Alcohol-containing fuel engine system and vehicle

Abstract

The present invention provides: an alcohol-containing fuel engine system that is capable of achieving both reproducibility of early combustion and target followability of an engine rotation speed in an engine in which in-cylinder injection is not performed; and a vehicle that includes the alcohol-containing fuel engine system. At start-up of the engine, a control device of the alcohol-containing fuel engine system specifies a first cycle, which corresponds to first combustion after the start-up, and a non-combustion preliminary cycle, which immediately precedes the first cycle, and executes a control sequence in which the first cycle and the non-combustion preliminary cycle are combined. In the first cycle, the control device: controls an intake air amount adjustment device to supply air in an amount which is smaller than the amount of air in a high idle state when warming up the alcohol-containing fuel engine; controls a fuel injection device to inject, into an intake passage, a fuel in an amount which is smaller than the maximum fuel injection amount; and controls the first combustion using a fuel which has been injected in the non-combustion preliminary cycle, stored in the intake passage, and vaporized, the fuel which has been injected in the first cycle, and the air in the amount which is smaller than the amount of air in the high idle state. In the non-combustion preliminary cycle, the control device: controls the intake air amount adjustment device to supply air in an amount which is smaller than the amount of air in the high idle state; controls the fuel injection device to inject, into the intake passage, a fuel in an amount which is smaller than the maximum fuel injection amount; and controls the storage of the alcohol-containing fuel which has been injected at an air flow rate that has been decreased in the intake passage so as to secure a time for the vaporization.

Description

Alcohol-containing fuel engine system and vehicle

[0001] The present invention relates to an engine system using an alcohol-containing fuel and a vehicle equipped with the same.

[0002] Patent Document 1 discloses a fuel injection control device for an internal combustion engine equipped with a fuel injection valve provided in each intake port. This fuel injection control device controls the amount of alcohol-blended fuel to be less than the combustible air-fuel ratio after cranking begins. The invention of Patent Document 1 aims to reduce the amount of alcohol carried over from the first cycle to the second cycle.

[0003] Patent Document 2 discloses a control device for an internal combustion engine equipped with a fuel injection valve that injects fuel into an intake passage. This control device controls the fuel injection valve and, when the alcohol mixing ratio is equal to or greater than a predetermined value, controls the bypass passage for a main passage provided with a throttle valve so that the bypass amount before the first explosion is smaller than the bypass amount after the first explosion.

[0004] JP 2014-231799 A JP 2009-74367 A

[0005] In an engine in which alcohol-containing fuel is injected into the intake passage without being injected into the cylinder, it is sometimes desirable to achieve both high robustness of early combustion at start-up and high target tracking ability of the engine rotation speed.

[0006] The object of the present invention is to provide an alcohol-containing fuel engine system that can achieve both high robustness of early combustion at start-up and high target tracking ability in engine rotation speed in an engine in which alcohol-containing fuel is injected through the intake passage without being injected into the cylinder, and a vehicle equipped with the same.

[0007] Alcohol-containing fuel has a latent heat of vaporization that is approximately three times higher than that of gasoline, and it takes a long time to vaporize, making it difficult to promote vaporization when the engine is cold. For this reason, in an engine in which alcohol-containing fuel is injected into the intake manifold, there is a high possibility that fluctuations in the combustion start timing due to unvaporized fuel will occur at each start.

[0008] The technology of Patent Document 1 aims to start combustion from the first cycle after starting. However, due to incomplete combustion caused by insufficient vaporization of the alcohol-containing fuel, there is a high possibility that the combustion timing will vary from start to start. In addition, there is a high possibility that rotational fluctuations will occur that deviate from the target rotational speed due to afterburning of the alcohol-containing fuel that was not burned due to incomplete combustion.

[0009] In view of the above-mentioned problems, the present inventors conducted extensive research into how to achieve target engine speed tracking while ensuring early combustion reproducibility in an engine in which alcohol-containing fuel is injected through the intake manifold without being injected directly into the cylinder. As a result, they discovered an innovative solution using two-cycle sequential control. Specifically, when starting the engine, a control device designates a first cycle, which is the first combustion after start, and the cycle immediately preceding the first cycle as non-combustion preliminary cycles, and executes two-cycle sequential control combining these cycles. In the first cycle, the control device controls the intake air amount regulator to supply an amount of air less than the amount during a high idle state when warming up the alcohol-containing fuel engine, controls the fuel injector to inject an amount of fuel less than the maximum fuel injection amount into the intake manifold, and controls the initial combustion using the fuel injected in the non-combustion preliminary cycle, stored in the intake manifold, and vaporized, the fuel injected in the first cycle, and an amount of air less than the amount during a high idle state. In the non-combustion preliminary cycle, the control device controls the intake air amount adjustment device to supply an amount of air less than the amount of air during high idle, controls the fuel injection device to inject an amount of fuel less than the maximum fuel injection amount into the intake passage, and controls the retention of the injected alcohol-containing fuel in the intake passage by reducing the air flow velocity in the intake passage so that time for vaporization is ensured.

[0010] In the non-combustion preliminary cycle, a low-flow environment is created in the intake passage by supplying a small amount of air. Therefore, in the non-combustion preliminary cycle, the fuel injected from the fuel injector is stored in the intake passage. More specifically, a portion of the alcohol-containing fuel injected from the fuel injector in the non-combustion preliminary cycle is dispersed throughout the space in the intake passage, and a portion of the alcohol-containing fuel adheres to the wall surfaces of the intake passage. Alcohol-containing fuel takes longer to vaporize than gasoline. Furthermore, in the low-flow environment of the non-combustion preliminary cycle, much of the alcohol-containing fuel is not carried away by the air heading toward the combustion chamber and adheres to the wall surfaces of the intake passage. While some of the alcohol-containing fuel injected from the fuel injector in the non-combustion preliminary cycle is delivered to the combustion chamber, the amount of alcohol-containing fuel injected from the fuel injector in the non-combustion preliminary cycle is small, and most of the alcohol-containing fuel adheres to the wall surfaces of the intake passage, so even less alcohol-containing fuel is delivered to the combustion chamber. The alcohol-containing fuel that adheres to the wall surface of the intake passage during the non-combustion preliminary cycle, and the alcohol-containing fuel that is dispersed within the intake passage but does not reach the combustion chamber and remains within the intake passage, are stored within the intake passage. The alcohol-containing fuel stored within the intake passage can vaporize over the time period of one cycle until the next first cycle. Although the alcohol-containing fuel has a property that makes it difficult to promote vaporization, vaporization is promoted within the intake passage over the time period of one cycle.

[0011] In the first cycle, a small amount of air is supplied, and an amount of alcohol-containing fuel less than the maximum fuel injection amount is injected into the intake passage. In the first cycle, the alcohol-containing fuel injected in the immediately preceding non-combustion preliminary cycle, stored in the intake passage, and vaporized is combined with the alcohol-containing fuel injected in the first cycle and supplied to the combustion chamber. The initial combustion is controlled by this combined fuel and an amount of air less than the amount of air during high idle. Therefore, the initial combustion occurs with high reliability in the first cycle. Because the initial combustion occurs with high reliability in the first cycle, the amount of unburned alcohol-containing fuel remaining in the combustion chamber after combustion is suppressed. Therefore, afterburning in the second cycle following the first cycle is suppressed, and deviation of the speed in the second cycle from the target speed is suppressed.

