JPS6411818B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a method for controlling fuel injection amount or ignition timing immediately after fuel cut-off of an internal combustion engine is stopped. [Prior Art] As a control method of a conventional electronically controlled fuel injection system immediately after fuel cut is stopped, the fuel injection amount or ignition timing immediately after fuel cut is stopped is determined by controlling whether the transmission is in a neutral position or not, or whether the engine is in a neutral position or not. A method of increasing the amount of fuel injection by a fixed amount regardless of whether the clutch that transmits power to the wheels is connected or disconnected (Japanese Patent Application Laid-Open No.
54-108127) and a method of retarding the ignition timing by a certain value (Japanese Patent Application Laid-Open No. 55-46057). [Problems to be Solved by the Invention] However, in the conventional control method immediately after stopping fuel cut, when the gear of the transmission is neutral or the clutch is disengaged, the engine is not engaged with the vehicle drive shaft. (hereinafter referred to as racing), immediately after fuel cut is stopped, or when the vehicle is running with the clutch engaged and the transmission in any gear other than neutral, the engine is not connected to the vehicle drive shaft. When the engine is engaged (hereinafter referred to as engine deceleration state), the fuel injection amount is quantitatively increased or the ignition timing is retarded, regardless of whether fuel cut has been stopped or not. If the correction is made uniformly based on the time of deceleration, there is a problem that an abnormal decrease in the engine rotation speed or the rotation of the engine is likely to occur immediately after the fuel cut is stopped during racing, and if the correction is made uniformly based on the time of racing,
Immediately after the fuel cut is stopped when the vehicle is decelerating while the vehicle is running, the transmitted torque suddenly changes, giving a shock to the vehicle. An object of the present invention is to provide a control method that can effectively prevent the rotation of an engine from stopping immediately after the fuel cut is stopped during racing, and the occurrence of an impact immediately after the fuel cut is stopped when the vehicle is decelerating while running. be. [Means for Solving the Problems] The gist of the present invention is to provide a system in which the engine is driving the vehicle when the transmission is in the neutral state or when the clutch that connects and disconnects the transmission of engine power to the vehicle drive shaft is disconnected. The fuel injection increase correction amount or the retardation correction amount (negative value) for the ignition advance value immediately after the internal combustion engine stops fuel cut when the transmission is in a state other than neutral and the clutch be selected to be larger than the fuel injection increase correction amount immediately after fuel cut is stopped or the retardation correction amount (negative value) for the ignition advance value when the engine is connected to the vehicle drive shaft and the engine is engaged with the vehicle drive shaft. A control method immediately after stopping fuel cut is characterized by: [Operation] In the present invention, the fuel injection increase correction amount or retardation correction amount (negative value) immediately after fuel cut is stopped during racing is set to be larger than that in the case immediately after fuel cut is stopped in an engine deceleration state. Therefore, when fuel injection is restarted, the fuel injection amount becomes larger or the ignition advance value becomes more advanced than when fuel injection is restarted in an engine deceleration state. Therefore, the engine speed, which had rapidly decreased during the fuel cut suspension period, quickly increases. On the other hand, when restarting fuel injection while the engine is decelerating, the fuel injection amount becomes smaller or the ignition advance value becomes more retarded than when restarting fuel injection during racing, so the engine output shaft torque It does not increase all at once. Therefore, the idling condition of the engine is kept good immediately after the fuel cut is stopped during racing, and no impact is given to the vehicle immediately after the fuel cut is stopped while the engine is decelerating. [Example] Hereinafter, an example of the present invention will be described with reference to the drawings. FIG. 1 schematically shows an electronically controlled fuel injection device to which the present invention is applied.
