Alcohol-containing fuel engine system and vehicle

Abstract

The purpose of the present invention is to provide an alcohol-containing fuel engine system using a high concentration alcohol-containing fuel, which is capable of satisfying the performance of a catalyst in both usage scenes at a cold start and under a high load while enhancing flexibility in designing the catalyst. In the present invention, a high concentration alcohol-containing fuel-air mixture combustion exhaust gas, which is obtained by combusting in a combustion chamber a high concentration alcohol-containing fuel-air mixture of air and a high concentration alcohol-containing fuel injected into an intake passage at an air-fuel ratio that is rich upon a cold start, is passed through an exhaust-gas-contact-time increased metallic catalyst. The catalyst is supported on a metallic exhaust pipe that forms an exhaust passage at a portion on the upstream of a muffler along the exhaust passage. A plurality of projections and recesses, or holes are formed in a passage wall of a metallic carrier in the catalyst.

Description

Alcohol-containing fuel engine system and vehicle

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

[0002] An alcohol-containing fuel engine system has been known in the art, and includes an alcohol-containing fuel engine configured to use an alcohol-containing fuel, an alcohol-containing fuel injection device configured to inject the alcohol-containing fuel into an intake passage connected to a combustion chamber of the alcohol-containing fuel engine, and a catalyst through which exhaust gases generated after burning an alcohol-containing fuel mixture of the alcohol-containing fuel and air in the combustion chamber pass.

[0003] Such an alcohol-containing fuel engine system is disclosed, for example, in Patent Document 1 listed below. In Patent Document 1, the alcohol content of the fuel supplied to the intake passage during cold start is adjusted, thereby adjusting the alcohol content of the exhaust gas flowing into the catalyst. This control addresses the improvement of startability at low temperatures. During cold start, the alcohol content of the fuel supplied to the intake passage is reduced.

[0004] JP 2014-51894 A

[0005] In alcohol-containing fuel engine systems that use fuel containing high concentrations of alcohol, there is a need to increase the degree of freedom in catalyst design while also satisfying catalyst performance in both cold start and high load usage scenarios.

[0006] An object of the present invention is to provide an alcohol-containing fuel engine system that uses a high-concentration alcohol-containing fuel, which can increase the degree of freedom in catalyst design while providing satisfactory catalyst performance in both cold start and high load usage scenarios.

[0007] The present inventors have studied ways to achieve the above-mentioned object. As a result, they have come to the following findings. The present inventors have studied an alcohol-containing fuel engine system that is not configured to adjust the alcohol concentration of the high-concentration alcohol-containing fuel injected into the intake passage depending on the situation. The engine system includes, for example, an alcohol-containing fuel tank configured to store high-concentration alcohol-containing fuel having a predetermined alcohol concentration, and an alcohol-containing fuel injection device connected to the fuel tank is configured to inject the high-concentration alcohol-containing fuel supplied from the fuel tank into the intake passage. In this engine system, to improve startability during cold start, the high-concentration alcohol-containing fuel is injected into the intake passage at an air-fuel ratio that is rich during cold start. However, the exhaust gas temperature tends to be low after combustion of the mixture of high-concentration alcohol-containing fuel and air injected into the intake passage at an air-fuel ratio that is rich during cold start (high-concentration alcohol-containing fuel mixture). Therefore, the present inventors have conducted further research from the perspective of accelerating catalyst temperature rise during cold start. During this process, the inventor realized that it was necessary to consider the need to ensure catalyst durability under high loads. The inventor also considered the application of the engine system. The engine system is applied to, for example, a vehicle. Examples of vehicles include saddle-ride vehicles. That is, depending on the application of the engine system, the catalyst layout, for example, may be limited. Even in such cases where the catalyst layout is limited, the inventor realized that consideration was also needed from the perspective of increasing catalyst design flexibility in order to accelerate catalyst temperature rise during cold start and ensure catalyst durability under high loads. As a result of this consideration, the inventor discovered that it would be sufficient to keep exhaust gas at as high a temperature as possible in contact with the catalyst for as long as possible while preventing the catalyst from becoming excessively hot when in contact with the exhaust gas. The present invention was completed based on this finding.

[0008] (1) An alcohol-containing fuel engine system according to one embodiment of the present invention comprises: an alcohol-containing fuel engine configured to use an alcohol-containing fuel; an alcohol-containing fuel injection device configured to inject the alcohol-containing fuel into an intake passage connected to a combustion chamber of the alcohol-containing fuel engine; and a catalyst configured to pass exhaust gas remaining after combustion of a mixture of the alcohol-containing fuel and air in the combustion chamber, wherein the alcohol-containing fuel engine system is configured such that the alcohol-containing fuel injection device injects high-concentration alcohol-containing fuel into the intake passage at an air-fuel ratio that is rich during cold start, and the high-concentration alcohol-containing fuel mixture combustion exhaust gas generated by combustion of the high-concentration alcohol-containing fuel mixture of the high-concentration alcohol-containing fuel and air in the combustion chamber is supplied to an exhaust gas contact time increasing metal catalyst supported on a metal exhaust pipe that forms the exhaust passage, upstream of a silencer in the exhaust passage, and the high-concentration alcohol-containing fuel is the alcohol-containing fuel having an alcohol concentration of more than 20% by volume, The exhaust gas contact time increasing metal catalyst is configured such that a plurality of irregularities or holes are formed on the passage walls of the metal carrier in the catalyst, thereby lengthening the time it takes for the high-concentration alcohol-containing fuel mixture combustion exhaust gas to pass through the catalyst compared to when the plurality of irregularities or holes are not formed, thereby increasing the amount of heat transferred from the high-concentration alcohol-containing fuel mixture combustion exhaust gas to the catalyst and facilitating the transfer of the heat transferred to the catalyst from the upstream portion to the downstream portion of the catalyst, thereby accelerating the temperature rise of the catalyst.