[0012] Two-cycle sequential control, consisting of a first cycle and an unburned preliminary cycle after the start of the engine, and simultaneous control of the intake air amount and fuel amount in both the first cycle and the unburned preliminary cycle are performed. The synergistic effect of the two-cycle sequential control and the simultaneous control of the intake air amount and fuel amount increases the amount of fuel stored and vaporized in the intake passage in the unburned preliminary cycle. In the first cycle, the fuel stored in the intake passage in the unburned preliminary cycle and the fuel newly injected into the intake passage in the first cycle, together with less air than in a high idle state, are introduced into the combustion chamber, resulting in highly reliable combustion. This results in highly robust early combustion. Furthermore, as a result of the highly reliable combustion in the first cycle, afterburning due to excess fuel in the next cycle caused by unburned fuel is suppressed. This results in high target tracking performance in engine speed. Therefore, in an engine in which alcohol-containing fuel is injected through the intake passage without being injected directly into the cylinder, both high robustness of early combustion at startup and high target tracking performance in engine speed are achieved.

[0013] According to the inventor's findings, by deliberately providing a non-combustion preliminary cycle, it is possible to ensure reliable combustion in the first cycle. The findings above introduce a new element, fuel storage in the intake passage, and provide a unique solution that ensures time for the alcohol fuel to vaporize.

[0014] Patent Document 2 also shows that the intake amount is suppressed. However, the invention of Patent Document 2 is premised on combustion starting from the first cycle after the start of the engine. The present invention solves the problems specific to alcohol-containing fuels with a new control method that combines an unconventional two-cycle sequence control with control of the injection amount and intake amount. Compared to the conventional "early combustion" inventions of Patent Documents 1 and 2, the present invention prioritizes "reliable vaporization" by adopting a reverse approach, achieving both high robustness of early combustion at startup and high target tracking ability in engine rotation speed.

[0015] In order to achieve the above object, according to one aspect of the present invention, an alcohol-containing fuel engine system has the following configuration.

[0016] (1) An alcohol-containing fuel engine system comprising: an alcohol-containing fuel engine; and a control device for controlling the alcohol-containing fuel engine, wherein the alcohol-containing fuel engine comprises: a combustion chamber; an intake passage communicating with the combustion chamber; an intake air amount adjustment device for adjusting the amount of air in the intake passage; and a fuel injection device for injecting all of the alcohol-containing fuel supplied to the combustion chamber into the intake passage, wherein the control device, at engine start-up, designates a first cycle which is the first combustion after start-up and the cycle immediately before the first cycle as non-combustion reserve cycles, and executes a control sequence combining these cycles; in the first cycle, controls the intake air amount adjustment device to supply an amount of air less than the amount of air in a high idle state when warming up the alcohol-containing fuel engine; and controls the fuel injection device to inject an amount of fuel less than the maximum fuel injection amount into the intake passage, The initial combustion is controlled using the fuel injected in the non-combustion preliminary cycle, stored in the intake passage, and vaporized, the fuel injected in the first cycle, and an amount of air less than the amount of air during the high idle state; in the non-combustion preliminary cycle, the intake air amount adjustment device is controlled to supply an amount of air less than the amount of air during the high idle state; the fuel injection device is controlled to inject an amount of fuel into the intake passage that is less than the maximum fuel injection amount; and the storage of the injected alcohol-containing fuel in the intake passage is controlled by reducing the air flow velocity in the intake passage so as to ensure time for vaporization.

[0017] In the non-combustion preliminary cycle, a low-flow environment is created in the intake passage by supplying a small amount of air. Therefore, in the non-combustion preliminary cycle, the fuel injected from the fuel injector is stored in the intake passage. More specifically, a portion of the alcohol-containing fuel injected from the fuel injector in the non-combustion preliminary cycle is dispersed throughout the space in the intake passage, and a portion of the alcohol-containing fuel adheres to the wall surfaces of the intake passage. Alcohol-containing fuel takes longer to vaporize than gasoline. Furthermore, in the low-flow environment of the non-combustion preliminary cycle, much of the alcohol-containing fuel adheres to the wall surfaces of the intake passage without being carried away by the air heading toward the combustion chamber. While some of the alcohol-containing fuel injected from the fuel injector in the non-combustion preliminary cycle is delivered to the combustion chamber, the amount of alcohol-containing fuel injected from the fuel injector in the non-combustion preliminary cycle is small, and most of the alcohol-containing fuel adheres to the wall surfaces of the intake passage, so even less alcohol-containing fuel is delivered to the combustion chamber. The alcohol-containing fuel that adheres to the wall surface of the intake passage during the non-combustion preliminary cycle, and the alcohol-containing fuel that is dispersed within the intake passage but does not reach the combustion chamber and remains within the intake passage, are stored within the intake passage. The alcohol-containing fuel stored within the intake passage can vaporize over the time period of one cycle until the next first cycle. Although the alcohol-containing fuel has the property of being difficult to promote vaporization, its vaporization is promoted within the intake passage over the time period of one cycle.

[0018] In the first cycle, a small amount of air is supplied, and an amount of alcohol-containing fuel less than the maximum fuel injection amount is injected into the intake passage. In the first cycle, the alcohol-containing fuel injected in the immediately preceding non-combustion preliminary cycle, stored in the intake passage, and vaporized is combined with the alcohol-containing fuel injected in the first cycle and supplied to the combustion chamber. The initial combustion is controlled by this combined fuel and an amount of air less than the amount of air during high idle. Therefore, the initial combustion occurs more reliably in the first cycle than in a case where, for example, the configuration (1) above is not provided. Because the initial combustion occurs more reliably in the first cycle, the amount of unburned alcohol-containing fuel remaining in the combustion chamber after combustion is reduced. Therefore, afterburning in the second cycle following the first cycle is reduced, and deviation of the speed in the second cycle from the target speed is reduced.

[0019] In this way, the alcohol-containing fuel engine system described above (1) performs two-cycle sequential control consisting of a first cycle and an unburned preliminary cycle after starting, and simultaneous control of the intake air amount and fuel amount in both the first cycle and the unburned preliminary cycle. The synergistic effect of the two-cycle sequential control and the simultaneous control of the intake air amount and fuel amount increases the amount of fuel stored and vaporized in the intake passage in the unburned preliminary cycle. In the first cycle, the fuel stored in the intake passage in the unburned preliminary cycle and the fuel newly injected into the intake passage in the first cycle are combined to draw less air into the combustion chamber than in a high idle state, resulting in highly reliable combustion. This results in highly robust early combustion. Furthermore, as a result of the highly reliable combustion in the first cycle, afterburning due to excess fuel in the next cycle caused by unburned fuel is suppressed. This results in high target tracking performance in the engine speed. Therefore, in an engine in which alcohol-containing fuel is injected through the intake passage without being injected into the cylinder, it is possible to achieve both high robustness of early combustion at start-up and high target tracking capability of the engine rotation speed.

[0020] An alcohol-containing fuel is a fuel composition containing alcohol as a primary component. The term "primary component" here means that the alcohol is not an impurity or an unavoidable mixture, and includes, for example, at least 1% by volume. An alcohol-containing fuel may also contain a hydrocarbon fuel. A hydrocarbon fuel may also be included as a primary component. Examples of alcohols include, but are not limited to, methanol, ethanol, propanol, and butanol. The alcohol concentration (volume concentration) may be greater than 0% by volume or substantially 100% by volume. Examples of hydrocarbon fuels include, but are not limited to, gasoline. E3, E10, E15, E20, E25, E85, and E100 may be used. E indicates the volume percentage of ethanol in a gasoline-ethanol mixture. A mixture with a different composition but equivalent concentration may also be used. The composition and alcohol concentration of the alcohol-containing fuel are not particularly limited, as long as they are applicable to an alcohol-fueled engine.

