JP2012159069A - Internal combustion engine control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an internal combustion engine control device capable of improving the startability of the engine while avoiding short of charging capacity of a battery by properly carrying out fuel heating control when heating the fuel before starting the engine.SOLUTION: The reheating of the fuel is carried out when the fuel temperature is lowered during the period from the time point (in Fig.5, t2) when the first heating of the fuel is completed to the starting of the engine. Reheating number of times NRHEAT is set based on the charging capacity RCHG of the battery when starting the first heating of the fuel (in Fig.5, t0), and the reheating of the fuel is carried within the range of the reheating number of times NRHEAT. It is surely prevented that the charging capacity of the battery comes short by executing the reheating within the range of the reheating number of times NRHEAT while setting power consumption quantity a time of the reheating in a constant value.

Description

  The present invention relates to a control device for an internal combustion engine, and more particularly to a control device that heats fuel supplied to the engine before starting the engine.

  Patent Document 1 discloses a control device for an internal combustion engine that uses a fuel mainly composed of alcohol. The engine includes a vaporizing chamber connected to the intake passage, a starting fuel injection valve that injects fuel into the vaporizing chamber when the engine is started, and a heater that heats the vaporizing chamber, and is injected from the starting fuel injection valve. The vaporization of the fuel is promoted by heating the produced fuel with a heater. Heating by the heater is started when the door lock of the vehicle on which the engine is mounted is released.

JP 2007-224878 A

  Since the above-described conventional apparatus promotes fuel vaporization by reducing the pressure in the vaporization chamber and saves power consumption of the heater, the heater is not energized in consideration of the charge capacity of the battery. . Therefore, heating of the heater is started when the door lock is released, and if the period until the driver starts starting becomes longer, the power consumption of the heater increases and the battery charge capacity becomes insufficient (the battery rises). )there is a possibility. Moreover, in order to avoid the battery running out, it is conceivable to stop energization when the heater energization time becomes long, but in that case, if the heater energization stop and restart control is not properly performed, It may be difficult to start the engine.

  The present invention has been made paying attention to the above-mentioned points, and appropriately performs fuel heating control when heating the fuel before starting the engine to improve the startability of the engine while avoiding the shortage of the battery charge capacity. It is an object of the present invention to provide a control device for an internal combustion engine that can be made to operate.

  In order to achieve the above object, an invention according to claim 1 is directed to a control apparatus for an internal combustion engine comprising fuel heating means for heating fuel supplied to the engine before starting the internal combustion engine using electric power supplied from a battery. And reheating means for heating the fuel again when the fuel temperature (TFUEL) decreases during a period from the end of heating by the fuel heating means (t2) to the start of the engine (t4). A heating limit number setting means for setting a heating limit number of times (NRHEAT) by the reheating means based on a charge capacity (BRCHG) of the battery when heating by the fuel heating means is started (t0). The reheating means reheats the fuel within the range of the heating limit number (NRHEAT).

  According to a second aspect of the present invention, in the control device for an internal combustion engine according to the first aspect, the reheating means includes a temperature parameter calculating means for calculating a temperature parameter (QHFUEL) indicating the fuel temperature, The reheating is performed when a temperature parameter (QHFUEL) falls below a predetermined threshold value (QHRHEAT), and the temperature parameter calculation unit is configured to perform the operation according to an elapsed time from the end point (t2) of heating by the fuel heating unit. A temperature parameter (QHFUEL) is calculated.

  According to the first aspect of the present invention, the fuel is heated again when the fuel temperature decreases during the period from the end of the heating of the fuel to the start of the engine. When starting the initial heating of the fuel, the heating limit number is set based on the charge capacity of the battery, and the fuel is reheated within the range of the heating limit number. By setting in advance the power consumption per reheating and executing the reheating within the range of the number of heating limits, it is possible to reliably avoid a shortage of battery charge capacity. Further, the engine startability can be improved within the range of the battery charge capacity at the start of heating.

  According to the second aspect of the present invention, the temperature parameter indicating the fuel temperature is calculated according to the elapsed time from the end of the first heating, and reheating is performed when the temperature parameter falls below a predetermined threshold value. Is called. Therefore, fuel heating control can be appropriately executed without providing a sensor for detecting the fuel temperature.

