JP2022119044A - Vehicle control apparatus - Google Patents

Abstract

To provide a vehicle control apparatus capable of improving fuel economy while securing vehicular starting performance.SOLUTION: A control unit makes an internal combustion engine automatically stop in a case where predetermined automatic stop conditions hold, and restarts the engine in a case where predetermined restart conditions hold while the engine is automatically stopped. The restart conditions includes an amount of brake operation becoming smaller than a given restart threshold. In a case where the engine is restarted using gas fuel (Yes at step S3), the control unit sets a restart threshold to a larger value (step S8) than in the case of restarting the engine using liquid fuel (No at step S3).SELECTED DRAWING: Figure 2

Description

The present invention relates to a vehicle control device.

BACKGROUND ART In recent years, among vehicles such as automobiles, there are bi-fuel vehicles equipped with an engine that uses gaseous fuel such as compressed natural gas (CNG) and liquid fuel such as gasoline as fuels. As a conventional vehicle of this type, one described in Patent Document 1 is known.

In Patent Document 1, when a request to start the engine using gaseous fuel is generated and it is determined that the warm-up is completed, the target air-fuel ratio of the engine is set to be leaner than the stoichiometric air-fuel ratio. A technique is described for starting an engine by Patent Document 1 discloses an internal combustion engine having an idle stop function 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. The point at which the technology is applied is described.

JP 2014-234791 A

However, it cannot be said that the technique described in Patent Document 1 ensures sufficient restartability of the internal combustion engine when gaseous fuel is used. By using gaseous fuel such as compressed natural gas, bi-fuel vehicle engines can improve fuel efficiency compared to using liquid fuel such as gasoline. Since it is longer than the path of the injector for liquid fuel, when starting the internal combustion engine using gaseous fuel, the starting torque necessary for starting the vehicle is generated after injecting the gaseous fuel and starting the internal combustion engine. It has the characteristic that it takes a long time to complete.

Therefore, when the internal combustion engine is restarted using gaseous fuel from an automatic stop state due to idling stop, the time from the start to the generation of starting torque becomes longer than when liquid fuel is used. There was a risk that the vehicle could not start on the street.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a vehicle control apparatus capable of improving fuel efficiency while ensuring the starting performance of the vehicle. .

The present invention is a control device for a vehicle equipped with an internal combustion engine that switches between gaseous fuel and liquid fuel, and automatically stops the internal combustion engine when a predetermined automatic stop condition is satisfied. A control unit that restarts the internal combustion engine when a predetermined restart condition is satisfied during automatic stop, the restart condition includes that the brake operation amount has become smaller than a predetermined restart threshold, When the gaseous fuel is used to restart the internal combustion engine, the control unit sets the restart threshold to a larger value than when the liquid fuel is used to restart the internal combustion engine. It is characterized by setting

As described above, according to the present invention, it is possible to provide a control device for a vehicle that can improve fuel efficiency while ensuring the starting performance of the vehicle.

FIG. 1 is a configuration diagram of a vehicle equipped with a control device according to a first embodiment or a second embodiment of the invention. FIG. 2 is a flow chart for explaining the operation of the vehicle control device according to the first embodiment of the present invention. FIG. 3 is a flow chart for explaining the operation of the vehicle control device according to the second embodiment of the present invention.

A control device for a vehicle according to an embodiment of the present invention is a control device for a vehicle equipped with an internal combustion engine that switches between a gaseous fuel and a liquid fuel, wherein the internal combustion engine stops when a predetermined automatic stop condition is satisfied. A control unit that automatically stops the engine and restarts the internal combustion engine when a predetermined restart condition is satisfied while the internal combustion engine is automatically stopped, and the restart condition is that the brake operation amount is greater than a predetermined restart threshold. When the internal combustion engine is restarted using gaseous fuel, the control unit sets the restart threshold to a larger value than when the internal combustion engine is restarted using liquid fuel. It is characterized in that it is set to As a result, the vehicle control device according to the embodiment of the present invention can improve the fuel efficiency while ensuring the starting performance of the vehicle.

