Bi-fuel vehicle

Abstract

To provide a bi-fuel vehicle capable of preventing a driver from feeling bothered even in a situation where restart occurs frequently.SOLUTION: A bi-fuel vehicle is equipped with an engine 2 to which one of two types of fuel: CNG, which is gaseous fuel; and gasoline, which is liquid fuel, selected and supplied as fuel to be injected into a combustion chamber of each cylinder, and comprises an ECU 8 that controls an idling stop function that stops the engine 2 when a preset automatic stop condition is established and restarts the engine 2 when the preset restart condition is established. The ECU 8 selects gasoline as the fuel to be injected into the combustion chamber of each cylinder of the engine 2 when it is predicted that automatic stopping and restarting of the engine 2 may be repeated a predetermined number of times or more within a predetermined time.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a bi-fuel vehicle. [Background technology]

[0002] As a bi-fuel vehicle capable of switching between gaseous fuel such as compressed natural gas (hereinafter referred to as "CNG") and liquid fuel such as gasoline, there is known a bi-fuel vehicle as described in Patent Document 1. The bi-fuel vehicle described in Patent Document 1 is equipped with an internal combustion engine having a so-called idling stop function that automatically stops the internal combustion engine when a predetermined automatic stop condition is met and restarts the internal combustion engine when a predetermined restart condition is met. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 7211015 Publication Summary of the Invention [Problem to be solved by the invention]

[0004] Here, gaseous fuel is superior to liquid fuel in terms of fuel economy and emissions, but has the characteristic that the time required to start an internal combustion engine using gaseous fuel is longer than the time required to start an internal combustion engine using liquid fuel, because the path from the injector for gaseous fuel to the combustion chamber is generally longer than the path for the injector for liquid fuel, and gaseous fuel has a higher ignition point than liquid fuel. Such a delay in starting is not a big deal if it occurs only once, but in situations where the internal combustion engine is automatically stopped and restarted repeatedly, such as when following a vehicle ahead at low speed on a congested road, a delay in restart occurs each time, which may be annoying to the driver.

[0005] Therefore, an object of the present invention is to provide a bi-fuel vehicle that can reduce the inconvenience felt by the driver even in situations where restarts occur frequently. [Means for solving the problem]

[0006] In order to solve the above problems, the present invention provides a bi-fuel vehicle equipped with an internal combustion engine that can be operated by switching between a first fuel and a second fuel that has relatively superior starting performance compared to the first fuel, and includes a control unit that automatically stops the internal combustion engine when a predetermined automatic stop condition is met and restarts the internal combustion engine when a predetermined restart condition is met, and the control unit switches the fuel used to the second fuel when it is predicted that the automatic stopping and restarting of the internal combustion engine will be performed a predetermined number of times or more within a predetermined time. Effect of the Invention

[0007] In this way, according to the present invention, even in a situation where restarts occur frequently, it is possible to suppress the driver from feeling annoyed. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic diagram of a bi-fuel vehicle according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a flowchart showing a procedure of a fuel-to-be-used switching control process performed by an ECU of a bi-fuel vehicle according to one embodiment of the present invention. [Diagram 3] FIG. 3 is a flowchart showing a procedure of fuel-usage switch flag setting processing by the ECU of the bi-fuel vehicle according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] A bi-fuel vehicle according to one embodiment of the present invention is a bi-fuel vehicle equipped with an internal combustion engine that can be operated by switching between a first fuel and a second fuel that has relatively superior starting performance compared to the first fuel, and is equipped with a control unit that automatically stops the internal combustion engine when a predetermined automatic stop condition is met and restarts the internal combustion engine when a predetermined restart condition is met, and the control unit is configured to switch the fuel used to the second fuel when it is predicted that the automatic stopping and restarting of the internal combustion engine will be performed repeatedly a predetermined number of times or more within a predetermined time.

[0010] As a result, the bi-fuel vehicle according to one embodiment of the present invention can reduce the annoyance felt by the driver even in situations where restarts occur frequently. EXAMPLES

[0011] Hereinafter, a bi-fuel vehicle according to an embodiment of the present invention will be described in detail with reference to the drawings.

