified example of the bypass valve. FIG. 14 is a diagram schematically showing a cross section of a sixth modified example of the bypass valve. FIG. 15 is a diagram schematically showing a side view of a bypass valve according to the sixth modified example of the bypass valve. FIG. 16 is a diagram schematically showing a cross section of a bypass valve according to a seventh modified example of the bypass valve. FIG. 17 is a diagram schematically showing a side view of a bypass valve according to the seventh modified example of the bypass valve. FIG. 18 is a diagram schematically showing a cross section of an eighth modified example of the bypass valve. FIG. 19 is a diagram schematically showing a side view of the eighth modified example of the bypass valve. FIG. 19 is a diagram schematically showing a saddle-ride type vehicle according to a sixth embodiment.

[0057] Hereinafter, the present invention will be described based on an embodiment with reference to the drawings.

[0058] [First Embodiment] Fig. 1 is a diagram that schematically shows an intake air amount control system according to a first embodiment. The left side of Fig. 1 schematically shows the intake air amount control system. The graph in the upper right of Fig. 1 shows the relationship between the bypass valve opening and the bypass intake air amount in the intake air amount control system. The graph in the lower right of Fig. 1 shows the change in the flow rate change rate in the intake air amount control system. Fig. 2 is a diagram that shows the relationship between the bypass valve opening and the intake air amount for the bypass valve 13, the throttle valve 71, and one of the conventional bypass valves (not shown) when the negative pressure of the internal combustion engine is a specific value.

[0059] 1 includes a throttle valve 71, a bypass intake air amount control device 11, and a bypass flow path 12. The bypass intake air amount control device 11 includes a bypass valve 13 and an actuator 13a. The intake air amount control system 1 is disposed in the intake path of an internal combustion engine (not shown).

[0060] The throttle valve 71 is, for example, a butterfly valve, and throttles the intake path according to the rotation angle of a valve body (not shown). The opening of the throttle valve 71 is also referred to as the throttle valve opening [%]. As the throttle valve opening increases, the opening area of ​​the intake path increases. As the opening area of ​​the intake path increases, the throttle intake amount [g / sec], which is the amount of intake air flowing through the throttle valve 71, increases.

[0061] The bypass flow path 12 forms an intake path that bypasses the throttle valve 71. The amount of intake air flowing into the internal combustion engine is the sum of the bypass intake air amount [g / sec], which is the amount of intake air flowing through the bypass flow path 12, and the throttle intake air amount. The bypass valve 13 is, for example, a poppet valve, and throttles the bypass flow path 12 according to the lift amount of a valve disc (not shown). The bypass valve opening [%] is a value that depends on the position and rotation angle of the valve disc. When the bypass valve is a poppet valve, the bypass valve opening is expressed by the lift amount of the valve disc or a value proportional to the lift amount. Note that, when the movement direction of the valve disc is defined as the up-down direction and the movement direction of the valve disc in the direction increasing the valve opening is defined as the up-down direction, the lift amount is the distance between the valve seat and the lower end of the valve disc. The lift amount of the valve disc at which the bypass valve 13 is in a "fully closed state" (described later) may be defined as a reference lift amount (lift amount = 0), and the distance between the reference lift amount and the lower end of the valve disc may be defined as the lift amount. When the bypass valve is a butterfly valve, the bypass valve opening is expressed by the rotation angle of the valve element or an amount proportional to the rotation angle. The larger the bypass valve opening, the larger the opening area (flow path cross-sectional area) of the bypass valve 13.

[0062] The state in which the bypass valve opening degree is 0% is also referred to as a "fully closed state." When the bypass valve opening degree is 0%, the flow path cross-sectional area of ​​the bypass valve 13 is approximately 0. When the bypass valve opening degree is 100%, the bypass flow path 12 is not throttled by the bypass valve 13. To control the bypass valve opening degree, the bypass valve 13 is provided with an actuator 13a. The actuator 13a is, for example, a stepping motor (not shown). The actuator 13a, together with the actuator of the throttle valve 71, is controlled by a control device of the internal combustion engine (not shown, for example, an ECU (electronic control unit)).

[0063] More specifically, the rotation angle of the actuator 13a changes depending on the number of times the pulse voltage is applied (i.e., the number of steps), and the bypass valve opening changes accordingly. A gear mechanism (e.g., a reducer) may be interposed in the torque transmission path from the actuator 13a to the valve disc. Therefore, when the pulse voltage is applied to the actuator 13a at equal intervals, the bypass valve opening increases or decreases at a constant rate. In other words, the bypass valve opening is a value that correlates with the position or rotation angle of the valve disc of the bypass valve 13, and also represents the displacement of the actuator 13a.

[0064] The control device of the internal combustion engine can obtain the displacement amount of the actuator 13a and the bypass valve opening degree of the bypass valve 13 based on the number of times the pulse voltage is applied to the actuator 13a. Note that the actuator 13a is not limited to a stepping motor. The actuator 13a may be, for example, a brushless DC motor. If the actuator 13a is a brushless DC motor, the control device of the internal combustion engine can obtain the displacement amount of the actuator 13a and the bypass valve opening degree of the bypass valve 13 based on the current value or voltage value applied to the actuator 13a.

[0065] The solid line L1a in the graph at the upper right of Fig. 1 shows the relationship between the bypass valve opening and the bypass intake air amount. More specifically, the solid line L1a shows the relationship between the bypass valve opening and the bypass intake air amount when the negative pressure at the downstream end of the bypass flow path 12 generated during the intake stroke of the internal combustion engine is a specific value. As shown by the solid line L1a, the bypass intake air amount increases as the bypass valve opening increases.

[0066] The change in the slope of the solid line L1a will be further explained. In the graph at the lower right of FIG. 1, the dashed line L2a is a tangent to the solid line L1a at a point corresponding to a bypass valve opening of approximately 0%. Similarly, the dashed line L2b is a tangent to the solid line L1a at a point corresponding to a bypass valve opening of approximately 100%. The slope of the dashed line L2b is greater than the slope of the dashed line L2a. That is, the larger the bypass valve opening, the greater the slope of the solid line L1a. In other words, the "rate of change in flow rate," which is the amount of change in the bypass intake air volume relative to a change in the bypass valve opening, increases as the bypass valve opening increases. The rate of change in flow rate is also the amount of change in the bypass intake air volume relative to a change in the position or rotation angle of the valve disc of the bypass valve.