A vehicle control apparatus according to a first embodiment of the present invention will be described below with reference to the drawings. 1 and 2 are diagrams for explaining a vehicle control apparatus according to a first embodiment of the present invention. As shown in FIG. 1, a vehicle 1 equipped with a vehicle control apparatus according to an embodiment of the present invention includes an internal combustion engine 2 (referred to as an engine in the drawing) as a drive source, and power from the internal combustion engine 2. A transmission 4 to which power is transmitted, a clutch 3 provided between the internal combustion engine 2 and the transmission 4, and driving wheels 5 to which power is transmitted from the transmission 4 are provided.

The vehicle 1 also includes an accelerator pedal sensor 12A, a brake pedal sensor 13A, a clutch pedal sensor 14A, a vehicle speed sensor 15, an acceleration sensor 16, and an ECU (Electronic Control Unit) that controls the internal combustion engine 2 and the transmission 4. 11.

The internal combustion engine 2 performs a series of four strokes consisting of an intake stroke, a compression stroke, an expansion stroke and an exhaust stroke. It is configured. In addition to the internal combustion engine 2, the vehicle 1 may include a motor as a drive source. The vehicle 1 has a starter 6 that starts the internal combustion engine 2 .

The transmission 4 is configured, for example, as a parallel shaft gear type transmission mechanism that is commonly used in manual transmissions. The clutch 3 is configured as a dry single-plate friction clutch, and has a flywheel 3A connected to the output shaft 2A of the internal combustion engine 2 and a clutch disk 3B connected to the transmission 4 .

The clutch 3 transmits power between the internal combustion engine 2 and the transmission 4 when the clutch disk 3B is switched to the engaged (connected) state with respect to the flywheel 3A, and is switched to the released (disconnected) state. power transmission between the internal combustion engine 2 and the transmission 4 is interrupted when the

In the vehicle 1 configured as described above, the rotation output from the internal combustion engine 2 is changed at a gear ratio corresponding to the gear stage established by the transmission 4, and is driven through a differential device and a drive shaft (not shown). transmitted to wheel 5;

The accelerator pedal sensor 12A is provided on the accelerator pedal 12 and detects the amount of operation of the accelerator pedal 12 . The brake pedal sensor 13A is provided on the brake pedal 13 and detects the amount of operation of the brake pedal 13 . The clutch pedal sensor 14A is provided on the clutch pedal 14 and detects the amount of operation of the clutch pedal 14 . Here, the amount of operation of each pedal is the amount of depression by the driver, and the greater the amount of depression, the greater the amount of operation. The brake pedal sensor 13A may detect the oil pressure of the master cylinder connected to the brake pedal 13 (master cylinder pressure) instead of the amount of depression of the brake pedal 13 . Hereinafter, the depression amount of the brake pedal 13 or the master cylinder pressure will be referred to as a brake operation amount.

A vehicle speed sensor 15 is provided on the drive wheel 5 and detects the vehicle speed based on the rotational speed of the drive wheel 5 . Acceleration sensor 16 detects the acceleration of vehicle 1 and the attitude of vehicle 1 .

The internal combustion engine 2 is a bi-fuel internal combustion engine that can use liquid fuel and gaseous fuel. Therefore, the vehicle 1 is a bi-fuel automobile. The internal combustion engine 2 can use gasoline or diesel fuel as liquid fuel, and can use compressed natural gas (CNG) as gaseous fuel.

The vehicle 1 includes a first fuel storage section 8 that stores liquid fuel and a second fuel storage section 9 that stores gaseous fuel. The liquid fuel is injected into the intake passage or the combustion chamber by an injector (not shown) for liquid fuel. The gaseous fuel is injected into the intake path by an injector (not shown) for gaseous fuel.

The vehicle 1 includes a fuel switching device 7 for switching the fuel supplied to the internal combustion engine 2 between liquid fuel and gaseous fuel, and a fuel selection switch 18 operated by the driver. Either liquid fuel or gaseous fuel selected by the used fuel selection switch 18 is supplied to the internal combustion engine 2 via the fuel switching device 7 .

