JP2008128156A - Engine start control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an engine start control device for preventing a starter from overrunning due to shortage of a racing maximum rotation number for a cranking stop rotation number and executing start control at optimum engine full explosion rotation number. <P>SOLUTION: The engine start control device has a nonvolatile memory for storing the cranking stop rotation number in an overwritable manner. An energization control unit of a starter motor includes a maximum rotation number measuring means S13 for measuring a racing maximum value Np of the engine rotation number by engine full explosion, comparing means S15, 16 for comparing the cranking stop rotation number Nsc and the racing maximum value Np when the starter switch is held down long and a cranking stop rotation number update means S18 for updating the cranking stop rotation number Nsc stored in the memory by writing over it with a new rotation number which is smallr than the rotation number when the racing maximum value Np does not exceed the cranking stop rotation number Nsc. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an engine start control device, and more particularly to an engine start control device that executes learning control in order to improve engine startability.

  When an internal combustion engine is started in a vehicle such as an automobile, generally, the starter motor is energized in accordance with a starter switch operation such as pressing of a start button by a driver, and the engine is started by the starter motor. At the time of starting, if the starter motor energization control is performed only in accordance with the starter switch operation, the start button must continue to be operated after the engine is completely exploded (the state where the engine starts to rotate by normal combustion). Therefore, the starter motor is frequently overrun, and the starter motor is likely to deteriorate early. On the other hand, the starter motor can be energized continuously until a certain period of time has elapsed after the start of energization or until a certain engine speed is reached, and then stopped. Alternatively, the startability of the engine greatly changes due to a change in fuel properties and the like, and it is easy for the starter to fail or the starter motor or the battery to deteriorate quickly. In view of this, various engine start control devices have been proposed for improving the startability of the engine and preventing deterioration of the starter motor and the battery.

  As a conventional engine start control device of this type, for example, the success or failure of the engine start is stored in the memory every time, and based on the history of the success or failure of the start, the upper limit value of one continuous energization time of the starter motor, The engine start conditions such as the fuel injection amount at the start and the ignition timing at the start are variably controlled (for example, refer to Patent Document 1), or the energization time is longer than the previous time when the start fails (for example, Patent Document 1) 2).

  The starter motor may be de-energized when the starter motor power supply voltage reaches the reference voltage or continuously increases due to the successful start of the engine. Since starter motor overruns cannot be reliably prevented due to low detection accuracy, the current voltage history and past voltage history are read, the voltage difference between the current and past starter power supplies is calculated, and the voltage difference is compared with the specified voltage. In some cases, the starter motor is turned off when the voltage difference is less than a predetermined voltage for a predetermined time or longer (see, for example, Patent Document 3).

Further, energization of the starter motor is continued until the engine speed reaches the first reference speed. When the engine speed reaches the first reference speed, the energization is stopped, and then the engine is stopped within a certain period. In some cases, energization of the starter motor is resumed when the rotational speed decreases to a second reference rotational speed lower than the first reference rotational speed (see, for example, Patent Document 4).
JP 2003-172174 A Japanese Patent Laid-Open No. 9-60567 JP 2002-295346 A JP 2002-188548 A

  However, the conventional engine start control device as described above has a problem that the history information is large and the control is complicated.

  On the other hand, cranking (rotating the crankshaft and rotating the crankshaft) until the engine reaches a complete engine rotation when the start button is kept pressed for a predetermined time or longer, such as when starting fails and restarting. If the predetermined cranking stop rotational speed is reached and the subsequent cranking is prohibited, the starting control can be simplified.

  However, in that case, when the engine is restarted at a high temperature when the coolant temperature is high, the engine may settle at the idle speed without reaching the cranking stop speed. May overrun the starter motor.

