JP2014025446A - Control device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control device for internal combustion engine capable of effectively avoiding an increase in cranking time.SOLUTION: An ECU 0 as a control device for internal combustion engine determines whether a battery voltage value at a start is less than a predetermined value v2 at which cranking is performed normally. When the battery voltage value is less than the predetermined value v2, the ECU calculates a deficient torque from a difference between a torque obtained when cranking is performed at the predetermined value v2 and a torque obtained when cranking is performed at a battery voltage value less than the predetermined value v2, makes an advance correction on an ignition period as a correction on a combustion control parameter for increasing the torque by combustion so as to compensate for the deficient torque, and then starts the cranking.

Description

  The present invention relates to a control device for stably starting an internal combustion engine.

  Conventionally, various techniques for stably starting an internal combustion engine even during a cold start have been proposed (see, for example, Patent Document 1).

  In the one described in Patent Document 1, the starter energization time at the start of the internal combustion engine, that is, the cranking time is measured so that the engine can be stably started even at the cold start when the battery voltage is lowered. When the cranking time exceeds a predetermined time, it is determined that the torque is insufficient due to a decrease in the battery voltage, and the ignition timing advance correction is performed as a correction of the combustion control parameter for increasing the torque in order to eliminate the torque shortage. Is to do.

  However, in the case of Patent Document 1, the start itself can be performed stably even when the battery voltage is lowered, but the advance correction is always performed after the cranking time exceeds a predetermined time. . In other words, in consideration of the fact that the cranking time does not exceed the predetermined time at the normal time when the advance angle correction is not performed, the cranking time is obviously longer when the battery voltage is lowered. Such a prolonged cranking time makes the driver accustomed to the normal cranking time uncomfortable. In particular, it is becoming common to implement an idling stop system that automatically stops idling rotation of an internal combustion engine during a signal stop or other temporary stop. Then, when restarting from the idling stop that is frequently performed during normal operation, the above-described discomfort is frequently given to the driver at each restart.

Japanese Patent Publication No. 63-28236

  The present invention focuses on such a problem, and an object of the present invention is to provide a control device for an internal combustion engine that can effectively avoid an increase in the cranking time.

  In order to achieve such an object, the present invention takes the following measures.

  That is, the control device for an internal combustion engine according to the present invention determines whether or not the battery voltage value is lower than a predetermined value at which the cranking can be normally performed at the start, and when the battery voltage value is lower than the predetermined value, Calculate the missing torque from the difference between the torque obtained when cranking at the predetermined value and the torque obtained when cranking at the battery voltage value lower than the predetermined value, and compensate for this insufficient torque. The combustion control parameter for increasing the torque due to combustion is corrected so as to obtain, and cranking is started after that.

  Here, the “predetermined value” of the battery voltage is not limited to a predetermined invariable value, and may be a value that varies depending on, for example, the engine temperature or other requirements.

  If this is the case, the sum of the torque of the cell motor used for cranking and the torque due to combustion is set larger than a predetermined value because the torque due to combustion is already increased by correcting the fuel control parameter at the start of cranking. be able to. As a result, it is possible to effectively avoid unnecessarily prolonging the cranking time even if the battery voltage deteriorates due to deterioration of the battery or low temperature, and it is possible to realize a comfortable start without causing the driver to feel uncomfortable. Become.

  Further, the combustion control parameter refers to a parameter that can increase the output of the internal combustion engine at the time of starting. Specifically, the ignition timing can be advanced or the fuel injection amount can be increased. However, in order to ensure the above effect while suppressing fuel consumption, correction of the combustion control parameter is required. It is more desirable to apply a correction to advance the ignition timing.

  ADVANTAGE OF THE INVENTION According to this invention, the control apparatus of the internal combustion engine which can avoid effectively the prolongation of cranking time can be provided.

The figure which shows the whole structure of the internal combustion engine in one Embodiment of this invention. The graph which shows the correlation with the ignition timing and torque of the internal combustion engine which concerns on the same embodiment. The graph which shows the correlation with the battery voltage and ignition timing. The graph which shows the correlation with the battery voltage and cranking rotation speed. The graph which shows the correlation with the battery voltage and cranking time.

