JP2019019712A - Control device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To optimize an upper limit of a time for continuing cranking for starting an internal combustion engine. SOLUTION: When starting a stopped internal combustion engine, fuel is injected into a cylinder while performing cranking in which the internal combustion engine is rotationally driven by an electric motor, and when the engine rotation speed rises above a threshold value, the cranking is terminated. On the other hand, if the engine speed does not rise above the threshold within the upper limit time after starting cranking, cranking and fuel injection are stopped, and the engine speed is the threshold from the start of cranking. A control device for an internal combustion engine is configured which measures the time required for the vehicle to rise above and increases or decreases the upper limit time according to the measured required time. [Selection diagram] Fig. 2

Description

  The present invention relates to a control device that controls an internal combustion engine mounted on a vehicle or the like.

  As is well known, when starting a stopped internal combustion engine, a crankshaft, which is an output shaft of the internal combustion engine, is driven to rotate by an electric motor, fuel is injected from an injector and burned in a cylinder. Perform cranking to accelerate rotation. Cranking is a complete explosion when the internal combustion engine starts from the first explosion to the continuous explosion and the rotational speed of the crankshaft, that is, the engine speed, exceeds a threshold determined according to the temperature of the internal combustion engine (especially the coolant temperature). The process is terminated (see, for example, the following patent document).

JP 2017-115610 A

  The motor during cranking is overloaded and consumes a large amount of power. Therefore, in the case where a complete explosion does not occur even after a certain period of time has elapsed since the start of cranking, the cranking and fuel injection by the motor are stopped to protect the motor and the battery. Reduce fuel waste and prepare for restarting internal combustion engines.

  In the conventional start control, when the internal combustion engine does not reach a complete explosion after the start of cranking, the upper limit of the time for continuing the cranking is set according to the temperature of the internal combustion engine. Specifically, cranking is continued for a longer time as the temperature at the start of the internal combustion engine is lower. However, except for the adjustment due to the temperature of the internal combustion engine, the length of the upper limit time during which cranking is continued is always constant.

  On the other hand, the ease of starting the internal combustion engine, in other words, the ease of acceleration of engine rotation, is affected by individual differences including aging of the internal combustion engine, the electric motor, and the battery. For individuals who are relatively difficult to start, if the upper limit time for continuing cranking is set short, the cranking will be interrupted midway though it should be able to complete the start. This leads to poor starting of the internal combustion engine. Conversely, for individuals that are relatively easy to start, setting the upper limit time for continuing cranking to a long time will accelerate the wear of the motor and battery if accidental startup fails, and wasteful fuel It will also consume.

  An object of the present invention is to optimize the upper limit of the time for continuing cranking for starting an internal combustion engine.

  In order to solve the above-described problems, in the present invention, when starting the stopped internal combustion engine, fuel is injected into the cylinder while performing cranking for rotationally driving the internal combustion engine with an electric motor, and the engine speed exceeds a threshold value. If the engine speed has risen, cranking is terminated. On the other hand, cranking and fuel injection are stopped if the engine speed does not rise above the threshold value within the upper limit time after cranking is started. The internal combustion engine control device is configured to measure the time required from the start of the engine until the engine speed increases to a threshold value or more and to increase or decrease the upper limit time according to the measured required time.

  Preferably, the upper limit time is set for each temperature at the start of the internal combustion engine, and based on the required time measured by executing the start when the temperature at the start of the internal combustion engine is a certain value. In addition to the upper limit time when the temperature at the start of the engine is the same value, the upper limit time when the temperature at the start of the internal combustion engine is another value is also increased or decreased.

  ADVANTAGE OF THE INVENTION According to this invention, the upper limit of the time which continues cranking for the start of an internal combustion engine can be optimized.

The figure which shows schematic structure of the internal combustion engine for vehicles and control apparatus in one Embodiment of this invention. The graph which shows the relationship between the temperature T at the time of start-up of an internal combustion engine, the average required time B (T) of cranking, and the upper limit time A (T). The table | surface which shows the relationship between the temperature T at the time of starting of an internal combustion engine, and a coefficient k (T). The table | surface which shows the relationship between the temperature T at the time of start-up of an internal combustion engine, and guard value _Bmin (T), _Amin (T), _Bmax (T), _Amax (T).