[0012] In FIG. 1, a bi-fuel vehicle 1 according to an embodiment of the present invention includes an engine 2 as an internal combustion engine, a transmission 3, and an ECU (Electronic Control Unit) 8 as a control unit.

[0013] A plurality of cylinders are formed in the engine 2. In this embodiment, the engine 2 is configured to perform a series of four strokes, which are an intake stroke, a compression stroke, an expansion stroke, and an exhaust stroke, for each cylinder.

[0014] A starter 21 is connected to the engine 2. The starter 21 is connected to a crankshaft of the engine 2. When electric power is supplied to the starter 21, the starter 21 rotates to rotate the crankshaft and provide the engine 2 with a rotational force at the time of starting.

[0015] In this engine 2, one of two types of fuel is selected and supplied as the fuel to be injected into the combustion chamber of each cylinder: CNG, which is a gaseous fuel, as the first fuel, and gasoline, which is a liquid fuel, as the second fuel. The engine 2 is equipped with a gasoline supply system that supplies gasoline stored in a gasoline tank 4 to the combustion chamber, and a gas fuel supply system that supplies CNG stored under high pressure in a gas fuel tank 5 to the combustion chamber.

[0016] The fuel switching device 6 switches the fuel to be injected into the combustion chamber of each cylinder of the engine 2. Under the control of the ECU 8, the fuel switching device 6 switches the fuel to be injected into the combustion chamber of each cylinder of the engine 2 between gasoline stored in the gasoline tank 4 and CNG stored in the gas fuel tank 5.

[0017] The transmission 3 changes the speed of the rotation output from the engine 2, and drives the drive wheels 10 via a drive shaft 11. The transmission 3 is equipped with a constant mesh type speed change mechanism made up of a parallel shaft gear mechanism (not shown).

[0018] A clutch 31 of, for example, a dry single-plate type is provided between the engine 2 and the transmission 3 , and the clutch 31 connects and disconnects the power transmission between the engine 2 and the transmission 3 .

[0019] In the transmission 3, the gear shifting in the transmission mechanism and the engagement and disengagement of the clutch 31 are performed by an actuator (not shown) controlled by the ECU 8.

[0020] The ECU8 is composed of a computer unit equipped with a CPU (Central Processing Unit), a RAM (Random Access Memory), a ROM (Read Only Memory), a flash memory for storing backup data, etc., an input port, and an output port.

[0021] The ROM of this computer unit stores various constants, various maps, and the like, as well as a program for causing the computer unit to function as the ECU 8.

[0022] That is, the CPU executes the programs stored in the ROM using the RAM as a working area, whereby this computer unit functions as the ECU 8 in this embodiment.

[0023] To an input port of the ECU 8, various sensors such as a fuel selection switch 9, a brake switch 82, an accelerator opening sensor 84, a forward vehicle detection unit 86, a vehicle speed sensor 87, and the like are connected.

[0024] The fuel selection switch 9 receives an operation by the driver and outputs a signal to select either gasoline or CNG as the fuel to be injected into the combustion chamber of each cylinder of the engine 2. The ECU 8 switches the fuel to be injected into the combustion chamber of each cylinder of the engine 2 according to the signal from the fuel selection switch 9.

[0025] The brake switch 82 detects whether or not the driver has depressed the brake pedal 81. The accelerator opening sensor 84 detects the opening of the accelerator pedal 83 operated by the driver.

[0026] The forward vehicle detection unit 86 is configured with, for example, a camera or the like, and detects the presence of a vehicle in front of the bi-fuel vehicle 1. The vehicle speed sensor 87 detects the speed of the bi-fuel vehicle 1 from the rotation speed of the drive wheels 10 and the like.

[0027] Meanwhile, various control objects including the above-mentioned fuel switching device 6, the starter 21, and an injector (not shown) are connected to an output port of the ECU 8. The injector supplies fuel to the engine 2. The ECU 8 controls the starter 21 and the injector to control the starting and stopping of the engine 2, the output torque, and the like.

[0028] The ECU 8 is configured to control an idling stop function that stops the engine 2 when a preset automatic stop condition is met, and restarts the engine 2 when a preset restart condition is met.