It is a figure which shows the structure of the internal combustion engine and its control apparatus concerning one Embodiment of this invention. It is a flowchart of the process which performs the heating control of a fuel. It is a flowchart of the reheating process performed by the process of FIG. It is a figure which shows the map referred by the process of FIG. It is a time chart for demonstrating the process of FIG.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a diagram showing a configuration of an internal combustion engine and a control device thereof according to an embodiment of the present invention. An internal combustion engine (hereinafter referred to as “engine”) 1 is a four-cylinder engine that can be operated using alcohol or a mixture of alcohol and gasoline as fuel. The intake pipe 2 of the engine 1 is provided with a throttle valve 3, and the fuel injection valve 6 is an intake valve (not shown) between the engine 1 and the throttle valve 3 in the middle of the intake pipe 2. A little upstream is provided for each cylinder.

  The fuel injection valve 6 is connected to a fuel tank (not shown) via a fuel supply passage 8, and a heater 7 for heating the fuel in the fuel supply passage 8 is provided in the vicinity of the fuel injection valve 6. ing. The fuel injection valve 6 and the heater 7 are connected to an electronic control unit (hereinafter referred to as “ECU”) 5, and the operation of the ECU 5 is controlled by the ECU 5.

  A cooling water temperature sensor 4 for detecting the cooling water temperature TW of the engine 1 is mounted on the main body of the engine 1, and the detection signal is supplied to the ECU 5. Each cylinder of the engine 1 is provided with a spark plug 9, and an ignition signal is supplied to the spark plug 9 from the ECU 5.

  The ECU 5 detects an outside air temperature sensor 10 that detects the outside air temperature TA, and an input / output current (charging current and discharging current) IB of a battery (not shown) that supplies power to the heater 7, the fuel injection valve 6, and the like. A current sensor 11 and a battery voltage sensor 12 for detecting the output voltage VB of the battery are connected, and detection signals from these sensors are supplied to the ECU 5. By monitoring the input / output current IB of the battery, the battery capacity (remaining charge capacity) BRCHG is detected.

The ECU 5 controls the operation of the fuel injection valve 6, the spark plug 9, and the heater 7 based on detection signals from the sensor and other sensors (not shown).
The ECU 5 shapes input signal waveforms from various sensors, corrects the voltage level to a predetermined level, converts an analog signal value into a digital signal value, etc., and a central processing unit (hereinafter referred to as “CPU”). A storage circuit for storing various calculation programs executed by the CPU, calculation results, and the like, an output circuit for supplying drive signals to the fuel injection valve 6, the heater 7, the spark plug 9, and the like.

  FIG. 2 is a flowchart of a process for controlling the fuel heating by the heater 7. This process is started by the CPU of the ECU 5 in accordance with, for example, an instruction by a driver's remote control operation, and thereafter executed every predetermined time.

  In step S11, it is determined whether or not the initialization flag FINI is “1”. Initially, since the initialization flag FINI is “0”, the process proceeds to step S12, and the NRHEAT map shown in FIG. 4A is searched according to the battery capacity (remaining charge amount) BRCHG and the outside temperature TA, and the number of heating limits NRHEAT is calculated. TA0, TA1, and TA2 in FIG. 4A are predetermined outside air temperatures and are set so as to satisfy the relationship TA0 <TA1 <TA2 (for example, −10 ° C., −5 ° C., and 0 ° C., respectively). . That is, the NRHEAT map map is set such that the heating limit frequency NRHEAT increases as the battery capacity BRCHG increases, and the heating limit frequency NRHEAT increases as the outside air temperature TA increases.

  In step S13, the value of the reheating number counter CRHEAT is set to the heating limit number NRHEAT. In step S14, the initialization flag FINI is set to “1”. By setting the initialization flag FINI to “1”, the process proceeds from step S11 to step S15 immediately after the next execution of this process.

