vehicle

Abstract

It efficiently supplies evaporated fuel to the engine's intake passage. [Solution] The vehicle comprises a supercharger that pressurizes intake air supplied to the engine through an intake passage connected to an engine having multiple cylinders, an ejector mechanism having an ejector body provided on the upstream side of the supercharger in the intake passage, a recirculation passage connecting the downstream side of the supercharger in the intake passage to the ejector body, and a purge passage connecting the canister and the ejector body, and a control device, the control device performing a first setting process to set the operating mode of the engine and supercharger to a purge priority mode, the purge priority mode is an operating mode in which, while performing cylinder reduction operation, the supercharger pressure by the supercharger is increased to a second supercharger pressure that is higher than the first supercharger pressure when all cylinders are operating, and purge gas of evaporated fuel is supplied from the ejector mechanism to the intake passage.

Description

Technical Field

[0001] The present invention relates to a vehicle.

Background Art

[0002] Conventionally, a technique has been adopted in which evaporated fuel generated in a fuel tank is supplied to an intake passage of an engine, and the evaporated fuel is burned in a combustion chamber. For example, Patent Document 1 discloses a canister that adsorbs evaporated fuel, a purge passage that connects the canister and an intake pipe of the engine, and a purge control valve provided in the purge passage.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the above technique of burning evaporated fuel generated in the fuel tank in the combustion chamber, there is a need to develop a technique for efficiently supplying the evaporated fuel to the intake passage of the engine.

[0005] In view of such problems, an object of the present invention is to provide a vehicle capable of efficiently supplying evaporated fuel to an intake passage of an engine.

Means for Solving the Problems

[0006] In order to solve the above problems, a vehicle according to an embodiment of the present invention includes an engine having a plurality of cylinders, an intake passage connected to the engine, a supercharger that pressurizes intake air supplied to the engine through the intake passage, a fuel tank that stores fuel supplied to the engine, A canister for temporarily storing evaporated fuel generated inside the fuel tank, An ejector mechanism having an ejector body provided on the upstream side of the supercharger in the intake passage, a recirculation passage connecting the downstream side of the supercharger in the intake passage to the ejector body, and a purge passage connecting the canister to the ejector body, A control device that controls the engine and the supercharger, Equipped with, The control device comprises one or more processors and one or more memories connected to the processors. The processor performs a first setting process to set the operating mode of the engine and the supercharger to purge priority mode. The purge priority mode is an operating mode in which a reduced cylinder operation is performed by stopping some of the multiple cylinders, while the boost pressure from the supercharger is increased to a second boost pressure that is higher than the first boost pressure during full-cylinder operation, and the ejector mechanism supplies purge gas of the evaporated fuel to the intake passage. [Effects of the Invention]

[0007] According to the present invention, it is possible to efficiently supply evaporated fuel to the intake passage of the engine. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 is a schematic diagram showing the general configuration of a vehicle according to an embodiment of the present invention. [Figure 2] Figure 2 is a block diagram showing an example of the functional configuration of the control device according to the same embodiment. [Figure 3] Figure 3 is a flowchart showing an example of the processing flow performed by the control device according to the same embodiment. [Figure 4] Figure 4 is a flowchart showing an example of the flow of step S116 performed by the control device according to the same embodiment. [Figure 5]Figure 5 is a graph illustrating the changes in the concentration of evaporated fuel, the amount of first fuel, the amount of fuel supplied from the injector, and the flow rate of purge gas in the purge-priority mode and fuel-efficiency-priority mode. [Modes for carrying out the invention]

[0009] Embodiments of the present invention will be described in detail below with reference to the attached drawings. The specific dimensions, materials, numerical values, etc., shown in these embodiments are merely examples to facilitate understanding of the invention and do not limit the present invention unless otherwise specified. In this specification and drawings, elements having substantially the same function and configuration are denoted by the same reference numerals to avoid redundant explanations, and elements not directly related to the present invention are omitted from the illustrations.

[0010] <1. Vehicle Configuration> First, the configuration of a vehicle 100 according to an embodiment of the present invention will be described with reference to Figure 1. Figure 1 is a schematic diagram showing the general configuration of a vehicle 100 according to an embodiment of the present invention. As shown in Figure 1, the vehicle 100 includes, for example, a fuel tank 102, an engine 110, an intake passage 160, an exhaust passage 170, an air-fuel ratio sensor 180, an atmospheric pressure sensor 182, a first pressure sensor 184, a second pressure sensor 186, a supercharger 190, an evaporative fuel treatment device 210, and a control device 250.

[0011] The fuel tank 102 stores the fuel supplied to the engine 110. The fuel tank 102 is, for example, a sealed container that stores liquid fuel. Within the fuel tank 102, the liquid fuel vaporizes, generating gaseous fuel, or evaporated fuel. The fuel tank 102 is connected to the injector 150 and the canister 212 of the evaporative fuel treatment device 210, which will be described later. Liquid fuel is supplied to the injector 150 from the fuel tank 102. Meanwhile, evaporated fuel is supplied to the canister 212 of the evaporative fuel treatment device 210 from the fuel tank 102.

[0012] The engine 110 functions as a drive source of the vehicle 100. That is, the vehicle 100 is an engine vehicle. The engine 110 is a gasoline engine or a diesel engine. Note that the vehicle 100 may be a hybrid vehicle that includes a motor as a drive source in addition to the engine 110.