The vehicle 1 includes a brake pressure holding section 17 . The brake pressure holding unit 17 increases, maintains, and reduces the braking force of the drive wheels 5 on the wheel cylinders (not shown). The brake pressure holding unit 17 realizes a so-called hill hold function, and when the brake operation amount becomes smaller than the restart threshold value, the brake pressure corresponding to the road surface inclination is held for a predetermined holding time and then reduced. . As a result, when the driver shifts his/her foot from the brake pedal 13 to the accelerator pedal 12 to start the vehicle 1 while the vehicle 1 is stopped on an uphill slope, the brake pressure is maintained even after releasing the brake pedal 13 . The holding portion 17 holds the brake pressure for a predetermined holding time, thereby preventing the vehicle 1 from sliding down when the vehicle 1 starts moving.

The ECU 11 is composed of a computer unit having a CPU (Central Processing Unit), a RAM (Random Access Memory), a ROM (Read Only Memory), a flash memory, an input port, and an output port. Control the target electrically.

The ROM of the ECU 11 stores a program for causing the computer unit to function as the ECU 11 along with various control constants, various maps, and the like. The computer unit functions as the ECU 11 when the CPU of the ECU 11 executes a program stored in the ROM.

Input ports of the ECU 11 are electrically connected to the internal combustion engine 2, various sensors such as an accelerator pedal sensor 12A, a brake pedal sensor 13A, a clutch pedal sensor 14A, a vehicle speed sensor 15, an acceleration sensor 16, and a fuel selection switch 18. It is connected to the.

Control targets such as the internal combustion engine 2, the starter 6, the fuel switching device 7, and the brake pressure holding unit 17 are connected to the output port of the ECU 11. FIG. The ECU 11 controls the control target connected to the output port based on detection signals from sensors and the like input to the input port.

In this embodiment, the ECU 11 is provided with a control section 11A. The control section 11A automatically stops the internal combustion engine 2 when a predetermined automatic stop condition is satisfied, and restarts the internal combustion engine 2 while the internal combustion engine 2 is automatically stopped. The internal combustion engine 2 is restarted when the conditions are met. Thus, the control unit 11A performs so-called idle stop control.

Here, the restart condition includes that the brake operation amount has become smaller than a predetermined restart threshold. The restart threshold is a threshold of the brake operation amount at which restart of the internal combustion engine 2 is started. As a result, the automatic stop of the internal combustion engine 2 is maintained while the amount of brake operation by the driver is equal to or greater than the restart threshold, and the restart condition is satisfied when the amount of brake operation by the driver becomes smaller than the restart threshold. Then, the internal combustion engine 2 is restarted. The ECU 11 also includes a tilt detection unit 11B, and the tilt detection unit 11B detects the road surface tilt based on the attitude of the vehicle 1 detected by the acceleration sensor 16 .

Here, in the internal combustion engine 2 that switches between the liquid fuel and the gaseous fuel, the path from the gaseous fuel injector to the combustion chamber is longer than the liquid fuel injector, and the injected gaseous fuel passes through the combustion chamber. Since the time required to reach the point is longer than in the case of liquid fuel, the time from the start of the internal combustion engine 2 to the generation of the starting torque necessary for starting the vehicle is longer. Therefore, when the driver releases the brake pedal 13 and the internal combustion engine 2 restarts from the automatic stop state due to the idle stop, the time until the start torque required for starting the vehicle 1 is generated. A restart with liquid fuel will take longer than a restart with liquid fuel.

Therefore, in the present embodiment, when the gaseous fuel is used to restart the internal combustion engine 2, the control unit 11A sets the restart threshold as compared with the case where the liquid fuel is used to restart the internal combustion engine 2. to a large value. Therefore, when the internal combustion engine 2 is restarted using gaseous fuel, the internal combustion engine 2 is restarted with a large brake operation amount compared to when the internal combustion engine 2 is restarted using liquid fuel. Startup is initiated. In other words, when gaseous fuel is used, the restart start timing of the internal combustion engine 2 is advanced compared to when liquid fuel is used.