[0021] An alcohol-containing fuel engine is not particularly limited as long as the upper limit of the alcohol concentration of the applicable alcohol-containing fuel is greater than 0% by volume. Examples of such upper limits include, by volume, 3, 10, 15, 20, 25, 85, and 100. An upper limit of 20% by volume means that the alcohol-containing fuel engine can use alcohol-containing fuels with alcohol concentrations up to 20% by volume. The higher the upper limit, the higher the alcohol concentration of the applicable alcohol-containing fuel can be. An alcohol-containing fuel engine may be configured so that the lower limit of the alcohol concentration of the applicable alcohol-containing fuel is 0% by volume. In other words, an alcohol-containing fuel engine may be able to use hydrocarbon fuels (e.g., gasoline) that do not contain alcohol. The alcohol concentration of the applicable alcohol-containing fuel is not particularly limited as long as it is within the above-mentioned upper and lower limit ranges. Furthermore, with regard to the number of cylinders, alcohol-containing fuel engines include, for example, single-cylinder engines and engines with two or more cylinders. The alcohol-fueled engine may be, for example, a single-cylinder engine, a two-cylinder engine, a variable-interval combustion three-cylinder engine, or a variable-interval combustion four-cylinder engine. When the alcohol-fueled engine has multiple cylinders, the control according to the present invention does not necessarily need to be performed on all cylinders. As long as the control according to the present invention is performed on any one cylinder, the engine system corresponds to the alcohol-fueled engine system according to the present invention.

[0022] "After starting" refers to, for example, after the crankshaft of the alcohol-containing fuel engine has started to rotate due to the drive of the starter motor.

[0023] The control device is composed of a computer having a processor, RAM, and ROM. The control device may be an ECU (Engine Control Unit). The processor performs arithmetic processing based on a control program. The processor receives data from multiple sensors provided in the system and outputs commands to control various devices in the system. The RAM functions as a memory area for temporary data storage. Examples of temporary data include data currently being processed and data from the sensors. The data from the sensors includes data related to the dynamic state of the vehicle. The ROM stores a control program and a control map. The control device controls an alcohol-fueled engine. The control device controls a fuel injection device and an ignition device in the engine. The control device may also control devices other than the alcohol-fueled engine. The control device may consist of a single device or multiple devices physically separated from each other. Because the control device controls an alcohol-fueled engine, different values ​​are used to adjust, for example, the fuel injection amount, intake air amount, and fuel mixture ratio compared to a gasoline engine. The present invention solves problems specific to alcohol-fueled engines.

[0024] The fuel injection device is a device that injects alcohol-containing fuel into the intake passage. The fuel injection device injects the alcohol-containing fuel into the intake passage. The fuel injection device may be a device dedicated to alcohol-containing fuel, or a general-purpose device that is also used for gasoline fuel. The fuel injection device can be selected depending on the alcohol concentration of the alcohol-containing fuel. When the fuel injection device injects all of the alcohol-containing fuel supplied to the combustion chamber into the intake passage, this means that the alcohol-containing fuel engine injects the alcohol-containing fuel into the intake passage without injecting it directly into the cylinder. In other words, the present invention does not include configurations that include a fuel injection device that injects alcohol-containing fuel into the cylinder.

[0025] The intake air amount adjusting device is, for example, a fast idle (FID) controller provided in a bypass passage of a throttle valve. However, the intake air amount adjusting device is not particularly limited, and may be, for example, the throttle valve or an idling speed controller (ISC) provided in a bypass passage of the throttle valve.

[0026] The cycle corresponds to a 720° rotation of the crankshaft of a four-stroke alcohol-containing fuel engine. The cycle begins with the injection of fuel. The cycle includes the injection and the subsequent ignition timing.

[0027] The maximum fuel injection quantity is the maximum amount of fuel that can be set during the starting period and the idling period. That is, it is the maximum amount of fuel that can be set during a cycle without the driver operating the accelerator. The maximum fuel injection quantity is, for example, the amount of fuel injected by the fuel injection device during the intake valve opening period. The intake valve is provided in an alcohol-containing fuel engine and opens to introduce air from the intake passage into the combustion chamber. "Less than the maximum fuel injection quantity" can be achieved, for example, by the fuel injection device injecting alcohol-containing fuel for a period shorter than the period corresponding to the maximum fuel injection quantity. For example, if the fuel injection device is capable of adjusting the injection period and the injection quantity per unit time in the injection state, the maximum fuel injection quantity is the amount of fuel injected during the intake valve opening period when the injection quantity per unit time in the injection state is at its maximum. The injection quantity per unit time in the injection state is adjusted, for example, by the voltage applied to the fuel injection device for injection. It is controlled by the supply pressure of the alcohol-containing fuel supplied. In this case, "reducing the fuel injection amount to less than the maximum" can be achieved by, for example, the fuel injection device injecting for a short period of time or injecting an injection amount per unit time less than the maximum state. Also, "reducing the fuel injection amount to less than the maximum" can be achieved by, for example, the fuel injection device injecting for a short period of time or injecting an injection amount per unit time less than the maximum state.

[0028] The high idle state is the idling state of an alcohol-containing fuel engine during cold start. The engine speed during high idle is higher than the idling speed during normal operating conditions. For example, if the intake air amount during idling is adjusted using a throttle valve, the throttle valve opening corresponds to the high idle state, thereby introducing an amount of air corresponding to the high idle state. Also, by controlling the throttle valve opening to be smaller than that during high idle, an amount of air less than that corresponding to the high idle state can be introduced. In contrast, for example, if the intake air amount during idling is adjusted using a bypass valve provided in the intake path that bypasses the throttle valve, the bypass valve opening corresponds to the high idle state, thereby introducing an amount of air corresponding to the high idle state. The high idle state is the state in which the engine speed is at its highest when the engine is started at normal outside temperature without operating the accelerator.

[0029] Combustion includes initial combustion and complete combustion. In this specification, complete combustion refers to a state in which combustion can continue without the need for an external driving force such as a starter motor. In this specification, complete combustion does not mean that all oxidizable components of the alcohol-containing fuel are completely oxidized. Initial combustion refers to a state in which the rotational speed of the crankshaft increases, but the combustion cannot continue without the need for an external driving force. Combustion may be either complete combustion or initial combustion as long as it increases the rotational speed of the crankshaft. Combustion that does not increase the rotational speed of the crankshaft is not combustion.

[0030] According to one aspect of the present invention, an alcohol-containing fuel engine system can employ the following configuration.

[0031] (2) The alcohol-containing fuel engine system of (1), wherein the alcohol-containing fuel engine comprises a cylinder and an intake valve provided between the cylinder and the intake passage, and the control device injects an amount of alcohol-containing fuel that is less than the maximum fuel injection amount into the fuel injection device in at least the non-combustion preliminary cycle and the first cycle so that a portion of the period during which the fuel injection device injects the alcohol-containing fuel overlaps with the opening period of the intake valve, and the start of injection of the alcohol-containing fuel occurs before the start of opening of the intake valve.

