JP7127475B2 - Start control device for internal combustion engine - Google Patents

Description

The present invention relates to a start control device for an internal combustion engine.

In Patent Document 1, during normal start of a bi-fuel internal combustion engine, liquid fuel with high energy density is used at low temperature start and high rotation range, and gas fuel is used at low rotation range and medium rotation range. is disclosed.

Japanese Patent Application Laid-Open No. 2004-211610

However, in an internal combustion engine that can be operated on either gaseous fuel or liquid fuel, if the liquid fuel is used every time the engine is started, the fuel efficiency of the liquid fuel is inferior to that of the gaseous fuel, resulting in a problem of poor fuel efficiency. .

On the other hand, when the pressure is low, the amount of temperature rise in the cylinder decreases during the compression stroke of the internal combustion engine. During normal operation after starting, there is no problem because the engine speed of the internal combustion engine is high and stable. As a result, operation with gaseous fuel, which has a higher ignition point than liquid fuel, is unstable, and startability deteriorates.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a start control apparatus for an internal combustion engine that can improve fuel efficiency while ensuring startability.

In order to solve the above problems, the present invention provides an internal combustion engine that can be operated with either gaseous fuel or liquid fuel, an atmospheric pressure acquisition unit that acquires atmospheric pressure, and when the atmospheric pressure is less than a predetermined threshold, a control unit for starting the internal combustion engine using the liquid fuel, and for starting the internal combustion engine using the gaseous fuel when the atmospheric pressure is equal to or higher than a predetermined threshold.

Thus, according to the present invention, it is possible to improve fuel efficiency while ensuring startability.

FIG. 1 is a block diagram of an internal combustion engine starting control system according to an embodiment of the present invention. FIG. 2 is a flow chart showing the procedure of the starting fuel selection process of the starting control system for an internal combustion engine according to one embodiment of the present invention. FIG. 3 is a flow chart showing the procedure of the starting fuel selection process of the internal combustion engine starting control system according to another aspect of the embodiment of the present invention.

An internal combustion engine start control apparatus according to an embodiment of the present invention includes an internal combustion engine that can be operated on either gaseous fuel or liquid fuel, an atmospheric pressure acquisition unit that acquires atmospheric pressure, and a threshold value for atmospheric pressure. a controller for starting the internal combustion engine using liquid fuel when the atmospheric pressure is less than or equal to a predetermined threshold, and for starting the internal combustion engine using gaseous fuel when the atmospheric pressure is equal to or greater than a predetermined threshold. ing.

As a result, the start control apparatus for an internal combustion engine according to the embodiment of the present invention can improve fuel efficiency while ensuring startability.

DETAILED DESCRIPTION OF THE INVENTION A start control apparatus for an internal combustion engine according to an embodiment of the present invention will now be described in detail with reference to the drawings.

In FIG. 1, a vehicle 1 equipped with an automatic stop control device for an internal combustion engine 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 section. and

A plurality of cylinders are formed in the engine 2 . In this embodiment, the engine 2 is constructed so that each cylinder performs a series of four strokes consisting of an intake stroke, a compression stroke, an expansion stroke and an exhaust stroke.

A starter 21 is connected to the engine 2 . Starter 21 is connected to the crankshaft of engine 2 . The starter 21 rotates when supplied with electric power, thereby rotating the crankshaft and giving the engine 2 a rotational force for starting.

The engine 2 is supplied with one selected from two types of fuel, gasoline as a liquid fuel and CNG as a gaseous fuel, as fuel to be injected into the combustion chamber of each cylinder. The engine 2 includes a gasoline supply system that supplies gasoline stored in the gasoline tank 4 into the combustion chamber, and a gas fuel supply system that supplies CNG stored under high pressure in the gas fuel tank 5 into the combustion chamber.

The fuel switching device 6 switches the fuel to be injected into the combustion chamber of each cylinder of the engine 2 . The fuel switching device 6 switches the fuel 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 under the control of the ECU 8 .

The transmission 3 changes the speed of the rotation output from the engine 2 to drive the drive wheels 10 via the drive shaft 11 . The transmission 3 has a constant-mesh transmission mechanism consisting of a parallel shaft gear mechanism (not shown). The transmission 3 selects a gear stage in the transmission mechanism according to the operation of a shift lever (not shown) by the driver.

The transmission 3 is, for example, a shift state of 1st speed to 5th speed corresponding to a predetermined gear ratio, a neutral state in which the rotation output from the engine 2 is not transmitted to the drive shaft 11, and a vehicle 1 shift state, depending on the operation of the shift lever. take one of the reverse states for moving backward.

A dry single-plate clutch 31 , for example, is provided between the engine 2 and the transmission 3 , and the clutch 31 connects or disconnects power transmission between the engine 2 and the transmission 3 .

The state transition between the connected state and the disconnected state of the power transmission in the clutch 31 corresponds to the depression position of the clutch pedal 81, that is, the clutch stroke.

When the clutch pedal 81 is not depressed, the clutch 31 is engaged and the rotation of the crankshaft is transmitted to the transmission 3 .