  An embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows an outline of an internal combustion engine for a vehicle in the present embodiment.

  The internal combustion engine in the present embodiment is a spark ignition gasoline engine and includes a plurality of cylinders 1 (one of which is shown in FIG. 1). In the vicinity of the intake port of each cylinder 1, an injector 11 for injecting fuel is provided. A spark plug 12 is attached to the ceiling of the combustion chamber of each cylinder 1. The spark plug 12 receives spark voltage generated by the ignition coil and causes spark discharge between the center electrode and the ground electrode. The ignition coil is integrally incorporated in a coil case together with an igniter that is a semiconductor switching element.

  The intake passage 3 for supplying intake air takes in air from the outside and guides it to the intake port of each cylinder 1. On the intake passage 3, an air cleaner 31, an electronic throttle valve 32, a surge tank 33, and an intake manifold 34 are arranged in this order from the upstream.

  The exhaust passage 4 for discharging the exhaust guides the exhaust generated as a result of burning the fuel in the cylinder 1 from the exhaust port of each cylinder 1 to the outside. An exhaust manifold 42 and an exhaust purification three-way catalyst 41 are disposed on the exhaust passage 4.

  An ECU (Electronic Control Unit) 0 that is a control device of the present embodiment is a microcomputer system having a processor, a memory, an input interface, an output interface, and the like.

  The input interface includes a vehicle speed signal a output from a vehicle speed sensor that detects the actual vehicle speed of the vehicle, a crank angle signal (N signal) b output from an engine rotation sensor that detects the rotation angle of the crankshaft and the engine speed, An accelerator opening signal c output from a sensor that detects the amount of depression of the accelerator pedal or the opening of the throttle valve 32 as an accelerator opening (so-called required load), and a brake that is output from a sensor that detects the amount of depression of the brake pedal Stepping amount signal d, intake air temperature / intake pressure signal e output from a temperature / pressure sensor for detecting intake air temperature and intake pressure in intake passage 3 (especially surge tank 33), water temperature sensor for detecting engine cooling water temperature A coolant temperature signal f output from a battery voltage signal g output from a voltmeter (not shown) that detects the battery voltage, A cam angle signal output from cam angle sensor at a plurality of cam angle of the gas camshaft or an exhaust camshaft (G signal) h or the like is input.

  From the output interface, an ignition signal i is output to the igniter of the spark plug 12, a fuel injection signal j is output to the injector 11, an opening operation signal k is output to the throttle valve 32, and the like.

  The processor of the ECU 0 interprets and executes a program stored in the memory in advance, calculates operation parameters, and controls the operation of the internal combustion engine. The ECU 0 acquires various information a, b, c, d, e, f, g, and h necessary for operation control of the internal combustion engine via the input interface, knows the engine speed, and is filled in the cylinder 1. Estimate the intake volume. Based on the engine speed, the intake air amount, etc., various operating parameters such as required fuel injection amount, fuel injection timing (including the number of times of fuel injection for one combustion), fuel injection pressure, and ignition timing are determined. . As the operation parameter determination method itself, a known method can be adopted. Accordingly, the ECU 0 applies various control signals i, j, k corresponding to the operation parameters via the output interface.

  The ECU 0 inputs a control signal o to a starter motor (cell motor, not shown) when the internal combustion engine is started (a cold start or a return from an idling stop). Cranking is performed by rotating the engine by engaging the pinion gear of the motor with the ring gear on the outer periphery of the drive plate. Cranking ends from the first explosion to the consecutive explosion, and ends when the engine speed exceeds a threshold determined according to the cooling water temperature or the like (assuming that the explosion has been completed).