[0032] According to the alcohol-containing fuel engine system of (2) above, in the non-combustion preliminary cycle and the first cycle, the start of injection occurs before the intake valve starts to open, and a portion of the injection period overlaps with the intake valve opening period. Therefore, during the intake valve opening period in the first cycle, the fuel injected in the non-combustion preliminary cycle, stored in the intake passage, and vaporized is introduced into the combustion chamber, and the alcohol-containing fuel injected in the first cycle is introduced into the combustion chamber together with the intake air with high efficiency. Therefore, it is possible to achieve both high robustness of early combustion at startup and high target tracking ability of the engine rotation speed while reducing the injection amount of the alcohol-containing fuel.

[0033] According to one aspect of the present invention, an alcohol-containing fuel engine system can employ the following configuration.

[0034] (3) In the alcohol-containing fuel engine system of (1) or (2), the control device injects an amount of alcohol-containing fuel from the fuel injection device that is less than the maximum fuel injection amount in the first cycle, and injects an amount of alcohol-containing fuel from the fuel injection device in the non-combustion preliminary cycle that is greater than the amount of alcohol-containing fuel injected from the fuel injection device in the first cycle.

[0035] According to the alcohol-containing fuel engine system of (3) above, an amount of alcohol-containing fuel less than the maximum fuel injection amount is injected in the first cycle, and an even larger amount of alcohol-containing fuel than that injected in the first cycle is injected in the non-combustion preliminary cycle. A portion of the alcohol-containing fuel injected in the first cycle also adheres to the intake pipe, remaining there and contributing to combustion in the next cycle. When injection of the alcohol-containing fuel begins in the first cycle, some of the fuel injected in the non-combustion preliminary cycle and adhering to the intake pipe remains. In contrast, when injection of the alcohol-containing fuel begins in the non-combustion preliminary cycle, no fuel typically adheres to the intake pipe. According to the alcohol-containing fuel engine system of (3), a larger amount of alcohol-containing fuel than that in the first cycle is injected into the intake pipe to which no fuel adheres before the non-combustion preliminary cycle. Therefore, even when no fuel adheres to the intake pipe immediately before injection in the non-combustion preliminary cycle, a large amount of alcohol-containing fuel is injected so that sufficient fuel is supplied to contribute to combustion in the next first cycle. Therefore, it is possible to achieve both higher robustness of early combustion at startup and high target tracking capability in engine rotation speed.

[0036] According to one aspect of the present invention, an alcohol-containing fuel engine system can employ the following configuration.

[0037] (4) In the alcohol-containing fuel engine system of any one of (1) to (3), the control device supplies an amount of air in the non-combustion preliminary cycle and the first cycle that is less than the amount of air in the high idle state of the alcohol-containing fuel engine, and when the combustion occurs in both the first cycle and the second cycle following the first cycle, controls the intake air amount adjustment device in at least one of the third to fifth cycles following the second cycle to supply the amount of air in the alcohol-containing fuel engine in the high idle state.

[0038] According to the alcohol-containing fuel engine system described above in (4), when effective combustion continues in both the first and second cycles, an amount of air equivalent to the maximum amount of air during idling is taken in, so that a smooth transition to a high idle state can be achieved while suppressing abrupt changes in rotation speed. This allows for both the reproducibility of early combustion and the ability to track the rotation speed target, including the transition to a high idle state.

[0039] Furthermore, in the alcohol-containing fuel engine system described in (4) above, if the injection period of the alcohol-containing fuel overlaps with the valve-open period and the injection starts before the intake valve starts to open, the air-fuel mixture containing the alcohol-containing fuel is efficiently introduced into the combustion chamber. This makes it possible to achieve both the reproducibility of early combustion and the ability to track the target rotation speed, including the transition to a high idle state, while further reducing the injection amount of the alcohol-containing fuel.

[0040] Furthermore, in the alcohol-containing fuel engine system described above in (4), when an amount of alcohol-containing fuel smaller than the maximum fuel injection amount is injected in the first cycle and an amount of alcohol-containing fuel smaller than the amount in the first cycle is injected in the non-combustion preliminary cycle, it is possible to further reduce the amount of alcohol-containing fuel injected in the non-combustion preliminary cycle that is discharged from the combustion chamber, while simultaneously achieving both the reproducibility of early combustion and the ability to track the target rotational speed, including the transition to a high idle state.

[0041] According to one aspect of the present invention, an alcohol-containing fuel engine system can employ the following configuration.

[0042] (5) The alcohol-containing fuel engine system according to any one of (1) to (4), further comprising a three-way catalyst provided in an exhaust passage of the alcohol-containing fuel engine.

[0043] According to the alcohol-containing fuel engine system described above in (5), the reproducibility of early combustion and the ability of the engine rotation speed to track the target are further improved, so that in addition to the reproducibility of early combustion and the ability of the rotation speed to track the target, the three-way catalyst also has high ability to track the target catalyst temperature, which affects the exhaust purification performance of the alcohol-containing fuel engine.

[0044] According to one aspect of the present invention, the vehicle can adopt the following configuration.

[0045] (6) A vehicle equipped with an alcohol-containing fuel engine system according to any one of (1) to (5).

[0046] According to the vehicle of (6) above, it is possible to achieve both the reproducibility of early combustion and the ability of the engine rotation speed to follow the target. Furthermore, if the vehicle is equipped with an alcohol-containing fuel tank that stores alcohol-containing fuel and supplies it to the alcohol-containing fuel engine system, it is possible to achieve both the reproducibility of early combustion and the ability of the engine rotation speed to follow the target by using the alcohol-containing fuel stored for driving.

[0047] A vehicle is a device for transportation. A vehicle is configured to operate in a manned or unmanned (automated) manner. A vehicle can be a personal transportation vehicle. For example, a vehicle may be a public transportation vehicle such as a bus. Examples of personal transportation vehicles include automobiles and saddle-type vehicles. A vehicle may or may not have wheels. Examples of vehicles without wheels include ships with propellers, drones and helicopters with propellers, snowmobiles, and watercraft. A vehicle may or may not have a cabin. Examples of vehicles with a cabin include automobiles and helicopters. One example of a vehicle is a saddle-type vehicle. A saddle-type vehicle is a vehicle equipped with a saddle-type seat. A saddle-type vehicle is a vehicle configured so that a rider sits astride the seat. Saddle-riding vehicles are not limited to scooter-type, moped-type, off-road-type, and on-road-type motorcycles, but also include snowmobiles, watercraft, all-terrain vehicles (ATVs), etc. Saddle-riding vehicles may have at least one front wheel and at least one rear wheel. Saddle-riding vehicles are not limited to motorcycles, but may be three-wheeled vehicles each having a pair of left and right front or rear wheels, or four-wheeled vehicles each having a pair of left and right front and rear wheels. Saddle-riding vehicles may be configured to lean. Vehicles configured to lean turn in a leaning position toward the center of a curve. Saddle-riding vehicles that can turn in a leaning position require agility, so small size and light weight are important. In a saddle-type vehicle configured to be able to turn in a lean position, it is important to achieve both the reproducibility of early combustion at startup and the ability to make the engine rotation speed follow a target without providing additional devices such as a dedicated device for promoting the vaporization of alcohol-containing fuel or a device for injecting fuel into a cylinder.The alcohol-containing fuel engine system described above in (1) can ensure reliable combustion in the first cycle by intentionally providing a non-combustion preliminary cycle, and can achieve both early combustion reproducibility and target engine speed tracking. Therefore, the system can be suitably applied to a saddle-type vehicle that can turn in a lean position. Saddle-type vehicles that can turn in a lean position are suitable for the vehicle of the present invention. Other examples of the vehicle include golf cars, tracked snowmobiles, and snowplows.