[0009] According to the alcohol-containing fuel engine system (1), the exhaust gas from combustion of a high-concentration alcohol-containing fuel mixture, which tends to have a low temperature due to the high-concentration alcohol-containing fuel injected into the intake passage at a rich air-fuel ratio during cold start, passes through a catalyst supported by a metal exhaust pipe forming the exhaust passage upstream of the muffler. The catalyst is a metal catalyst for increasing exhaust gas contact time, with multiple irregularities or holes formed in the passage wall of the metal carrier of the catalyst. This increases the temperature of the exhaust gas contacting the catalyst while lengthening the time the exhaust gas contacts the catalyst. This allows the highest possible temperature of exhaust gas to be in contact with the catalyst for as long as possible, thereby accelerating the catalyst temperature rise during cold start. This shortens the time it takes for the catalyst to reach its activation temperature during cold start. For example, the position, size, number, range, and type of the multiple irregularities or holes formed in the passage wall of the metal carrier of the catalyst can be adjusted depending on the distance from the engine to the catalyst. For example, this increases the degree of freedom in catalyst layout. By utilizing heat conduction due to metal-to-metal contact, the exhaust gas contact time is increased under high load conditions, allowing heat to escape from the metal catalyst to the metal exhaust pipe. This prevents the catalyst from becoming excessively hot. As a result, in an alcohol-fueled engine system that uses high-concentration alcohol-containing fuel, it is possible to increase the design freedom of the catalyst while still achieving satisfactory catalyst performance in both cold start and high-load conditions. More details are as follows.

[0010] High-concentration alcohol-containing fuel has a high alcohol concentration. Therefore, the combustion temperature of high-concentration alcohol-containing fuel tends to be low. The temperature of the exhaust gas after combustion, i.e., the high-concentration alcohol-containing fuel mixture combustion exhaust gas, also tends to be low. Fuel injection into the intake passage requires fuel injection that takes into account the amount of fuel adhering to the intake passage wall surface. In addition, fuel is injected at a rich air-fuel ratio during cold start. As a result, a larger amount of excess alcohol-containing fuel tends to be contained in the high-concentration alcohol-containing fuel mixture combustion exhaust gas. The excess alcohol-containing fuel absorbs heat from the high-concentration alcohol-containing fuel mixture combustion exhaust gas and vaporizes. This further reduces the temperature of the high-concentration alcohol-containing fuel mixture combustion exhaust gas flowing into the exhaust gas contact time increasing metal catalyst. According to the alcohol-containing fuel engine system (1), the exhaust gas contact time increasing metal catalyst is located upstream of the muffler in the exhaust passage. This allows for higher-temperature high-concentration alcohol-containing fuel mixture combustion exhaust gas to pass through. As a result, it is easier to increase the temperature of the exhaust gas contact time increasing metal catalyst. Here, the exhaust gas contact time increasing metal catalyst has a metal support. Additionally, the exhaust gas contact time increasing metal catalyst has multiple irregularities or holes formed on the passage walls of the metal support. This increases the residence time (contact time with the exhaust gas contact time increasing metal catalyst) of the high-concentration alcohol-containing fuel mixture combustion exhaust gas. The exhaust gas contact time increasing metal catalyst facilitates heat transfer from the upstream to the downstream of the exhaust gas contact time increasing metal catalyst. The exhaust gas contact time increasing metal catalyst facilitates further increasing the temperature of the exhaust gas contact time increasing metal catalyst. In other words, with the alcohol-containing fuel engine system (1), even if the temperature of the high-concentration alcohol-containing fuel mixture combustion exhaust gas tends to decrease due to the high-concentration alcohol-containing fuel injected into the intake passage at a rich air-fuel ratio during cold start, by using the above-mentioned exhaust gas contact time increasing metal catalyst as the catalyst through which the exhaust gas passes, the catalyst temperature rise during cold start can be accelerated. Here, with the alcohol-containing fuel engine system (1), the temperature of the high-concentration alcohol-containing fuel combustion exhaust gas contacting the exhaust gas contact time increasing metal catalyst can be adjusted by adjusting the distance from the alcohol-containing fuel engine to the exhaust gas contact time increasing metal catalyst.By adjusting the position, size, number, range, and type of multiple irregularities or holes formed on the passage walls of the metal support, the contact time of the high-concentration alcohol-containing fuel combustion exhaust gas with the exhaust gas contact time-increasing metal catalyst, i.e., the catalyst passage time of the high-concentration alcohol-containing fuel combustion exhaust gas, can be adjusted. For example, the position, size, number, range, and type of multiple irregularities or holes formed on the passage walls of the metal support of the catalyst can be adjusted depending on the distance from the alcohol-containing fuel engine to the exhaust gas contact time-increasing metal catalyst. For example, this increases the degree of freedom in catalyst layout. For example, this increases the degree of freedom in adopting a heating device to increase the catalyst temperature and a thermal insulation material to keep the catalyst warm. This increases the degree of freedom in catalyst design. Furthermore, according to the alcohol-containing fuel engine system (1), the exhaust gas contact time-increasing metal catalyst, which has multiple irregularities or holes formed on the passage walls of the metal support, is supported on a metal exhaust pipe that forms the exhaust passage, allowing heat dissipation through metal-to-metal contact. Therefore, heat can be dissipated from the exhaust gas contact time-increasing metal catalyst to the metal exhaust pipe under high load. In addition, the temperature of the combustion exhaust gas of a high-concentration alcohol-containing fuel mixture flowing into the exhaust gas contact time-increasing metal catalyst tends to be low due to the high-concentration alcohol-containing fuel being injected into the intake passage at a rich air-fuel ratio during cold start. This can suppress or prevent catalyst sintering under high load. This can ensure catalyst durability under high load. In other words, according to the alcohol-containing fuel engine system (1), in an alcohol-containing fuel engine system that uses a high-concentration alcohol-containing fuel, it is possible to increase the degree of freedom in catalyst design while still achieving satisfactory catalyst performance in both cold start and high load usage scenarios.