[0013] In the present embodiment, the engine 110 is a multi-cylinder engine having a plurality of cylinders 112a. The engine 110 includes, for example, a cylinder block 112, a crankcase 114, a cylinder head 116, a head cover 118, an oil pan 120, pistons 122, connecting rods 124, a crankshaft 128, intake valves 140, exhaust valves 142, intake valve cams 144, exhaust valve cams 146, injectors 150, and spark plugs 152.

[0014] The crankcase 114 is integrally formed with the cylinder block 112. The cylinder head 116 is joined to the cylinder block 112 on the side opposite to the crankcase 114. The head cover 118 is joined to the cylinder head 116 on the side opposite to the cylinder block 112. The oil pan 120 is joined to the crankcase 114 on the side opposite to the cylinder block 112.

[0015] A plurality of cylinders 112a are formed in the cylinder block 112. In the present embodiment, for example, four cylinders 112a are formed in the cylinder block 112. Inside the plurality of cylinders 112a, the pistons 122 are slidably supported by the connecting rods 124. In the engine 110, a space surrounded by the cylinder 112a, the cylinder head 116, and the crown surface of the piston 122 slidably supported inside the cylinder 112a is formed as a combustion chamber 126.

[0016] In the engine 110, a space surrounded by the crankcase 114 and the oil pan 120 is formed as a crank chamber. Inside the crank chamber, a crankshaft 128 is rotatably supported. The piston 122 is connected to the crankshaft 128 via a connecting rod 124.

[0017] In the cylinder head 116, an intake port 130 and an exhaust port 132 are provided so as to communicate with the combustion chamber 126. The tip of the intake valve 140 is located between the intake port 130 and the combustion chamber 126. The tip of the exhaust valve 142 is located between the exhaust port 132 and the combustion chamber 126.

[0018] In the engine 110, a space surrounded by the cylinder head 116 and the head cover 118 is formed as a cam chamber. Inside the cam chamber, a cam 144 for the intake valve and a cam 146 for the exhaust valve are provided. The cam 144 for the intake valve is abutted against the other end of the intake valve 140. By rotating, the cam 144 for the intake valve abuts and separates the intake valve 140 from the valve seat of the intake port 130. Thereby, the intake valve 140 opens and closes between the intake port 130 and the combustion chamber 126. The cam 146 for the exhaust valve is abutted against the other end of the exhaust valve 142. By rotating, the cam 146 for the exhaust valve abuts and separates the exhaust valve 142 from the valve seat of the exhaust port 132. Thereby, the exhaust valve 142 opens and closes between the exhaust port 132 and the combustion chamber 126.

[0019] The cylinder head 116 is equipped with an injector 150 whose fuel injection port opens into the combustion chamber 126. The injector 150 supplies fuel stored in the fuel tank 102 to the combustion chamber 126 of the engine 110. The cylinder head 116 is also equipped with a spark plug 152 whose tip is positioned inside the combustion chamber 126. The fuel injected from the injector 150 into the combustion chamber 126 mixes with the air supplied to the combustion chamber 126 from the intake port 130 to form a fuel-air mixture. Then, at a predetermined timing, the spark plug 152 ignites, and the fuel contained in the fuel-air mixture generated in the combustion chamber 126 is burned. This combustion causes the piston 122 to reciprocate, and this reciprocating motion is converted into rotational motion of the crankshaft 128 via the connecting rod 124.

[0020] The intake passage 160 is connected to the engine 110. In this embodiment, the intake passage 160 includes an intake manifold 162. The intake manifold 162 is connected to an intake port 130 formed in each cylinder 112a of the engine 110.

[0021] Furthermore, upstream of the intake manifold 162 in the intake passage 160, for example, an air cleaner 164, an intercooler 166, and a throttle valve 168 are provided.

[0022] The air cleaner 164 removes foreign matter such as dust and dirt contained in the air taken into the intake passage 160. The intercooler 166 is installed between the air cleaner 164 and the intake manifold 162 in the intake passage 160. The intercooler 166 is, for example, a heat exchanger that exchanges heat between the intake air flowing in the intake passage 160 and the outside air. The intercooler 166 cools the intake air flowing in the intake passage 160.

[0023] The throttle valve 168 is located between the intercooler 166 and the intake manifold 162 in the intake passage 160. The throttle valve 168 is driven to open and close by an actuator in accordance with the opening of the accelerator (not shown). The throttle valve 168 adjusts the flow rate of intake air sent to the engine 110 through the intake passage 160 in accordance with the opening of the accelerator. The flow rate of intake air sent to the engine 110 changes according to the opening of the throttle valve 168.

[0024] The exhaust passage 170 is connected to the engine 110. In this embodiment, the exhaust passage 170 includes an exhaust manifold 172. The exhaust manifold 172 is connected to an exhaust port 132 formed in each cylinder 112a of the engine 110.

[0025] Furthermore, downstream of the exhaust manifold 172 in the exhaust passage 170, for example, catalytic converters 174, 176, and a muffler 178 are provided.

[0026] Catalysts 174 and 176 purify the exhaust gas emitted from the engine 110. Catalyst 174 is, for example, a three-way catalytic converter. Catalyst 176 is, for example, a NOx storage and reduction catalyst. The exhaust gas purified by catalysts 174 and 176 is discharged to the outside through the muffler 178.