[0067] In other words, the larger the bypass valve opening, the larger the increase in the bypass intake air volume when the bypass valve opening is increased by a unit amount.It can also be said that the larger the bypass valve opening, the larger the increase in the opening of the bypass valve 13 (i.e., the flow path cross-sectional area) when the valve opening is increased by a unit amount.In addition, it can be said that the opening of the bypass valve 13 increases nonlinearly or exponentially when the valve disc of the bypass valve 13 is displaced at a constant angular velocity.

[0068] In each of the graphs at the upper right and lower right of FIG. 1 , the range of values ​​that the bypass valve opening degree can take (i.e., the range from 0% to 100%) is divided into three equal parts: a first region, a second region, and a third region. The first to third regions can also be considered to be regions obtained by dividing into thirds the time region in which the bypass valve actuator increases the position or rotation angle of the valve disc at a constant rate from a value corresponding to a fully closed state to a value corresponding to a fully open state. When the internal combustion engine control device determines that the internal combustion engine should be put into an idle state, it executes, for example, a "first idle operation control." The first idle operation control is one type of idle operation control. The first idle operation control is executed, for example, when a saddle-type vehicle equipped with an internal combustion engine is temporarily stopped. During the execution of the first idle operation control, the throttle valve opening degree is set to approximately zero. In addition, the bypass valve opening degree is controlled to a value included in the first region. More specifically, during the execution of the first idle operation control, the bypass valve 13 is controlled so that the bypass valve opening degree falls within part or all of the first region.

[0069] On the other hand, when the control device for the internal combustion engine determines that an exhaust gas purifying catalyst (not shown) installed in the exhaust path of the internal combustion engine needs to be activated by heating it up earlier, it executes "early catalyst activation control" as idle operation control. The early catalyst activation control is control that increases the bypass valve opening compared to when the first idle operation control is executed. When the early catalyst activation control is executed, the bypass valve opening is controlled to a value included in the third range. More specifically, when the early catalyst activation control is executed, the bypass valve 13 is controlled so that the bypass valve opening is included in part or all of the third range. As a result, the bypass intake air amount when the early catalyst activation control is executed is larger than when the first idle operation control is executed.

[0070] The control device for the internal combustion engine may execute "second idle operation control" as the idle operation control. When the second idle operation control is executed, the bypass valve opening is controlled to a value included in the third region. The second idle operation control is executed, for example, when the temperature of the coolant of the internal combustion engine is relatively low.

[0071] The bypass valve 13 is not limited to the poppet valve or butterfly valve described above, and may be, for example, a linear valve. Another example of the relationship between the bypass valve opening and the bypass intake air amount in this embodiment is shown by the dashed line L1b and the dashed-dotted line L1c in the graph at the upper right of Figure 1.

[0072] In either case, when the negative pressure of the internal combustion engine is a predetermined specific value, the flow rate change rate when the bypass valve opening is within the first range (also referred to as the "first range flow rate change rate") is equal to or less than the flow rate change rate when the bypass valve opening is within the third range (also referred to as the "third range flow rate change rate"). More specifically, as shown by the solid line L1a, the flow rate change rate of the bypass valve 13 increases as the bypass valve opening increases. As shown by the dashed line L1b, for one of the other bypass valves, when the bypass valve opening is small, the flow rate change rate increases as the bypass valve opening increases. In other words, the flow rate change rate changes. In addition, when the bypass valve opening increases to a certain extent, the flow rate change rate becomes a constant value. As shown by the dashed line L1c, for the other of the other bypass valves, when the bypass valve opening is small, the flow rate change rate becomes a relatively small constant value. In addition, when the bypass valve opening increases to a certain extent, the flow rate change rate becomes a relatively large constant value.

[0073] Alternatively, the bypass intake air amount control device 11 may be configured so that the first region flow rate change rate is smaller than the third region flow rate change rate (i.e., so that the first region flow rate change rate is not equal to the third region flow rate change rate). Furthermore, the bypass intake air amount control device 11 may be configured so that the first region flow rate change rate is equal to or smaller than the third region flow rate change rate when the negative pressure of the internal combustion engine is not limited to a specific value but is within a range that can occur when the engine is idling (also referred to as the "idle negative pressure range"). Alternatively, the bypass intake air amount control device 11 may be configured so that the first region flow rate change rate is smaller than the third region flow rate change rate when the negative pressure of the internal combustion engine is within the idle negative pressure range.

[0074] As shown by the solid line L1a in Fig. 2, when the bypass valve opening degree of the bypass valve 13 is 100%, the amount of intake air passing through the bypass valve 13 is A1max [g / sec]. The dashed line L3a shows the relationship between the throttle valve opening degree of the throttle valve 71 and the throttle intake air amount. When the throttle valve opening degree is 100% (i.e., when the throttle valve 71 is in a wide open throttle (WOT) state), the amount of intake air passing through the throttle valve 71 is Atmax [g / sec]. The dashed dotted line L3b shows the relationship between the bypass valve opening degree of a conventional bypass valve and the bypass intake air amount. When the bypass valve opening degree is 100%, the amount of intake air passing through the conventional bypass valve is Acmax [g / sec].

[0075] 2, when the bypass valve opening degree is included in the third region, the bypass intake air amount at the bypass valve 13 is smaller than the intake air amount flowing through the throttle valve 71 when the value of the throttle opening degree is equal to the bypass valve opening degree. In addition, when the bypass valve opening degree is included in the third region, the bypass intake air amount at the bypass valve 13 is larger than the intake air amount flowing through a conventional bypass valve.

[0076] One reason why the bypass intake air amount in the bypass valve 13 is larger than that in a conventional bypass valve will be explained. The valve ratio in the intake air amount control system 1 is a value slightly larger than 20%, which is larger than the valve ratio in a conventional bypass valve. The valve ratio in the intake air amount control system 1 is a value obtained by dividing the cross-sectional area (flow path cross-sectional area) of the bypass valve 13 by the cross-sectional area (flow path cross-sectional area) of an intake port in an internal combustion engine to which the intake air amount control system 1 is applied. The intake port in the internal combustion engine is, for example, the intake port 73 shown in FIG. 3 , which will be described later. The cross-sectional area of ​​the intake port is the flow path cross-sectional area of ​​a communication portion 73a between the intake port 73, which is opened and closed by the intake valve 62, and the combustion chamber 61.

