Vehicle control method and vehicle control device

Abstract

Restart the internal combustion engine that has stopped idling as quickly as possible. [Solution] In the process of the vehicle automatically stopping the internal combustion engine when the idle stop condition is met, the engine speed of the internal combustion engine reaches the first rotational speed R f If the brake pedal is released during the above period, the engine speed of the internal combustion engine will reach the first rotational speed R. f The system attempts to restart the internal combustion engine by restarting fuel injection and ignition without cranking the engine with the starter motor until the pressure drops below a certain level. This allows the vehicle to restart the idle-stopped internal combustion engine as quickly as possible.

Description

[Technical Field]

[0001] This invention relates to a vehicle control method and a vehicle control device. [Background technology]

[0002] For example, Patent Document 1 discloses a technology that sets the restart permission brake fluid pressure based on the crank stop position of an internal combustion engine that has been stopped by an idle stop system, and restarts the internal combustion engine when the brake fluid pressure falls below the restart permission brake fluid pressure.

[0003] Patent Document 1 describes a method for restarting an internal combustion engine that has been idled, based on the crank stop position of the internal combustion engine when the rotation of the crankshaft stops, and the restart of the internal combustion engine is performed while the rotation of the crankshaft has stopped. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2015-86700 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] Therefore, in Patent Document 1, it is not possible to restart the internal combustion engine while the rotational speed of the internal combustion engine is decreasing due to idle stop. In other words, in Patent Document 1, if a request to restart the internal combustion engine arises immediately after idle stop, the engine will be restarted only after waiting for the rotation of the crankshaft of the internal combustion engine to stop.

[0006] In other words, in vehicles that implement idle stop for internal combustion engines, there is room for further improvement in order to quickly restart the idled internal combustion engine. [Means for solving the problem]

[0007] The vehicle of the present invention automatically stops the internal combustion engine when predetermined idle stop permission conditions, including pressing the brake pedal, are met, and restarts the internal combustion engine when predetermined idle stop release conditions, including releasing the brake pedal, are met. In the process of automatically stopping the internal combustion engine after the idle stop permission conditions are met, if the brake pedal is released, the vehicle attempts to restart the internal combustion engine by restarting fuel injection without cranking by the starter motor. [Effects of the Invention]

[0008] According to the present invention, a vehicle can restart an internal combustion engine that has been idled as quickly as possible. [Brief explanation of the drawing]

[0009] [Figure 1] A schematic diagram illustrating the system configuration of an internal combustion engine 1 installed in a vehicle to which the present invention is applied. [Figure 2] A timing chart showing the various behaviors when an internal combustion engine restarts after the idle stop release conditions are met, by resuming fuel injection and ignition. [Figure 3] This timing chart shows the various behaviors that occur when the internal combustion engine restarts due to the resumption of fuel injection and ignition while the accelerator pedal is pressed after the idle stop release conditions have been met. [Figure 4] A timing chart showing the various behaviors that occur when an internal combustion engine is restarted by cranking after the idle stop release conditions have been met. [Modes for carrying out the invention]

[0010] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. Figure 1 is a schematic diagram illustrating the system configuration of an internal combustion engine 1 mounted on a vehicle to which the present invention is applied.

[0011] The internal combustion engine 1 is, for example, a multi-cylinder spark ignition internal combustion engine, and is mounted on a vehicle such as an automobile. The internal combustion engine 1 transmits the rotation of a crankshaft (not shown) as driving force to the driving wheels of the vehicle. The internal combustion engine 1 has a starter motor 2 that cranks when starting, a fuel injection valve (not shown), a spark plug (not shown), etc. The starter motor 2, the fuel injection amount of the fuel injection valve, the fuel injection timing of the fuel injection valve, the ignition timing of the spark plug, etc. are optimally controlled by the control unit 3.

[0012] The control unit 3 is a well-known digital computer equipped with a CPU, a ROM, a RAM, and an input / output interface.