[0027] The air-fuel ratio sensor 180 is installed, for example, between catalysts 174 and 176 in the exhaust passage 170. The air-fuel ratio sensor 180 detects the air-fuel ratio of the exhaust gas flowing through the exhaust passage 170. The air-fuel ratio sensor 180 is, for example, an A / F sensor.

[0028] The atmospheric pressure sensor 182 is provided, for example, within the housing of the control device 250, which will be described later. The atmospheric pressure sensor 182 detects atmospheric pressure.

[0029] The first pressure sensor 184 is installed, for example, in the intake manifold 162. The first pressure sensor 184 detects the pressure inside the intake manifold 162.

[0030] The second pressure sensor 186 is installed, for example, between the intercooler 166 and the throttle valve 168 in the intake passage 160. The second pressure sensor 186 detects the pressure upstream of the throttle valve 168.

[0031] The supercharger 190 pressurizes the intake air supplied to the engine 110 through the intake passage 160. In this embodiment, the supercharger 190 includes, for example, a turbine 192, a compressor 194, a turbine shaft 196, a bypass passage 200, and a wastegate valve 202.

[0032] The turbine 192 is located upstream of the catalyst 174 in the exhaust passage 170. The compressor 194 is located between the air cleaner 164 and the intercooler 166 in the intake passage 160. The turbine shaft 196 connects the turbine 192 and the compressor 194 so that they can rotate as a single unit. The turbine 192 is rotated by the exhaust gas discharged from the exhaust port 132. The compressor 194 rotates in conjunction with the rotation of the turbine 192 and compresses the intake air from which foreign matter has been removed by the air cleaner 164 and supplies it downstream.

[0033] A bypass passage 200 is provided in the exhaust passage 170 to bypass the turbine 192. A wastegate valve 202 is provided in the bypass passage 200. The wastegate valve 202 adjusts the opening of the bypass passage 200. In other words, the wastegate valve 202 adjusts the flow rate of exhaust gases flowing through the bypass passage 200. The wastegate valve 202 is, for example, a solenoid valve.

[0034] The evaporative fuel treatment device 210 supplies evaporated fuel along with air to the combustion chamber 126 of the engine 110 in order to suppress the release of evaporated fuel into the atmosphere. The evaporated fuel is generated inside the fuel tank 102. The evaporative fuel treatment device 210 includes a canister 212 and an ejector mechanism 220.

[0035] The canister 212 temporarily stores evaporated fuel generated inside the fuel tank 102. For example, the canister 212 contains activated carbon that adsorbs the evaporated fuel in a desorbable manner. The canister 212 is also connected to the evaporated fuel passage 212a, the atmospheric vent passage 212b, and the first purge passage 226 of the ejector mechanism 220, which will be described later.

[0036] The evaporative fuel passage 212a connects the fuel tank 102 and the canister 212. Evaporative fuel generated inside the fuel tank 102 is supplied to the canister 212 through the evaporative fuel passage 212a. The atmospheric vent passage 212b opens the canister 212 to the atmosphere. The atmospheric vent passage 212b is equipped with an air filter (not shown) and a valve 212c. The air filter removes foreign matter such as dust and dirt contained in the air taken into the canister 212. The valve 212c opens and closes the atmospheric vent passage 212b. The valve 212c is opened when the evaporated fuel stored in the canister 212 is supplied to the combustion chamber 126 of the engine 110 along with air. Hereinafter, the mixture of evaporated fuel and air will be referred to as purge gas. The valve 212c is, for example, a solenoid valve.

[0037] The ejector mechanism 220 includes an ejector body 222, a recirculation passage 224, and a first purge passage 226 (purge passage). The ejector body 222 is located upstream of the supercharger 190 in the intake passage 160. In this embodiment, the ejector body 222 is located between the air cleaner 164 and the compressor 194 of the supercharger 190 in the intake passage 160.

[0038] The recirculation passage 224 connects the downstream side of the turbocharger 190 in the intake passage 160 to the ejector body 222. In this embodiment, the recirculation passage 224 connects the space between the compressor 194 and the intercooler 166 of the turbocharger 190 in the intake passage 160 to the ejector body 222. The end of the recirculation passage 224 that connects to the ejector body 222 is a tapered nozzle in which the cross-sectional area of ​​the passage gradually decreases towards the tip.

[0039] The first purge passage 226 connects the canister 212 and the ejector body 222. The first purge passage 226 is provided with a valve 226a and a check valve 226b. Valve 226a adjusts the opening degree of the first purge passage 226. In other words, valve 226a adjusts the flow rate of purge gas flowing through the first purge passage 226. Valve 226a is, for example, a solenoid valve. The check valve 226b is provided between valve 226a and the ejector body 222 in the first purge passage 226. The check valve 226b prevents backflow of intake air from the recirculation passage 224.

[0040] Furthermore, the evaporative fuel treatment device 210 may also include a second purge passage 228. The second purge passage 228 connects the first purge passage 226 to the intake passage 160. In this embodiment, the second purge passage 228 connects the space between valve 226a and check valve 226b in the first purge passage 226 to the intake manifold 162. A check valve 228a is also provided in the second purge passage 228. The check valve 228a prevents backflow of intake air from the intake manifold 162.