[0011] 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, E22, E25, E27, E85, and E100. 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 it is applicable to an alcohol-fueled engine. A high-concentration alcohol-containing fuel is an alcohol-containing fuel with an alcohol concentration greater than 20% by volume. The alcohol-containing fuel engine is not particularly limited as long as the upper limit of the alcohol concentration of the applicable alcohol-containing fuel exceeds 20% by volume. Examples of such upper limits include 22, 25, 27, 85, and 100% by volume. An upper limit of 22% by volume means that the alcohol-containing fuel engine can use alcohol-containing fuels with alcohol concentrations up to 22% by volume. The higher the upper limit, the higher the alcohol concentration of the applicable alcohol-containing fuel. The alcohol-containing fuel engine may be configured so that the lower limit of the alcohol concentration of the applicable alcohol-containing fuel exceeds 0% by volume. 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 limits. Furthermore, with regard to the number of cylinders, the alcohol-containing fuel engine includes, for example, a single-cylinder engine and an engine with two or more cylinders. In other words, the alcohol-containing fuel engine includes, for example, an engine with one or two or more combustion chambers. The alcohol-fueled engine may be, for example, a single cylinder engine, a two-cylinder engine, a non-uniform firing three-cylinder engine, or a non-uniform firing four-cylinder engine.When an alcohol-containing fuel engine has multiple combustion chambers, each of which is connected to an intake passage, the alcohol-containing fuel injection device according to the present invention does not necessarily inject fuel into all of the intake passages. The alcohol-containing fuel injection device according to the present invention may inject fuel into any of the multiple intake passages. The alcohol-containing fuel engine may include, for example, an alcohol-containing fuel ignition device. The alcohol-containing fuel ignition device is a device that ignites a high-concentration alcohol-containing fuel mixture introduced into a combustion chamber. This device may be, for example, an ignition system. This device does not need to be a dedicated device for alcohol-containing fuel; it may be a general-purpose device that is also used for gasoline fuel. "The alcohol-containing fuel injection device injects a high-concentration alcohol-containing fuel into the intake passage at a rich air-fuel ratio" includes, for example, the alcohol-containing fuel injection device injecting a high-concentration alcohol-containing fuel into the intake passage so that the air-fuel ratio of the mixture before combustion, i.e., the high-concentration alcohol-containing fuel mixture, becomes rich. The alcohol-containing fuel injection device is configured, for example, to inject the entire amount of alcohol-containing fuel supplied to the combustion chamber into the intake passage. The alcohol-containing fuel injection device is, for example, an injector. The alcohol-containing fuel injection device may be a dedicated device for alcohol-containing fuel, or a general-purpose device that is also used for gasoline fuel. The alcohol-containing fuel injection device may be selected depending on the alcohol concentration of the alcohol-containing fuel. The manner in which the alcohol-containing fuel injection device injects the alcohol-containing fuel into the intake passage is not particularly limited. For example, the alcohol-containing fuel injection device may inject the alcohol-containing fuel into an intake port that forms the intake passage, or may inject the alcohol-containing fuel into an intake pipe that forms the intake passage. Here, the intake port is formed in a cylinder head that constitutes the alcohol-containing fuel engine. The intake pipe is connected to the cylinder head so as to communicate with the intake port. Note that in-cylinder injection is not performed in an alcohol-containing fuel engine. The catalyst is provided in the exhaust passage. The catalyst is not provided in the muffler. One catalyst may be provided in the exhaust passage, or multiple catalysts may be provided in the exhaust passage.When multiple catalysts are provided in an exhaust passage, the catalyst according to the present invention may be, for example, the most upstream of the multiple catalysts. For example, some of the multiple catalysts may be provided in a muffler. When an alcohol-containing fuel engine has multiple combustion chambers and each combustion chamber is connected to an exhaust passage, the catalyst according to the present invention is provided downstream of the junction of the multiple exhaust passages. The catalyst may be, for example, a three-way catalyst. The three-way catalyst is, for example, a catalytic converter for simultaneously converting carbon monoxide, hydrocarbons, and nitrogen oxides emitted from an alcohol-containing fuel engine. The catalyst may have, for example, a metal honeycomb structure. The surface of the honeycomb structure is coated with a catalytic noble metal (e.g., Pt, Pd, Rh, etc.). In other words, the metal honeycomb structure is the metal support of the catalyst. The walls of the metal honeycomb structure that form the passages through which exhaust gas flows are the passage walls of the metal support of the catalyst. The multiple irregularities or holes formed in the passage walls are not particularly limited as long as they contribute to extending the time that exhaust gas passes through the catalyst. The multiple irregularities or holes include, for example, multiple punched holes (through holes), multiple embossments, multiple dimples, multiple protrusions, and multiple recesses. The protrusions may be, for example, small pieces formed by raising portions of the passage wall from the passage wall toward the inside of the passage. The small pieces are formed, for example, so as to protrude from the passage wall. The multiple irregularities or holes may be composed of the same type of irregularities or holes, or may be composed of multiple different types of irregularities or holes. The catalyst may be a dedicated product for alcohol-containing fuels or a general-purpose product also used for gasoline fuels. The metal catalyst for increasing exhaust gas contact time is a metal catalyst in which multiple irregularities or holes are formed on the passage wall of the metal carrier of the catalyst. The material of the metal carrier in the catalyst has, for example, the same or similar thermal conductivity as the material of the metal exhaust pipe. The material of the metal carrier in the catalyst may have, for example, a lower thermal conductivity than the material of the metal exhaust pipe, or a higher thermal conductivity than the material of the metal exhaust pipe. The cold start refers, for example, to at least a portion of the period from the start of startup until the catalyst inlet temperature reaches a predetermined temperature.The start of the starting operation refers to, for example, the start of operation of a motor that applies driving force to the crankshaft of an alcohol-containing fuel engine when the alcohol-containing fuel engine is started. The predetermined temperature is, for example, the temperature at which a catalyst is activated. Cold start refers to, for example, the period from the start of the starting operation to complete combustion. Complete combustion refers to a state in which the crankshaft of an alcohol-containing fuel engine is driven independently by the combustion of a high-concentration alcohol-containing fuel mixture of high-concentration alcohol-containing fuel and air without the need for an external driving force such as a motor. The number of ignitions required to achieve complete combustion is not particularly limited; complete combustion may be achieved by the first ignition, or by a second or subsequent ignitions. After complete combustion, the alcohol-containing fuel injection device may, for example, inject high-concentration alcohol-containing fuel into the intake passage at an air-fuel ratio that is leaner than that during cold start. An air-fuel ratio that is leaner than that during cold start is, for example, an air-fuel ratio that is at or close to the stoichiometric air-fuel ratio. "Injecting high-concentration alcohol-containing fuel into the intake passage at an air-fuel ratio leaner than that during cold start" includes, for example, injecting high-concentration alcohol-containing fuel into the intake passage so that the air-fuel mixture before combustion, i.e., the high-concentration alcohol-containing fuel mixture, has an air-fuel ratio leaner than that during cold start. Cold start refers to, for example, the period from the start of the starting operation to the first injection before complete combustion or the first explosion injection. The first explosion refers to, for example, the first combustion of the high-concentration alcohol-containing fuel mixture in the combustion chamber after the start of the starting operation. The