[0013] Detection signals of various sensors such as a crank angle sensor 4 that detects the crank angle of the crankshaft, an accelerator opening sensor 5 that detects the depression amount of an accelerator pedal (not shown), a vehicle speed sensor 6 that detects the vehicle speed of the vehicle, a brake switch 7 that detects the presence or absence of depression of the brake pedal, an air-fuel ratio sensor 8 that detects the exhaust air-fuel ratio of the internal combustion engine 1, an air flow meter 9 that detects the intake air amount of the internal combustion engine 1, and a throttle sensor 10 that detects the valve opening degree (throttle opening degree) of a throttle valve (not shown) that controls the intake air amount of the internal combustion engine 1 are input to the control unit 3.

[0014] The control unit 算出 the engine speed of the internal combustion engine 1 from the detection signal of the crank angle sensor 4.

[0015] The control unit 3 corresponds to a control unit, and automatically stops (idle stop) the internal combustion engine 1 when a predetermined idle stop permission condition including depression of the brake pedal is satisfied. Further, when a predetermined idle stop release condition including release of the brake pedal is satisfied during the automatic stop (idle stop) of the internal combustion engine 1, the control unit 3 restarts the internal combustion engine 1.

[0016] The conditions for enabling idle stop include, for example, the accelerator pedal not being pressed, the brake pedal being pressed, and the vehicle being stopped.

[0017] Internal combustion engine 1 will perform an idle stop when all idle stop permission conditions are met.

[0018] The conditions for disabling idle stop include, for example, the accelerator pedal being depressed and the brake pedal not being depressed.

[0019] The internal combustion engine 1 restarts if any of the idle stop release conditions are met. In other words, the internal combustion engine 1 restarts if any of the idle stop permission conditions are not met while idle stop is active.

[0020] When the internal combustion engine 1 automatically stops due to the idle stop condition being met, it takes a certain amount of time for the crankshaft to completely stop rotating. In other words, even after the idle stop condition is met, the internal combustion engine 1 continues to rotate due to inertia. As long as the crankshaft is rotating due to inertia, the internal combustion engine 1 can resume combustion operation (self-sustaining operation) by restarting fuel injection and ignition without cranking by the starter motor 2.

[0021] Furthermore, the internal combustion engine 1 has a resonant band in which resonance occurs in a rotational speed range lower than the idle speed (for example, 200 rpm to 400 rpm). In other words, the internal combustion engine 1 has a resonance band in which the engine speed is equal to the upper limit of the resonant rotational speed R. VH and the lower limit of the resonant rotational speed R VL There exists a resonant frequency band where resonance occurs when the frequency is within a certain range.

[0022] Furthermore, the internal combustion engine 1 operates at a predetermined first rotational speed R, which is lower than the idle speed. f If the above conditions are met, the engine can be restarted by resuming fuel injection and ignition. First rotation speed R f The upper limit of the resonant rotational speed is R.VH will reach a higher rotational speed. That is, when the engine speed of the internal combustion engine 1 is lower than the first rotational speed R f restart cannot be achieved by restarting fuel injection and ignition. Note that when the engine speed of the internal combustion engine 1 is at or higher than a predetermined second rotational speed higher than the first rotational speed R f restart can be surely achieved by restarting fuel injection and ignition. That is, when the engine speed of the internal combustion engine 1 is equal to or higher than the first rotational speed R f and lower than the second rotational speed, there is a possibility of restarting by restarting fuel injection and ignition.

[0023] Therefore, in the present invention, in the process of automatically stopping the internal combustion engine 1 when the idle stop condition is satisfied, that is, in the process where the idle stop condition is satisfied and the engine speed is decreasing, when there is an operation of releasing the brake pedal, an attempt is made to restart the internal combustion engine 1 by restarting fuel injection and ignition without performing cranking by the starter motor 2.