[0041] The control device 250 controls the engine 110 and the supercharger 190. The control device 250 includes one or more processors 250a and one or more memories 250b connected to the processors 250a. The processors 250a include, for example, a CPU (Central Processing Unit). The memories 250b include, for example, ROM (Read Only Memory) and RAM (Random Access Memory). ROM is a memory element that stores programs and arithmetic parameters used by the CPU. RAM is a memory element that temporarily stores data such as variables and parameters used in processing performed by the CPU.

[0042] The control device 250 communicates with various devices installed in the vehicle 100, such as the engine 110, throttle valve 168, air-fuel ratio sensor 180, atmospheric pressure sensor 182, first pressure sensor 184, second pressure sensor 186, supercharger 190, and evaporative fuel treatment device 210. Communication between the control device 250 and each device is achieved, for example, using CAN (Controller Area Network) communication.

[0043] Figure 2 is a block diagram showing an example of the functional configuration of the control device 250 according to this embodiment. For example, as shown in Figure 2, the control device 250 includes an acquisition unit 252, a control unit 254, an arithmetic unit 256, and a storage unit 258. Various processes, including those described below, which are performed by at least one of the acquisition unit 252, the control unit 254, and the arithmetic unit 256, can be executed by the processor 250a. In detail, various processes are executed by the processor 250a executing a program stored in the memory 250b. The functions of the storage unit 258 are realized by the memory 250b.

[0044] The acquisition unit 252 acquires various information used in processing performed by either or both of the control unit 254 and the calculation unit 256, and outputs it to either or both of the control unit 254 and the calculation unit 256. For example, the acquisition unit 252 acquires information from the engine 110, air-fuel ratio sensor 180, atmospheric pressure sensor 182, first pressure sensor 184, second pressure sensor 186, wastegate valve 202, valve 226a, etc.

[0045] The control unit 254 controls the operation of each device provided in the vehicle 100. In this embodiment, the control unit 254 controls the intake valve 140, exhaust valve 142, injector 150, and spark plug 152 provided in each cylinder 112a of the engine 110 to perform full-cylinder operation or reduced-cylinder operation. Full-cylinder operation is operation using all of the multiple cylinders 112a provided in the engine 110. Reduced-cylinder operation is operation in which some of the multiple cylinders 112a provided in the engine 110 are stopped and some other cylinders 112a are operated. When performing reduced-cylinder operation, the control unit 254, for example, closes the intake valve 140 and exhaust valve 142 of the cylinder 112a to be stopped and stops the injection of fuel from the injector 150.

[0046] Furthermore, the control unit 254 adjusts the boost pressure from the compressor 194 by adjusting the opening degree of the wastegate valve 202 of the supercharger 190. For example, the control unit 254 increases the boost pressure from the compressor 194 by decreasing the opening degree of the wastegate valve 202. Conversely, the control unit 254 decreases the boost pressure from the compressor 194 by increasing the opening degree of the wastegate valve 202.

[0047] Furthermore, increasing the boost pressure from the compressor 194 increases the torque of the engine 110. For example, when performing reduced-cylinder operation, the control unit 254 increases the boost pressure from the compressor 194 to a second boost pressure that is higher than the first boost pressure during full-cylinder operation, thereby achieving the same torque as when performing full-cylinder operation at the first boost pressure.

[0048] In this embodiment, the control unit 254 also performs a first setting process to set the operating mode of the engine 110 and the supercharger 190 to the purge priority mode. The purge priority mode is an operating mode that increases the boost pressure from the compressor 194 to increase the supply flow rate of purge gas from the canister 212 to the intake passage 160 through the ejector mechanism 220. The purge priority mode is an operating mode that prioritizes the consumption of purge gas over the fuel efficiency of the engine 110. The control unit 254 may also perform a second setting process to set the operating mode of the engine 110 and the supercharger 190 to the fuel efficiency priority mode. The control unit 254 may also perform a determination process to determine whether to perform the first setting process or the second setting process. The fuel efficiency priority mode is an operating mode that improves fuel efficiency while maintaining the torque of the engine 110. The fuel efficiency priority mode is an operating mode that prioritizes the fuel efficiency of the engine 110 over the consumption of purge gas. Details of the first setting process, the second setting process, and the judgment process will be described later.

[0049] The calculation unit 256 performs, for example, concentration calculation processing and fuel consumption calculation processing.

[0050] The concentration calculation process calculates the concentration of evaporated fuel contained in the purge gas supplied from the canister 212 to the intake passage 160. For example, in the concentration calculation process, the calculation unit 256 calculates the concentration of evaporated fuel based on the detected value of the air-fuel ratio sensor 180 and the flow rate of the purge gas. When supercharged, the calculation unit 256 refers to the supercharged flow rate map described later and calculates the flow rate of the purge gas based on the detected value of the atmospheric pressure sensor 182, the detected value of the second pressure sensor 186, and the opening degree of the valve 226a. When not supercharged, the calculation unit 256 refers to the non-supercharged flow rate map described later and calculates the flow rate of the purge gas based on the detected value of the atmospheric pressure sensor 182, the detected value of the first pressure sensor 184, and the opening degree of the valve 226a.