[0077] In the bypass intake air amount control device 11, the rate of change of the flow rate during first idle operation control (i.e., when the bypass valve opening is within the first range) is not as large as during catalyst early activation control (i.e., when the bypass valve opening is within the third range). Therefore, precise control of the bypass intake air amount through the bypass flow path 12 during first idle operation control is relatively easy. Meanwhile, during catalyst early activation control, the bypass intake air amount through the bypass flow path 12 can be rapidly increased. In addition, the valve ratio of the intake air amount control system 1 exceeding 20% ​​also contributes to the increase in the bypass intake air amount. Furthermore, the calculation load on the internal combustion engine control device can be prevented from becoming excessive when rapidly increasing the bypass intake air amount.

[0078] [Second embodiment] Fig. 3 is a diagram schematically showing an intake air amount control system according to a second embodiment. Fig. 4 is a diagram schematically showing a cross section of a bypass valve provided in the intake air amount control system according to the second embodiment. Fig. 5 is a diagram schematically showing a side view of the bypass valve. Components similar to those in the first embodiment are given the same reference numerals as those in the intake air amount control system 1 shown in Fig. 1, and some descriptions will be omitted.

[0079] The intake air amount control system 21 according to this embodiment differs from the intake air amount control system 1 according to the first embodiment in that it includes a first intake air passage 7. The intake air amount control system 21 is applied to an internal combustion engine 6. The first intake air passage 7 includes a throttle valve 71, an upstream intake air passage 72, and an intake port 73. The throttle valve 71 is provided in the upstream intake air passage 72. An intake port 73 is connected to the downstream end of the upstream intake air passage 72. Intake air (fresh air) is introduced into the upstream end (upstream end) of the upstream intake air passage 72. The intake port 73 is connected to a combustion chamber 61 (i.e., a cylinder) of the internal combustion engine 6. Therefore, the intake air introduced into the upstream intake air passage 72 flows into the combustion chamber 61 of the internal combustion engine 6 via the intake port 73. The intake valve 62 opens and closes a communication portion 73a between the intake port 73 and the combustion chamber 61.

[0080] The bypass intake air amount control device 22 included in the intake air amount control system 21 includes a bypass flow path 23 and a bypass valve 24. The bypass valve 24 is provided in the bypass flow path 23. The upstream end of the bypass flow path 23 is connected to a position upstream of the throttle valve 71 in the upstream intake flow path 72. That is, the bypass flow path 23 branches off from the upstream intake flow path 72 upstream of the throttle valve 71. The downstream end of the bypass flow path 23 is connected to a position downstream of the throttle valve 71 in the upstream intake flow path 72. That is, the bypass flow path 23 merges with the upstream intake flow path 72 downstream of the throttle valve 71.

[0081] 4 and 5, the bypass valve 24 includes a cylinder 241, a supply port 242, an output port 243, a valve element 244, a shaft 245, and an actuator 246. The cylinder 241, the supply port 242, and the output port 243 each have a substantially cylindrical shape. The cylinder 241, the supply port 242, and the output port 243 are integrally molded. An axis L4a is the central axis of the cylinder 241 and the supply port 242. An axis L4b is the central axis of the output port 243.

[0082] The cylinder 241, the supply port 242, and the output port 243 constitute a part of the bypass flow path 23. More specifically, when the bypass valve opening degree of the bypass valve 24 is greater than 0%, the intake air that branches off from the upstream intake flow path 72 and flows into the bypass flow path 23 flows into the cylinder 241 via the supply port 242. The intake air in the cylinder 241 flows into the upstream intake flow path 72 via the output port 243. The valve element 244 has a substantially cylindrical shape. The valve element 244 is movable in the direction of the axis L4a while sliding within the cylinder 241. One end of a shaft 245 is connected to the valve element 244.

[0083] The actuator 246 has a generally cylindrical shape and a space 246a into which the other end of the shaft 245 is inserted. The actuator 246 includes a coil that generates a magnetic force acting on the shaft 245 and a spring that biases the shaft 245 (neither of which are shown), thereby moving the shaft 245 along the axis L4a. The shaft 245 can also be considered an armature or movable iron core of the actuator 246. The actuator 246 displaces the valve element 244 via the shaft 245, thereby controlling the bypass valve opening of the bypass valve 24. The bypass valve opening of the bypass valve 24 represents the amount of displacement of the valve element 244 relative to the cylinder 241. In other words, when the actuator 246 displaces the shaft 245 at a constant speed, the bypass valve opening increases or decreases at a constant speed. A control device (not shown) for the internal combustion engine 6 can control the bypass valve opening of the bypass valve 24 by controlling the current flowing through the coil of the actuator 246.

[0084] 4 and 5 closes the communication portion (boundary portion) between the cylinder 241 and the output port 243. That is, in this case, the bypass valve opening degree of the bypass valve 24 is 0%, and the bypass valve 24 is in a fully closed state. When the valve disc 244 moves in a direction approaching the actuator 246, the blockage by the valve disc 244 at the communication portion between the cylinder 241 and the output port 243 is released. More specifically, when the valve disc 244 approaches the actuator 246, the bottom surface 244a of the valve disc 244 on the supply port 242 side reaches the end of the inner circumferential surface of the output port 243 on the supply port 242 side, and the bypass valve opening degree starts to increase from 0%.

[0085] In the communication portion between the cylinder 241 and the output port 243, the area of ​​the region where the blockage by the valve element 244 is released (i.e., the flow path formed between the cylinder 241 and the output port 243) is the opening area of ​​the bypass valve 24. In other words, the opening area of ​​the bypass valve 24 increases as the valve element 244 approaches the actuator 246. That is, as the valve element 244 approaches the actuator 246, the bypass valve opening degree of the bypass valve 24 increases.

[0086] When the valve element 244 approaches the actuator 246 and the bottom surface 244b of the valve element 244 on the actuator 246 side comes into contact with the inner surface 241a of the valve element 244 on the valve element 244 side in the space formed in the cylinder 241, the bypass valve opening degree becomes 100%. That is, in this case, the bypass valve 24 is in a fully open state. It can be said that the bypass valve opening degree of the bypass valve 24 is determined depending on the position of the shaft 245 relative to the actuator 246. Therefore, the control device of the internal combustion engine 6 can obtain the bypass valve opening degree of the bypass valve 24 by detecting the position of the valve element 244 relative to the cylinder 241 or the position of the shaft 245 relative to the actuator 246.