On the other hand, when the clutch pedal 81 is depressed, the clutch 31 is disengaged and power transmission from the crankshaft to the transmission 3 is cut off.

A clutch pedal switch 82 is provided on the clutch pedal 81 . A clutch pedal switch 82 detects whether or not the clutch 31 is in a disengaged state.

The ECU 8 is a computer having a CPU (Central Processing Unit), a RAM (Random Access Memory), a ROM (Read Only Memory), a flash memory for storing backup data, an input port, and an output port. made up of units.

In the ROM of this computer unit, various constants, various maps, etc., and a program for causing the computer unit to function as the ECU 8 are stored.

That is, the computer unit functions as the ECU 8 in this embodiment by the CPU executing a program stored in the ROM using the RAM as a work area.

In addition to the above-described clutch pedal switch 82, the input port of the ECU 8 includes a fuel selection switch 9, an accelerator opening sensor 84, a brake switch 86, a vehicle speed sensor 87, a water temperature sensor 88, and an atmospheric pressure sensor 89 as an atmospheric pressure acquisition unit. Various sensors such as are connected.

The used fuel selection switch 9 receives a driver's operation and outputs a signal for selecting 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 to be used.

The accelerator opening sensor 84 detects the accelerator opening, which is the opening of the accelerator pedal 83 operated by the driver. A brake switch 86 detects whether or not the brake pedal 85 has been depressed by the driver. A vehicle speed sensor 87 detects the speed of the vehicle 1 from the rotational speed of the driving wheels 10 and the like.

A water temperature sensor 88 detects the temperature of cooling water for the engine 2 . The atmospheric pressure sensor 89 detects atmospheric pressure.

On the other hand, an output port of the ECU 8 is connected to various controlled objects including an injector (not shown) in addition to the fuel switching device 6 and the starter 21 described above. The injector supplies fuel to the engine 2 . By controlling the starter 21 and injectors, the ECU 8 controls starting and stopping of the engine 2, output torque, and the like.

The ECU 8 controls an idling stop function that stops the engine 2 when a preset automatic stop condition is satisfied and restarts the engine 2 when a preset restart condition is satisfied.

The automatic stop conditions include, for example, that the vehicle speed is equal to or less than a predetermined vehicle speed, that the transmission 3 is in a neutral state, that the brake pedal 85 is depressed, that the clutch pedal 81 is not depressed, and that the accelerator pedal 81 is not depressed. The condition is that all conditions such as that the degree of opening is equal to or less than a predetermined degree of opening are satisfied. On the other hand, the restart condition is, for example, that either the clutch pedal 81 is depressed or the brake pedal 85 is not depressed while the transmission 3 is in the neutral state.

When the atmospheric pressure detected by the atmospheric pressure sensor 89 is less than a predetermined threshold, the ECU 8 starts the engine 2 using gasoline with good startability, and the atmospheric pressure detected by the atmospheric pressure sensor 89 reaches the predetermined threshold. In the case above, the engine 2 is started using CNG with good fuel efficiency.

When the atmospheric pressure sensor 89 becomes abnormal and the atmospheric pressure cannot be obtained, the ECU 8 uses gasoline to start the engine 2 .

The starting fuel selection process performed by the internal combustion engine starting control apparatus according to the present embodiment configured as described above will be described with reference to FIG. 2 . Note that the starting fuel selection process described below is executed when the engine is started.

In step S1, the ECU 8 determines whether or not the engine start condition (including the above-described restart condition) is satisfied. When determining that the engine starting condition is not satisfied, the ECU 8 terminates the process.

When it is determined that the engine start condition is satisfied, in step S2, the ECU 8 determines whether or not the atmospheric pressure sensor has a failure. If it is determined that there is a failure in the atmosphere sensor, in step S4, the ECU 8 selects gasoline with good startability as the fuel to be used for starting.

If it is determined in step S2 that there is no failure in the atmospheric pressure sensor, the ECU 8 determines in step S3 whether or not the atmospheric pressure detected by the atmospheric pressure sensor 89 is less than a predetermined threshold value. When it is determined that the atmospheric pressure is less than the predetermined threshold value, in step S4, the ECU 8 selects gasoline with good startability as the fuel to be used for starting.

When it is determined that the atmospheric pressure is not less than the predetermined threshold value, in step S5, the ECU 8 selects CNG, which has good fuel efficiency, as the fuel to be used for starting.

In step S6, the ECU 8 starts the engine 2 using the fuel selected in step S4 or step S5.

As described above, in this embodiment, when the atmospheric pressure detected by the atmospheric pressure sensor 89 is less than a predetermined threshold value, the engine 2 is started using gasoline which has a lower ignition point than CNG and is easy to start. When the atmospheric pressure detected by the atmospheric pressure sensor 89 is equal to or higher than a predetermined threshold, the engine 2 is started using CNG with good fuel efficiency.

As a result, when the pressure is low, the startability is ensured by starting with the liquid fuel excellent in startability, and when the pressure is not low, the fuel consumption can be improved by starting with the gaseous fuel with good fuel efficiency.

Further, when the atmospheric pressure sensor 89 fails, the engine 2 can be reliably started even if the atmospheric pressure is low because liquid fuel with good startability is always used for starting.