[0048] 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 meaning in the context of this disclosure, and should not be interpreted in an idealized or overly formal sense unless explicitly defined herein. It is understood that numerous techniques and processes are disclosed in the description of the present invention. Each of these has distinct advantages, and each can also be used with one or more, or in some cases all, of the other disclosed technologies. Therefore, for the sake of 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. Novel alcohol-containing fuel engine systems and vehicles are described herein. 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.

[0049] According to the present invention, an alcohol-containing fuel engine system can be provided in an engine in which alcohol-containing fuel is injected into the intake passage without being injected into the cylinder, which can achieve both high robustness of early combustion at start-up and high target tracking ability in engine rotation speed.

[0050] 1 is a diagram illustrating an alcohol-containing fuel engine system according to one embodiment; FIG. 2 is a diagram illustrating an example of the alcohol-containing fuel engine system shown in FIG. 1; FIG. 3 is a diagram illustrating a second example of the alcohol-containing fuel engine system shown in FIG. 1; and FIG. 4 is a diagram illustrating a vehicle equipped with the alcohol-containing fuel engine system shown in FIG. 1.

[0051] 1 is a diagram illustrating an alcohol-containing fuel engine system according to one embodiment, with part (a) of FIG. 1 being a block diagram that schematically illustrates the alcohol-containing fuel engine system.

[0052] The alcohol-containing fuel engine system 1 includes an alcohol-containing fuel engine 2 and a control device 3 .

[0053] The alcohol-containing fuel engine 2 uses an alcohol-containing fuel as fuel. The alcohol-containing fuel engine 2 has a crankshaft 2a. The alcohol-containing fuel engine 2 outputs power through the rotation of the crankshaft 2a. The alcohol-containing fuel engine 2 is a four-stroke internal combustion engine. As the crankshaft 2a rotates, the alcohol-containing fuel engine 2 repeatedly executes a cycle consisting of an intake stroke, a compression stroke, a combustion stroke, and an exhaust stroke. In the alcohol-containing fuel engine 2, fuel is injected for each cycle. In this specification, the criterion for the start of a cycle is the injection of fuel.

[0054] The alcohol-containing fuel engine system 1 is also provided with a starter motor M. The starter motor M drives the crankshaft 2 a to rotate the crankshaft 2 a. The starter motor M starts the alcohol-containing fuel engine 2 by rotating the crankshaft 2 a.

[0055] The control device 3 controls the alcohol-containing fuel engine 2. The control device 3 includes a processor 3 a and a memory 3 b. In the control device 3, the processor 3 a controls the alcohol-containing fuel engine 2 by executing a program stored in the memory 3 b.

[0056] The alcohol-containing fuel engine 2 includes at least one cylinder 5. In this embodiment, the alcohol-containing fuel engine 2 is a single-cylinder engine. However, the number of cylinders of the alcohol-containing fuel engine 2 is not particularly limited.

[0057] The alcohol-containing fuel engine 2 includes a combustion chamber 6, an intake passage 7, an intake air amount adjustment device 4, and a fuel injection device 9 for each cylinder.

[0058] The combustion chamber 6 is configured to combust an air-fuel mixture containing alcohol-containing fuel inside. The alcohol-containing fuel is not injected (so-called in-cylinder injection) into the combustion chamber 6. The combustion chamber 6 is in communication with both an intake passage 7 and an exhaust passage 8.

[0059] The intake passage 7 communicates with the combustion chamber 6. Air to be taken into the combustion chamber 6 passes through the intake passage 7.

[0060] The intake air amount adjustment device 4 adjusts the amount of air in the intake passage 7. In this way, the intake air amount adjustment device 4 adjusts the amount of air taken into the combustion chamber 6. The intake air amount adjustment device 4 adjusts the amount of air under the control of the control device 3. Part (a) of FIG. 1 shows a throttle valve as an example of the intake air amount adjustment device 4. However, the shape of the intake air amount adjustment device 4 is not particularly limited, and for example, it may be provided in a bypass passage of the throttle valve, independent of the throttle valve. The independent bypass passage may be, for example, a fast idle (FID) controller, or it may be an idling speed controller (ISC) provided in a bypass passage different from the FID controller.

[0061] The fuel injection device 9 injects the alcohol-containing fuel into the intake passage 7. The fuel injection device 9 injects the entire amount of the alcohol-containing fuel supplied to the combustion chamber 6 into the intake passage 7. In other words, the alcohol-containing fuel engine 2 does not inject the alcohol-containing fuel directly into the combustion chamber 6.

[0062] The alcohol-containing fuel engine 2 also includes an intake valve 12, an exhaust passage 8, an exhaust valve 13, and an ignition device 10. The intake valve 12 is provided between the combustion chamber 6 and the intake passage 7. When the intake valve 12 opens, an air-fuel mixture containing alcohol-containing fuel and air is taken into the combustion chamber 6 from the intake passage 7. The exhaust valve 13 is provided between the combustion chamber 6 and the exhaust passage 8.

[0063] The ignition device 10 is configured to ignite the alcohol-containing fuel mixture introduced into the combustion chamber 6. The ignition device 10 is controlled by the control device 3.

[0064] The control device 3 controls the intake air amount regulator 4 and the fuel injection device 9. The control device 3 also controls the ignition device 10 and the starter motor M. In this way, the control device 3 controls the alcohol-containing fuel engine 2. When starting the engine, the control device 3 designates a first cycle C1, which is the first combustion after starting, and the cycle immediately before the first cycle C1 as a non-combustion preliminary cycle C0, and executes two-cycle sequence control that combines these.

[0065] In the non-combustion preliminary cycle C0, the control device 3 controls the intake air amount adjustment device 4 to supply an amount of air that is less than the amount of air during a high idle state. The amount of air during a high idle state is the amount of air required to warm up the alcohol-containing fuel engine 2. In addition, in the non-combustion preliminary cycle C0, the control device 3 controls the fuel injection device 9 to inject an amount of fuel that is less than the maximum fuel injection amount into the intake passage 7. The control device 3 controls the retention of the injected alcohol-containing fuel in the intake passage 7 by reducing the air flow velocity in the intake passage 7 so that the injected alcohol-containing fuel has time to vaporize.

[0066] In the first cycle C1, the control device 3 controls the intake air amount adjustment device 4 to supply an amount of air that is less than the amount of air during high idle. Also, in the first cycle C1, the control device 3 controls the fuel injection device 9 to inject an amount of fuel that is less than the maximum fuel injection amount into the intake passage. In the first cycle C1, the control device 3 controls the initial combustion using the fuel that was injected in the non-combustion preliminary cycle C0, stored in the intake passage 7, and vaporized, the fuel injected in the first cycle C1, and an amount of air that is less than the amount of air during high idle.

[0067] The two-cycle sequential control will be explained in more detail over time. Parts (b) to (e) of Fig. 1 are block diagrams conceptually showing changes in the state of fuel in the two-cycle sequential control of an alcohol-containing fuel engine system. Parts (b) to (e) of Fig. 1 are schematic diagrams of an alcohol-containing fuel engine 2 viewed in the radial direction of the cylinder and in the vertical height direction. To make the relationship between fuel and air easier to understand, the fuel injection device 9 is also drawn obliquely relative to the intake passage 7 in parts (b) to (e) of Fig. 1.