[0087] The bypass intake air amount control device 22 has flow characteristics similar to those of the bypass intake air amount control device 11 according to the first embodiment. That is, the flow rate change rate when the bypass valve opening degree of the bypass valve 24 is within the first range (i.e., the first range flow rate change rate) is equal to or less than the flow rate change rate when the bypass valve opening degree is within the third range (i.e., the third range flow rate change rate). Alternatively, the bypass intake air amount control device 22 may be configured so that the first range flow rate change rate is smaller than the third range flow rate change rate.

[0088] According to the intake air amount control system 21, the first idle operation control and the catalyst early activation control are each performed by the bypass flow path 23 (i.e., one bypass flow path) and the bypass valve 24 (i.e., one bypass valve), which increases the possibility of suppressing increases in weight and volume compared to when multiple bypass flow paths and bypass valves are used.

[0089] The fully open state of the bypass valve 24 may be different from the above-described "state in which the bottom surface 244b of the valve element 244 is in contact with the inner surface 241a of the cylinder 241." For example, if the rate of change of the flow rate increases as the valve element 244 approaches the actuator 246 within a range up to when the valve element 244 reaches a specific position, the specific position may be treated as the position of the valve element 244 corresponding to a state in which the bypass valve opening degree is 100%.

[0090] The downstream end of the bypass flow path 23 of the bypass intake air amount control device 22 according to this embodiment may be connected to the intake port 73. That is, the intake air that has passed through the bypass valve 24 may directly flow into the intake port 73.

[0091] The first intake passage 7 according to this embodiment may include an intake manifold (not shown). The upstream end of the intake manifold is connected to the downstream end of the upstream intake passage 72. Each of the multiple downstream ends of the intake manifold is connected to an intake port 73. FIG. 3 shows one of the multiple intake ports 73 provided in the internal combustion engine. In this case, the downstream end of the bypass passage 23 associated with the bypass intake air amount control device 22 may be connected to the intake manifold. That is, the intake air that has passed through the bypass valve 24 flows directly into the intake manifold.

[0092] Furthermore, in the intake air amount control system 21 according to this embodiment, the upstream end of the bypass passage 23 does not have to be connected to the upstream intake passage 72. In this case, for example, intake air that has passed through different air cleaners (not shown) is introduced into the upstream intake passage 72 and the bypass passage 23. The bypass passage 23 may merge with the upstream intake passage 72 downstream of the throttle valve 71. Alternatively, the downstream end of the bypass passage 23 may be connected to the intake port 73 or the intake manifold. The bypass passage 23 is also referred to as a "first bypass passage."

[0093] [Third embodiment] Fig. 6 is a diagram schematically showing an intake air amount control device according to a third embodiment. Components similar to those in the second embodiment are denoted by the same reference numerals as those in the intake air amount control system 21 shown in Fig. 3, and some of the descriptions thereof will be omitted.

[0094] The intake air amount control system 31 according to this embodiment differs from the intake air amount control system 21 according to the second embodiment in that the upstream ends of the bypass flow path and the upstream intake flow path are connected to an air cleaner. The first intake flow path 7a according to this embodiment includes an air cleaner 74 that purifies the intake air.

[0095] The upstream end of the upstream intake flow path 72 is connected to an air cleaner 74. In addition, the upstream end of a bypass flow path 33 provided in the bypass intake air amount control device 32 of the intake air amount control system 31 is connected to the air cleaner 74. The downstream end of the bypass flow path 33 is connected to a position downstream of the throttle valve 71 in the upstream intake flow path 72. The bypass flow path 33 is also referred to as a "first bypass flow path."

[0096] [Fourth embodiment] Fig. 7 is a diagram schematically showing an intake air amount control device according to a fourth embodiment. Components similar to those in the second embodiment are denoted by the same reference numerals as those in the intake air amount control system 21 shown in Fig. 3, and some of the descriptions thereof will be omitted.

[0097] The intake air amount control system 41 according to this embodiment differs from the intake air amount control system 21 according to the second embodiment in that it includes a plurality of bypass flow paths and bypass valves. A bypass intake air amount control device 42 included in the intake air amount control system 41 includes a bypass flow path 43 and a bypass valve 44 in addition to the bypass flow path 23 and the bypass valve 24. The bypass valve 44 is provided in the bypass flow path 43. The bypass valve 44 has a structure similar to that of the bypass valve 24 and includes an actuator 446. The bypass valve opening degree of the bypass valve 44 is controlled by the actuator 446.

[0098] The first intake flow path 7b according to this embodiment includes an air cleaner 74a that purifies the intake air. The upstream ends of the upstream intake flow path 72 and the bypass flow path 43 are connected to the air cleaner 74a. That is, the upstream end of the bypass flow path 43 is not connected to the upstream intake flow path 72. The downstream end of the bypass flow path 43 is connected to the intake port 73. The bypass flow path 23 according to this embodiment is also referred to as the "first bypass flow path." The bypass flow path 43 is also referred to as the "second bypass flow path."

[0099] The bypass flow passage provided in the bypass intake air amount control device 42 may be configured in various ways. For example, the downstream end of the bypass flow passage 23 associated with the bypass intake air amount control device 42 may be connected to the intake port 73 instead of the upstream intake flow passage 72. Alternatively, the downstream end of the bypass flow passage 23 may be connected to the intake manifold. Additionally, the bypass flow passage 43 may be connected to the upstream intake flow passage 72 at a position downstream of the throttle valve 71 instead of the intake port 73. Alternatively, the bypass flow passage 43 may be connected to the intake manifold instead of the intake port 73. Furthermore, the cross-sectional area of ​​the bypass flow passage 43 may be equal to or different from that of the bypass flow passage 23. For example, if the cross-sectional area of ​​the bypass flow passage 43 is larger than that of the bypass flow passage 23, the bypass valve 24 provided in the bypass flow passage 23 may be opened when the first idle operation control is performed, and the bypass valve 44 provided in the bypass flow passage 43 may be opened when the catalyst early activation control is performed. Additionally, the bypass intake air amount control device 42 may further include one or more bypass flow paths in addition to the bypass flow path 23 and the bypass flow path 43. The bypass intake air amount control device 42 may also include a bypass flow path that is not provided with a bypass valve.

[0100] Furthermore, the bypass valves included in the bypass intake air amount control device 42, including the bypass valves 24, 44, may be valves of different types. For example, the bypass valve 24 may be a butterfly valve, and the bypass valve 44 may be a poppet valve. Regardless of the type of bypass valve, when the position or rotation angle of the valve element of the bypass valve 24, 44 is displaced at a constant speed, the bypass valve opening of the bypass valve 24, 44 increases or decreases at a constant speed.