As another aspect of the present embodiment, the ECU 8 is different from the initial start when the engine 2 is started by turning on the ignition key or the ignition switch and the restart when the engine 2 is started after the above-described automatic stop. Set the atmospheric pressure threshold higher than the atmospheric pressure threshold at the first start.

The start-up fuel selection process by the start-up control apparatus for an internal combustion engine according to another aspect of this embodiment, which is configured in this manner, will be described with reference to FIG. 3 . Note that the starting fuel selection process described below is executed when the engine is started.

As in the above-described embodiment, in step S1, the ECU 8 determines whether or not the engine start condition (including the above-described restart condition) is satisfied. When determining that the engine start condition is not satisfied, the ECU 8 terminates the process.

When it is determined that the engine start condition is satisfied, in step S11, the ECU 8 determines whether or not the engine is restarted from idling stop. If it is determined that the engine is to be restarted, in step S12, a high atmospheric pressure threshold value is selected as the threshold value for determining the atmospheric pressure.

If it is determined that the engine is not to be restarted, in step S13, a low atmospheric pressure threshold value lower than the high atmospheric pressure threshold value is selected as the threshold value for determining the atmospheric pressure.

In step S2, the ECU 8 determines whether or not the atmospheric pressure sensor has failed. If it is determined that there is a failure in the atmosphere sensor, in step S4, the ECU 8 selects gasoline with good startability as the fuel to be used for starting.

If it is determined in step S2 that there is no failure in the atmospheric pressure sensor, in step S3, the ECU 8 uses the threshold value selected in step S12 or step S13 to cause the atmospheric pressure sensor 89 to detect A determination is made as to whether the applied atmospheric pressure is less than a selected threshold. When it is determined that the atmospheric pressure is less than the predetermined threshold value, in step S4, the ECU 8 selects gasoline with good startability as the fuel to be used for starting.

When it is determined that the atmospheric pressure is not less than the predetermined threshold value, in step S5, the ECU 8 selects CNG, which has good fuel efficiency, as the fuel to be used for starting.

In step S6, the ECU 8 starts the engine 2 using the fuel selected in step S4 or step S5.

Thus, in another aspect of the present embodiment, since the atmospheric pressure threshold at restart is set higher than the atmospheric pressure threshold at initial restart, the atmospheric pressure for starting with liquid fuel at restart By expanding the area, it is possible to suppress the delay in starting due to the deterioration of startability due to low atmospheric pressure.

In both the initial start and the restart, if the start of the engine 2 is not completed before the driver performs the start operation, the start will be delayed. Also, at the time of restart, the time from start to start operation is shorter than at the time of initial start. Therefore, when restarting, the atmospheric pressure range in which the engine is started with liquid fuel is expanded to suppress slow start due to deterioration of startability due to low pressure.

In this embodiment, the transmission 3 is a manual transmission. Transmission), etc., the same effect can be obtained.

In addition, the case of a vehicle equipped with a bi-fuel engine that is driven only by a bi-fuel engine is shown, but a strong hybrid vehicle equipped with an electric motor for driving and a mild hybrid equipped with an electric motor equipped with an engine start function in addition to power generation Even if it is a vehicle, if it is equipped with a bi-fuel engine, it can be implemented in the same way.

In addition, although the atmospheric pressure sensor 89 was used as the atmospheric pressure acquisition unit, the position information is acquired by radio waves from the GNSS (Global Navigation Satellite System) satellite, and the atmospheric pressure is acquired by the weather information acquired by communication based on the position information. It may be configured to

In this embodiment, an example has been described in which the ECU 8 makes various determinations and calculations based on various sensor information. Various judgments and calculations are performed by the external device based on the detection information of various sensors transmitted from the unit, the judgment results and calculation results are received by the communication unit, and the received judgment results and calculation results are used to perform various control may be performed.

Although embodiments of the present invention have been disclosed, it will be apparent that modifications may be made by those skilled in the art without departing from the scope of the invention. All such modifications and equivalents are intended to be included in the following claims.

1 vehicle 2 engine 6 fuel switching device 8 ECU (control unit)
9 Used fuel selection switch 21 Starter 89 Atmospheric pressure sensor (atmospheric pressure acquisition unit)

Claims (3)

an internal combustion engine operable on either gaseous or liquid fuel;
an atmospheric pressure acquisition unit that acquires atmospheric pressure;
When the atmospheric pressure is less than a predetermined threshold, the liquid fuel is used to start the internal combustion engine, and when the atmospheric pressure is greater than or equal to the predetermined threshold, the gaseous fuel is used to start the internal combustion engine. and a control unit for starting the internal combustion engine. The control unit automatically stops the internal combustion engine when a preset automatic stop condition is satisfied, restarts the internal combustion engine when a preset restart condition is satisfied,
2. The start control device for an internal combustion engine according to claim 1, wherein said threshold value at said restart is set higher than at the time of initial start of said internal combustion engine. 3. The start control device for an internal combustion engine according to claim 1, wherein the control unit starts the internal combustion engine using the liquid fuel when an abnormality is detected in the atmospheric pressure acquisition unit.

Images