first explosion injection refers to, for example, the injection of high-concentration alcohol-containing fuel that constitutes the high-concentration alcohol-containing fuel mixture related to the first explosion. The alcohol-containing fuel engine system further includes, for example, a control device. The control device controls, for example, the alcohol-containing fuel injection device to inject high-concentration alcohol-containing fuel into the intake passage at an air-fuel ratio rich during cold start. The control device determines whether or not cold start is occurring based on, for example, the output of at least one sensor. The at least one sensor includes, for example, a sensor for measuring the temperature of cooling water that cools the alcohol-containing fuel engine or a sensor for measuring the temperature of a catalyst. The control device controls the alcohol-containing fuel injection device so that, for example, during high load, the high-concentration alcohol-containing fuel is injected into the intake passage at an air-fuel ratio that is leaner than during cold start.A high-load state refers to, for example, a period when the temperature and / or pressure of exhaust gas emitted from an alcohol-containing fuel engine are high, thereby increasing the load on the catalyst. A high-load state refers to, for example, a period when the engine speed of an alcohol-containing fuel engine is in a high engine speed range. A high engine speed range refers to, for example, the highest engine speed range obtained by dividing the range from the idling speed of the alcohol-containing fuel (e.g., the idling speed during steady-state operation) to the engine speed at the rev limit into thirds. During a high-load state, for example, high-concentration alcohol-containing fuel is injected into the intake passage at an air-fuel ratio that is leaner than during a cold start. Therefore, the amount of excess alcohol-containing fuel contained in the exhaust gas is reduced compared to during a cold start. The tendency for the exhaust gas temperature to decrease due to the vaporization of the excess alcohol-containing fuel is suppressed. As a result, the exhaust gas temperature tends to increase during a high-load state. The alcohol-containing fuel engine system further includes, for example, a sensor that detects the alcohol concentration of the alcohol-containing fuel. Based on the output of the sensor, the control device sets, for example, a stoichiometric air-fuel ratio and / or a rich air-fuel ratio according to the detected alcohol concentration. The sensor is provided, for example, in an alcohol-containing fuel tank that stores alcohol-containing fuel, in a pipe connecting the alcohol-containing fuel tank to an alcohol-containing fuel injection device, or in the alcohol-containing fuel injection device. A rich air-fuel ratio is, for example, an air-fuel ratio that is lower than the stoichiometric air-fuel ratio, that is, an air-fuel ratio in which the fuel ratio is higher than stoichiometric. The stoichiometric air-fuel ratio of an alcohol-containing fuel is determined, for example, by the type of alcohol contained and the concentration of the alcohol. The alcohol-containing fuel engine system further includes, for example, a sensor that detects the oxygen concentration in exhaust gas. The control device controls, for example, the air-fuel ratio based on the output of the sensor. The sensor is, for example, an oxygen sensor or an air-fuel ratio sensor. The control device controls the air-fuel ratio based, for example, on the output of a sensor that detects the oxygen concentration in exhaust gas and the output of a sensor that detects the alcohol concentration of the alcohol-containing fuel.The alcohol-containing fuel engine system is, for example, an alcohol-containing fuel engine system that is not configured to adjust the alcohol concentration of the high-concentration alcohol-containing fuel injected into the intake passage depending on the situation. The engine system includes, for example, an alcohol-containing fuel tank configured to store high-concentration alcohol-containing fuel having a predetermined alcohol concentration, and an alcohol-containing fuel injection device connected to the fuel tank configured to inject the high-concentration alcohol-containing fuel supplied from the fuel tank into the intake passage. The engine system is, for example, configured to use the high-concentration alcohol-containing fuel supplied as is. Here, "using the supplied high-concentration alcohol-containing fuel as is" includes, for example, refueling with high-concentration alcohol-containing fuel having an alcohol concentration different from that of the high-concentration alcohol-containing fuel previously supplied and using the high-concentration alcohol-containing fuel. Changes in alcohol concentration due to refueling are not included in adjusting the alcohol concentration depending on the situation. "Adjusting the alcohol concentration depending on the situation" means, for example, making the alcohol concentration different between during cold start and after completion of cold start. The engine system includes, for example, a fuel tank configured to store gasoline and a fuel tank configured to store alcohol or an alcohol-containing fuel to be mixed with gasoline, and is not configured to adjust the mixture ratio of gasoline and alcohol or an alcohol-containing fuel according to circumstances. The material of the metal exhaust pipe is, for example, stainless steel, titanium, or a titanium alloy. The metal exhaust pipe may be, for example, a steel exhaust pipe with a plated surface. "An exhaust gas contact time increasing metal catalyst is supported on a metal exhaust pipe" means, for example, that the exhaust gas contact time increasing metal catalyst is supported on a metal exhaust pipe so that heat is dissipated from the catalyst to the exhaust pipe by thermal conduction due to metal-to-metal contact. "An exhaust gas contact time increasing metal catalyst is supported on a metal exhaust pipe" means, for example, that at least a portion of the exhaust gas contact time increasing metal catalyst is supported on a metal exhaust pipe.The phrase "the exhaust gas contact time increasing metal catalyst is supported on the metal exhaust pipe" includes, for example, a case where at least a portion of the metal carrier constituting the exhaust gas contact time increasing metal catalyst is supported on the metal exhaust pipe. The exhaust gas contact time increasing metal catalyst is supported on the metal exhaust pipe, for example, via a metal stay. In other words, the phrase "the exhaust gas contact time increasing metal catalyst is supported on the metal exhaust pipe" includes, for example, a case where the exhaust gas contact time increasing metal catalyst is indirectly supported on the metal exhaust pipe via a metal stay or the like. The phrase "the exhaust gas contact time increasing metal catalyst is supported on the metal exhaust pipe" includes, for example, a case where the exhaust gas contact time increasing metal catalyst is directly supported on the metal exhaust pipe. The phrase "the exhaust gas contact time increasing metal catalyst is directly supported on the metal exhaust pipe" includes, for example, a case where the exhaust gas contact time increasing metal catalyst is welded to the metal exhaust pipe with at least a portion of the outer surface of the exhaust gas contact time increasing metal catalyst in contact with the metal exhaust pipe. The exhaust gas contact time increasing metal catalyst is supported on the metal exhaust pipe, for example, at its upstream portion, downstream portion, or both the upstream portion and downstream portion. The upstream portion is the portion located upstream of the bisecting point when the exhaust gas contact time increasing metal catalyst is divided in half in the exhaust gas flow direction. The downstream portion is the portion located downstream of the bisecting point when the exhaust gas contact time increasing metal catalyst is divided in half in the exhaust gas flow direction. The exhaust gas contact time increasing metal catalyst is supported on the metal exhaust pipe, for example, so that at least a portion of its outer surface is in contact with the metal exhaust pipe. "At least a portion of the outer surface of the exhaust gas contact time increasing metal catalyst is in contact with the metal exhaust pipe" includes, for example, at least a portion of the outer surface of a metal support constituting the exhaust gas contact time increasing metal catalyst is in contact with the metal exhaust pipe. "At least a portion of the outer surface of the exhaust gas contact time increasing metal catalyst is in contact with the metal exhaust pipe" may mean, for example, that at least a portion of the outer surface of the exhaust gas contact time increasing metal catalyst is in direct contact with the metal exhaust pipe, or may mean that at least a portion of the outer surface of the exhaust gas contact time increasing metal catalyst is in indirect contact with the metal exhaust pipe via a metal stay or the like.