[0101] The bypass intake air amount control device 42, which includes multiple bypass valves (i.e., bypass valves 24, 44), has flow characteristics similar to those of the bypass intake air amount control device 11 according to the first embodiment. That is, the flow rate change rate when the bypass valve opening degrees of the bypass valves 24, 44 are within the first range (i.e., first range flow rate change rate) is equal to or less than the flow rate change rate when the bypass valve opening degrees are within the third range (i.e., third range flow rate change rate). Alternatively, the bypass intake air amount control device 42 may be configured so that the first range flow rate change rate is smaller than the third range flow rate change rate.

[0102] The bypass intake air amount control device 42 may be configured, for example, so that the increase in the bypass intake air amount when the bypass valve opening degrees of the bypass valves 24, 44 are both increased by a unit amount in the first range is larger than the increase in the bypass intake air amount when the bypass valve opening degrees of these bypass valves are both increased by a unit amount in the third range. In this example, the increase in the bypass intake air amount when the bypass valve opening degrees of the bypass valves 24, 44 are increased by a unit amount while remaining equal may be compared between the first range and the third range. The bypass intake air amount in this example is the amount of intake air that bypasses the throttle valve 71 and flows into the internal combustion engine 6.

[0103] [Fifth embodiment] Fig. 8 is a diagram showing a schematic diagram of an intake air amount control device according to a fifth embodiment. Components similar to those in the fourth embodiment are denoted by the same reference numerals as those in the intake air amount control system 41 shown in Fig. 7, and some of the descriptions thereof will be omitted.

[0104] An intake air amount control system 51 according to this embodiment differs from the intake air amount control system 41 according to the fourth embodiment in that an upstream end of one of the bypass flow paths is connected to another of the bypass flow paths. A bypass intake air amount control device 52 according to the intake air amount control system 51 includes bypass flow paths 53-54 and bypass valves 55-56. The bypass valves 55-56 are provided in the bypass flow paths 53-54, respectively. The flow path cross-sectional area of ​​the bypass flow path 54 is smaller than that of the bypass flow path 53.

[0105] The bypass valves 55 to 56 have the same structure as the bypass valve 24 and are provided with actuators 556 and 566, respectively. The opening degrees of the bypass valves 55 to 56 are controlled by the actuators 556 and 566.

[0106] The upstream end of the bypass flow path 53 is connected to the upstream intake flow path 72 at a position upstream of the throttle valve 71. The downstream end of the bypass flow path 53 is connected to the upstream intake flow path 72 at a position downstream of the throttle valve 71. The bypass flow path 53 is also referred to as a "first bypass flow path." The upstream end of the bypass flow path 54 is connected to the bypass flow path 53 at a position upstream of the bypass valve 55. The downstream end of the bypass flow path 54 is connected to the intake port 73. The bypass flow path 54 is also referred to as a "second bypass flow path."

[0107] The bypass flow passage provided in the bypass intake air quantity control device 52 may be configured in various ways. For example, the downstream end of the bypass flow passage 53 of the bypass intake air quantity control device 52 may be connected to the intake port 73 instead of the upstream intake flow passage 72. Alternatively, the downstream end of the bypass flow passage 53 may be connected to the intake manifold. In addition, the downstream end of the bypass flow passage 54 may be connected to a position downstream of the throttle valve 71 in the upstream intake flow passage 72 instead of the intake port 73. Alternatively, the downstream end of the bypass flow passage 54 may be connected to the intake manifold. Furthermore, the flow passage cross-sectional area of ​​the bypass flow passage 54 may be equal to that of the bypass flow passage 53. Alternatively, the flow passage cross-sectional area of ​​the bypass flow passage 54 may be larger than that of the bypass flow passage 53. In addition, the bypass intake air quantity control device 52 may further include one or more bypass flow passages in addition to the bypass flow passages 53 and 54. The bypass intake air quantity control device 52 may also include a bypass flow passage without a bypass valve.

[0108] Furthermore, the bypass valves included in the bypass intake air amount control device 52, including the bypass valves 55 and 56, may be valves of different types. For example, the bypass valve 55 may be a butterfly valve, and the bypass valve 56 may be a poppet valve. Regardless of the type of bypass valve, when the position or rotation angle of the valve element of the bypass valves 55 and 56 is displaced at a constant speed, the bypass valve opening degree of the bypass valves 55 and 56 increases or decreases at a constant speed.

[0109] The bypass intake air amount control device 52, which includes multiple bypass valves (i.e., bypass valves 55-56), has flow characteristics similar to those of the bypass intake air amount control device 11 according to the first embodiment. That is, the flow rate change rate when the bypass valve openings of the bypass valves 55-56 are within the first range (i.e., first range flow rate change rate) is equal to or less than the flow rate change rate when the bypass valve openings are within the third range (i.e., third range flow rate change rate). Alternatively, the bypass intake air amount control device 52 may be configured so that the first range flow rate change rate is smaller than the third range flow rate change rate.

[0110] The bypass intake air amount control device 52 may be configured, for example, so that the increase in the bypass intake air amount when the bypass valve opening degrees of the bypass valves 55 to 56 are all increased by a unit amount in the first range is larger than the increase in the bypass intake air amount when the bypass valve opening degrees of these bypass valves are all increased by a unit amount in the third range. In this example, the increase in the bypass intake air amount when the bypass valve opening degrees of the bypass valves 55 to 56 are all increased by a unit amount while remaining equal may be compared between the first range and the third range. The bypass intake air amount in this example is the amount of intake air that bypasses the throttle valve 71 and flows into the internal combustion engine 6.

[0111] As described above, because the cross-sectional area of ​​the bypass flow path 54 is smaller than that of the bypass flow path 53, the bypass valve 56 may be opened preferentially over the bypass valve 55 during execution of the first idle operation control. By opening the bypass valve 56 preferentially, the bypass intake air amount can be precisely controlled during execution of the first idle operation control. Similarly, the bypass valve 55 may be opened preferentially over the bypass valve 56 during execution of the catalyst early activation control. By opening the bypass valve 55 preferentially, the bypass intake air amount can be quickly increased during execution of the catalyst early activation control. Note that the relationship between the cross-sectional area of ​​the bypass flow path 54 and the cross-sectional area of ​​the bypass flow path 53 described above is merely an example. For example, the cross-sectional area of ​​the bypass flow path 54 may be larger than that of the bypass flow path 53. In this case, the bypass valve 55 may be opened preferentially over the bypass valve 56 during execution of the first idle operation control, and the bypass valve 56 may be opened preferentially over the bypass valve 55 during execution of the catalyst early activation control.