  That is, at the time of normal start, it is a control that automatically performs cranking from an engine speed of about 500 to 600 rpm just by pressing the start button for a short time, and when the engine does not start due to poor startability due to fuel properties, Within a certain time limit (for example, 30 seconds), if the start button is continuously pressed for a predetermined time or longer (hereinafter referred to as long press), until the engine speed reaches a predetermined cranking stop speed (for example, about 1200 rpm) Cranking hold control can be executed to continue cranking (see FIG. 4A), but if the start button is pressed for a long time when the engine water temperature is high and the engine is restarted at a high temperature, the engine speed of the engine rise is low. Therefore, as shown in FIG. 4B, the maximum rotational speed Np of the blow-up reaches the cranking stop rotational speed Ns. May inadvertently settled in idle speed without, in such a case, also continue to starter motor activated until the time limit in complete explosion of the engine, a problem that cranking will be continued occurs.

  If the cooling water temperature is above a certain level during restart, etc., it may be possible to reduce the cranking stop speed slightly, but in that case, set the switching pattern for the cranking stop speed under conditions suitable for each vehicle. The engine stalls may occur because the engine does not explode when using poor fuel or at extremely low temperatures.

  Therefore, the present invention executes learning control so that the engine can be started at the optimum engine explosion speed every time the engine is started, and it is possible to maintain the engine stall and starter without holding a lot of history information or adding a special work process. An object of the present invention is to provide an engine start control device that can reliably prevent overrun of a motor.

  In order to achieve the above object, the present invention provides (1) a starter switch operated to start an engine, a starter motor that performs cranking of the engine by energization, and a rotation that detects the engine speed of the engine. And a stop condition storage means for storing a stop condition for stopping the cranking, and control of energization to the starter motor based on the engine speed, the operation state of the starter switch, and the stop condition. In the engine start control device comprising an energization control unit, the stop condition storage means includes a non-volatile memory that rewriteably stores a cranking stop rotational speed for stopping the cranking, and the energization control unit However, based on the detection information of the rotational speed sensor, the engine due to the complete explosion of the engine Maximum rotation number measuring means for measuring the maximum value of the engine speed increase, and when the starter switch is operated continuously for a predetermined time or more, the cranking stop rotation speed and the engine speed increase maximum And a cranking stop stored in the memory when a maximum value of the engine rotation speed does not exceed the cranking stop rotation speed based on a comparison result of the comparison means and a comparison result of the comparison means And a cranking stop rotational speed updating means for updating the rotational speed by rewriting the rotational speed to a new rotational speed lower than the rotational speed.

  With this configuration, when the maximum value of the measured engine speed (hereinafter referred to as the maximum engine speed) does not exceed the cranking stop speed, the set cranking stop stored in the memory is set. Learning is performed to update to a new cranking stop rotational speed lower than the rotational speed, and the learning result is reflected in the cranking stop rotational speed at the next start. Therefore, the cranking stop rotation speed can be set to a sufficiently high engine speed that can be said to be the rotation speed after the complete explosion in any vehicle model at the beginning, and the optimum cranking stop rotation speed suitable for each vehicle type is set. Without providing a work process for setting the number, it is ensured that the start-up motor overrun occurs because the maximum value of the engine speed, that is, the maximum engine speed does not exceed the cranking stop speed. Is prevented. Further, it is not necessary to store a lot of start history information, and control is not complicated.

  In the engine start control device of the present invention, (2) the cranking stop rotational speed updating means subtracts a predetermined rotational speed from the cranking stop rotational speed stored in the memory to determine the new rotational speed. Is preferred. Thus, the cranking stop rotational speed can be gradually updated and optimized while ensuring startability.

  In the engine start control device having the configuration of (2) above, (3) an update lower limit determination unit that determines whether or not the energization control unit is greater than or equal to a preset lower limit guard value. The cranking stop rotational speed update means is stored in the memory only when the new rotational speed is equal to or higher than the lower limit guard value based on the determination result of the update lower limit determination means. It is recommended to perform the update. As a result, it is possible to prevent the startability from being lowered by excessively reducing the cranking stop rotational speed.