[0051] The fuel consumption calculation process calculates the first fuel amount, second fuel amount, and third fuel amount when the torque of the engine 110 is equal. The first fuel amount is the amount of fuel supplied to the engine 110 by the purge gas. The second fuel amount is the target fuel amount during reduced cylinder operation. The third fuel amount is the target fuel amount during full cylinder operation. The first fuel amount, second fuel amount, and third fuel amount are, for example, the amount of fuel per unit time.

[0052] For example, in the fuel consumption calculation process, the calculation unit 256 calculates a first fuel amount based on the concentration of evaporated fuel contained in the purge gas supplied from the canister 212 to the intake passage 160 and the purge flow rate. Also in the fuel consumption calculation process, the calculation unit 256 refers to the cylinder reduction fuel consumption map described later and calculates a second fuel amount based on the rotational speed of the engine 110 and the required torque of the engine 110. In the fuel consumption calculation process, the calculation unit 256 refers to the full cylinder fuel consumption map described later and calculates a third fuel amount based on the rotational speed of the engine 110 and the required torque of the engine 110.

[0053] The memory unit 258 stores, for example, a turbocharged flow rate map, a non-turbocharged flow rate map, a reduced cylinder fuel consumption map, a full cylinder fuel consumption map, and so on.

[0054] The supercharged flow rate map is information that associates the difference between the pressure upstream of the throttle valve 168 and atmospheric pressure, the opening degree of valve 226a, and the flow rate of purge gas flowing through the ejector body 222. The non-supercharged flow rate map is information that associates the difference between the pressure in the intake manifold 162 and atmospheric pressure, the opening degree of valve 226a, and the flow rate of purge gas flowing through the second purge passage 228.

[0055] The cylinder reduction fuel consumption map contains information that associates the engine speed and required torque of engine 110 with the amount of fuel for the second cylinder. The all-cylinder fuel consumption map contains information that associates the engine speed and required torque of engine 110 with the amount of fuel for the third cylinder.

[0056] The functions of the control device 250 according to this embodiment may be divided among multiple devices, or multiple functions may be implemented by a single device. If the functions of the control device 250 are divided among multiple devices, these multiple devices may be connected to each other via a communication bus such as CAN.

[0057] <2. Operation of the evaporative fuel treatment device> Next, with reference to Figure 1, the operation of the evaporative fuel treatment apparatus 210 according to an embodiment of the present invention will be described.

[0058] When the intake air is being supercharged by the supercharger 190, i.e., during supercharging, the evaporated fuel stored in the canister 212 is supplied as purge gas to the intake air passage 160 through the first purge passage 226 and the ejector body 222, together with the air supplied from the open-flow passage 212b. On the other hand, when the intake air is not being supercharged by the supercharger 190, i.e., during non-supercharging, the purge gas is supplied to the intake air passage 160 through the first purge passage 226 and the second purge passage 228.

[0059] In more detail, during supercharging, the downstream side of the compressor 194 in the intake passage 160 is under higher pressure than the upstream side. Therefore, the intake air is returned to the ejector body 222 through the recirculation passage 224. As described above, the end of the recirculation passage 224 connected to the ejector body 222 is a tapered nozzle. Therefore, the intake air returned to the ejector body 222 through the recirculation passage 224 is depressurized at its end, creating negative pressure around the end of the recirculation passage 224. Consequently, this negative pressure draws purge gas into the ejector body 222 from the first purge passage 226. The drawn purge gas, along with the intake air returned from the recirculation passage 224, is supplied to the upstream side of the compressor 194 in the intake passage 160 through the ejector body 222. The purge gas is then supplied to the combustion chamber 126 through the intake port 130, passing through the compressor 194, intercooler 166, throttle valve 168, and intake manifold 162.

[0060] Furthermore, the lower the pressure around the end of the recirculation channel 224, the greater the flow rate of purge gas drawn into the ejector body 222 from the first purge channel 226. The pressure around the end of the recirculation channel 224 decreases as the flow velocity of the intake air flowing through the recirculation channel 224 increases. The flow velocity of the intake air flowing through the recirculation channel 224 increases as the differential pressure between the downstream and upstream sides of the compressor 194 in the intake air channel 160 increases, that is, as the supercharging pressure from the compressor 194 increases. Therefore, the higher the supercharging pressure from the compressor 194, the greater the flow rate of purge gas drawn into the ejector body 222 from the first purge channel 226.

[0061] Furthermore, since the canister 212 is at atmospheric pressure, the intake manifold 162 is under higher pressure than the canister 212 during supercharging. Therefore, during supercharging, purge gas is hardly supplied from the canister 212 to the intake manifold 162 through the first purge passage 226 and the second purge passage 228. In addition, since the second purge passage 228 is provided with a check valve 228a, backflow of intake air from the intake manifold 162 to the first purge passage 226 can be prevented.

[0062] On the other hand, when not supercharged, the intake manifold 162 is under negative pressure. Therefore, when not supercharged, purge gas is supplied from the canister 212 to the intake manifold 162 through the first purge passage 226 and the second purge passage 228.

[0063] Furthermore, when not supercharged, the pressure downstream of the compressor 194 in the intake passage 160 is lower than that upstream. Therefore, no intake air is recirculated to the ejector body 222 through the recirculation passage 224. Consequently, when not supercharged, purge gas is hardly supplied from the canister 212 to the intake passage 160 through the first purge passage 226 and the ejector body 222. In addition, since the first purge passage 226 is provided with a check valve 226b, backflow of intake air from the ejector body 222 to the first purge passage 226 can be prevented.