  ECU0 of this embodiment can perform what is called an idling stop by functioning as an automatic stop start device in such a configuration. In executing the idling stop, the ECU 0 stores an idling stop program, and an idling stop condition and a restart condition are set in the idling stop program. The idling stop condition is that at least the charge amount of the battery is equal to or higher than the predetermined charge amount, the outside air temperature is equal to or higher than the predetermined temperature, the engine temperature is equal to or higher than the predetermined temperature, and the vehicle speed is a predetermined speed after the previous idle stop. There is a history of traveling as described above, a predetermined time has elapsed since the last engine start, a predetermined stop time has elapsed since the vehicle stopped, and a predetermined idle time in an idle operation state It has passed and the brake pedal is being depressed. The idling stop is performed when all of these idling stop conditions are satisfied.

  On the other hand, the restart condition is that at least the operation of the brake pedal (for example, depressing) is stopped, the accelerator pedal is operated (for example, depressing), and a predetermined restart time has elapsed since the start of the idling stop. Etc. The restart is performed when at least one of the restart conditions is satisfied. The idling stop condition and the restart condition described above are not limited to the listed items, and those known in this field may be adopted.

  The ECU 0 according to the present embodiment determines whether or not the battery voltage value is lower than a predetermined value v2 at which the cranking can be normally performed at the time of starting, and when the battery voltage value is lower than the predetermined value v2, the predetermined value The deficient torque can be calculated from the difference between the torque obtained when cranking is performed at v2 and the torque obtained when the cranking is performed with the battery voltage value lower than the predetermined value v2, and the deficient torque can be compensated. As described above, as the correction of the combustion control parameter for increasing the torque due to combustion, the advance timing of the ignition timing is corrected, and then cranking is started.

  FIG. 2 is a graph showing the correlation between the advance amount of the ignition timing and the torque due to combustion. The ignition timing is gradually increased as the advance amount is increased, and when it is further advanced, the ignition timing is gradually decreased at the maximum torque ignition timing MBT, which is also called the optimum ignition timing. Normally, the starting ignition timing D, which is used as a reference at the time of starting from the time of shipment of the automobile, is set to the left side of the figure, that is, a fixed amount retarded side with respect to the maximum value. Is also a small value. The difference between the maximum torque ignition timing MBT and the starting ignition timing D is referred to as reserve torque Δt, and the torque can be increased within a range equal to or less than the reserve torque Δt. In other words, in the present embodiment, in order to effectively use the reserve torque Δt, the ignition timing is advanced from the starting ignition timing D to a value retarded from the maximum torque ignition timing MBT, as indicated by an arrow in FIG. Corner correction is performed.

  The advance angle correction will be specifically described. The torque deficient in this embodiment is calculated from the difference between the torque obtained when cranking is performed at the predetermined value v2 and the torque obtained when cranking is performed at a battery voltage value lower than the predetermined value v2. The However, the predetermined value v2 of the battery voltage that can start normal startup is not always constant. In other words, even when the battery voltage is the same, the torque required for cranking is increased because the water pump load and oil pump load (not shown) increase when the engine temperature is low, such as during cold start in an environment where the outside air temperature is low. It becomes larger than when the engine temperature is sufficiently high. Therefore, in the present embodiment, for example, at least during cold start, torque values that are insufficient when various engine temperatures and battery voltages are indicated are calculated in advance and stored in a map so that the battery voltage signal g and the cooling water temperature are stored. When the signal f is obtained, the insufficient torque value is read from the map, or the ignition timing advanced from the start-time set ignition timing D corresponding to the insufficient torque value is read, and the ignition timing is advanced. Corner correction is performed. In the embodiment, the cooling water temperature signal f is applied as an index for knowing the engine temperature. In addition to the cooling water temperature signal f, the indices for knowing the engine temperature include the lubricating oil temperature, the intake air temperature, and the engine surface temperature. Etc. may be applied.

  On the other hand, when restarting from the idling stop, it is considered that the engine temperature has sufficiently increased, and the advance amount of the ignition timing may be determined based only on the battery voltage value.