[0024] Specifically, in the present invention, in the process of automatically stopping the internal combustion engine 1 when the idle stop condition is satisfied, when there is an operation of releasing the brake pedal while the engine speed of the internal combustion engine 1 is equal to or higher than the first rotational speed R f an attempt is made to restart the internal combustion engine 1 by restarting fuel injection and ignition without performing cranking by the starter motor 2 until the engine speed of the internal combustion engine 1 becomes lower than the first rotational speed R f

[0025] Further, in the present invention, in the process of automatically stopping the internal combustion engine 1 when the idle stop condition is satisfied, when the internal combustion engine 1 does not restart until the engine speed of the internal combustion engine 1 enters the resonance band despite the operation of releasing the brake pedal, if the engine speed of the internal combustion engine 1 is lower than the resonance rotational speed lower limit value R VL which is the lower limit rotational speed of this resonance band and is lower than a preset predetermined cranking permission rotational speed R s at which cranking by the starter motor 2 is possible, wait until the engine speed becomes lower than the predetermined cranking permission rotational speed R and then attempt to restart the internal combustion engine 1 by cranking with the starter motor 2. The upper limit rotational speed of the resonance band is the resonance rotational speed upper limit value R​VH This is the case. First rotations R f and cranking permitted rotational speed R s This represents a rotational speed outside the resonant frequency range.

[0026] Figure 2 is a timing chart showing various behaviors when the internal combustion engine 1 restarts after the idle stop release condition is met, by resuming fuel injection and ignition.

[0027] Time t1 in Figure 2 is the moment when the idle stop permission condition is met and the idle stop judgment flag switches from "0" to "1". The engine speed of internal combustion engine 1 begins to decrease from the idle speed at time t1 in Figure 2.

[0028] Time t2 in Figure 2 is the moment when the brake switch 7 is switched off during the process of automatically stopping the internal combustion engine 1. In other words, time t2 in Figure 2 is the moment when the brake switch 7 is switched off during the process in which the idle stop permission condition is met and the engine speed of the internal combustion engine 1 is decreasing, and the idle stop release condition is met. Therefore, the control unit 3 attempts to restart the internal combustion engine 1 by restarting fuel injection and ignition from the moment t2 in Figure 2. At this time, the control unit 3 controls the internal combustion engine 1 so that the equivalence ratio is greater than "1". That is, from the moment t2 in Figure 2, the control unit 3 attempts to restart the internal combustion engine 1 with an air-fuel ratio richer than the stoichiometric air-fuel ratio.

[0029] Time t3 in Figure 2 is the moment when the internal combustion engine 1 resumes combustion operation (autonomous operation) due to the restart of fuel injection and ignition of the internal combustion engine 1.

[0030] Figure 3 is a timing chart showing various behaviors when the internal combustion engine 1 restarts due to the resumption of fuel injection and ignition while the accelerator pedal is pressed after the idle stop release condition has been met.

[0031] Time t1 in Figure 3 is the moment when the idle stop permission condition is met and the idle stop judgment flag switches from "0" to "1". The engine speed of internal combustion engine 1 begins to decrease from the idle speed at time t1 in Figure 3.

[0032] Time t2 in Figure 3 is the moment when the brake switch 7 is switched off during the process of automatically stopping the internal combustion engine 1. In other words, time t2 in Figure 3 is the moment when the brake switch 7 is switched off during the process in which the idle stop permission condition is met and the engine speed of the internal combustion engine 1 is decreasing, and the idle stop release condition is met. Therefore, the control unit 3 attempts to restart the internal combustion engine 1 by restarting fuel injection and ignition from the moment t2 in Figure 3. At this time, the control unit 3 controls the internal combustion engine 1 so that the equivalence ratio is greater than "1". That is, from the moment t2 in Figure 3, the control unit 3 attempts to restart the internal combustion engine 1 with an air-fuel ratio richer than the stoichiometric air-fuel ratio.

[0033] Time t3 in Figure 3 is the moment when the accelerator pedal is pressed.