  In the engine start control device having any one of the above configurations (1) to (3), (4) the energization control unit is configured such that when the engine speed exceeds the cranking stop speed, the starter Regardless of the operation of the switch, it is more preferable to stop energization to the starter motor and prohibit the cranking. As a result, even if the starter switch operation is continued by mistake, the starter motor does not operate, and overrun of the starter motor is reliably prevented.

In the engine start control device having the configuration of (1) above, (5) it is preferable that the memory is configured by a static RAM.
With this configuration, the cranking stop rotational speed updating process can be executed quickly, and the static RAM normally mounted on the existing control unit can be used.

  In the engine start control device having the configuration of (1) above, (6) the memory may be composed of an EEPROM. In this case, even if the battery power source is removed, the stored information on the updated cranking stop rotational speed can be retained.

  According to the present invention, when the maximum blow-up speed does not exceed the cranking stop speed, it is updated to a new cranking stop speed lower than that, and the updated value is the cranking stop at the next start. Since it is reflected in the rotational speed, the maximum blow-up rotational speed can be set to the cranking stop rotational speed without preparing a large amount of history information or providing an optimal cranking stop rotational speed setting work process suitable for each vehicle type. Therefore, it is possible to provide an engine start control device that can reliably prevent the starter motor from being overrun and prevent the starter motor from overrun, and can ensure a reliable startability.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

(First embodiment)
1 to 3 show an engine start control device according to a first embodiment of the present invention.

  First, the configuration will be described. As shown in FIG. 1, the engine start control device of the present embodiment executes a cranking of the engine 1 by energization with a starter switch 11 operated to start the engine 1. A starter motor 12, a rotational speed sensor 13 for detecting the engine rotational speed NE of the engine 1, and an engine electronic control unit (hereinafter referred to as engine ECU) 20 are provided.

The starter switch 11 has a start button 11a that is pushed (pressed) by the driver and a contact portion 11b, and is turned on when the start button 11a is pressed. The starter switch 11 causes the engine ECU 20 to input a power supply signal through a buffer (not shown) in the input interface circuit 26.
The starter motor 12 has, for example, a toothed output shaft 12a that removably meshes with external teeth (not shown) formed on the outer periphery of the flywheel 1w of the engine 1, and is connected to the flywheel 1w. It is possible to rotate the crankshaft 1c in the engine 1 and the valve mechanisms and pumps that are linked to the crankshaft 1c.

  The rotation speed sensor 13 is a crank angle sensor that detects the rotation of the crankshaft 1c of the engine 1 in units of a predetermined angle.

  The engine ECU 20 includes a CPU (Central Processing Unit) 21, a ROM (Read Only Memory) 22, a RAM (Random Access Memory) 23, and a backup RAM (hereinafter referred to as B-RAM) 24 using a battery as a backup power source. An input interface circuit 26 including a / D converter and a buffer, an output interface circuit 27 including a relay drive circuit, and a constant voltage power supply circuit 28 are included.

  The B-RAM 24 is composed of SRAM (Static RAM) or EEPROM (Electronically Erasable and Programmable Read Only Memory) that operates using a battery (a positive terminal is indicated as “B +” in the drawing, and details are not shown). This is a non-volatile memory that rewritably stores the cranking stop rotational speed for stopping the cranking. That is, the B-RAM 24 can function as a stop condition storage unit that stores a stop condition for stopping the cranking when the engine speed NE increases due to cranking.

  In addition to the rotational speed sensor 13, the input interface circuit 26 includes various sensor groups (not shown in detail, but an air flow meter, a throttle sensor, a vehicle speed sensor, an oxygen sensor, a cylinder discrimination sensor, an intake air temperature sensor, a water temperature sensor, etc.) Are connected, and sensor information from these sensor groups is taken into the engine ECU 20.

  The output interface circuit 27 is connected to a relay switch circuit 31 that energizes the starter motor 12 using a battery (not shown in detail) as a power source and turns on / off the energization. Further, an injector (fuel injection valve) for fuel injection, an igniter for driving the spark plug, a relay switch circuit for turning on / off the fuel pump, and the like are connected.