  In step S15, a current heat quantity QHFUEL indicating the current holding heat quantity of the fuel to be heated is calculated. Specifically, in the heating mode (mode in which initial heating and reheating described later) are performed to increase the temperature (heat amount) of the fuel, the duty DUTY (supply heat amount) of the current supplied to the heater 7, the outside air temperature TA, In the heat retention mode in which the current heat quantity QHFUEL is calculated according to the elapsed time TS from the current supply start time and the current heat quantity QHFUEL is maintained, the current heat quantity QHFUEL is held at the previous value, and in the leaving mode in which no current is supplied to the heater 7 The QHFUEL map shown in FIG. 4B is searched according to the elapsed time TC and the outside air temperature TA from when the current supply is stopped, and the current heat quantity QHFUEL is calculated. The QHFUEL map shown in FIG. 4B is set such that the current heat quantity QHFUEL decreases as the elapsed time TC increases, and the current heat quantity QHFUEL increases as the outside air temperature TA increases.

  In step S16, it is determined whether or not the current heat quantity QHFUEL is equal to or greater than a predetermined target heat quantity QHCMD. If the answer is negative (NO), the downcount timer TMHOLD is set to a predetermined holding time THOLD and started. (Step S17). In step S18, the heating mode duty DTYHEAT is calculated by searching a DTYHEAT map (not shown) set in accordance with the outside air temperature TA. The DTYHEAT map is set such that the heating mode duty DTYHEAT decreases as the outside air temperature TA increases, and the heating mode duty DTYHEAT increases as the alcohol concentration in the fuel increases.

  In step S19, the current duty DUTY supplied to the heater 7 is set to the heating mode duty DTYHEAT. Thereby, the fuel is heated by the heater 7.

  If the answer to step S16 is affirmative (YES), that is, if the current heat amount QHFUEL is equal to or greater than the target heat amount QHCMD, it is determined whether or not the value of the timer TMHOLD is “0” (step S20). Since the answer to this question is initially negative (NO), the process proceeds to step S21, and a DTYHOLD map (not shown) set in accordance with the outside air temperature TA is searched to calculate the heat retention mode duty DTYHOLD. The DTYHOLD map is set such that the heat retention mode duty DTYHOLD decreases as the outside air temperature TA increases, and the heat retention mode duty DTYHOLD increases as the alcohol concentration in the fuel increases.

In step S22, the current duty DUTY is set to the heat retention mode duty DTYHOLD. Thereby, the heat insulation of the fuel by the heater 7 is performed.
When the value of the timer TMHOLD becomes “0”, the process proceeds from step S20 to step S23, and the reheating process shown in FIG. 3 is executed.

  In step S31 of FIG. 3, it is determined whether or not the reheating prohibition flag FRHIN is “1”. At first, since the reheating prohibition flag FRHIN is “0”, the process proceeds to step S32, and it is determined whether or not the current heat quantity QHFUEL is equal to or less than the reheating determination threshold value QHRHEAT. If this answer is negative (NO), the current duty DUTY is set to “0” (step S37), and this process is terminated.

  If the answer to step S32 is affirmative (YES) and the current heat quantity QHFUEL is equal to or less than the reheating determination threshold value QHRHEAT, it is determined whether or not the value of the reheating number counter CRHEAT is “0” (step S33). ). Initially, the answer is negative (NO), so the process proceeds to step S34, the value of the reheating number counter CRHEAT is decreased by "1", and the current duty DUTY is set to a predetermined reheating mode duty DTYRHEAT (step S35), reheating is executed. In the reheating mode, only one energization with a set current duty is executed (for example, an amount of heat corresponding to 500 J is applied).

  If reheating is executed for the number of times set in the reheating number counter CRHEAT, the answer to step S33 is affirmative (YES), so the process proceeds to step S36, and the current duty DUTY is set to “0” and reheating is prohibited. The flag FRHIN is set to “1”.

  FIG. 5 is a time chart for explaining the transition of the fuel temperature TFUEL in the present embodiment. TEST shown in this figure is the lowest startable fuel temperature (hereinafter referred to as “startable temperature threshold”).

  At time t0, for example, when fuel heating is instructed by a remote control key, the process of FIG. 2 is started. At this time, the reheat count NRHEAT is calculated and the reheat counter CRHEAT is set according to the battery capacity BRCHG and the outside air temperature TA, and the heating mode is started. Therefore, the fuel temperature TFUEL increases.

  At time t1, the current heat quantity QHFUEL reaches the target heat quantity QHCMD and shifts to the heat retention mode. At time t2 when a predetermined holding time THOLD has elapsed from time t1, the heat retention mode ends, and the mode shifts to the neglect mode.