[0064] <3. Operation of the control device> Next, with reference to Figure 3, the operation of the control device 250 according to an embodiment of the present invention will be described.

[0065] Figure 3 is a flowchart showing an example of the processing flow performed by the control device 250 according to this embodiment. Figure 4 is a flowchart showing an example of the flow of step S116 performed by the control device 250 according to this embodiment.

[0066] As shown in Figure 3, when the engine 110 is operating, first, in step S110, the calculation unit 256 of the control device 250 performs a concentration calculation process to estimate the concentration of evaporated fuel contained in the purge gas. Next, in step S112, the control unit 254 of the control device 250 performs a determination process to determine whether to perform a first setting process or a second setting process based on the concentration of evaporated fuel contained in the purge gas. For example, in the determination process, the control unit 254 determines whether the concentration of evaporated fuel contained in the purge gas estimated by the calculation unit 256 is above a threshold. The threshold is set, for example, based on legal regulations. If it is determined that the concentration of evaporated fuel is above the threshold (YES in step S112), the control unit 254 moves the process to step S114. On the other hand, if it is determined that the concentration of evaporated fuel is not above the threshold, that is, the concentration of evaporated fuel is below the threshold (NO in step S112), the control unit 254 moves the process to step S116.

[0067] In step S114, the control unit 254 performs a first setting process to set the operating mode of the engine 110 and the supercharger 190 to the purge priority mode. The purge priority mode is an operating mode in which, while performing reduced cylinder operation, the boost pressure from the supercharger 190 is increased to a second boost pressure that is higher than the first boost pressure during full-cylinder operation, and the ejector mechanism 220 supplies purge gas of evaporated fuel to the intake passage 160. Once the first setting process is completed, the control unit 254 moves on to step S118.

[0068] In step S116, the control unit 254 performs a second setting process to set the operating mode to the fuel efficiency priority mode. The fuel efficiency priority mode is an operating mode in which the boost pressure from the supercharger 190 is used as the second boost pressure or first boost pressure, while either reduced cylinder operation or full cylinder operation, and purge gas is supplied from the ejector mechanism 220 to the intake passage 160. Once the second setting process is completed, the control unit 254 moves on to step S118.

[0069] In step S118, the control unit 254 determines whether the engine 110 has stopped. If it determines that the engine 110 has stopped (YES in step S118), the control unit 254 terminates the control flow shown in Figure 3. On the other hand, if it determines that the engine 110 has not stopped (NO in step S118), the control unit 254 returns to step S110.

[0070] As shown in Figure 4, in fuel efficiency priority mode, in step S116-1, the control unit 254 performs a process to select either reduced-cylinder operation or full-cylinder operation based on the first fuel amount Q1 supplied to the engine 110 by purge gas, the second fuel amount Q2 which is the target fuel amount during reduced-cylinder operation, and the third fuel amount Q3 which is the target fuel amount during full-cylinder operation. For example, in step S116-1, the control unit 254 determines whether the difference ΔQ2 (=Q2-Q1) between the first fuel amount Q1 and the second fuel amount Q2 is less than the difference ΔQ3 (=Q3-Q1) between the first fuel amount Q1 and the third fuel amount Q3. In other words, in step S116-1, the control unit 254 determines whether the amount of fuel supplied from the injector 150 during reduced-cylinder operation is less than the amount of fuel supplied from the injector 150 during full-cylinder operation. As a result, if it is determined that the difference ΔQ2 between the first fuel amount Q1 and the second fuel amount Q2 is less than the difference ΔQ3 between the first fuel amount Q1 and the third fuel amount Q3 (YES in step S116-1), the control unit 254 moves to step S116-2. On the other hand, if it is determined that the difference ΔQ2 between the first fuel amount Q1 and the second fuel amount Q2 is greater than or equal to the difference ΔQ3 between the first fuel amount Q1 and the third fuel amount Q3 (NO in step S116-1), the control unit 254 moves to step S116-3.

[0071] In step S116-2, the control unit 254 performs cylinder reduction operation. In step S116-3, the control unit 254 performs full cylinder operation.

[0072] <4. Specific examples of control device operation> Next, with reference to Figure 5, a specific example of the operation of the control device 250 according to an embodiment of the present invention will be described.

[0073] Figure 5 is a graph illustrating the changes in the concentration of evaporated fuel, the amount of the first fuel, the amount of fuel supplied from the injector 150, and the flow rate of the purge gas in the purge-priority mode and the fuel-efficiency-priority mode. In Figure 5, the solid line shows the changes during reduced-cylinder operation, and the dashed line shows the changes during full-cylinder operation. In the example shown in Figure 5, full-cylinder operation shows the case where all four cylinders 112a mounted on the engine 110 are used, and reduced-cylinder operation shows the case where two cylinders 112a are stopped and two cylinders 112a are operating. In Figure 5, supercharging is performed by the turbocharger 190, and the example shows the region where the target fuel amount Q3 during full-cylinder operation is less than the target fuel amount Q2 during reduced-cylinder operation.

