JP2013024157A - Engine stop/start control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase the opportunity of implementing idling stop even in the state where the charging state of a battery is low or the temperature of the battery is low.SOLUTION: An engine stop/start control device includes a voltage detection means for detecting the voltage of a battery. When an automatic stop inhibition condition where a battery temperature detected by a battery temperature detection means is equal to or lower than a preset temperature, is established, a control means executes automatic stop inhibition control for performing control not to automatically stop an engine even when the engine automatic stop condition is established. Even under the establishment of the automatic stop inhibition control, the lowest voltage of a battery voltage that is reduced when starting the engine is detected by the voltage detection means and on the basis of the lowest voltage, the charging rate threshold value of the battery to permit the engine automatic stop is set and when the charging rate of the battery is higher than the charging rate threshold value, the engine is controlled to be automatically stopped.

Description

  The present invention relates to an engine stop / start control device, and more particularly, to an engine stop / start control device capable of increasing the chance of an idle stop for automatically stopping an engine.

2. Description of the Related Art There is an engine stop / start control device that performs a so-called idling stop (automatic engine stop) when a predetermined condition is satisfied for the purpose of reducing fuel consumption of a vehicle and reducing emissions.
As the engine restart control after idling stop by the conventional engine stop / start control device, the starter torque is limited from the temperature of the starter battery as disclosed in Japanese Patent Application Laid-Open Nos. 2004-044522 and 2007-321651. By doing so, there was something that prevented the voltage drop of the battery.

JP 2004-044522 A JP 2007-321651 A

However, the control disclosed in the above publication has a problem in that it takes time to automatically restart the engine at a low temperature, resulting in a delay in traveling. In vehicles with an idling stop function that has been released recently, when the battery temperature or the environmental temperature is about 0 ° C. or less, the idling stop is prohibited and the engine is not automatically restarted. There is a problem that idling stops can hardly be implemented in winter.
If the vehicle is not used for a long period of time, the voltage of the battery decreases, and charging from the alternator by operating the engine is required. For this reason, in vehicles that have not been used for a long period of time, there is also a problem that it takes time (due to charging from the alternator) until control of idling stop is permitted. Therefore, it is not possible to reduce fuel consumption or emissions.

  An object of the present invention is to increase the chances of performing idling stop even in a state where the state of charge of the battery is low (the battery voltage is low) or the temperature of the battery is low.

  The present invention includes an engine starting means for starting an engine, a battery for supplying electric power to the engine starting means, a battery temperature detecting means for detecting the temperature of the battery, and the engine automatically when a predetermined engine automatic stop condition is satisfied. In the engine stop / start control device comprising: a control means for stopping and restarting the engine when a predetermined engine automatic start condition different from the engine automatic stop condition is satisfied during the automatic stop of the engine, the voltage of the battery is detected Voltage detecting means for controlling the engine, and the control means is configured such that when the automatic stop prohibition condition is satisfied when the battery temperature detected by the battery temperature detecting means is equal to or lower than a preset temperature, the engine automatic stop condition is satisfied. In addition to executing automatic stop prohibition control to prevent automatic stop Even when the automatic stop prohibition condition is satisfied, the voltage detection means detects the minimum battery voltage that drops when the engine starts, and based on this minimum voltage, the battery charge rate threshold for permitting automatic engine stop is determined. A value is set, and when the charging rate of the battery is higher than the charging rate threshold, the engine is controlled to automatically stop.

  The engine stop start control device of the present invention automatically stops the engine when the battery charge rate is higher than the charge rate threshold even when the battery temperature is low or the battery charge amount is small. Opportunities to perform idling stop can be increased. Therefore, the engine stop / start control device of the present invention can reduce fuel consumption.

FIG. 1 is a system block diagram of an engine stop / start control device. (Example) FIG. 2 is a diagram showing a map 1 of the initial charge amount determined by the battery voltage before starting the engine. (Example) FIG. 3 is a diagram showing a charge rate threshold value set according to the minimum voltage of the battery at the time of starting the engine and a map 2 of discharge rate threshold values set corresponding to the charge rate threshold value. (Example) FIG. 4 is a diagram showing a discharge rate threshold value determined by the amount of charge during idling. (Example) FIG. 5 is a flowchart of the engine stop / start control device. (Example) FIG. 6 is a time chart of the engine stop / start control device. (Example)

  Embodiments of the present invention will be described below with reference to the drawings.