  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 type four-stroke engine and includes a plurality of cylinders 1 (for example, three cylinders, 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 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 external EGR (Exhaust Gas Recirculation) device 2 realizes a so-called high-pressure loop EGR. The EGR device 2 includes an external EGR passage 21 that communicates the upstream side of the catalyst 41 in the exhaust passage 4 and the downstream side of the throttle valve 32 in the intake passage 3, an EGR cooler 22 provided on the EGR passage 21, and an EGR passage 21. And an EGR valve 23 that controls the flow rate of the EGR gas flowing through the EGR passage 21. The inlet of the EGR passage 21 is connected to the exhaust manifold 42 in the exhaust passage 4 or a predetermined location downstream thereof. The outlet of the EGR passage 21 is connected to a predetermined location downstream of the throttle valve 32 in the intake passage 3, specifically to a surge tank 33.

  An ECU (Electronic Control Unit) 0 serving as a control device for an internal combustion engine according to 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 sensor (engine rotation sensor) that detects the rotation angle of the crankshaft of the internal combustion engine and the engine speed. Angular signal b, accelerator pedal depression amount or throttle valve 32 opening as an accelerator opening (engine output required by the driver, so-called required load), an accelerator opening signal c output from a sensor, and brake pedal Brake pedal amount signal d output from a sensor that detects the amount of depression or a sensor that detects the pressure of the hydraulic fluid discharged from the master cylinder, and the intake air temperature in the intake passage 3 (in particular, the surge tank 33) And an intake air temperature / intake pressure signal e output from a temperature / pressure sensor for detecting intake pressure, an internal combustion engine The cooling water temperature signal f output from the water temperature sensor that detects the cooling water temperature indicating the temperature of the engine, the cam angle signal g output from the cam angle sensor at a plurality of cam angles of the intake camshaft, and the atmospheric pressure that detects the atmospheric pressure An atmospheric pressure signal h or the like output from the sensor is input.

  From the output interface, the ignition signal i for the igniter of the spark plug 12, the fuel injection signal j for the injector 11, the opening operation signal k for the throttle valve 32, and the opening operation signal l for the EGR valve 23. Etc. are output.

  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., the required fuel injection amount, fuel injection timing (including the number of times of fuel injection for one combustion), fuel injection pressure, ignition timing, required EGR rate (or EGR rate) Various operating parameters such as gas amount) are determined. The ECU 0 applies various control signals i, j, k, and l corresponding to the operation parameters via the output interface.

  Further, the ECU 0 is an electric motor (starter motor or ISG (Integrated Starter Generator)) when cold-starting the internal combustion engine that has been stopped due to the ignition key (or the ignition switch) being operated from OFF to ON. The control signal o is input to the crankshaft and the crankshaft is rotated by the motor. Cranking means that the internal combustion engine has completed a complete explosion when the internal combustion engine has gone from the first explosion to the continuous explosion and the engine speed has exceeded a threshold determined according to the temperature of the internal combustion engine (especially the cooling water temperature). Consider and finish.

  However, if the internal combustion engine fails to start for some reason, i.e., if the engine speed has not risen above the threshold value within the upper limit after starting cranking, cranking is not continued any further and the motor is turned off. Stop and stop the startup process.

  In addition, when the internal combustion engine is successfully started, the ECU 0 of the present embodiment measures the time required from the start of cranking until the engine speed increases to a threshold value or more. The above upper limit time is increased or decreased based on the history.

  More specifically, the ECU 0 sets the average time B (T) of the time required for cranking for starting each time the internal combustion engine is cold started successfully, and the time for continuing the cranking in the subsequent starting of the internal combustion engine. The upper limit A (T) is learned. In general, the upper limit time A (T) is obtained by adding a safety margin to an average B (T) of cranking required times measured in the past. Therefore, the upper limit time A (T) is longer than the average required time B (T). As shown in FIG. 2, the average required time B (T) and the upper limit time A (T) each vary according to the temperature T at the start of the internal combustion engine. As a general rule, the lower the temperature T at start-up, the greater the friction loss of the internal combustion engine, so the average required time B (T) becomes longer and the upper limit time A (T) becomes longer. The ECU 0 learns learning values of the average required time B (T) and the upper limit time A (T) for each temperature T at the start of the internal combustion engine, and stores and stores it in the memory.