[0112] [First Modified Example of Bypass Valve] Fig. 9 is a diagram schematically showing a cross section of a bypass valve according to a first modified example of the bypass valve. Fig. 10 is a diagram schematically showing a side view of the bypass valve. Components similar to those of the bypass valve according to the second embodiment are denoted by the same reference numerals as those of the bypass valve 24 provided in the intake air amount control system 21 shown in Figs. 4 and 5, and some descriptions will be omitted.

[0113] The bypass valve 81 according to this modification includes a cylinder 811 and an output port 813 instead of the cylinder 241 and the output port 243. The cylinder 811 and the output port 813 are molded separately and then joined together. The output port 813 is formed with a flow path having a generally cylindrical shape whose inner diameter increases as it approaches the cylinder 811.

[0114] The cylinder 811 has a substantially cylindrical shape. Three holes 811a to 811c are formed in the side surface of the cylinder 811. Each of the holes 811a to 811c is a circular through-hole. The cylinder 811 and the output port 813 are in communication with each other via the holes 811a to 811c.

[0115] 9 and 10 , when the bypass valve opening degree of the bypass valve 81 is 0%, all of the holes 811a to 811c are blocked by the valve element 244. As the valve element 244 approaches the actuator 246, the area of ​​the holes 811a to 811c blocked by the valve element 244 decreases. In other words, as the valve element 244 approaches the actuator 246, the opening area of ​​the bypass valve 81 increases, that is, the bypass valve opening degree of the bypass valve 81 increases. More specifically, as the bypass valve opening degree of the bypass valve 81 increases from 0%, the blockage of the hole 811b by the valve element 244 begins to be released. As the valve element 244 moves further, the holes 811a and 811c are unblocked.

[0116] When the valve element 244 moves to the upper end within the cylinder 811, the bypass valve opening of the bypass valve 81 becomes 100%. Alternatively, if the rate of change of the flow rate increases as the valve element 244 approaches the actuator 246 within the range up to when the valve element 244 reaches a specific position, the specific position may be treated as the position of the valve element 244 corresponding to a state in which the bypass valve opening is 100%.

[0117] [Second Modification of Bypass Valve] Fig. 11 is a diagram schematically showing a cross section of a bypass valve according to a second modification of the bypass valve. Fig. 12 is a diagram schematically showing a side view of the bypass valve. Components similar to those of the first modification are given the same reference numerals as those of the bypass valve 81 shown in Figs. 9 and 10, and some descriptions will be omitted.

[0118] The bypass valve 82 according to this modification includes a cylinder 821 instead of the cylinder 811. Six holes 821a to 821f are formed in the side surface of the cylinder 821. Each of the holes 821a to 821f is a circular through-hole. The cylinder 821 and the output port 813 are connected to each other via the holes 821a to 821f.

[0119] 11 and 12 , when the bypass valve opening degree of the bypass valve 82 is 0%, all of the holes 821a to 821f are blocked by the valve element 244. As the valve element 244 approaches the actuator 246, the area of ​​the region of the holes 821a to 821f blocked by the valve element 244 decreases. In other words, as the valve element 244 approaches the actuator 246, the opening area of ​​the bypass valve 82 increases, that is, the bypass valve opening degree of the bypass valve 82 increases.

[0120] [Third Modification of Bypass Valve] Figure 13 is a diagram schematically showing a cross section of a bypass valve according to a third modification of the bypass valve. Figure 14 is a diagram schematically showing a side view of the bypass valve. Components similar to those of the first modification are given the same reference numerals as those of the bypass valve 81 shown in Figures 9 and 10, and some descriptions will be omitted.

[0121] The bypass valve 83 according to this modification includes a cylinder 831 instead of the cylinder 811. A hole 831a is formed in the side surface of the cylinder 831. The hole 831a is a through-hole having a substantially triangular shape. The cylinder 831 and the output port 813 are in communication with each other through the hole 831a.

[0122] 13 and 14 , when the bypass valve opening degree of the bypass valve 83 is 0%, the entire hole 831a is blocked by the valve element 244. As the valve element 244 approaches the actuator 246, the area of ​​the region of the hole 831a blocked by the valve element 244 decreases. In other words, as the valve element 244 approaches the actuator 246, the opening area of ​​the bypass valve 83 increases, that is, the bypass valve opening degree of the bypass valve 83 increases.

[0123] [Fourth Modification of Bypass Valve] Fig. 15 is a diagram schematically showing a cross section of a bypass valve according to a fourth modification of the bypass valve. Fig. 16 is a diagram schematically showing a side view of the bypass valve. Components similar to those of the first modification are given the same reference numerals as those of the bypass valve 81 shown in Figs. 9 and 10, and some descriptions will be omitted.

[0124] The bypass valve 84 according to this modification includes a cylinder 841 instead of the cylinder 811. Three holes 841a to 841c are formed in the side surface of the cylinder 841. The holes 841a to 841c are through-holes with different lengths in the direction of the axis L4a. The holes 841a to 841c connect the cylinder 841 and the output port 813.

[0125] More specifically, each of the holes 841a to 841c is an elongated hole extending from one end closer to the actuator 246 to the other end. The distance between one end of each of the holes 841a to 841c and the actuator 246 in the direction of the axis L4a is approximately equal. On the other hand, the distance between the other end of the hole 841a and the actuator 246 is greater than that of the hole 841b. Similarly, the distance between the other end of the hole 841b and the actuator 246 is greater than that of the hole 841c.

[0126] 15 and 16, when the bypass valve opening degree of the bypass valve 84 is 0%, all of the holes 841a to 841c are blocked by the valve element 244. As the valve element 244 approaches the actuator 246, the area of ​​the regions of the holes 841a to 841c blocked by the valve element 244 decreases. In other words, as the valve element 244 approaches the actuator 246, the opening area of ​​the bypass valve 84 increases, that is, the bypass valve opening degree of the bypass valve 84 increases. Note that while FIG. 16 shows an example in which three holes 841a to 841c are formed on the side surface of the cylinder 841, the number of holes is not limited to this.