[0012] According to one aspect of the present invention, an alcohol-containing fuel engine system can employ the following configuration: (2) The alcohol-containing fuel engine system according to (1), wherein the alcohol-containing fuel engine system is configured so that the combustion exhaust gas of the high-concentration alcohol-containing fuel mixture is supplied to the exhaust gas contact time increasing metal catalyst supported by the metal exhaust pipe at a position for suppressing a decrease in the temperature of the exhaust gas flowing into the catalyst, upstream of the muffler in the exhaust passage, and the position for suppressing a decrease in the temperature of the exhaust gas flowing into the catalyst is a position where the distance from the downstream end of an exhaust port provided in the alcohol-containing fuel engine to the upstream end of the exhaust gas contact time increasing metal catalyst is shorter than the distance from the upstream end of the exhaust gas contact time increasing metal catalyst to the downstream end of the exhaust passage.

[0013] According to the alcohol-containing fuel engine system of (2), the exhaust gas contact time increasing metal catalyst can be positioned closer to the alcohol-containing fuel engine, thereby making it possible to more satisfactorily perform the catalyst, particularly in use scenarios during cold start.

[0014] The distance from the upstream end of the exhaust gas contact time increasing metal catalyst to the downstream end of the exhaust passage includes, for example, the length of the passage in the muffler. The length of the passage in the muffler is the actual length of the passage formed in the muffler, and is not the length of the external shape of the muffler, i.e., the external length from the upstream end to the downstream end of the muffler.

[0015] According to one aspect of the present invention, an alcohol-containing fuel engine system can employ the following configuration: (3) The alcohol-containing fuel engine system according to (1) or (2), wherein the alcohol-containing fuel injection device injects the high-concentration alcohol-containing fuel into the intake passage at a rich air-fuel ratio during cold start, and the high-concentration alcohol-containing fuel mixture of the high-concentration alcohol-containing fuel and air is combusted in the combustion chamber, resulting in a high-concentration alcohol-containing fuel mixture combustion exhaust gas, which is supplied to the exhaust gas contact time increasing metal catalyst supported on the metal exhaust pipe forming the exhaust passage, upstream of the muffler in the exhaust passage, and wherein the high-concentration alcohol-containing fuel has an alcohol concentration of 85% by volume or more.

[0016] According to the alcohol-containing fuel engine system of (3), even when a higher concentration of alcohol-containing fuel is used, the catalyst performance can be satisfied in both cold start and high load usage scenarios.

[0017] According to one aspect of the present invention, an alcohol-containing fuel engine system can employ the following configuration: (4) The alcohol-containing fuel engine system according to any one of (1) to (3), wherein the alcohol-containing fuel used by the alcohol-containing fuel engine has an alcohol concentration of more than 0% by volume.

[0018] According to the alcohol-containing fuel engine system of (4), it is possible to use a fuel containing alcohol at a lower concentration.