[0068] Parts (b) and (c) of FIG. 1 show the state in the non-combustion preliminary cycle C0 in the two-cycle sequence control.

[0069] As shown in part (b) of Fig. 1, in the non-combustion preliminary cycle C0, first, the control device 3 controls the fuel injector 9 to inject the alcohol-containing fuel F into the intake passage 7. The amount of fuel injected into the intake passage 7 is less than the maximum fuel injection amount. The number of circles for the alcohol-containing fuel F shown in parts (b) to (e) of Fig. 1 indicates the fuel amount. Part (b) of Fig. 1 shows the alcohol-containing fuel F with an amount of fuel less than the maximum fuel injection amount.

[0070] As shown in part (c) of Figure 1, in the non-combustion preliminary cycle C0, a low flow velocity environment is realized in the intake passage 7 by supplying a small amount of air. Therefore, in the non-combustion preliminary cycle C0, the alcohol-containing fuel F injected from the fuel injector 9 is accumulated in the intake passage 7. More specifically, a portion of the alcohol-containing fuel F injected from the fuel injector 9 in the non-combustion preliminary cycle C0 is dispersed in the space within the intake passage 7, and another portion adheres to the wall surface of the intake passage 7. Part (c) of Figure 1 shows the fuel dispersed in the space and the fuel adhering to the wall surface in the intake passage 7. When the intake valve 12 opens in the non-combustion preliminary cycle C0, a portion of the alcohol-containing fuel F injected into the intake passage 7 is sent to the combustion chamber 6.

[0071] Alcohol-containing fuel F takes longer to vaporize than gasoline. Furthermore, in the low-flow-velocity environment of the non-combustion preliminary cycle C0, much of the alcohol-containing fuel accumulates in the intake passage 7, adhering to the wall of the intake passage 7 without being carried away by the air heading toward the combustion chamber 6. While a portion of the alcohol-containing fuel F injected from the fuel injector 9 is delivered to the combustion chamber 6, the amount of alcohol-containing fuel F injected from the fuel injector 9 in the non-combustion preliminary cycle C0 is small, and most of the alcohol-containing fuel F adheres to the wall of the intake passage 7, so even less alcohol-containing fuel is delivered to the combustion chamber 6. Therefore, effective combustion does not occur in the non-combustion preliminary cycle C0. Some of the alcohol-containing fuel delivered to the combustion chamber 6 in the non-combustion preliminary cycle C0 is vaporized. The open circles conceptually represent the amount of vaporized alcohol-containing fuel. While some of the alcohol-containing fuel delivered to the combustion chamber 6 may ignite, effective combustion that would affect engine rotation speed does not occur. The alcohol-containing fuel fed into the combustion chamber 6 in the non-combustion preliminary cycle C0 is exhausted from the combustion chamber 6 through the exhaust passage 8 in the exhaust stroke.

[0072] The alcohol-containing fuel that adheres to the wall surface of the intake passage 7 in the non-combustion preliminary cycle C0, and the alcohol-containing fuel that has dispersed within the intake passage 7 but remains in the intake passage 7 without being taken into the combustion chamber 6, are stored in the intake passage 7. The alcohol-containing fuel stored in the intake passage 7 can be vaporized over the time period of one cycle until the next first cycle C1. Although the alcohol-containing fuel has the property that it is difficult to promote vaporization, vaporization is promoted by leaving the alcohol-containing fuel in the intake passage for the time period of one cycle.

[0073] Parts (d) and (e) of FIG. 1 show the state in the first cycle C1 in the two-cycle sequence control.

[0074] Part (d) of FIG. 1 shows the alcohol-containing fuel injected in the non-combustion preliminary cycle C0 and vaporized by the time the first cycle C1 arrives. In the first cycle C1, an amount of air less than that during high idle is supplied, and a fuel amount F2 less than the maximum fuel injection amount is injected into the intake passage 7. As shown in part (e) of FIG. 1 , in the first cycle C1, the alcohol-containing fuel F injected in the immediately preceding non-combustion preliminary cycle C0, stored in the intake passage 7, and vaporized is combined with the alcohol-containing fuel F2 injected in the first cycle C1 and supplied to the combustion chamber 6. The initial combustion is controlled by this combined fuel and an amount of air less than that during high idle. Therefore, the initial combustion (comb) occurs with high reliability. Because the initial combustion occurs with high reliability in the first cycle C1, the amount of unburned alcohol-containing fuel remaining in the combustion chamber after combustion is reduced. Therefore, afterburning in the second cycle following the first cycle C1 is suppressed, and deviation of the speed in the second cycle from the target speed is suppressed.

[0075] In this manner, the alcohol-containing fuel engine system 1 of this embodiment performs two-cycle sequential control consisting of the first cycle C1 and the unburned preliminary cycle C0 after the engine has started, and simultaneous control of the intake air amount and fuel amount in both the first cycle C1 and the unburned preliminary cycle C0. The synergistic effect of the two-cycle sequential control and the simultaneous control of the intake air amount and fuel amount increases the amount of fuel stored and vaporized in the intake passage 7 in the unburned preliminary cycle C0. In the first cycle C1, the fuel stored in the intake passage 7 in the unburned preliminary cycle C0 and the fuel newly injected into the intake passage 7 in the first cycle C1 are combined to draw less air into the combustion chamber 6 than in a high idle state, resulting in highly reliable combustion. This results in highly robust early combustion. Furthermore, as a result of the highly reliable combustion in the first cycle C1, afterburning due to excess fuel in the next cycle caused by unburned fuel in the combustion chamber is suppressed. This results in high target tracking performance in the engine rotation speed. Therefore, in an engine in which alcohol-containing fuel is injected through the intake passage without being injected into the cylinder, it is possible to achieve both high robustness of early combustion at start-up and high target tracking capability of the engine rotation speed.

[0076] Fig. 2 is a diagram illustrating an embodiment of the alcohol-containing fuel engine system shown in Fig. 1. Part (a) of Fig. 2 is a flowchart illustrating the control of the control device 3 of the alcohol-containing fuel engine system 1.

[0077] After starting the alcohol-containing fuel engine 2 by starting the starter motor M (S10), the control device 3 performs non-combustion preliminary cycle control (S11). In the non-combustion preliminary cycle control, the control device 3 supplies an amount of air less than that during a high idle state and injects an amount of fuel less than the maximum fuel injection amount into the intake passage. Next, the control device 3 performs first cycle control (S12). In the first cycle control, the control device 3 supplies an amount of air less than that during a high idle state and injects an amount of fuel less than the maximum fuel injection amount into the intake passage. Next, the control device 3 performs continuation cycle control (S13). The continuation cycle control executed after the first cycle control (S12) is specifically the second cycle control. After this, if combustion occurs consecutively in the first cycle control (S12) and the continuation cycle control (S13) (Yes in S13), the control device 3 stops the starter motor M (S14) and executes idling control (S15). As a result, the alcohol-containing fuel engine 2 starts to burn and enters an idling state, and the control described with reference to Fig. 1 is carried out. For example, if combustion does not occur continuously due to an injection malfunction or the like (No in S13), the control device 3 repeats the continuous cycle control (S13).

[0078] Part (a) of FIG. 2 is a time chart illustrating the operation of the alcohol-containing fuel engine system 1.