Further, in this embodiment, the automatic stop condition includes that the amount of brake operation has become larger than a predetermined automatic stop threshold. Then, when the internal combustion engine 2 is automatically stopped during use of the gaseous fuel, the control unit 11A sets the automatic stop threshold to a larger value than when the internal combustion engine 2 is automatically stopped during use of the liquid fuel. do. Therefore, when gaseous fuel is used, both the restart threshold value and the automatic stop threshold value of idle stop control are set to larger values than when liquid fuel is used.

Note that the restart of the internal combustion engine 2 by idle stop control is performed in a state in which the internal combustion engine 2 is stopped by automatic stop. It is set to a value greater than the threshold.

Next, the operation flow of the vehicle control device according to the present embodiment will be described with reference to the flowchart shown in FIG. FIG. 2 shows the operation of the control unit 11A when the internal combustion engine 2 is restarted due to a decrease in the brake stroke while the internal combustion engine 2 is automatically stopped by idle stop control, and the vehicle 1 starts moving. .

In FIG. 2, the control unit 11A acquires the engine state (step S1) and determines whether or not the engine is automatically stopped (step S2). Here, the engine state refers to the operating state of the internal combustion engine 2 . Further, the automatic engine stop state refers to a state in which the operation of the internal combustion engine 2 is stopped by idle stop control.

If the control unit 11A determines that the engine is not in the automatic stop state in step S2, the process returns to step S1. If it is determined in step S2 that the engine is in the automatic stop state, the control unit 11A determines whether gaseous fuel is selected. (Step S3).

If the determination in step S3 is NO, that is, if the liquid fuel is selected, the control unit 11A acquires the brake stroke amount as the brake operation amount (step S4), and determines whether the brake stroke amount is less than threshold 2. is determined (step S5).

When the control unit 11A determines that the brake stroke amount is not less than the threshold value 2 in step S5, the process returns to step S4. is started (step S6).

On the other hand, if the determination in step S3 is YES, that is, if the gaseous fuel is selected, the control unit 11A acquires the brake stroke amount (step S7) and determines whether the brake stroke amount is less than the threshold value 1. (Step S8). Here, threshold 1 and threshold 2 are restart thresholds in the present invention. The controller 11A sets the threshold 1 to a value larger than the threshold 2 (large brake stroke amount threshold).

If the control unit 11A determines that the brake stroke amount is not less than the threshold value 1 in step S8, it returns to step S7. is started (step S9).

After the internal combustion engine 2 is started in step S6 or step S9, the vehicle 1 starts when the brake stroke amount is further decreased (step S10).

As described above, the vehicle control apparatus of this embodiment automatically stops the internal combustion engine 2 when a predetermined automatic stop condition is satisfied, and when a predetermined restart condition is satisfied while the internal combustion engine 2 is automatically stopped. is provided with a control unit 11A for restarting the internal combustion engine 2. Further, the restart condition includes that the brake operation amount has become smaller than a predetermined restart threshold. Then, when the internal combustion engine 2 is restarted using the gaseous fuel, the control unit 11A sets the restart threshold to a larger value than when the internal combustion engine 2 is restarted using the liquid fuel. is doing.

As a result, the internal combustion engine 2 is automatically stopped when the predetermined automatic stop condition is satisfied, so the fuel efficiency can be improved.

Further, when the internal combustion engine 2 is started using gaseous fuel, the restart threshold value of the brake operation amount is increased compared to when liquid fuel is used. can start with Therefore, starting torque can be generated at the same timing as when the internal combustion engine 2 is started using liquid fuel.

As a result, it is possible to improve the fuel efficiency while ensuring the starting performance of the vehicle 1 .