[0019] (5) An alcohol-containing fuel engine system according to any one of (1) to (4), wherein the alcohol-containing fuel injection device injects the high-concentration alcohol-containing fuel into the intake passage at a rich air-fuel ratio during cold start, and the high-concentration alcohol-containing fuel mixture of the high-concentration alcohol-containing fuel and air is combusted in the combustion chamber, resulting in the high-concentration alcohol-containing fuel mixture combustion exhaust gas, which is supplied to the exhaust gas contact time increasing metal catalyst supported on the metal exhaust pipe forming the exhaust passage upstream of the muffler in the exhaust passage, and the high-concentration alcohol-containing fuel has an alcohol concentration such that its Reid vapor pressure is equal to or lower than the Reid vapor pressure of gasoline.

[0020] According to the alcohol-containing fuel engine system of (5), even when a higher concentration of alcohol-containing fuel is used, the catalyst performance can be satisfied in both cold start and high load usage scenarios.

[0021] (6) A vehicle equipped with an alcohol-containing fuel engine system according to any one of (1) to (5).

[0022] According to the vehicle (6), in a vehicle equipped with an alcohol-containing fuel engine system that uses a high-concentration alcohol-containing fuel, it is possible to increase the design freedom of the catalyst while satisfying catalyst performance in both cold start and high-load usage scenarios.

[0023] 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. An example of a vehicle is a small vehicle for one or two passengers. An 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 passenger sits astride a saddle. 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), and the like. 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 with a pair of front or rear wheels, or four-wheeled vehicles with a pair of front and rear wheels, respectively. Saddle-riding vehicles may be configured to be able to turn in a lean position toward the inside of a curve. Saddle-riding vehicles that can turn in a lean position require the rider to shift their weight when turning or performing other actions. Therefore, mobility, agility, and ease of use are required for saddle-riding vehicles that can turn in a lean position. Therefore, there is a strong demand for smaller and lighter saddle-riding vehicles that can turn in a lean position. The alcohol-containing fuel engine system of the present invention allows for greater freedom in catalyst design, making it easier to adapt the catalyst layout to saddle-ride vehicles that are capable of turning in a lean position and for which there is a strong demand for compactness and light weight. Therefore, the alcohol-containing fuel engine system of the present invention can be suitably applied to saddle-ride vehicles that are configured to be able to turn in a lean position.A saddle-type vehicle configured to be able to turn in a lean position is suitable as the vehicle of the present invention. A vehicle configured to be able to turn in a lean position may be, for example, a tilting vehicle whose body tilts when turning. In a tilting vehicle, for example, the wheels may tilt together with the body when turning. A tilting vehicle may be configured, for example, so that a passenger does not ride in a position straddling the saddle. Other examples of the vehicle include golf cars, caterpillar-type snowmobiles, and snowplows.

[0024] The above and other objects, features, aspects, and advantages of the present invention will become more apparent from the following detailed description of embodiments of the present invention taken in conjunction with the accompanying drawings. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items. As used herein, the use of the terms "including," "comprising," or "having" and variations thereof specifies 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. 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 meaning in the context of the relevant technology and 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 the claims. In the following description, for purposes of explanation, numerous specific details are set forth 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 in the following drawings or description.

[0025] According to the present invention, in an alcohol-containing fuel engine system that uses a fuel containing a high concentration of alcohol, it is possible to increase the degree of freedom in catalyst design while ensuring satisfactory catalyst performance in both cold start and high load usage scenarios.

[0026] The present invention relates to an engine system for use in an alcohol-containing fuel, and an engine for use in an alcohol-containing fuel.

[0027] Hereinafter, with reference to the drawings, details of an alcohol-containing fuel engine system according to an embodiment of the present invention will be described. Note that the embodiment described below is merely an example. The present invention should not be construed as being limited in any way by the embodiment described below.

[0028] Referring to FIG. 1, an alcohol-containing fuel engine system 20 according to an embodiment of the present invention will be described.

[0029] The alcohol-containing fuel engine system 20 is employed in a vehicle 10. The vehicle 10 is equipped with, for example, a plurality of wheels. Power generated by the alcohol-containing fuel engine system 20 is transmitted to any of the plurality of wheels. This allows the vehicle 10 to move.

[0030] The alcohol-containing fuel engine system 20 includes an alcohol-containing fuel engine 22 , an alcohol-containing fuel injector 24 , and a catalyst 26 .

[0031] The alcohol-containing fuel engine 22 is configured to use an alcohol-containing fuel. The alcohol-containing fuel engine 22 is configured to allow the use of a high-concentration alcohol-containing fuel having an alcohol concentration of more than 20% by volume.

[0032] The alcohol-containing fuel injection device 24 is configured to inject alcohol-containing fuel into an intake passage 23 connected to a combustion chamber 221 of the alcohol-containing fuel engine 22. The alcohol-containing fuel injection device 24 is configured to inject high-concentration alcohol-containing fuel into the intake passage 23 at a rich air-fuel ratio during cold start.

[0033] The catalyst 26 is configured to pass exhaust gas remaining after burning a mixture of alcohol-containing fuel and air in the combustion chamber 221. The catalyst 26 is configured to pass exhaust gas remaining after burning a high-concentration alcohol-containing fuel mixture in the combustion chamber 221, the high-concentration alcohol-containing fuel mixture being made of air and high-concentration alcohol-containing fuel injected into the intake passage 23 at a rich air-fuel ratio during cold start. The catalyst 26 is supported on a metal exhaust pipe 29 that forms the exhaust passage 28, upstream of a muffler 30 provided in the exhaust passage 28, and a passage wall 271 of a metal carrier 27 in the catalyst 26 is formed with a plurality of protrusions 272 that form a plurality of irregularities, thereby lengthening the time it takes for the high-concentration alcohol-containing fuel mixture combustion exhaust gas to pass through the catalyst compared to when the plurality of protrusions 272 are not formed, thereby increasing the amount of heat transferred from the high-concentration alcohol-containing fuel mixture combustion exhaust gas to the catalyst 26, while making it easier for the heat transferred to the catalyst 26 to be transferred from the upstream portion to the downstream portion of the catalyst 26, thereby accelerating the temperature rise of the catalyst 26. This is an exhaust gas contact time increasing metal catalyst 261.