The ECU 0 of the present embodiment calculates learning values for the average required time B (T) and the upper limit time A (T) according to the following equations [1] and [2].
B _n (T) = B _n−1 (T) + k (T) × α × (A _n−1 (T) −B _n−1 (T)) [1]
A _n (T) = A _n−1 (T) + k (T) × α × (A _n−1 (T) −B _n−1 (T)) (2)
The subscript n represents the current learning opportunity, and the subscript n-1 represents the latest past learning opportunity. The above equations [1] and [2] are obtained by using learning values B _n-1 (T) and A _n-1 (T) learned in the last past as learning values B _n (T) and A newly obtained this time. _n means updating by (T).

  The coefficient k (T) is a learning reflection rate corresponding to the temperature T at the start of the internal combustion engine, and is a positive number smaller than 1. As illustrated in FIG. 3, the coefficient k (T) when the temperature T at the start is high is smaller than the coefficient k (T) when the temperature T at the start is lower.

The coefficient α is determined by a required time C _n measured from the start of cranking until the engine speed increases to a threshold value or more, which is measured when the internal combustion engine is successfully started. ECU0 calculates | requires coefficient (alpha) according to the following Formula [3].
α = (C _n −B _n−1 (T ₀ )) / (A _n−1 (T ₀ ) −B _n−1 (T ₀ )) (3)
The coefficient α indicates how far the actual required time C _n required for the current start deviates from the average required time B (T). T ₀ is the temperature at the start of the internal combustion engine at the current learning opportunity. B _n-1 (T ₀ ) and A _n-1 (T ₀ ) are respectively B _n-1 (T) and A _n-1 (under the condition of the temperature T = T ₀ at the start of the internal combustion engine. T).

As already described, the ECU 0 of this embodiment executes learning of the learning values B _n (T) and A _n (T) every time the internal combustion engine is successfully started. At this time, the ECU ₀ satisfies not only the learning values B _n (T ₀ ) and A _n (T ₀ ) corresponding to the temperature T ₀ of the internal combustion engine at the time of this start, but also the condition of the temperature T ≠ T ₀ at the time of start. The lower learning values B _n (T) and A _n (T) are also calculated simultaneously, and the learning values B _n (T) and A _n (T) are stored in the memory. In calculating the learning values B _n (T) and A _n (T) corresponding to the temperature T other than T ₀ , the coefficient k (T) includes the coefficient k (T) under the condition of the temperature T other than T _0. T). On the other hand, the coefficient α includes B _n-1 (T ₀ ) and A _n-1 (T ₀ ) under the condition of the temperature T ₀ at the start of the internal combustion engine at the current learning opportunity, and the actual measurement time C. _The coefficient α calculated using _n is assigned. That is, in the present embodiment, a common coefficient α is used to calculate the learning values B _n (T) and A _n (T) under various temperature conditions T in one learning opportunity.

As a result, the average required time B _n (T) and the upper limit time _An (T) are longer as the time C _n required for cranking for starting the internal combustion engine is longer (or the actually required time C _n is averaged). It becomes longer as it deviates greatly from the required time B _n-1 (T ₀ ), and becomes shorter as this becomes shorter (or as the deviation of C _n from B _n-1 (T ₀ ) becomes smaller).

However, for learning values B _n (T) and A _n (T), lower limit guard values B _min (T), A _min (T) and upper limit guard values B _max (T), A _max (T) Is provided. If the learning value B _n (T) calculated according to the above calculation formulas [1] to [3] is lower than the lower limit guard value B _min (T), the ECU 0 learns the value B _n (T) = B _min. This is stored in the memory as (T), and if the calculated learning value B _n (T) exceeds the upper guard value B _max (T), this is set as learning value B _n (T) = B _max (T). Store in memory. Similarly, if the calculated learning value A _n (T) falls below the lower limit guard value A _min (T), this is stored in the memory as the learning value A _n (T) = A _min (T), and the calculated learning is performed. If the value A _n (T) exceeds the upper guard value A _max (T), this is stored in the memory as the learning value A _n (T) = A _max (T).

The lower limit guard values B _min (T), A _min (T) and the upper limit guard values B _max (T), A _max (T) each depend on the temperature T at the start of the internal combustion engine. As illustrated in FIG. 4, the guard values B _min (T), A _min (T), B _max (T), and A _max (T) when the temperature T at the start is high are determined by the temperature T at the start. The lower guard values B _min (T), A _min (T), B _max (T), and A _max (T) are smaller.