[0029] The automatic stop condition is, for example, that all of the following conditions are met: the vehicle speed is equal to or lower than a predetermined vehicle speed, the transmission 3 is in neutral, the brake pedal 81 is depressed, the accelerator opening is equal to or lower than a predetermined opening, etc. On the other hand, the restart condition is, for example, that any one of the following conditions is met: the brake pedal 81 is not depressed, etc.

[0030] The ECU 8 selects gasoline as the fuel to be injected into the combustion chamber of each cylinder of the engine 2 when it is predicted that the automatic stopping and restarting of the engine 2 will be repeated a predetermined number of times or more within a predetermined time.

[0031] For example, the ECU 8 predicts traffic congestion and the like ahead of the bi-fuel vehicle 1 from images captured by an on-board camera, and predicts the frequency with which the engine 2 will automatically stop and restart.

[0032] Furthermore, the ECU 8 may predict congestion on the roads ahead of the bi-fuel vehicle 1 by using, for example, congestion information from an on-board navigation system, and may predict how often the automatic stopping and restarting of the engine 2 will be repeated.

[0033] The predetermined time is not one hour or two hours, but is a shorter time such as one minute to a few minutes.

[0034] For example, the ECU 8 may set a fuel to be used switching flag when it is predicted that automatic stopping and restarting of the engine 2 will be repeated a predetermined number of times or more within a predetermined time, and when the fuel to be used switching flag is set, select gasoline as the fuel to be injected into the combustion chamber of each cylinder of the engine 2.

[0035] The ECU 8 selects gasoline as the fuel to be injected into the combustion chamber of each cylinder of the engine 2 when the number of times the brake pedal 81 is operated within a predetermined brake determination time exceeds a threshold value.

[0036] The ECU 8 selects gasoline as the fuel to be injected into the combustion chambers of each cylinder of the engine 2 when the forward vehicle detection unit 86 detects the presence of a vehicle in front of the bi-fuel vehicle 1 .

[0037] The fuel-to-be-used switching control process by the ECU 8 of the bi-fuel vehicle 1 according to this embodiment configured as above will be described with reference to Fig. 2. The fuel-to-be-used switching control process described below is started when the ECU 8 starts operating, and is executed at preset time intervals.

[0038] In step S1, the ECU 8 determines whether or not CNG, which is a gaseous fuel, is being used.

[0039] If it is determined that CNG is being used, the ECU 8 executes the process of step S2. If it is determined that CNG is not being used, the ECU 8 ends the fuel-used switching control process.

[0040] In step S2, the ECU 8 determines whether or not a fuel-to-be-used switch flag is set.

[0041] If it is determined that the used fuel switching flag is set, the ECU 8 executes the process of step S3. If it is determined that the used fuel switching flag is not set, the ECU 8 ends the used fuel switching control process.

[0042] In step S3, the ECU 8 switches the fuel to be used to gasoline, which is a liquid fuel. After executing the process of step S3, the ECU 8 ends the fuel to be used switch control process.

[0043] Next, the fuel-used switching flag setting process by the ECU 8 of the bi-fuel vehicle 1 according to this embodiment will be described with reference to Fig. 3. The fuel-used switching flag setting process described below is started when the ECU 8 starts operating, and is executed at preset time intervals.

[0044] In step S11, the ECU 8 determines whether or not the number of operations of the brake pedal 81 within a braking determination time is equal to or greater than a threshold value.

[0045] If it is determined that the number of times the brake pedal 81 is operated within the braking determination time is equal to or greater than the threshold, the ECU 8 executes the process of step S12. If it is determined that the number of times the brake pedal 81 is operated within the braking determination time is not equal to or greater than the threshold, the ECU 8 ends the fuel use switching flag establishment process.

[0046] In step S12, the ECU 8 determines whether or not a vehicle is present ahead. If it is determined that a vehicle is present ahead, the ECU 8 executes the process of step S13. If it is determined that no vehicle is present ahead, the ECU 8 ends the fuel use switching flag establishment process.

[0047] In step S13, the ECU 8 sets the used fuel switching flag to ON. After executing the process of step S13, the ECU 8 ends the used fuel switching flag setting process.