[0034] 1 , the metal carrier 27 of the catalyst 26 is supported on the metal exhaust pipe 29 by an upstream metal stay 273 and a downstream metal stay 274. The upstream metal stay 273 is welded to both the metal carrier 27 and the metal exhaust pipe 29. The downstream metal stay 274 is welded to the metal exhaust pipe 29 but not to the metal carrier 27. This allows for thermal expansion of the metal carrier 27.

[0035] In the enlarged view of the catalyst 26 in FIG. 1 , the dashed arrows conceptually show how heat is transferred from the exhaust gas to the metal carrier 27 and further from the metal carrier 27 to the metal exhaust pipe 29 via the upstream metal stay 273 and the downstream metal stay 274, while the phantom arrows conceptually show how heat is transferred from the upstream portion of the catalyst 26 to the downstream portion during cold start. The enlarged view conceptually shows how, during cold start, the temperature of the upstream portion of the catalyst 26 rises due to heat from the exhaust gas, and the heat from the upstream portion is transferred to the downstream portion. The enlarged view conceptually shows how, under high load, the catalyst 26 is heated substantially uniformly from the upstream portion to the downstream portion, and the heat from the catalyst 26 is transferred to the metal exhaust pipe 29.

[0036] The graph in Figure 1 conceptually shows that by locating the catalyst 26 upstream of the muffler 30 in the exhaust passage 28, exhaust gas at a higher temperature enters the catalyst 26. The graph in Figure 1 conceptually shows that the exhaust gas temperature is more likely to drop during cold start than during high load. The graph in Figure 1 does not show the continuity of the exhaust gas temperature before and after passing through the catalyst 26. If the temperature of the catalyst 26 is lower than the exhaust gas temperature, the heat of the exhaust gas is transferred to the catalyst 26 as the exhaust gas passes through the catalyst 26, thereby lowering the exhaust gas temperature.

[0037] In the alcohol-containing fuel engine system 20, the catalyst 26 through which the combustion exhaust gas of a high-concentration alcohol-containing fuel mixture, whose temperature tends to decrease due to the high-concentration alcohol-containing fuel injected into the intake passage 23 at a rich air-fuel ratio during cold start, passes is supported by a metal exhaust pipe 29 forming the exhaust passage 28 upstream of the muffler 30. The catalyst 26 is an exhaust gas contact time-increasing metal catalyst 261, which has multiple protrusions 272 formed on a passage wall 271 of a metal carrier 27 of the catalyst 26. This increases the temperature of the exhaust gas contacting the catalyst 26 while lengthening the time the exhaust gas contacts the catalyst 26. This allows exhaust gas at the highest possible temperature to be in contact with the catalyst for as long as possible, thereby accelerating the temperature rise of the catalyst 26 during cold start. This also shortens the time it takes for the catalyst 26 to reach its activation temperature during cold start. For example, the position, size, number, range, type, etc. of the multiple protrusions 272 formed on the passage walls 271 of the metal carrier 27 of the catalyst 26 can be adjusted depending on the distance from the alcohol-containing fuel engine 22 to the catalyst 26. For example, the degree of freedom in the layout of the catalyst 26 is increased. By utilizing heat conduction due to metal-to-metal contact, heat can be dissipated from the metal catalyst 261 to the metal exhaust pipe 29, increasing the exhaust gas contact time under high load. As a result, in the alcohol-containing fuel engine system 20 that uses a high-concentration alcohol-containing fuel, the degree of freedom in designing the catalyst 26 can be increased, while still providing satisfactory catalyst performance in both cold start and high-load usage scenarios.

[0038] For example, the exhaust gas contact time increasing metal catalyst 261 may be positioned so that the distance from the downstream end of the exhaust port 222 provided in the alcohol-containing fuel engine 22 to the upstream end of the exhaust gas contact time increasing metal catalyst 261 is shorter than the distance from the upstream end of the exhaust gas contact time increasing metal catalyst 261 to the downstream end of the exhaust passage 28.

[0039] For example, the alcohol-containing fuel injection device 24 may be configured to inject high-concentration alcohol-containing fuel having an alcohol concentration of 85% by volume or more into the intake passage 23 at an air-fuel ratio that is rich during cold start. The exhaust gas contact time increasing metal catalyst 261 may be configured to pass the high-concentration alcohol-containing fuel mixture combustion exhaust gas obtained after burning the high-concentration alcohol-containing fuel mixture of air and high-concentration alcohol-containing fuel having an alcohol concentration of 85% by volume or more, which is supplied into the intake passage 23 at an air-fuel ratio that is rich during cold start, in the combustion chamber 221.

[0040] For example, the alcohol-containing fuel used by the alcohol-containing fuel engine 22 may have an alcohol concentration greater than 0% by volume.

[0041] For example, the alcohol-containing fuel injection device 24 may be configured to inject a high-concentration alcohol-containing fuel having an alcohol concentration such that the Reid vapor pressure of the fuel is equal to or lower than the Reid vapor pressure of gasoline into the intake passage 23 at an air-fuel ratio that is rich during cold start. The exhaust gas contact time increasing metal catalyst 261 may be configured to pass the high-concentration alcohol-containing fuel mixture combustion exhaust gas obtained after burning, in the combustion chamber 221, a high-concentration alcohol-containing fuel mixture containing air and a high-concentration alcohol-containing fuel having an alcohol concentration such that the Reid vapor pressure of the fuel is equal to or lower than the Reid vapor pressure of gasoline, which is supplied into the intake passage 23 at an air-fuel ratio that is rich during cold start.