The flow rate of the air sucked in from the engine is controlled by a throttle valve 3 provided in the throttle body 2 and linked to an accelerator pedal in the driver's cab, and then passed through a surge tank 4, an intake pipe 5, and an intake valve 6 to the engine body 7.
is guided to the combustion chamber 8. The combustion chamber 8 has a piston 9
After combustion, the air-fuel mixture in the combustion chamber 8 is guided to an exhaust pipe 11 via an exhaust valve 10. The fuel injection valve 15 is provided near the intake port and supplies fuel, which is pressure-fed from the fuel tank 16 through the fuel passage 18 by the fuel pump 17, to the intake system. The opening and closing of the fuel injection valve 15 is controlled by electrical signals from an electronic control section 19. Next, the electronic control unit 19 includes a logic operation circuit formed mainly of a CPU (central processing unit), ROM (read-on memory), and RAM (random access memory), an input/output circuit, a D/A converter,
It is composed of an A/D converter and the like. The above ROM contains various data such as programs and ignition advance value maps to determine the optimal fuel injection amount and ignition advance value depending on the engine condition and to keep the engine in good condition. There is. The above input/output circuit also includes an air flow meter 2 installed upstream of the throttle valve 3 to measure the amount of intake air.
3. Crank angle sensor 2 provided in the distributor 24 to detect the rotation angle of the crankshaft
5. A water temperature sensor 26 installed in the water jacket 29 of the engine body 7 to detect the engine cooling water temperature;
A throttle switch 27 that detects the fully closed state of the throttle valve 3 and a vehicle speed sensor 28 that detects the rotational speed of the output shaft of the transmission are connected to the D/A converter,
They are connected via an A/D converter and signals from each sensor are input. The electronic control unit 19 having the above configuration calculates the basic injection amount based on the inflow air amount data from the air flow meter 23 and the engine rotation speed data from the crank angle sensor 25, and calculates the engine cooling amount from the water temperature sensor 26. The fuel injection amount is determined after increasing the amount based on the water temperature data. Also, based on the above data, the basic ignition advance value and the corrected ignition advance value are determined, and the ignition timing is determined.
By controlling the timing of energization to the primary side of the controller 24, the timing of applying high voltage to the distributor 24 is determined and the ignition timing is controlled. Further, the electronic control unit 19 controls fuel cut and fuel cut cancellation based on input data from each sensor. That is, when conditions such as the throttle valve 3 is fully closed and the engine speed reaches a predetermined value or higher are met, fuel cut is started and the fuel is cut off.

[Table] However, in the table, N represents neutral, 1 represents 1st speed, 2 represents 2nd speed, 3 represents 3rd speed, and 4 represents 4th speed, and the gear ratio decreases as you move from 1st to 4th speed. The minimum transmission ratio of the transmission is achieved in fourth gear. In addition, Q ₀ to _{Q 4} represent the fuel injection increase correction amount,
A ₀ to _{A 4} represent retard angle correction amounts (negative values) for the ignition advance value. First, the reason why the fuel increase correction amounts Q ₀ to _{Q 4} are set as shown in the table above will be explained. That is, immediately after fuel cut is stopped while the engine is decelerating, the inner wall of the intake pipe is dry, so some of the injected fuel adheres to the inner wall of the intake pipe, reducing the amount of fuel sent into the combustion chamber 8. The air-fuel mixture taken into the combustion chamber 8 cannot be controlled to an appropriate air-fuel ratio. Therefore, it has been considered to increase the amount of injected fuel than before. However, if the injection is performed by increasing the amount of fuel by the same amount regardless of the gear position of the transmission, the engine output shaft torque will suddenly increase and give a shock to the vehicle, especially when the transmission is in a low gear position. Therefore, the lower the gear, the smaller the increase correction amount is set. On the other hand, immediately after the fuel cut is stopped during racing, the engine speed is rapidly decreasing compared to when the engine is decelerating. Unable to quickly recover from a drop in rotational speed. Therefore, under such operating conditions, the fuel increase correction amount (Q ₀ ) is set to a larger value than when the engine is in a decelerated state. Next, the retardation correction amount A ₀ to _{A 4} for the ignition advance value