  At time t3, the current heat quantity QHFUEL becomes equal to or less than the reheating determination threshold value QHRHEAT, and reheating is executed (four times in the illustrated example). By executing the reheating, the fuel temperature TFUEL does not fall below the startable temperature threshold value TEST, and the fuel temperature TFUEL can be reliably started when the driver gives an instruction to start the engine at time t4. If reheating is not performed, the fuel temperature TFUEL decreases as shown by the broken line in FIG. 5, and the engine cannot be started at time t4.

  As described above, in the present embodiment, the fuel is reheated when the fuel temperature is lowered during the period from the end of the initial heating of the fuel (FIG. 5, t2) to the start of the engine. When the first heating of the fuel is started (FIG. 5, t0), the reheating frequency NRHEAT is set based on the battery charge capacity BRCHG, and the fuel is reheated within the range of the reheating frequency NRHEAT. The power consumption per reheating is set to a value corresponding to, for example, 500 J. Therefore, by executing reheating within the range of the reheating frequency NRHEAT, the battery charge capacity BRCHG is insufficient. While avoiding reliably, engine startability can be improved within the range of the battery charge capacity BRCHG at the heating start time (t0). In addition, in order to determine whether or not the battery capacity BRCHG can be heated each time reheating is performed, it is necessary to grasp the accurate battery capacity BRCHG every time, whereas in this embodiment, heating is started. When recognizing the battery capacity BRCHG only once, reheating can be appropriately executed.

  Further, the current heat quantity QHFUEL correlated with the fuel temperature TFUEL is calculated according to the elapsed time TC from the end point (t2) of the first heating, and the reheating is performed when the current heat quantity QHFUEL falls below the reheating determination threshold value QHRHEAT. Is done. Therefore, fuel heating control can be appropriately executed without providing a sensor for detecting the fuel temperature TFUEL.

  In this embodiment, the heater 7 constitutes a part of the fuel heating means and the reheating means, and the ECU 5 constitutes a part of the fuel heating means and the reheating means, a heating limit number setting means, and a temperature parameter calculation means. . Specifically, steps S15 to S22 in FIG. 2 correspond to the fuel heating means, the processing in FIG. 3 corresponds to the reheating means, and steps S12 and S13 in FIG. 2 correspond to the heating limit number setting means. S15 corresponds to temperature parameter calculation means.

  The present invention is not limited to the embodiment described above, and various modifications can be made. For example, in the above-described embodiment, the current heat quantity QHFUEL indicating the amount of heat held by the fuel to be heated is used as a temperature parameter. May be. Further, a fuel temperature sensor that detects the fuel temperature in the vicinity of the heater 7 may be provided, and the detected fuel temperature may be used as a temperature parameter.

In the map search shown in FIG. 4, the outside air temperature TA is used, but the engine cooling water temperature TW detected by the cooling water temperature sensor 4 may be used instead.
The present invention is applicable not only to an internal combustion engine that uses alcohol or a mixed fuel of alcohol and gasoline, but also to a diesel internal combustion engine that uses light oil as a fuel. The present invention can also be applied to the control of such marine propulsion engine.

1 Internal combustion engine 5 Electronic control unit (fuel heating means, reheating means, heating limit number setting means, temperature parameter calculation means)
6 Fuel injection valve 7 Heater (fuel heating means, reheating means)
8 Fuel supply passage

Claims (2)

In a control device for an internal combustion engine comprising fuel heating means for heating fuel supplied to the engine before starting the internal combustion engine using electric power supplied from a battery,
Reheating means for reheating the fuel when the fuel temperature decreases during a period from the time when heating by the fuel heating means is completed to the start of the engine;
A heating limit number setting means for setting a heating limit number of times by the reheating means based on a charge capacity of the battery when heating by the fuel heating means is started,
The control apparatus for an internal combustion engine, wherein the reheating means reheats the fuel within a range of the heating limit number. The reheating means has temperature parameter calculation means for calculating a temperature parameter indicating the fuel temperature, and performs the reheating when the temperature parameter falls below a predetermined threshold value,
2. The control device for an internal combustion engine according to claim 1, wherein the temperature parameter calculation unit calculates the temperature parameter according to an elapsed time from the end of heating by the fuel heating unit.

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