Further, in this embodiment, the automatic stop condition includes that the amount of brake operation has become larger than a predetermined automatic stop threshold. Then, when the internal combustion engine 2 is automatically stopped during use of the gaseous fuel, the control unit 11A sets the automatic stop threshold to a larger value than when the internal combustion engine 2 is automatically stopped during use of the liquid fuel. is doing.

As a result, it is possible to prevent the difference between the automatic stop threshold value and the restart threshold value from becoming small when gaseous fuel is used. You can avoid restarting. Therefore, restart of the internal combustion engine 2 not intended by the driver can be prevented.

Next, the operation flow of the vehicle control apparatus according to the second embodiment will be described with reference to the flowchart shown in FIG. In this embodiment, the operation of the control section 11A of the ECU 11 is changed in the vehicle 1 having the configuration shown in FIG. The operation of the control section 11A of the ECU 11 will be described below. FIG. 3 shows the operation of the control unit 11A when the internal combustion engine 2 is restarted due to a decrease in the brake stroke while the internal combustion engine 2 is automatically stopped by idle stop control, and the vehicle 1 starts moving. .

In FIG. 3, the control unit 11A acquires the road surface inclination from the inclination detection unit 11B (step S11), acquires the engine state (step S12), and determines whether or not the engine is automatically stopped (step S13). .

If the control unit 11A determines that the engine is not automatically stopped in step S13, it returns to step S12, and if it is determined that the engine is automatically stopped in step S13, it determines whether the gaseous fuel is selected. (Step S14).

If the determination in step S14 is NO, that is, if the liquid fuel is selected, the control unit 11A acquires the brake stroke amount as the brake operation amount (step S15), and determines whether the brake stroke amount is less than threshold 2. is determined (step S16).

When the control unit 11A determines that the brake stroke amount is not less than the threshold value 2 in step S16, the process returns to step S15. is started (step S17). After that, the controller 11A quickly reduces the brake holding pressure (step S18). Here, the controller 11A reduces the brake pressure after holding it for a predetermined holding time. The retention time in step S18 is shorter than the retention time in step S22, which will be described later. Therefore, the brake holding pressure is reduced relatively quickly.

On the other hand, if the determination in step S14 is YES, that is, if the gaseous fuel is selected, the control unit 11A acquires the brake stroke amount (step S19), and determines whether the brake stroke amount is less than the threshold value 1. (Step S20).

Here, threshold 1 and threshold 2 are restart thresholds in the present invention. Further, when the inclination detection unit 11B detects that the road surface inclination is an upward slope and the internal combustion engine 2 is restarted using the gaseous fuel, the control unit 11A uses the liquid fuel to restart the internal combustion engine. The restart threshold is set to a larger value than when the engine 2 is restarted. That is, when the slope detection unit 11B detects that the road surface slope is an upward slope, the control unit 11A sets the threshold value 1, which is the restart threshold value when restarting the internal combustion engine 2 using the gaseous fuel. , is set to a value (larger brake stroke amount threshold) than threshold 2, which is a restart threshold when the internal combustion engine 2 is restarted using liquid fuel.

If the control unit 11A determines that the brake stroke amount is not less than the threshold value 1 in step S20, the process returns to step S19. is started (step S21). After that, the controller 11A gently reduces the brake holding pressure (step S22). Here, the controller 11A reduces the brake pressure after holding it for a predetermined holding time. The holding time in step S22 is longer than the holding time in step S18. Therefore, the brake holding pressure is reduced relatively gently.

Then, when the predetermined holding time elapses in step S18 or step S22 and the brake holding pressure decreases, the vehicle 1 starts (step S23).

When the slope detection unit 11B detects that the road slope is an upward slope, the control unit 11A sets the threshold 1 to be larger than the threshold 2. Both threshold 1 and threshold 2 may be increased compared to when no gradient is detected.

As described above, in this embodiment, the internal combustion engine 2 is automatically stopped when a predetermined automatic stop condition is satisfied, and the internal combustion engine 2 is restarted when a predetermined restart condition is satisfied while the internal combustion engine 2 is automatically stopped. It is provided with a controller 11A for restarting and an inclination detector 11B for detecting the inclination of the road surface. Further, the restart condition includes that the brake operation amount has become smaller than a predetermined restart threshold.