[0048] Thus, in this embodiment, when it is predicted that automatic stopping and restarting of the engine 2 will be repeated a predetermined number of times or more within a predetermined time, the ECU 8 selects gasoline as the fuel to be injected into the combustion chamber of each cylinder of the engine 2.

[0049] If CNG, which has poor starting performance, is used in a situation where the engine 2 is repeatedly stopped and restarted automatically, a delay in restarting may occur each time the engine is restarted, which may be annoying to the driver. Therefore, in such a situation, by switching the fuel used in advance to gasoline, which has excellent starting performance, the annoyance caused by frequent restart delays can be reduced.

[0050] In addition, in a situation where the engine 2 is repeatedly stopped and restarted automatically, a quick restart can be achieved by switching the fuel used to gasoline fuel or the like, thereby making it possible to secure opportunities to perform idling stop.

[0051] Furthermore, the ECU 8 selects gasoline as the fuel to be injected into the combustion chamber of each cylinder of the engine 2 when the number of times the brake pedal 81 is operated within a predetermined brake determination time is equal to or greater than a threshold value.

[0052] When the brake pedal 81 is operated multiple times within a certain period of time, when the vehicle is following a vehicle ahead at a low speed on a congested road, etc., it is highly likely that the automatic stopping and restarting of the engine 2 will be repeatedly performed. Therefore, by switching the fuel to be used to gasoline in advance, the inconvenience caused by frequent restart delays can be reduced.

[0053] Furthermore, the ECU 8 selects gasoline as the fuel to be injected into the combustion chambers of each cylinder of the engine 2 when the forward vehicle detection unit 86 detects the presence of a vehicle in front of the bi-fuel vehicle 1 .

[0054] By adding the condition of the presence or absence of a vehicle ahead to the number of times the brake pedal 81 is operated, it is possible to more accurately determine whether or not the situation is one in which automatic stopping and restarting of the engine 2 will be repeatedly executed.

[0055] If the engine 2 is not completely warmed up, restarting using gaseous fuel may result in failure to start, and if restarting fails, the fuel used may be switched to gasoline fuel, further delaying restarting. Therefore, the control of this embodiment may be performed only when the engine 2 is not completely warmed up.

[0056] In this embodiment, an example has been described in which the ECU 8 performs various determinations and calculations based on various sensor information, but the present invention is not limited to this. The bi-fuel vehicle 1 may be provided with a communication unit capable of communicating with an external device such as an external server, and various determinations and calculations may be performed by the external device based on the detection information of the various sensors transmitted from the communication unit. The determination results and calculation results may be received by the communication unit, and various controls may be performed using the received determination results and calculation results.

[0057] Although an embodiment of the invention has been disclosed, it will be apparent to one of ordinary skill in the art that modifications may be made thereto without departing from the spirit and scope of the invention, and it is intended that all such modifications and equivalents be included in the following claims. [Explanation of symbols]

[0058] 1 Bi-fuel vehicle 2. Engine (internal combustion engine) 6 Fuel Switching Device 8 ECU (control unit) 9 Fuel selection switch 21 Starter 81 Brake pedal 82 Brake switch 86 Front vehicle detection unit 87 Vehicle speed sensor

Claims

1. A bi-fuel vehicle equipped with an internal combustion engine capable of switching between a first fuel and a second fuel having relatively superior starting performance compared to the first fuel, a control unit that automatically stops the internal combustion engine when a predetermined automatic stop condition is satisfied and restarts the internal combustion engine when a predetermined restart condition is satisfied; A bi-fuel vehicle in which the control unit switches the fuel used to the second fuel when it is predicted that automatic stopping and restarting of the internal combustion engine will be repeated a predetermined number of times or more within a predetermined time.

2. The bi-fuel vehicle according to claim 1 , wherein the control unit switches the fuel used to the second fuel when the number of times the brake pedal is operated within a predetermined brake determination time is equal to or greater than a threshold value.

3. A forward vehicle detection unit is provided to detect the presence of a vehicle ahead of the vehicle; The bi-fuel vehicle according to claim 2 , wherein the control unit switches the fuel used to the second fuel when the forward vehicle detection unit detects the presence of a forward vehicle.

4. 4. The bi-fuel vehicle according to claim 1, wherein the first fuel is compressed natural gas and the second fuel is gasoline.

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