[0042] (Variations of the Support Structure of the Catalyst 26) In the example shown in FIG. 1 , the metal carrier 27 of the catalyst 26 is supported on the metal exhaust pipe 29 by an upstream metal stay 273 and a downstream metal stay 274. However, for example, as shown in FIG. 2 , the catalyst 26 may be supported on the metal exhaust pipe 29 so that the outer surface of the metal carrier 27 of the catalyst 26 is in direct contact with the metal exhaust pipe 29. In this case, the metal exhaust pipe 29 includes an upstream metal exhaust pipe 291 with which the outer surface of the metal carrier 27 of the catalyst 26 is in contact, and a downstream metal exhaust pipe 292 welded to the upstream metal exhaust pipe 291 with the upstream metal exhaust pipe 291 inserted. The metal carrier 27 of the catalyst 26 is welded to the upstream metal exhaust pipe 291 with its outer surface in contact with the upstream metal exhaust pipe 291. In the example shown in FIG. 2 , the contact area of ​​the catalyst 26 with the metal exhaust pipe 29 is increased compared to the example shown in FIG. 1 . This makes it easier for heat to dissipate from the catalyst 26 to the metal exhaust pipe 29.

[0043] (Other Embodiments) The embodiments and variations described and / or illustrated in this specification are intended to facilitate understanding of the present disclosure and are not intended to limit the scope of the present disclosure. The above-described embodiments and variations may be modified or improved without departing from the spirit of the present disclosure. This spirit encompasses equivalent elements, modifications, deletions, combinations (e.g., combinations of features across embodiments and variations), improvements, and modifications that would be recognized by a person skilled in the art based on the embodiments disclosed herein. The limitations in the claims should be interpreted broadly based on the terms used in the claims and should not be limited to the embodiments and variations described in the specification or prosecution of this application. Such embodiments and variations should be construed as non-exclusive. For example, in this specification, the terms "preferably" and "good" are non-exclusive and mean "preferably but not limited to" or "good but not limited to."

[0044] REFERENCE SIGNS LIST 10 Vehicle 20 Alcohol-containing fuel engine system 22 Alcohol-containing fuel engine 221 Combustion chamber 23 Intake passage 24 Alcohol-containing fuel injection device 26 Catalyst 261 Metal catalyst for increasing exhaust gas contact time 27 Metal carrier 271 Passage wall 272 Hole 28 Exhaust passage 29 Metal exhaust pipe 30 Muffler

Claims

1. An alcohol-containing fuel engine configured to use an alcohol-containing fuel, an alcohol-containing fuel injection device configured to inject the alcohol-containing fuel into an intake passage connected to a combustion chamber of the alcohol-containing fuel engine, and a catalyst configured to allow exhaust gas after combustion of an air-fuel mixture of the alcohol-containing fuel and air to pass therethrough. The alcohol-containing fuel engine system is configured such that, at cold start, the alcohol-containing fuel injection device injects a high-concentration alcohol-containing fuel into the intake passage at an air-fuel ratio that becomes rich, and high-concentration alcohol-containing fuel combustion exhaust gas generated by combustion of the high-concentration alcohol-containing fuel and air mixture in the combustion chamber is supplied to an exhaust gas contact time increasing metal catalyst supported by a metal exhaust pipe forming the exhaust passage upstream of the muffler. The high-concentration alcohol-containing fuel is the alcohol-containing fuel having an alcohol concentration of more than 20% by volume. The exhaust gas contact time increasing metal catalyst is configured such that a plurality of irregularities or holes are formed in a passage wall of a metal carrier in the catalyst, so that the catalyst passage time of the high-concentration alcohol-containing fuel combustion exhaust gas is longer than when the plurality of irregularities or holes are not formed. Thereby, while increasing the amount of heat transferred from the high-concentration alcohol-containing fuel combustion exhaust gas to the catalyst, the heat transferred to the catalyst is easily transferred from the upstream part to the downstream part of the catalyst to accelerate the temperature rise of the catalyst.

2. The alcohol-containing fuel engine system according to claim 1, wherein the alcohol-containing fuel engine system is configured such that the high-concentration alcohol-containing fuel combustion exhaust gas is supplied to the exhaust gas contact time increasing metal catalyst supported by the metal exhaust pipe at a catalyst inflow exhaust gas temperature reduction suppression position upstream of the muffler in the exhaust passage. The catalyst inflow exhaust gas temperature reduction suppression position is a position where the distance from the downstream end of the exhaust port provided in the alcohol-containing fuel engine to the upstream end of the exhaust gas contact time increasing metal catalyst is shorter than the distance from the upstream end of the exhaust gas contact time increasing metal catalyst to the downstream end of the exhaust passage.

3. The alcohol-containing fuel engine system according to claim 1 or 2, wherein the alcohol-containing fuel injection device injects the high-concentration alcohol-containing fuel into the intake passage at an air-fuel ratio that becomes rich during cold start, and the high-concentration alcohol-containing fuel mixture combustion exhaust gas generated by combustion of the high-concentration alcohol-containing fuel mixture of the high-concentration alcohol-containing fuel and air in the combustion chamber is supplied to the exhaust gas contact time-increasing metal catalyst supported by the metal exhaust pipe forming the exhaust passage upstream of the muffler in the exhaust passage. The high-concentration alcohol-containing fuel has an alcohol concentration of 85% by volume or more.

4. The alcohol-containing fuel engine system according to any one of claims 1 to 3, wherein the alcohol-containing fuel used by the alcohol-containing fuel engine has an alcohol concentration of more than 0% by volume.

5. The alcohol-containing fuel engine system according to any one of claims 1 to 4, wherein the alcohol-containing fuel injection device injects the high-concentration alcohol-containing fuel into the intake passage at an air-fuel ratio that becomes rich during cold start, and the high-concentration alcohol-containing fuel mixture combustion exhaust gas generated by combustion of the high-concentration alcohol-containing fuel mixture of the high-concentration alcohol-containing fuel and air in the combustion chamber is supplied to the exhaust gas contact time-increasing metal catalyst supported by the metal exhaust pipe forming the exhaust passage upstream of the muffler in the exhaust passage. The high-concentration alcohol-containing fuel has an alcohol concentration such that its Reid vapor pressure is equal to or lower than that of gasoline.

6. A vehicle comprising the alcohol-containing fuel engine system according to any one of claims 1 to 5.

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