[0127] [Fifth Modification of Bypass Valve] Fig. 17 is a diagram schematically showing a cross section of a bypass valve according to a fifth modification of the bypass valve. Fig. 18 is a diagram schematically showing a side view of the bypass valve. Components similar to those of the first modification are given the same reference numerals as those of the bypass valve 81 shown in Figs. 9 and 10, and some descriptions will be omitted.

[0128] As shown in FIGS. 17 and 18 , a bypass valve 85 according to this modification includes a cylinder 851 instead of the cylinder 811. Two holes 851 a and 851 b are formed in the side surface of the cylinder 851. The holes 851 a to 851 b are through-holes with different shapes. The cylinder 851 and the output port 813 are in communication with each other through the holes 851 a to 851 b. More specifically, the hole 851 a is an elongated hole extending along the axis L4 a. The hole 851 b has a circular shape.

[0129] When the bypass valve opening degree of the bypass valve 85 is 0%, all of the holes 851a to 851b are blocked by the valve element 244. As the valve element 244 approaches the actuator 246, the area of ​​the region of the holes 851a to 851b blocked by the valve element 244 decreases. In other words, as the valve element 244 approaches the actuator 246, the opening area of ​​the bypass valve 85 increases, that is, the bypass valve opening degree of the bypass valve 85 increases.

[0130] [Sixth Modification of Bypass Valve] Fig. 19 is a diagram schematically showing a cross section of a bypass valve according to a sixth modification of the bypass valve. Fig. 20 is a diagram schematically showing a side view of the bypass valve. Components similar to those in the second embodiment are denoted by the same reference numerals as those in the bypass valve 24 shown in Figs. 4 and 5, and some descriptions will be omitted.

[0131] The bypass valve 86 according to this modification includes a valve element 864 and a shaft 865 instead of the valve element 244 and the shaft 245. One end of the shaft 865 is inserted into the space 246a of the actuator 246. The valve element 864 is connected to the other end of the shaft 865. That is, the actuator 246 displaces the valve element 864 via the shaft 865, thereby controlling the bypass valve opening of the bypass valve 86. The valve element 864 is disposed coaxially with the shaft 865. The valve element 864 has a tapered shape. That is, the outer diameter of the valve element 864 decreases as it moves away from the actuator 246. The valve element 864 can also be considered an umbrella portion.

[0132] 19 and 20 , when the bypass valve opening degree of bypass valve 86 is 0%, the communication portion with supply port 242 in cylinder 241 is blocked by valve element 864. At this time, the head portion of valve element 864 enters supply port 242 and contacts the communication portion with supply port 242 formed on inner surface 241b on the supply port 242 side in the space formed in cylinder 241. In other words, inner surface 241b is a valve seat (seat surface) for valve element 864.

[0133] As the valve element 864 approaches the actuator 246, the valve element 864 moves away from the inner surface 241b as shown by the valve element 864a. In other words, as the valve element 864 approaches the actuator 246, the opening area of ​​the bypass valve 86 increases, that is, the bypass valve opening degree of the bypass valve 86 increases.

[0134] [Seventh Modification of Bypass Valve] Figure 21 is a diagram schematically showing a cross section of a bypass valve according to a seventh modification of the bypass valve. Figure 22 is a diagram schematically showing a side view of the bypass valve. Components similar to those of the first modification are given the same reference numerals as those of the bypass valve 81 shown in Figures 9 and 10, and some descriptions will be omitted. Similarly, components similar to those of the sixth modification are given the same reference numerals as those of the bypass valve 86 shown in Figures 19 and 20, and some descriptions will be omitted.

[0135] The bypass valve 87 according to this modification includes a valve body 874 and a shaft 875 instead of the valve body 244 and the shaft 245. One end of the shaft 875 is inserted into the space 246a of the actuator 246. The valve body 874 is connected to the other end of the shaft 875.

[0136] The valve body 874 includes a cylindrical portion 874a and an umbrella portion 874b. The cylindrical portion 874a and the umbrella portion 874b are each arranged coaxially with the shaft 875. The cylindrical portion 874a is a part of the valve body 874 on the shaft 875 side. The cylindrical portion 874a is slidable within the cylinder 241 and is movable in the direction of the axis L4a.

[0137] 21 and 22 , when the bypass valve opening degree of the bypass valve 87 is 0%, the communication portion with the supply port 242 in the cylinder 241 is blocked by the umbrella portion 874b. In addition, at this time, all of the holes 811a to 811c are blocked by the cylindrical portion 874a. As the valve disc 874 approaches the actuator 246, the umbrella portion 874b moves away from the inner surface 241b, and the blockage of the holes 811a to 811c by the cylindrical portion 874a is released. In other words, as the valve disc 874 approaches the actuator 246, the opening area of ​​the bypass valve 87 increases, that is, the bypass valve opening degree of the bypass valve 87 increases.

[0138] [Eighth Modification of Bypass Valve] Fig. 23 is a diagram schematically showing a cross section of a bypass valve according to an eighth modification of the bypass valve. Fig. 24 is a diagram schematically showing a side view of the bypass valve. Components similar to those of the bypass valve according to the second embodiment are denoted by the same reference numerals as those of the bypass valve 24 provided in the intake air amount control system 21 shown in Figs. 4 and 5, and some descriptions will be omitted.

[0139] The bypass valve 88 according to this embodiment includes an output port 883, a valve element 884, and a shaft 885 instead of the output port 243, the valve element 244, and the shaft 245. One end of the shaft 885 is inserted into the space 246a of the actuator 246. The valve element 884 is connected to the other end of the shaft 885.

[0140] The valve element 884 includes a disk portion 884a and a cylindrical portion 884b. The disk portion 884a and the cylindrical portion 884b are each arranged coaxially with the shaft 875. The disk portion 884a is a part of the valve element 884 on the shaft 885 side. The cylindrical portion 884b is slidable within the cylinder 241 and is movable in the direction of the axis L4a.

[0141] The output port 883 has a cylindrical shape similar to the output port 243. The axis L4c is the central axis of the output port 883. The cylinder 241 and the output port 883 are in communication with each other via a communication portion 883a. Meanwhile, a hole 884c corresponding to the communication portion 883a is formed in the side surface of the cylindrical portion 884b facing the output port 883.

[0142] 23 and 24 , when the bypass valve opening degree of the bypass valve 88 is 0%, the flow path from the supply port 242 to the output port 883 is blocked by the valve element 884. As the valve element 884 approaches the actuator 246, the communication portion 883a and the hole 884c begin to overlap with each other. In other words, the bypass valve opening degree of the bypass valve 88 begins to increase from 0%.