  FIG. 3 shows a correlation between the battery voltage and the advance amount of the ignition timing according to the present embodiment. The battery voltage value gradually decreases from the initial voltage value v1 due to deterioration due to use or deterioration over time. In this embodiment, the battery voltage value is determined from a predetermined value v2 that is appropriately determined in consideration of the engine temperature and the like as described above. When the battery voltage value is lower, the advance angle correction is performed, and the lower the battery voltage value, the more the advance angle amount is corrected within a range smaller than the maximum torque ignition position MBT. Further, the advance correction of the ignition timing is performed from the first ignition at the start. In this figure, it goes without saying that the planned value v2 can move to the left side of the figure as the engine temperature is lower as described above.

  FIG. 4 shows the correlation between the cranking speed and the battery voltage realized by the advance correction of the ignition timing set as shown in FIG. As shown in the figure, the cranking speed value behaves roughly proportional to the battery voltage value. As a result, the battery voltage normally takes a value lower than the necessary rotational speed P necessary for normal starting as shown by the broken line when the cranking rotational speed is not greater than the predetermined value v2 when the advance angle correction is not performed. . Therefore, in this embodiment, advance angle correction is performed when the value falls below the predetermined value v2. Therefore, in this embodiment, the advance amount is increased to increase the torque due to combustion as the battery voltage value is smaller. As a result, as shown by a solid line in the figure, the increase in torque due to combustion pushes up the cranking rotational speed, whereby the cranking rotational speed can be increased to the required rotational speed P.

  FIG. 5 shows the correlation between the cranking time and the battery voltage when starting with the ignition timing corrected to advance as shown in FIG. As shown in the figure, even when the battery voltage value is lower than the predetermined value v2, the cranking time is clearly shortened compared with the case where the advance angle correction indicated by the broken line is not performed, and is lower than the predetermined value v2. It is closer to the cranking time when the battery voltage value is large. This makes it difficult for the driver to feel the difference in the length of the cranking time between when the battery voltage value is equal to or higher than the predetermined value v2 and when the battery voltage value falls below the predetermined value v2, and feels a sense of incongruity due to the difference in the cranking time. Contributes to comfortable driving.

  As described above, according to the present embodiment, at the start of cranking, the torque due to combustion is already increased by correcting the advance of the ignition timing, so that the sum of the torque of the cell motor used for cranking and the torque due to combustion is a predetermined value. It can be set larger than v2. As a result, it is possible to effectively avoid unnecessarily prolonging the cranking time even when the battery is deteriorated or the battery voltage value is lowered due to low temperatures, and a comfortable start without causing the driver to feel uncomfortable is realized.

  Although the embodiment of the present invention has been described above, the specific configuration of each unit is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.

  For example, in the above-described embodiment, the aspect in which the cranking rotation speed is maintained by correcting the advance of the ignition timing is disclosed. Of course, the increase torque due to combustion can also be increased by increasing the fuel injection amount. Therefore, for example, when the torque cannot be sufficiently increased only by the advance correction of the ignition timing as in the above-described embodiment, the increase correction of the fuel injection amount may be also performed. . In this case, when the map based on the cooling water temperature and the battery voltage value is used as in the above-described embodiment, the fuel injection amount increase correction is used in combination in a region where both the cooling water temperature and the battery voltage value are extremely low. do it. Of course, the correction for increasing the fuel injection amount is performed from the time of the first combustion injection.

  The specific timing for obtaining the battery voltage value and the cooling water temperature value and the specific mode for determining the predetermined value of the battery voltage value are not limited to those of the above embodiment, The thing of the aspect of can be applied.

  In addition, the specific configuration of each part is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention.

  The present invention can be used as a control device for stably starting an internal combustion engine.

0 ... Control device (ECU) for internal combustion engine
v2 ... predetermined value

Claims (1)

It is determined whether or not the battery voltage value falls below a predetermined value at which cranking can be normally performed at the start, and when the battery voltage value is lower than the predetermined value, it is obtained when cranking is performed at the predetermined value. Is calculated from the difference between the torque obtained and the torque obtained when cranking at a battery voltage value lower than the predetermined value, and the combustion control parameter increases the torque due to combustion so that the insufficient torque can be compensated A control device for an internal combustion engine, which corrects the above and thereafter starts cranking.

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