  The relay switch circuit 31 has a relay coil portion 31a excited by the engine ECU 20, and a contact portion 31b that is turned on when the relay coil portion 31a is excited.

  The engine ECU 20 controls the energization state of the starter motor 12 by turning the relay switch circuit 31 on and off based on the engine speed NE, the operation state of the starter switch 11 and the cranking stop condition together with the relay switch circuit 31. In order to perform this function, a start control processing program and stop condition setting data, which will be described later, are stored and stored in the ROM 23 and the B-RAM 24 of the engine ECU 20. Yes.

  More specifically, the engine ECU 20 determines the maximum value Np (hereinafter referred to as the engine speed NE) when the engine speed NE rises during the measurement period until the engine speed NE suddenly increases due to the complete explosion of the engine 1 and then stabilizes. , Which is called a maximum engine speed Np), during the start-up of the engine 1 during the start-up control processing program stored in the ROM 23 and the B-RAM 24. A program portion for monitoring the rotational speed information NE from the rotational speed sensor 13 and measuring the maximum rotational speed Np of the engine 1 is included.

  Further, the engine ECU 20 functions as a comparison means for comparing the cranking stop rotational speed Nsc and the maximum blow-up rotational speed Np when the starter switch 11 is continuously operated for a predetermined time or more by the start button 11a. Based on the comparison result of the comparison means, when the maximum blow-up rotation speed Np does not exceed the cranking stop rotation speed Nsc, the cranking stop rotation speed Nsc stored in the B-RAM 24 is set to a new rotation lower than the rotation speed. In the start control processing program stored in the ROM 23 and the B-RAM 24 in order to exhibit these functions. In addition, a program for executing a comparison determination process and an update process of the cranking stop rotational speed Nsc described later Min and data includes setting values.

  The engine ECU 20 further subtracts a fixed rotation speed, for example, 10 rpm from the cranking stop rotation speed Nsc (for example, 1200 rpm) stored in the B-RAM 24 used as the cranking stop rotation speed updating means, and obtains a new rotation speed. And a function of an update lower limit determination means for determining whether or not the new rotation speed is equal to or higher than a preset lower limit guard value (lower limit cranking stop rotation speed; for example, 1000 rpm) Nb. And the function of the engine ECU 20 as the cranking stop rotational speed update means is based on the result determined as the update lower limit determination means only when the new rotational speed is equal to or higher than the update lower limit value. An update process of the cranking stop rotational speed stored in the B-RAM 24 is executed.

  Next, the operation will be described.

  When the engine 1 is started, cranking hold control as schematically shown in FIG. 2 is executed. The engine ECU 20 starts this program every predetermined time, and when a start operation is performed, necessary processing is executed.

  First, it is determined whether or not the start button 11a of the starter switch 11 has been pressed (step S11). When the engine 1 is started, a start operation of pressing the start button 11a is performed by the driver of the vehicle, and the contact portion 11b of the starter switch 11 is thereby turned ON, so that the determination result is YES. (If YES at step S11).

  At this time, the engine ECU 20 activates the starter motor 12 by exciting the relay coil portion 31 a of the relay switch circuit 31 to turn on the relay switch circuit 31 and supplying power to the starter motor 12. The starter motor 12 rotates, for example, the toothed output shaft 12a meshing with the outer peripheral portion of the flywheel 1w of the engine 1, rotates the crankshaft 1c in the engine 1, and each interlocked with the crankshaft 1c. The engine 1 is started by operating a valve mechanism or a pump. That is, the starter motor 12 performs cranking of the engine 1 (step S12). Therefore, normally, the engine 1 is in a blow-up state in which the engine 1 is completely exploded and the engine speed NE increases rapidly.

  On the other hand, during this time, the engine speed NE of the engine 1 is taken into the engine ECU 20 from the speed sensor 13 together with other sensor information, and the engine speed during the start-up period in which the cranking is performed is predetermined work in the RAM 23 every predetermined time. It is stored in the memory area and the maximum blow-up speed Np is measured (step S13).