[0143] When the valve element 884 approaches the actuator 246 and as a result all of the holes 884c overlap with the communication portions 883a, the flow path from the supply port 242 to the output port 883 is not blocked by the valve element 884. At this time, the bypass valve opening degree of the bypass valve 88 is 100%.

[0144] Sixth Embodiment FIG. 25 is a diagram schematically showing a saddle-ride type vehicle according to a sixth embodiment.

[0145] The saddle-riding type vehicle 9 according to this embodiment includes a vehicle body 91, a front wheel 92, and a rear wheel 93. The vehicle body 91 is equipped with an internal combustion engine (not shown) that generates driving force for the saddle-riding type vehicle 9. The internal combustion engine is provided with the intake amount control system 1 described above.

[0146] The vehicle body 91 includes a saddle 94 and a steering handlebar 95. The saddle 94 is configured so that a driver sits astride the saddle 94. The handlebar 95 is provided so as to extend in the left-right direction of the saddle-type vehicle 9. The saddle-type vehicle 9 is a lean vehicle, and is configured to turn when the driver, holding the handlebar 95, shifts his / her weight to lean toward the inside of a curve.

[0147] 1, 21, 31, 41, 51 Intake air amount control system 11, 22, 32, 42, 52 Bypass intake air amount control device 12, 23, 33, 43, 53, 54 Bypass flow path 13, 24, 44, 55, 56 Bypass valve 81, 82, 83, 84, 85, 86, 87, 88 Bypass valve 13a, 246, 446, 556, 566 Actuator 241 Cylinder 241a Inner surface 241b Inner surface 242 Supply port 243 Output port 244 Valve body 244a Bottom surface 244b Bottom surface 245 Shaft 246a Space 6 Internal combustion engine 61 Combustion chamber 62 Intake valve 7, 7a, 7b First intake flow path 71 Throttle valve 72 Upstream intake flow path 73 Intake port 73a Communication portion 74, 74a Air cleaner 811, 821, 831, 841, 851 Cylinder 813, 883 Output port 864, 864a, 874, 884 Valve body 874a Cylindrical portion 874b Umbrella portion 865, 875, 885 Shaft 883a Communication portion 884a Disk portion 884b Cylindrical portion 811a to 811c, 821a to 821f, 831a Hole 841a to 841c, 851a to 851b, 884c Hole 9 Straddle-type vehicle 91 Vehicle body 92 Front wheel 93 Rear wheel 94 Saddle 95 Bar handle

Claims

1. An intake air amount control system for an internal combustion engine that, during idling, performs first idle operation control and catalyst early activation control, which activates an exhaust gas purification catalyst by increasing the intake air amount to a level higher than that during the first idle operation control, comprising: a throttle valve whose opening is changed to change the intake air amount of the internal combustion engine; at least one bypass flow path that bypasses the throttle valve; and a bypass intake air amount control device that controls the flow rate of the at least one bypass flow path, wherein the bypass intake air amount control device comprises: at least one bypass valve provided in at least one of the at least one bypass flow paths to change the opening of the corresponding flow path; and an actuator configured to open and close the at least one bypass valve, and the bypass intake air amount control device is variable by the actuator from a fully closed state in which all of the at least one bypass valve are fully closed to a fully open state in which all of the at least one bypass valve are fully opened, an intake air amount control system configured such that, when a time domain when the output of the actuator is changed at a constant speed or a constant angular velocity from the fully closed state to the fully open state is divided into three equal parts and defined as a first domain, a second domain, and a third domain from the fully closed state to the fully open state, the first idle operation control is executed in the first domain, and the catalyst early activation control is executed in the third domain, and when the negative pressure of the internal combustion engine is constant, the rate of change of flow rate in the total of all of the at least one bypass flow path is greater or equal in the third domain than in the first domain.

2. An intake air amount control system according to claim 1, wherein the rate of change of the flow rate in the first region is smaller than the rate of change of the flow rate in the third region.

3. An intake air amount control system according to claim 1 or 2, wherein the at least one bypass valve nonlinearly changes the opening of the corresponding flow passage in response to a constant speed or constant angular velocity output of the actuator.

4. An intake air amount control system according to claim 3, wherein said at least one bypass valve exponentially changes the opening of the corresponding flow passage in response to a constant speed or constant angular velocity output of said actuator.

5. An intake air quantity control system according to any one of claims 1 to 4, wherein, when the valve ratio of the bypass intake air quantity control device is defined as the value obtained by dividing the total cross-sectional area of ​​all of the at least one bypass valve included in the bypass intake air quantity control device by the cross-sectional area of ​​the intake port of the internal combustion engine, the bypass intake air quantity control device is configured so that the valve ratio is 20% or more.

6. An intake air amount control system according to any one of claims 1 to 5, further comprising a first intake air flow path in which the throttle valve is provided, and at least one of the at least one bypass flow path is configured to branch off from the first intake air flow path upstream of the throttle valve and merge into the first intake air flow path downstream of the throttle valve.

7. An intake air quantity control system according to any one of claims 1 to 5, further comprising a first intake air passage in which the throttle valve is provided, wherein the upstream end of a first bypass passage which is at least one of the at least one bypass passage is not connected to the first intake air passage, and the downstream end of the first bypass passage merges with the first intake air passage downstream of the throttle valve.

8. An intake air quantity control system according to any one of claims 1 to 5, further comprising a first intake flow path in which the throttle valve is provided, wherein a first bypass flow path which is at least one of the at least one bypass flow paths branches off from the first intake flow path upstream of the throttle valve and merges into the first intake flow path downstream of the throttle valve, and wherein an upstream end of a second bypass flow path which is at least one of the at least one bypass flow paths is not connected to the first intake flow path, and wherein a downstream end of the second bypass flow path merges into the first intake flow path downstream of the throttle valve.

9. An intake air amount control system according to any one of claims 1 to 5, further comprising a first intake air flow path in which the throttle valve is provided, wherein a first bypass flow path which is at least one of the at least one bypass flow paths branches off from the first intake air flow path upstream of the throttle valve and merges into the first intake air flow path downstream of the throttle valve, and wherein a second bypass flow path which is at least one of the at least one bypass flow paths branches off from the first bypass flow path upstream of the at least one bypass valve and merges into the first intake air flow path downstream of the throttle valve.

10. A straddle-type vehicle equipped with an intake air amount control system according to any one of claims 1 to 9.

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