[0034] Time t4 in Figure 3 is the moment when the internal combustion engine 1 resumes combustion operation (autonomous operation) due to the restart of fuel injection and ignition of the internal combustion engine 1.

[0035] Figure 4 is a timing chart showing various behaviors when the internal combustion engine 1 cannot be restarted by restarting fuel injection and ignition after the idle stop release condition is met, and is restarted by cranking.

[0036] Time t1 in Figure 4 is the moment when the idle stop permission condition is met and the idle stop judgment flag switches from "0" to "1". The engine speed of internal combustion engine 1 begins to decrease from the idle speed at time t1 in Figure 4.

[0037] Time t2 in Figure 4 is the moment when the brake switch 7 is switched off during the process of automatically stopping the internal combustion engine 1. In other words, time t2 in Figure 4 is the moment when the brake switch 7 is switched off during the process in which the idle stop permission condition is met and the engine speed of the internal combustion engine 1 is decreasing, and the idle stop release condition is met. Therefore, the control unit 3 attempts to restart the internal combustion engine 1 by restarting fuel injection and ignition from the timing of time t2 in Figure 4. At this time, the control unit 3 controls the internal combustion engine 1 so that the equivalence ratio is greater than "1". That is, from the timing of time t2 in Figure 4, the control unit 3 attempts to restart the internal combustion engine 1 with an air-fuel ratio richer than the stoichiometric air-fuel ratio.

[0038] At time t3 in Figure 4, the engine speed of internal combustion engine 1 is the first rotational speed R. f This is the timing when the value becomes less than [value missing]. At time t3 in Figure 4, the control unit 3 determines that restarting the internal combustion engine 1 is difficult with only fuel injection and ignition restart, and switches the idle stop determination flag from "0" to "1".

[0039] At time t4 in Figure 4, the engine speed of internal combustion engine 1 passes through the resonant band and reaches the cranking permission speed R. s This is the timing when the voltage drops to this level. The starter motor start request flag switches from "0" to "1" at time t4 in Figure 4. When the starter motor start request flag switches from "0" to "1", starter motor 2 cranks the internal combustion engine 1. The equivalence ratio is also controlled to become "1" from the time cranking by starter motor 2 begins.

[0040] Time t5 in Figure 4 is the point at which a predetermined time has elapsed since the cranking of the internal combustion engine 1 was determined to be fully combusted. At time t5 in Figure 4, the internal combustion engine 1 significantly retards the ignition timing, and then gradually advances the ignition timing, thereby reducing the increase in engine speed.

[0041] The starter motor start request flag switches from "1" to "0" a predetermined time after the internal combustion engine 1 has fully ignited. The starter motor 2 is stopped before the starter motor start request flag switches from "1" to "0".

[0042] As explained above, in the vehicle of the embodiment described above, in the process of the internal combustion engine 1 automatically stopping when the idle stop permission condition is met, the engine speed of the internal combustion engine 1 is the first rotational speed R f If the brake pedal is released during the above period, the system attempts to restart the internal combustion engine 1 by restarting fuel injection and ignition without cranking by the starter motor 2.

[0043] This allows the vehicle to restart the internal combustion engine 1, which has been idled, as quickly as possible.

[0044] Furthermore, in the vehicle of the above-described embodiment, the internal combustion engine 1 rotates at a first rotational speed R f The engine has a resonance band in the following rotational speed range, and in the process of automatically stopping the internal combustion engine 1 when the idle stop permission condition is met, if the brake pedal is released before the engine speed of the internal combustion engine 1 passes through the resonance band, the engine speed of the internal combustion engine 1 will reach the first rotational speed R f Until this point is reached, the system attempts to restart the internal combustion engine 1 by restarting fuel injection and ignition without cranking by the starter motor 2.

[0045] This allows the vehicle to attempt to restart the internal combustion engine 1 by restarting fuel injection and ignition without cranking by the starter motor 2. In other words, the vehicle can maximize the opportunity for the internal combustion engine 1 to restart through fuel injection and ignition.