1 to 6 show an embodiment of the present invention. In FIG. 1, 1 is an engine mounted on a vehicle, and 2 is an engine stop / start control device. The engine stop / start control device 2 includes an engine starter 3 such as a starter that starts the engine 1, a battery 4 that supplies power to the engine starter 3, a battery temperature detector 5 that detects the temperature of the battery 4, and a battery Voltage detecting means 6 for detecting the voltage 4, electric power generating means 7 such as an alternator driven by the engine 1 to charge the battery 4, and control means 8 for controlling the engine 1 to stop and start. .
The control means 8 automatically stops the engine 1 when a predetermined engine automatic stop condition is satisfied, and restarts the engine 1 when a predetermined engine automatic start condition different from the engine automatic stop condition is satisfied during the automatic stop of the engine 1. .

The control means 8 of the engine stop / start control device 2 controls the engine 1 even when the engine automatic stop condition is satisfied when the automatic stop prohibition condition is satisfied when the battery temperature detected by the battery temperature detection means 5 is equal to or lower than a preset temperature. The automatic stop prohibition control is executed to control so as not to stop automatically.
Further, the control means 8 detects the lowest voltage of the battery voltage that drops when the engine is started by the voltage detection means 6, and sets the charging rate threshold value of the battery 4 that permits automatic engine stop based on the lowest voltage, Even when the automatic stop prohibition condition is satisfied, the engine 1 is controlled to automatically stop when the charging rate of the battery 4 is higher than the set charging rate threshold.
Further, the control means 8 sets a discharge rate threshold value of the battery 4 necessary for restarting the engine 1 during the engine automatic stop based on the minimum voltage at the time of engine start, and the battery 4 during the engine automatic stop. When the discharge rate is higher than the set discharge rate threshold, the engine 1 is controlled to restart.

Considering the start of the engine 1, basically, in the engine start by key operation, the friction of the engine 1 is the highest, and the battery temperature and voltage are the lowest, so if the engine can be started by key operation, If the temperature and charge state of the battery 4 at the time of automatic engine start after automatic engine stop (idling stop) exceed the state at the time of start by key operation (or the previous automatic start), automatic start is possible.
This engine stop / start control device 2 permits idling stop depending on the state of the battery 4 being started from immediately before the start of the engine by the first key operation and the change in the state of charge (SOC and charge amount) of the battery 4 thereafter. And determine when to restart the engine. The engine stop / start control device 2 performs idling stop even when the battery temperature in winter is low or when the state of charge (SOC) of the battery 4 is lowered due to long-term leaving of the vehicle or the like and before the full charge is completed. Allow under certain conditions.

Next, the operation of the engine stop / start control device 2 will be described along the flowchart of FIG. 5 with reference to maps 1 to 3 of FIGS.
In FIG. 5, the engine stop / start control device 2 starts the determination of permission for idling- ₁ engine stop (automatic engine stop) (S01), and when the key is operated to start the engine 1 (S02), the engine start means 3 is driven to start the engine 1. The voltage V of the battery 4 immediately before the start of the engine start is measured (S03), and the current i, the temperature T, and the voltage V of the battery 4 are measured simultaneously with the start of the engine start (S04).
When the start of the engine 1 is completed (S05), the initial charge state SOCi is determined from the voltage V immediately before the engine start using the map 1 (FIG. 2) (S06), and current integration is performed based on the initial charge state SOCi. The current state of charge SOCx is calculated (SOCx = SOCx− ₁ + i * t / 3600 / Fc * 100, the first time SOCx− ₁ = SOCi) (S07).
When the start of the engine 1 is completed (S05), on the other hand, the minimum voltage Vmin of the battery voltage that drops during engine start is calculated (S08), and idling is performed from the minimum voltage Vmin using the map 2 (FIG. 3). The charging rate threshold value X of the battery 4 that permits the stop is set (S09), and the current charging rate of the battery 4 is calculated (charging rate = i * t / 3600 / Fc * 100) (S10).