When starting the stopped internal combustion engine, the ECU 0 reads the learned value of the upper limit time A (T) corresponding to the temperature T of the internal combustion engine at that time from the memory, and executes cranking. If the engine speed rises above the threshold from the start of cranking until the upper limit time A (T) elapses, it is determined that the internal combustion engine has been successfully started and cranking is terminated (fuel injection and It goes without saying that the operation of the internal combustion engine by ignition combustion is continued), and learning and updating of the average required time B (T) and the upper limit time A (T) are performed using the measured required time C _n . On the other hand, if the engine speed does not increase above the threshold from the start of cranking until the upper limit time A (T) elapses, it is determined that the internal combustion engine has failed to start and cranking and fuel injection are performed. Cancel.

In this embodiment, when starting the stopped internal combustion engine, fuel is injected into the cylinder 1 while performing cranking for rotationally driving the internal combustion engine with an electric motor. If the engine speed rises above a threshold value, cranking is performed. On the other hand, if the engine speed does not rise above the threshold value within the upper limit time A (T) after cranking is started, cranking and fuel injection are stopped. The internal combustion engine control device 0 is configured to measure a time C _n required for the engine speed to rise to a threshold value or more from the time and increase or decrease the upper limit time A (T) according to the measured required time C _n . .

  According to this embodiment, it is possible to optimize the upper limit A (T) of the time for which cranking for starting is continued in consideration of individual differences between the internal combustion engine and the electric motor. For an individual that is relatively difficult to start, it is possible to extend the upper limit time A (T) for continuing the cranking, and to complete the starting without stopping the cranking in the middle of starting the internal combustion engine. On the other hand, for an individual that is relatively easy to start, the upper limit time A (T) for continuing cranking is further shortened to suppress the wear of the electric motor and the battery when the start fails accidentally. It is possible to prepare for a start-up retry. In addition, wasted fuel can be avoided.

In this embodiment, the upper limit time A (T) is set for each temperature T at the start of the internal combustion engine, and the start is started when the temperature T at the start of the internal combustion engine is a certain value T _0. Based on the required time C _n that is executed and measured, together with the upper limit time A (T ₀ ) when the temperature T at the start of the internal combustion engine is the same value T ₀ , the temperature T at the start of the internal combustion engine is another value. The upper limit time A (T) in the case of a value is also increased or decreased. Thereby, in one learning opportunity, not only the upper limit time A (T ₀ ) under the condition of the temperature T = T ₀ at the start but also the upper limit time under the condition of the temperature T ≠ T ₀ at the start A (T) can also be updated, the number of learning of the upper limit time A (T) corresponding to various temperature conditions T is effectively increased, and the upper limit time A for the temperature condition T that is less frequently realized. Learning of (T) can also be performed. As a result, the accuracy of the value of the upper limit time A (T) is further increased.

  The present invention is not limited to the embodiment described in detail above. Various modifications can be made to the specific configuration of each part, the contents of processing, and the like without departing from the spirit of the present invention.

  The present invention can be applied to control of an internal combustion engine mounted on a vehicle or the like.

0 ... Control unit (ECU)
DESCRIPTION OF SYMBOLS 1 ... Cylinder 11 ... Injector 12 ... Spark plug 3 ... Intake passage 32 ... Throttle valve 4 ... Exhaust passage b ... Crank angle signal e ... Intake temperature / intake pressure signal f ... Cooling water temperature signal g ... Cam angle signal i ... Ignition signal j ... Fuel injection signal k ... Opening operation signal o ... Motor control signal for cranking

Claims (2)

When starting the internal combustion engine that has been stopped, fuel is injected into the cylinder while cranking the rotational drive of the internal combustion engine with an electric motor, and if the engine speed rises above a threshold value, the cranking is terminated. If the engine speed does not rise above the threshold within the upper limit time after starting the ranking, the cranking and fuel injection are stopped,
A control device for an internal combustion engine, which measures a time required from the start of cranking until the engine speed increases to a threshold value or more and increases or decreases the upper limit time according to the measured required time. The upper limit time is set for each temperature at the start of the internal combustion engine,
Based on the required time measured by executing the start when the temperature at the start of the internal combustion engine is a certain value, together with the upper limit time when the temperature at the start of the internal combustion engine is the same value, The control apparatus for an internal combustion engine according to claim 1, wherein the upper limit time when the temperature is other value is also increased or decreased.

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