Then, when the inclination detection unit 11B detects that the road surface inclination is an upward slope and the internal combustion engine 2 is restarted using the gaseous fuel, the control unit 11A uses the liquid fuel to restart the internal combustion engine. The restart threshold is set to a larger value than when the engine 2 is restarted.

As a result, when the internal combustion engine 2 is started using gaseous fuel on an uphill slope, the restart threshold value of the brake operation amount is increased compared to when liquid fuel is used. 2 can be started at an early timing. Therefore, starting torque can be generated at the same timing as when the internal combustion engine 2 is started using liquid fuel. Therefore, it is possible to prevent the vehicle 1 from sliding downhill when starting the vehicle 1 even on an uphill slope that requires a larger starting torque than on a flat road.

As a result, it is possible to improve the fuel efficiency while ensuring the starting performance of the vehicle 1 .

Further, in this embodiment, when the brake operation amount becomes smaller than the restart threshold value, a brake pressure holding unit is provided that reduces the brake pressure corresponding to the road surface inclination after holding it for a predetermined holding time. When the gaseous fuel is used to restart the internal combustion engine 2, the control unit 11A sets the holding time to a longer value than when the liquid fuel is used to restart the internal combustion engine 2. ing.

As a result, when the internal combustion engine 2 is restarted using gaseous fuel on an uphill slope and the vehicle 1 is started, a sufficient length of holding time for changing the pedal position is ensured. It is possible to reliably prevent slippage.

Further, in this embodiment, the automatic stop condition includes that the amount of brake operation has become larger than a predetermined automatic stop threshold. When the internal combustion engine 2 is automatically stopped during use of gaseous fuel, the automatic stop threshold is set to a larger value than when the internal combustion engine 2 is automatically stopped during use of liquid fuel.

As a result, it is possible to prevent the difference between the automatic stop threshold value and the restart threshold value from becoming small when gaseous fuel is used. You can avoid restarting. Therefore, restart of the internal combustion engine 2 not intended by the driver can be prevented.

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 internal combustion engine 11A control unit 11B inclination detection unit 17 brake pressure holding unit

Claims (4)

A control device for a vehicle equipped with an internal combustion engine that switches between gaseous fuel and liquid 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 during the automatic stop of the internal combustion engine;
The restart condition includes that the brake operation amount has become smaller than a predetermined restart threshold,
The control unit
When restarting the internal combustion engine using the gaseous fuel, the restart threshold is set to a larger value than when restarting the internal combustion engine using the liquid fuel. vehicle control device. A control device for a vehicle equipped with an internal combustion engine that switches between gaseous fuel and liquid 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 during the automatic stop of the internal combustion engine;
A tilt detection unit that detects a road surface tilt,
The restart condition includes that the brake operation amount has become smaller than a predetermined restart threshold,
The control unit
When the slope detection unit detects that the road surface slope is an upward slope and the gaseous fuel is used to restart the internal combustion engine, the liquid fuel is used to restart the internal combustion engine. A control device for a vehicle, characterized in that the restart threshold value is set to a larger value than when the vehicle is started. a brake pressure holding unit that reduces the brake pressure after holding the brake pressure corresponding to the road surface inclination for a predetermined holding time when the brake operation amount becomes smaller than the restart threshold;
The control unit
When restarting the internal combustion engine using the gaseous fuel, the holding time is set to a longer value than when restarting the internal combustion engine using the liquid fuel. 3. The vehicle control device according to claim 2. The automatic stop condition includes that the brake operation amount is greater than a predetermined automatic stop threshold,
When automatically stopping the internal combustion engine while using the gaseous fuel, the automatic stop threshold is set to a larger value than when automatically stopping the internal combustion engine while using the liquid fuel. The control device for a vehicle according to any one of claims 1 to 3, wherein:

Images