[0074] For example, as the operating time in 4-cylinder operation progresses, if the concentration of evaporated fuel in the purge gas exceeds a threshold (YES in step S112), the control unit 254 sets the operating mode of the engine 110 and the supercharger 190 to purge priority mode (step S114). In purge priority mode, while operating in 2-cylinder mode, the boost pressure from the supercharger 190 is increased to a second boost pressure, which is higher than the first boost pressure during 4-cylinder operation. Thus, while set to purge priority mode, the boost pressure is increased to the second boost pressure, and as shown in the bottom graph of Figure 5, the flow rate of the purge gas increases compared to 4-cylinder operation. For this reason, while set to purge priority mode, the concentration of evaporated fuel in the purge gas gradually decreases, as shown in the top graph of Figure 5. Also, as shown in the second graph from the top of Figure 5, the amount of first fuel supplied to the engine 110 by the purge gas gradually decreases. Therefore, as shown in the third graph from the top in Figure 5, the amount of fuel supplied from the injector 150 to the combustion chamber 126 gradually increases.

[0075] Then, when the concentration of evaporated fuel in the purge gas falls below a threshold while the engine is operating in two cylinders (NO in step S112), the control unit 254 switches the operating mode of the engine 110 and the supercharger 190 from purge priority mode to fuel efficiency priority mode (step S116). At this time, as shown in the third graph from the top in Figure 5, the amount of fuel supplied from the injector 150 during two-cylinder operation, i.e., the difference ΔQ2 between the first fuel amount Q1 and the second fuel amount Q2, is less than the amount of fuel supplied from the injector 150 during four-cylinder operation, i.e., the difference ΔQ3 between the first fuel amount Q1 and the third fuel amount Q3 (YES in step S116-1). For this reason, immediately after switching from purge priority mode to fuel efficiency priority mode, the engine is maintained in two-cylinder operation (step S116-2). This improves the fuel efficiency of the engine 110.

[0076] Then, as the operating time in 2-cylinder operation progresses, the first fuel amount gradually decreases, and as shown in the third graph from the top in Figure 5, when the amount of fuel supplied from the injector 150 during 2-cylinder operation (difference ΔQ2) increases to the amount of fuel supplied from the injector 150 during 4-cylinder operation (difference ΔQ3) (NO in step S116-1), the control unit 254 switches from 2-cylinder operation to 4-cylinder operation (step S116-3). This suppresses the deterioration of the fuel efficiency of the engine 110.

[0077] <5. Vehicle Effects> Next, the effects of the vehicle 100 according to the embodiment of the present invention will be described.

[0078] The vehicle 100 according to this embodiment includes an engine 110 having a plurality of cylinders 112a, an intake passage 160 connected to the engine 110, a supercharger 190 that pressurizes the intake air supplied to the engine 110 through the intake passage 160, a fuel tank 102 that stores the fuel supplied to the engine 110, a canister 212 that temporarily stores evaporated fuel generated inside the fuel tank 102, an ejector body 222 provided on the upstream side of the supercharger 190 in the intake passage 160, a recirculation passage 224 connecting the downstream side of the supercharger 190 in the intake passage 160 to the ejector body 222, and a purge passage 226 connecting the canister 212 to the ejector body 222. The system comprises a turbocharger mechanism 220 and a control device 250 that controls the engine 110 and the turbocharger 190. The control device 250 includes one or more processors 250a and one or more memories 250b connected to the processors 250a. The processor 250a performs a first setting process to set the operating mode of the engine 110 and the turbocharger 190 to a purge-priority mode. The purge-priority mode is an operating mode in which a reduced-cylinder operation is performed, stopping some of the cylinders 112a among the multiple cylinders 112a, while increasing the boost pressure from the turbocharger 190 to a second boost pressure higher than the first boost pressure during full-cylinder operation, and supplying purge gas of evaporated fuel from the ejector mechanism 220 to the intake passage 160.

[0079] Thus, in the purge-priority mode, the vehicle 100 can increase the boost pressure and efficiently supply evaporated fuel to the intake passage 160. Furthermore, in the purge-priority mode of this embodiment, the boost pressure is increased when cylinder reduction operation is performed, so the torque of the engine 110 can be increased to the same extent as when operating with all cylinders, even when operating with fewer cylinders. For this reason, even when switching from full-cylinder operation to cylinder reduction operation, the vehicle 100 of this embodiment can suppress fluctuations in the torque of the engine 110, thereby suppressing malfunctions of the vehicle 100 and a decrease in the ride comfort of the vehicle 100.

[0080] Furthermore, the processor 250a according to this embodiment may perform a second setting process to set the operating mode to a fuel-efficient mode, and it is preferable that the fuel-efficient mode is an operating mode in which purge gas is supplied from the ejector mechanism 220 to the intake passage 160 with the boost pressure from the supercharger 190 as the second boost pressure or the first boost pressure while performing either reduced cylinder operation or full cylinder operation.

[0081] Thus, the vehicle 100 according to this embodiment can achieve both improved fuel efficiency of the engine 110 and the supply of evaporated fuel to the intake passage 160. Furthermore, the vehicle 100 according to this embodiment can supply evaporated fuel to the intake passage 160 not only in the purge priority mode but also in the fuel efficiency priority mode. Therefore, the vehicle 100 according to this embodiment can extend the period during which evaporated fuel is supplied from the canister 212 to the intake passage 160. Consequently, the vehicle 100 according to this embodiment can supply evaporated fuel to the intake passage 160 even more efficiently.