[0079] At time t1, in the non-combustion preliminary cycle C0 after the start of the starter motor M, an air amount Amin less than the air amount Amax during high idle is supplied. A fuel amount F1 less than the maximum fuel injection amount Fmax is injected into the intake passage 7. A portion of the fuel amount F1 is not taken into the combustion chamber 6 but is stored in the intake passage 7 (t2), and vaporization is promoted during the period until the next first cycle C1. The amount of alcohol-containing fuel injected in the non-combustion preliminary cycle C0 and taken into the combustion chamber 6 in the non-combustion preliminary cycle C0 is less than the lower limit amount required for combustion to occur. In the non-combustion preliminary cycle C0, the amount of alcohol-containing fuel not stored in the intake passage 7 but taken into the combustion chamber 6 is less than the lower limit amount required for combustion to occur, so that the alcohol-containing fuel is injected in such an amount. In the first cycle C1 at time t3, a small air amount Amin is supplied, and a fuel amount F2 is injected into the intake passage 7. A portion of the fuel amount F2 is stored in the intake passage 7 without being taken into the combustion chamber 6 (t4). However, the remaining portion of the fuel amount F2 and the alcohol-containing fuel amount Fres that was stored in the intake passage 7 and vaporized in the non-combustion preliminary cycle C0 are combined and taken into the combustion chamber 6. The combined amount of alcohol-containing fuel taken into the combustion chamber 6 exceeds the lower limit amount Fcomb required for combustion to occur, and combustion occurs in the first cycle C1. The sum of the amount of alcohol-containing fuel injected and taken into the combustion chamber 6 in the first cycle C1 and the amount of alcohol-containing fuel that was stored in the intake passage 7 and vaporized in the combustion preliminary cycle C0 and taken into the combustion chamber 6 in the first cycle C1 is greater than the lower limit amount required for combustion to occur. Thereafter, the starter motor M is stopped, the combustion operation of the alcohol-containing fuel engine 2 is started, and the engine enters an idling state.

[0080] Figure 3 is a diagram illustrating a second example of the alcohol-containing fuel engine system shown in Figure 1. Part (a) of Figure 3 is a block diagram that schematically illustrates the alcohol-containing fuel engine system in the second example. Part (c) of Figure 3 illustrates the operation of the starter motor. Part (d) of Figure 3 illustrates the intake air amount. Part (e) of Figure 3 illustrates the injection amount of alcohol-containing fuel. For ease of understanding, elements in Figure 3 that are common to Figure 1 will be described using the same reference numerals as in Figure 1.

[0081] In the example shown in part (a) of FIG. 3 , the intake passage 7 includes a passage having a throttle valve 4a and a bypass passage 7b for the throttle valve 4a. The bypass passage 7b is provided with an intake air amount adjuster 4b. The intake air amount adjuster 4b is, for example, an FID controller. The intake air amount adjuster 4b adjusts the amount of air taken into the combustion chamber 6 through the bypass passage 7b under the control of the control device 3. For example, during the starting and idling periods, the throttle valve 4a sets the air amount to zero, and the FID controller serving as the intake air amount adjuster 4b adjusts the air amount within a range from an air amount corresponding to a low idle state to an air amount corresponding to a high idle state under the control of the control device 3. In this case, the throttle valve 4a may be connected to the accelerator by a mechanical cable, for example, without the control device 3. Although not shown in part (a) of FIG. 3 , a configuration may also be adopted in which, in addition to the bypass passage 7b, a passage for ISC is provided as a second bypass passage.

[0082] Part (e) of Figure 3 shows the opening period V of the intake valve 12. The opening timing of the intake valve 12 corresponds to the rotational position of the crankshaft 2a. The control device 3 causes the fuel injection device 9 to inject an amount of alcohol-containing fuel that is smaller than the maximum fuel injection amount Fmax. The control device 3 may control the fuel injection device 9 so that part of the period during which the fuel injection device 9 injects the alcohol-containing fuel overlaps with the opening period V of the intake valve 12, and so that the injection of the alcohol-containing fuel starts before the intake valve 12 starts opening.

[0083] Because the injection of the alcohol-containing fuel begins before the intake valve 12 begins to open, the injected alcohol-containing fuel is contained in the air in the intake passage 7 at the time when air begins to be taken from the intake passage 7 into the combustion chamber 6. Therefore, a mixture containing the injected alcohol-containing fuel is taken into the combustion chamber 6 with high efficiency. This makes it possible to further improve the reproducibility of early combustion and the ability of the engine rotation speed to track the target while reducing the injection amount of the alcohol-containing fuel.

[0084] The control device 3 causes the fuel injection device 9 to inject an amount of alcohol-containing fuel that is smaller than the maximum fuel injection amount Fmax in the first cycle C1. As shown in part (e) of Fig. 3 , the control device 3 may cause the fuel injection device 9 to inject an amount F1 of alcohol-containing fuel in the non-combustion preliminary cycle C0 that is larger than the amount F2 of alcohol-containing fuel injected in the first cycle C1.

[0085] A portion of the alcohol-containing fuel injected in the first cycle C1 adheres to the intake pipe and remains there, further contributing to combustion in the next cycle. When injection of the alcohol-containing fuel begins in the first cycle C1, some of the fuel injected in the non-combustion preliminary cycle C0 and adhering to the intake pipe remains. In contrast, when injection of the alcohol-containing fuel begins in the non-combustion preliminary cycle C0, no fuel is typically stored in the intake passage 7. According to the example of the alcohol-containing fuel engine system 1 shown in FIG. 3 , a larger amount of alcohol-containing fuel is injected into the intake pipe where no fuel is stored before the non-combustion preliminary cycle C0 than in the first cycle C1. This allows a large amount of alcohol-containing fuel to be injected into the intake pipe where no fuel is stored before the non-combustion preliminary cycle C0, ensuring that sufficient fuel is supplied in anticipation of combustion in the next first cycle C1, even when no fuel is stored in the non-combustion preliminary cycle C0. This allows for both higher robustness of early combustion during startup and high target tracking performance in engine speed.

[0086] Furthermore, the control device 3 causes the intake air amount Amin to be less than the air amount Amax corresponding to the high idle state in the non-combustion preliminary cycle C0 and the first cycle C1. Then, as shown in part (d) of FIG. 3 , when effective combustion occurs in both the first cycle C1 and the second cycle C2, the control device 3 may cause the intake air amount regulator 4 to supply the air amount Amax corresponding to the high idle state in at least one of the third to fifth cycles (C3, C4, C5). By supplying the air amount Amax corresponding to the high idle state, the alcohol-containing fuel engine 2 enters the high idle state. Thereafter, the control device 3 adjusts the air amount based on the temperature of the alcohol-containing fuel engine 2, the temperature of the exhaust gas passing through the exhaust passage 8, the temperature of the three-way catalyst 15, or a combination of these temperatures. More specifically, the control device 3 gradually reduces the amount of air taken in by the intake air amount regulator 4b as the temperature rises due to the combustion operation of the alcohol-containing fuel engine 2. When the temperature finally exceeds the reference value, the control device 3 causes the intake of the amount of air Amin corresponding to the low idle state.

[0087] When effective combustion continues in the first cycle C1 and the second cycle C2, the maximum amount of air Amax during idling is taken in, so that a sudden change in rotation speed can be suppressed and a smooth transition to a high idling state can be achieved.