Subsequent to the processes (S07) and (S10), the state of charge SOC at the time point (S11) when the vehicle speed (for example, 0 km / h) at which idling is stopped exceeds a predetermined value (for example, 80%). (S12).
If this determination (S12) is YES, it is determined whether the temperature T of the battery 4 exceeds a predetermined value (for example, −10 ° C.) (S13).
If this determination (S13) is YES, the map 3 (FIG. 4) is used to determine the dischargeable discharge rate threshold value Z (time t1 × current) at which the eye drink can be stopped from the current state of charge SOCx. (S14), the idling stop permission (normal) state is entered (S15), and the engine 1 is automatically stopped to perform idling stop.
During the idling stop, the discharge rate is calculated (discharge rate = i * t / 3600 / Fc * 100) (S16), and it is determined whether the discharge rate exceeds the discharge rate threshold value Z (S17), Eye drink stop is continued until the discharge rate reaches the discharge rate threshold value Z.
If the determination (S17) is NO, this determination (S17) is repeated. If the determination (S17) is YES, the engine 1 is automatically started (S18), and the process returns to the measurement of the current i, temperature T, and voltage V of the battery 4 at the time of engine start (S04).

On the other hand, when the state of charge SOC at a time point (S11) at which the vehicle speed (for example, 0 km / h) at which the idling stop is performed is not more than a predetermined value (for example, 80%) and the determination (S12) is NO, It is determined whether the charging rate exceeds the charging rate threshold value X (S19).
If this determination (S19) is YES, an idling stop permission (short term) state is entered (S20), and the engine 1 is automatically stopped to perform idling stop.
During the idling stop, the discharge rate is calculated (discharge rate = i * t / 3600 / Fc * 100) (S21), and the discharge rate threshold Y corresponding to the charge rate threshold value X (time) It is determined whether or not (t2 × current) has been exceeded (S22), and the eye drink stop is continued until the discharge rate reaches the discharge rate threshold value Y.
If the determination (S22) is NO, this determination (S22) is repeated. If the determination (S22) is YES, the engine 1 is automatically started (S18), and the process returns to the measurement of the current i, temperature T, and voltage V of the battery 4 at the time of engine start (S04).
If the determination (S19) is NO, the idle stop prohibition state is set (S23), and the process returns to the processing after the completion of engine start (S05).
If the determination (13) is NO, it is determined whether the charging rate exceeds the charging rate threshold value X (S19). If the determination (S19) is YES, idling stop permission (short term) is determined. A state is reached (S20), and the engine 1 is automatically stopped to perform idling stop. That is, if the state of charge SOC exceeds a predetermined value (for example, 80%), the idling stop is permitted in a short period even if the temperature T of the battery 4 is lower than the predetermined value (for example, −10 ° C.).

Next, the operation of the engine stop / start control device 2 will be described with reference to the time chart of FIG.
In FIG. 6, when the engine start means (starter) 3 is driven by key operation in FIG. 6 to start the engine 1 (t1), the engine stop / start control device 2 adjusts the current / temperature / voltage of the battery 4 simultaneously with the engine start. Start measurement.
Immediately after the start of the engine 1 is completed (t2), the state of charge SOCi and the minimum voltage Vmin are determined (t3). As a vehicle, the vehicle speed is 0 km / h, the engine 1 continues in the idling state (A), the battery 4 is charged with the electric power from the electric power generation means 7 (alternator), and the charging rate increases. In addition, the state of charge SOC also increases.
When the vehicle speed starts to increase (t4) and the charging rate exceeds the charging rate threshold value X in the running state, an idling stop permission (short term) state is set (t5).
When the vehicle speed reaches 0 km / h in the idling stop permission (short term) state (t6), the engine 1 is automatically stopped and the idling stop state (B) is entered. In the idling stop state (B), when the discharge rate exceeds the discharge rate threshold value Y (t7), the engine starting means (starter) 3 is driven to forcibly automatically restart the engine 1. Here, the vehicle speed is 0 km / h, and the vehicle is in an idling state (C).