The reason for setting as shown in the table above will be explained. That is, when the engine is decelerated, if the engine output shaft torque suddenly increases when fuel injection is restarted, a shock will be given to the vehicle. Therefore, it has been conventionally considered to retard the ignition advance value to suppress the engine output shaft torque. However, if the retarding angle is corrected uniformly regardless of the gear position of the transmission, it is difficult to alleviate the shock at a low gear position. Therefore, the lower the gear, the more the ignition advance value is retarded. In other words, the retard angle correction amount, which is a negative value, is set to be smaller as the speed gear becomes lower. On the other hand, during racing, the ignition advance value only needs to be set in accordance with the idling speed, so the ignition advance value only needs to be retarded very slightly compared to when the engine is decelerating. Therefore, the retard angle correction amount (A ₀ ), which is a negative value, is set larger than in the case of the engine deceleration state. Therefore, the retard angle correction amount, which is a negative value, has the relationship shown in the table (A ₁ < A ₂ < A ₃ <
A ₄ ≪A ₀ ). Next, a control method performed in the above-mentioned electronically controlled fuel injection system immediately after fuel cut is stopped will be explained based on the drawings. Figure 3 shows the transition of the fuel injection increase correction amount immediately after the fuel cut is stopped,
The horizontal axis represents time t, _t1 represents the fuel cut stop time,
The vertical axis represents the fuel injection increase correction amount Q _a . First, in the case of racing, immediately after stopping fuel cut, the engine speed is rapidly decreasing, so it is necessary to increase the amount by a relatively large amount to prevent engine stall. Therefore, immediately after the fuel cut is stopped, fuel is injected in an amount obtained by adding the increase correction amount Q ₀ to the basic injection amount Q _b determined from the normal idling speed etc. to prevent the engine speed from dropping. After that, the fuel injection amount is gradually reduced to the basic injection Q _b that corresponds to the idling speed.
Keep the engine in good idling condition. In this case, the ignition advance angle value may be set to an advance angle value that is suitable for the idling speed, so that the engine can be maintained in a good condition by slightly retarding the engine (A ₀ ). Next, when the vehicle is in an engine deceleration state, immediately after the fuel cut is stopped, the basic injection amount Q ₀ determined from the inflow air amount data, etc. is increased by the fuel injection amount increase selected according to the gear position of the transmission. Correction amount Q ₁ , Q ₂ ,
The fuel containing Q ₃ and Q ₄ is injected into the combustion chamber 8.
maintains the air-fuel mixture sucked into the engine at an appropriate air-fuel ratio. After that, the injection amount is gradually reduced to the normal basic injection amount Q _b . In this way, the air-fuel mixture immediately after the fuel cut is stopped is maintained at an appropriate ratio, and combustion in the engine is restarted smoothly. At the same time, the ignition advance value is also retarded according to the gear position of the transmission to suppress the engine output shaft torque, thereby achieving smooth matching with the drive shaft torque. In other words, immediately after the fuel cut is stopped, the engine output shaft torque is suppressed by correcting the ignition advance angle using the retard angle correction amounts A ₁ , A ₂ , A ₃ , and A ₄ selected according to the gear position from the table above. Thereafter, the ignition advance value is gradually advanced to the normal ignition advance value to gradually increase the torque. For example, an example of the ignition advance value control is shown in FIG. The horizontal axis of the graph shown in Figure 4 is time t, t1
represents the fuel cut stop time, the vertical axis represents the ignition advance value A, and the higher the vertical axis is, the more advanced the ignition advance value is. The solid line in the graph shows the transition of the ignition advance value due to the above-mentioned ignition advance value control, and is the ignition advance value obtained by retarding the ignition advance value at time t1. The broken line graph shows the transition of the ignition advance value when no special ignition advance value control is performed immediately after the fuel cut is stopped. Immediately after fuel cut is stopped, in order to prevent the engine output shaft torque from suddenly increasing, the ignition advance value corresponding to the normal engine speed is changed to the retardation correction amount A ₁ , A ₂ , or The engine output shaft torque is suppressed by correcting A ₃ and A ₄ , and then the engine output shaft torque is gradually increased by gradually advancing the ignition angle to the ignition advance value corresponding to the normal engine speed. In this way, the engine output shaft torque is smoothly transmitted to the drive shaft and does not cause any shock to the vehicle. As described in detail above, in the control method immediately after the fuel cut is stopped according to the present embodiment, the fuel cut is controlled depending on the vehicle deceleration state during racing, and also according to the gear position of the transmission when the vehicle is in the vehicle deceleration state. The injection amount is increased appropriately. At the same time, the ignition advance value is also appropriately retarded, making it possible to prevent an abnormal drop in engine speed or engine rotation stop that occurs immediately after stopping fuel cut during racing, and to prevent fuel cut when the vehicle is decelerating. Immediately after stopping, the engine torque and the drive shaft torque can be smoothly matched in accordance with the gear position of the transmission, which has the excellent effect of preventing shocks caused by torque mismatch. In addition, in the above embodiment, the method is to control the synchronous fuel injection amount, but it is also possible to increase the fuel injection amount by using asynchronous fuel injection. FIG. 2 shows the injection pulse signal sent from the electronic control unit 19 to the fuel injection valve 15, the horizontal axis represents time t, and _t1 represents the fuel cut stop time. The asynchronous fuel injection pulse 33 occurs at time _t1 regardless of the rotation of the engine crankshaft, and is distinguished from the synchronous fuel injection pulse 34 that occurs in synchronization with the rotation of the engine crankshaft. For example, immediately after the throttle valve 3 is opened and fuel cut is stopped, asynchronous fuel injection is immediately performed to increase the fuel injection amount to maintain the mixture in the combustion chamber at an appropriate ratio. The fuel injection increase correction amount due to this asynchronous fuel injection is the same as in the above embodiment. In this way, even with asynchronous fuel injection, it is possible to prevent an abnormal decrease in the engine speed and stoppage of engine rotation, as well as to prevent shocks caused by torque mismatch, as in the above-described embodiments. [Effects of the Invention] As described above, in the control method immediately after fuel cut is stopped according to the present invention, the fuel injection amount is controlled depending on whether or not the engine is engaged with the drive shaft of the vehicle. Since the fuel amount is appropriately increased or the ignition advance value is appropriately retarded, it is possible to prevent the engine speed from abnormally decreasing or stopping, which occurs immediately after the fuel cut is stopped during racing, and also to prevent engine rotation while the vehicle is running. Immediately after the fuel cut is stopped during deceleration, by smoothly matching the engine torque and the drive shaft torque, it is possible to prevent shocks caused by torque mismatch.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram of an electronically controlled fuel injection device to which the present invention is applied, and FIG. 2 is a timing chart showing an asynchronous injection pulse signal and a synchronous injection pulse signal output immediately after fuel cut is stopped.
Fig. 3 is a graph showing the time course of the injected fuel increase correction amount immediately after the fuel cut is stopped, and Fig. 4 is a graph showing the time course of the retarded ignition advance value immediately after the fuel cut is stopped. . 3... Throttle valve, 15... Fuel injection valve, 19...
Electronic control section, 25... Crank angle sensor, 27...
...Throttle switch, 28...Vehicle speed sensor.

Claims (1)

[Scope of Claims] 1. When the transmission is in the neutral state or when the clutch that disconnects and disconnects the transmission of engine power to the vehicle drive shaft is not engaged,
When the engine is not engaged with the vehicle drive shaft, the fuel injection increase correction amount immediately after the fuel cut of the internal combustion engine is stopped or the retardation correction amount (negative value) for the ignition advance value is set when the transmission is other than neutral. from the fuel injection increase correction amount or retardation correction amount (negative value) for the ignition advance value immediately after fuel cut is stopped when the clutch is connected and the engine is engaged with the vehicle drive shaft. A control method immediately after fuel cut is stopped, characterized by: selecting a large size;