[0088] The control device 3 may take in an air amount that is less than the air amount Amax corresponding to the high idle state and the median air amount Amid corresponding to the low idle state, at least in both the uncombusted preliminary cycle C0 and the first cycle C1.

[0089] Because the pressure in the intake passage 7 is reduced, the amount of evaporation of the alcohol-containing fuel increases compared to when an amount of air greater than the median value Amid is taken in. This increases the probability that effective combustion will occur in the combustion stroke of the first cycle C1.

[0090] As shown in part (a) of FIG. 3, the alcohol-containing fuel engine system 1 may further include a three-way catalyst 15 provided in the exhaust passage 8 of the alcohol-containing fuel engine 2 .

[0091] As described above, the reproducibility of early combustion and the ability of the engine rotation speed to track the target are further improved in the alcohol-containing fuel engine system 1. Therefore, in addition to the reproducibility of early combustion and the ability of the rotation speed to track the target in the alcohol-containing fuel engine 2, the ability of the catalyst temperature to track the target, which affects the ability of the three-way catalyst 15 to purify exhaust gas from the alcohol-containing fuel engine 2, is also further improved.

[0092] FIG. 4 is a diagram showing a vehicle equipped with the alcohol-containing fuel engine system shown in FIG.

[0093] 4 shows a vehicle 100 equipped with an alcohol-containing fuel engine system 1. The vehicle 100 is, for example, a saddle-ride type vehicle. The vehicle 100 includes an alcohol-containing fuel tank 1t. The alcohol-containing fuel tank 1t stores alcohol-containing fuel and supplies it to the alcohol-containing fuel engine system. Because the vehicle 100 includes the above-described alcohol-containing fuel engine system 1, it is possible to achieve both early combustion reproducibility and target engine rotation speed tracking by using the alcohol-containing fuel required for driving.

[0094] A straddle-type vehicle is shown as an example of a vehicle in Fig. 4. However, the vehicle is not limited to a straddle-type vehicle, and may include, for example, a four-wheeled automobile.

[0095] The above-described embodiment is not limited to the example described with reference to Fig. 3, and various modifications can be added. Furthermore, as an example of this embodiment, any one of the elements described with reference to Fig. 3 or a combination of any two or more elements may be provided. For example, with reference to Fig. 3, an example has been described in which the fuel injection device 9 is controlled so that the injection of the alcohol-containing fuel starts before the intake valve 12 starts to open. However, the start of the injection of the alcohol-containing fuel is not particularly limited, and may be, for example, after the intake valve 12 starts to open.

[0096] 3, for example, it has been described that in the injection in the uncombustion preliminary cycle C0, the fuel injection device 9 injects an amount F1 of alcohol-containing fuel that is greater than the fuel amount F2 of alcohol-containing fuel injected from the fuel injection device 9 in the injection in the first cycle C1. However, the relationship between the injection amounts in the uncombustion preliminary cycle C0 and the first cycle C1 is not particularly limited, and for example, the injection amount in the uncombustion preliminary cycle C0 may be less than or equal to the injection amount in the first cycle C1.

[0097] 3, it has been explained that when effective combustion occurs in the first cycle C1 and the second cycle C2, the control device 3 causes the intake air amount adjustment device 4b to introduce the amount of air Amax corresponding to the high idle state in at least one of the second to fifth cycles. However, the conditions for introducing the amount of air Amax corresponding to the high idle state are not particularly limited, and for example, when effective combustion occurs in the first cycle C1, the control device 3 may introduce the amount of air Amax corresponding to the high idle state.

[0098] 3, for example, it has been described that the amount of air taken in is less than the median value Amid in both the uncombustion preliminary cycle C0 and the first cycle C1. However, the amount of air taken in in the uncombustion preliminary cycle C0 and the first cycle C1 is not particularly limited as long as it is less than the air amount Amax corresponding to the high idle state, and an amount of air taken in that is greater than the median value Amid may also be used.

[0099] 3, an example in which the three-way catalyst 15 is provided in the exhaust passage 8 has been described. However, the location and type of catalyst are not particularly limited.

[0100] 1: Alcohol-containing fuel engine system 2: Alcohol-containing fuel engine 3: Control device 4, 4b: Intake air amount adjustment device 6: Combustion chamber 7: Intake passage 8: Exhaust passage 9: Fuel injection device 12: Intake valve 15: Three-way catalyst 100: Vehicle C0: Non-combustion preliminary cycle C1: First cycle

Claims

1. An alcohol-containing fuel engine system comprising: an alcohol-containing fuel engine; and a control device for controlling the alcohol-containing fuel engine, the alcohol-containing fuel engine comprising: a combustion chamber; an intake passage communicating with the combustion chamber; an intake air amount adjustment device for adjusting the amount of air in the intake passage; and a fuel injection device for injecting all of the alcohol-containing fuel supplied to the combustion chamber into the intake passage, the control device: at engine start, designates a first cycle which is the first combustion after start and the cycle immediately before the first cycle as non-combustion reserve cycles, and executes a control sequence combining these, in the first cycle, controls the intake air amount adjustment device to supply an amount of air less than the amount of air in a high idle state when warming up the alcohol-containing fuel engine, and controls the fuel injection device to inject an amount of fuel less than the maximum fuel injection amount into the intake passage, an initial combustion is controlled using the fuel injected in the non-combustion preliminary cycle, stored in the intake passage, and vaporized, the fuel injected in the first cycle, and an amount of air less than the amount of air during the high idle state; in the non-combustion preliminary cycle, the intake air amount regulator is controlled to supply an amount of air less than the amount of air during the high idle state; the fuel injection device is controlled to inject an amount of fuel less than the maximum fuel injection amount into the intake passage; and the storage of the injected alcohol-containing fuel in the intake passage is controlled by reducing the air flow velocity in the intake passage so that time for vaporization is ensured.

2. The alcohol-containing fuel engine system according to claim 1, wherein the alcohol-containing fuel engine comprises a cylinder and an intake valve provided between the cylinder and the intake passage, and the control device causes the fuel injection device to inject an amount of alcohol-containing fuel less than the maximum fuel injection amount so that, in at least the non-combustion preliminary cycle and the first cycle, a part of the period during which the fuel injection device injects the alcohol-containing fuel overlaps with the opening period of the intake valve, and injection of the alcohol-containing fuel begins before the intake valve begins to open.

3. An engine system with a fuel containing alcohol as described in claim 1 or 2, wherein the control device causes the fuel injection device to inject an amount of alcohol-containing fuel that is smaller than the maximum fuel injection amount in the first cycle, and causes the fuel injection device to inject an amount of alcohol-containing fuel that is greater than the amount of alcohol-containing fuel injected from the fuel injection device in the first cycle in the non-combustion preliminary cycle.

4. An alcohol-containing fuel engine system according to any one of claims 1 to 3, wherein the control device supplies an amount of air in the non-combustion preliminary cycle and the first cycle that is less than the amount of air in the high idle state of the alcohol-containing fuel engine, and, if the combustion occurs in both the first cycle and the second cycle following the first cycle, controls the intake air amount adjustment device in at least one of the third to fifth cycles following the second cycle to supply the amount of air in the high idle state of the alcohol-containing fuel engine.

5. An engine system using an alcohol-containing fuel according to any one of claims 1 to 4, further comprising a three-way catalyst provided in an exhaust passage of the engine using an alcohol-containing fuel.

6. A vehicle equipped with an alcohol-containing fuel engine system according to any one of claims 1 to 5.

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