Even if the vehicle speed starts to increase (t8), the vehicle speed reaches 0 km / h again (t9) when the vehicle is in a running state, the charging rate does not exceed the charging rate threshold value X. The idling state (D) is entered without performing the above.
When the vehicle speed starts increasing again and the charging rate exceeds the charging rate threshold value X during traveling (t10), an idling stop permission (short-term) state is entered. When the vehicle continues to travel, the charging rate further increases, and the state of charge SOC exceeds a predetermined value (for example, 80%) (t11), an idling stop permission (normal) state is entered.
Next, when the vehicle speed reaches 0 km / h (t12), the engine 1 is automatically stopped to enter an idling stop state (E). In the idling stop state (E), when the driver releases the brake, the engine 1 is automatically started (t13), and the running state is entered.
At this time, the state of charge SOC is a predetermined value (for example, 80%) or less, and the idling stop permission (normal) state is cancelled, but the discharge rate does not exceed the discharge rate threshold value Y, so the idling is performed. The stop permission (short term) state is maintained.
When charging proceeds during traveling and the state of charge SOC exceeds 80% (t14), an idling stop permission (normal) state is entered.

Thus, when the temperature of the battery 4 is low, or when the charge amount of the battery 4 is small, the engine stop / start control device 2 is used when the charge rate of the battery 4 is higher than the charge rate threshold value X. Since the engine 1 is automatically stopped, the opportunity to perform idling stop can be increased. Therefore, the engine stop / start control device 2 can reduce fuel consumption.
The engine stop / start control device 2 sets a discharge rate threshold value Y of the battery 4 for restarting the engine 1 during the engine automatic stop based on the minimum voltage Vmin at the time of engine start, and the battery during the engine automatic stop. When the discharge rate of 4 is higher than the discharge rate threshold value Y, the engine 1 is controlled to restart.
As a result, the engine stop / start control device 2 can continue the idling stop state as much as possible while avoiding that the amount of charge of the battery 4 is reduced too much and the engine cannot be restarted. Therefore, the engine stop / start control device 2 can reduce fuel consumption.

  This invention can increase the chance of idling stop even when the state of charge of the battery is low or the temperature of the battery is low, and is not limited to a vehicle equipped with an engine, and is equipped with an engine and a motor. It can also be applied to HEV (hybrid electric vehicle) engine automatic start control.

DESCRIPTION OF SYMBOLS 1 Engine 2 Engine stop start control apparatus 3 Engine start means 4 Battery 5 Battery temperature detection means 6 Voltage detection means 7 Electric power generation means 8 Control means

Claims (2)

  Engine starting means for starting the engine, battery for supplying electric power to the engine starting means, battery temperature detecting means for detecting the temperature of the battery, and automatically stopping the engine when a predetermined engine automatic stop condition is satisfied, In the engine stop / start control apparatus, the voltage detection means for detecting the voltage of the battery, comprising: a control means for restarting the engine when a predetermined engine automatic start condition different from the engine automatic stop condition is satisfied during the automatic engine stop The control means does not automatically stop the engine even if the automatic engine stop condition is satisfied when the automatic stop prohibition condition is satisfied when the battery temperature detected by the battery temperature detection means is equal to or lower than a preset temperature. The automatic stop prohibition control is performed so that the automatic stop Even if the prohibition condition is satisfied, the voltage detection means detects the lowest voltage of the battery voltage that drops when the engine starts, and sets the battery charge rate threshold value that permits automatic engine stop based on the lowest voltage The engine stop / start control device controls the engine to automatically stop when the charge rate of the battery is higher than the charge rate threshold.   The control means sets a discharge rate threshold value of the battery for restarting the engine during automatic engine stop based on the minimum voltage, and the discharge rate of the battery during the automatic engine stop is the threshold discharge rate. 2. The engine stop / start control apparatus according to claim 1, wherein control is performed so that the engine is restarted when the value is higher than the value.

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