[0082] Furthermore, in the fuel efficiency priority mode, the processor 250a of this embodiment preferably performs a process to select either reduced-cylinder operation or full-cylinder operation based on a first fuel amount Q1 supplied to the engine 110 by purge gas, a second fuel amount Q2 which is the target fuel amount during reduced-cylinder operation, and a third fuel amount Q3 which is the target fuel amount during full-cylinder operation. As a result, the vehicle 100 of this embodiment can improve the fuel efficiency of the engine 110 while suppressing fluctuations in the torque of the engine 110.

[0083] Furthermore, in the process to be selected, the processor 250a preferably selects reduced cylinder operation when the difference ΔQ2 between the first fuel amount Q1 and the second fuel amount Q2 is less than the difference ΔQ3 between the first fuel amount Q1 and the third fuel amount Q3, and selects full cylinder operation when the difference ΔQ2 between the first fuel amount Q1 and the second fuel amount Q2 is greater than or equal to the difference ΔQ3 between the first fuel amount Q1 and the third fuel amount Q3. As a result, the vehicle 100 according to this embodiment can further improve the fuel efficiency of the engine 110 while suppressing fluctuations in the torque of the engine 110.

[0084] Furthermore, in the vehicle 100 according to this embodiment, it is preferable that the processor 250a performs a determination process to determine whether to perform the first setting process or the second setting process based on the concentration of evaporated fuel contained in the purge gas.

[0085] If the operating mode is set to purge priority mode when the concentration of evaporated fuel is low, the fuel efficiency of the engine 110 may deteriorate. Therefore, the vehicle 100 according to this embodiment can suitably achieve both improved fuel efficiency of the engine 110 and supply of evaporated fuel to the intake passage 160 by determining whether to execute the first setting process or the second setting process based on the concentration of evaporated fuel contained in the purge gas.

[0086] Preferred embodiments of the present invention have been described above with reference to the attached drawings, but it goes without saying that the present invention is not limited to these embodiments. It will be obvious to those skilled in the art that various modifications or alterations can be conceived within the scope of the claims, and these will naturally also fall within the technical scope of the present invention.

[0087] For example, the processes described using flowcharts in this specification do not necessarily have to be performed in the order shown in the flowcharts. Additional processing steps may be adopted, and some processing steps may be omitted.

[0088] Furthermore, in the above embodiment, for example, the turbocharger 190 is described as comprising a turbine 192, a bypass passage 200, and a wastegate valve 202. However, the turbocharger 190 may also include, in addition to or interchangeably with, the turbine 192, the bypass passage 200, and the wastegate valve 202, an electric motor for rotating the compressor 194. [Explanation of Symbols]

[0089] 100 vehicles 102 Fuel Tank 110 engine 112a cylinder 160 Intake passage 190 Supercharger 212 Canister 220 Ejector mechanism 222 Ejector Unit 224 Reflux channel 226 First purge channel (purge channel) 250 Control device 250a Processor 250b memory

Claims

1. An engine with multiple cylinders, An intake passage connected to the engine, A supercharger that pressurizes the intake air supplied to the engine through the aforementioned intake passage, A fuel tank for storing fuel supplied to the engine, A canister for temporarily storing evaporated fuel generated inside the fuel tank, An ejector mechanism having an ejector body provided on the upstream side of the supercharger in the intake passage, a recirculation passage connecting the downstream side of the supercharger in the intake passage to the ejector body, and a purge passage connecting the canister to the ejector body, A control device that controls the engine and the supercharger, Equipped with, The control device comprises one or more processors and one or more memories connected to the processors. The processor performs a first setting process to set the operating mode of the engine and the supercharger to the purge priority mode. The purge priority mode is an operating mode in which, while performing cylinder reduction operation by stopping some of the multiple cylinders, the boost pressure from the supercharger is increased to a second boost pressure that is higher than the first boost pressure during full-cylinder operation, and the ejector mechanism supplies purge gas of the evaporated fuel to the intake passage.

2. The processor then performs a second setting process to set the driving mode to the fuel efficiency priority mode. The vehicle according to claim 1, wherein the fuel efficiency priority mode is an operating mode in which the purge gas is supplied from the ejector mechanism to the intake passage, with the boost pressure from the supercharger as the second boost pressure or the first boost pressure, while either the cylinder reduction operation or the full cylinder operation is performed.

3. The vehicle according to claim 2, wherein the processor, in the fuel efficiency priority mode, performs a process to select either the cylinder reduction operation or the cylinder reduction operation based on the first fuel amount supplied to the engine by the purge gas, the second fuel amount which is the target fuel amount during cylinder reduction operation, and the third fuel amount which is the target fuel amount during cylinder reduction operation.

4. The aforementioned processor, in the selected process, If the difference between the first fuel amount and the second fuel amount is less than the difference between the first fuel amount and the third fuel amount, the cylinder reduction operation is selected. The vehicle according to claim 3, wherein all-cylinder operation is selected when the difference between the first fuel amount and the second fuel amount is greater than or equal to the difference between the first fuel amount and the third fuel amount.

5. The aforementioned processor, The vehicle according to claim 2 or 3, wherein a determination process is performed to determine whether to perform the first setting process or the second setting process based on the concentration of the evaporated fuel contained in the purge gas.

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