[0046] In the vehicle of the above-described embodiment, during the process of the internal combustion engine 1 automatically stopping when the idle stop permission condition is met, if the brake pedal is released before the engine speed of the internal combustion engine 1 passes through the resonant band, and the internal combustion engine 1 does not restart before the engine speed of the internal combustion engine 1 enters the resonant band, the engine speed of the internal combustion engine 1 will reach the cranking permission speed R. s After waiting for the following conditions to be met, an attempt is made to restart the internal combustion engine 1 by cranking with starter motor 2.

[0047] As a result, even if the vehicle fails to restart the internal combustion engine 1 by fuel injection, the starter motor 2 can restart the internal combustion engine 1, allowing the engine to be restarted without delay.

[0048] Although specific embodiments of the present invention have been described above, the present invention is not limited to the embodiments described above, and various modifications are possible without departing from the spirit of the invention.

[0049] For example, the engine speed of internal combustion engine 1 is the first rotational speed R. f If the brake pedal is released during the above period, the engine speed of internal combustion engine 1 will reach the upper limit of the resonant speed R. VH The internal combustion engine 1 may be attempted to be restarted by restarting fuel injection and ignition without cranking by the starter motor 2 until the pressure drops below a certain level.

[0050] The above-described embodiment relates to a vehicle control method and a vehicle control device. [Explanation of symbols]

[0051] 1…Internal combustion engine 2… Starter motor 3…Control Unit 4…Crank angle sensor 5…Accelerator position sensor 6…Vehicle speed sensor 7...Brake switch 8…Air-fuel ratio sensor 9…Airflow meter 10…Throttle sensor

Claims

1. A vehicle control method comprising an internal combustion engine having a starter motor and a brake switch capable of detecting the depression of the brake pedal, wherein the internal combustion engine is automatically stopped when predetermined idle stop permission conditions, including the depression of the brake pedal, are met, and the internal combustion engine is restarted when predetermined idle stop release conditions, including the release of the brake pedal, A vehicle control method characterized in that, if the brake pedal is released during the process of automatically stopping the internal combustion engine after the above idle stop permission conditions are met, the vehicle attempts to restart the internal combustion engine by restarting fuel injection without cranking by the starter motor.

2. The above-mentioned internal combustion engine has a resonant band in a rotational speed range below a predetermined first rotational speed, which allows the internal combustion engine to be restarted by restarting fuel injection. The vehicle control method according to claim 1, characterized in that, in the process of automatically stopping the internal combustion engine after the above idle stop permission conditions are met, if the brake pedal is released before the engine speed of the internal combustion engine passes the above resonance band, the vehicle attempts to restart the internal combustion engine by restarting fuel injection without cranking by the starter motor until the engine speed of the internal combustion engine reaches the above first rotation speed.

3. The vehicle control method according to claim 2, characterized in that, in the process of automatically stopping the internal combustion engine when the above idle stop permission conditions are met, if the brake pedal is released before the engine speed of the internal combustion engine passes the above resonance band, and the internal combustion engine does not restart before the engine speed of the internal combustion engine enters the above resonance band, the vehicle control method is characterized in that, after waiting for the engine speed of the internal combustion engine to fall below a predetermined cranking permission speed, the vehicle control method is attempted to restart the internal combustion engine by cranking with the starter motor.

4. An internal combustion engine having a starter motor, A brake switch capable of detecting the pressure applied to the brake pedal, A vehicle control device having a control unit that automatically stops the internal combustion engine when predetermined idle stop permission conditions, including pressing the brake pedal, are met, and restarts the internal combustion engine when predetermined idle stop release conditions, including releasing the brake pedal, are met, The control unit described above is a vehicle control device characterized in that, when the brake pedal is released during the process of automatically stopping the internal combustion engine after the idle stop permission conditions are met, it attempts to restart the internal combustion engine by restarting fuel injection without cranking by the starter motor.

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