  Next, when it is determined that the engine speed NE has blown up and the complete explosion speed Nsc has been reached in response to a short-time start operation, as shown in FIG. The relay coil part 31a of 31 is de-energized, the relay switch circuit 31 is turned off, the energization from the battery to the starter motor 12 is stopped, and the cranking by the starter motor 12 is stopped (step S14).

  Even when the start button 11a is pressed for longer than a predetermined time, the cranking of the engine 1 is continued by energizing the starter motor 12, so that the engine 1 has the cranking stop rotational speed. When the complete explosion speed Nsc is reached, the maximum blow-up speed Np exceeds the cranking stop speed Nsc (step S14), and continuation of further cranking is prohibited.

Next, it is determined whether or not the start button 11a is in a long-pressed state in which the start button 11a is kept pressed for a predetermined time (step S15). If not long-pressed, the current process ends (NO in step S15). ).
If the start button 11a has been pressed for a long time (for example, YES in step S15) because the engine has failed to start for some reason, or because the fuel property is poor or the environment is extremely low temperature, the engine ECU 20 Go to the next step.

  Next, the current maximum blow-up speed Np was sufficiently higher than the complete explosion speed Nsc, which is the cranking stop speed at the time of long press, that is, as shown in FIG. It is determined whether or not the difference is exceeded (step S16). If the determination result is YES, the current process is terminated.

  On the other hand, as shown in FIG. 3B, when the maximum blow-up rotation speed Np is close to or below the complete explosion rotation speed Nsc that is the cranking stop rotation speed, the determination result in step S16 is NO. .

  In this case, it is then determined whether or not a value obtained by subtracting the predetermined rotation speed a from the complete explosion rotation speed Nsc (Nsc−a = N1, N2, etc.) is equal to or less than a preset lower limit guard value Nb (step S17). If the complete explosion speed Nsc exceeds the lower limit guard value Nb (NO in step S17), the complete explosion speed Nsc is then lowered by a predetermined speed a. That is, for example, the initial complete rotation speed is changed from 1200 rpm to a new speed 1190 rpm lower by 10 rpm (or a new speed lower than that). Then, the new rotational speed Nsc is written into the B-RAM 24, the value of the complete explosion rotational speed Nsc, which is the cranking stop rotational speed, is updated (step S18), and the current process is terminated.

  On the other hand, if the cranking stop rotational speed Nsc is equal to or lower than the lower limit guard value Nb (in the case of YES at step S17), the current process is terminated without performing the cranking stop rotational speed update process.

  In the engine start control device of the present embodiment in which such processing is executed, the cranking stop rotational speed Nsc is initially set to an engine speed that can be said to be the rotational speed after the complete explosion of any vehicle, It is written in the B-RAM 24.

  Therefore, when the cranking stop rotational speed Nsc does not exceed the measured maximum blow-up rotational speed Np, the cranking stop rotational speed Nsc is set to a new low cranking stop rotational speed N1 (or further to N2) as shown in FIG. Learning to be updated is performed, and the learning result is reflected in the cranking stop rotational speed Nsc at the next restart. Therefore, the starter motor 12 is not overrun because the maximum blow-up rotation speed Np does not exceed the cranking stop rotation speed Nsc without providing an operation process for setting the optimum cranking stop rotation speed Nsc suitable for each vehicle type. It is reliably suppressed that it occurs. As a result, it is possible to provide an engine start control device capable of reliably preventing both the stall of the engine 1 and the overrun of the starter motor 12 by performing the start control at the optimum engine explosion speed every start. it can.

  In addition, in the engine start control device of the present invention, the engine ECU 20 as the cranking stop rotational speed update means determines that the new rotational speeds N1, N2, etc. are equal to or higher than the lower limit guard value based on the determination result as the update lower limit determination means. Since the cranking stop rotational speed Nsc stored in the B-RAM 24 is updated only at a certain time, it is possible to prevent the cranking stop rotational speed Nsc from being excessively lowered and the startability from being lowered.

  Furthermore, in the engine start control device of the present embodiment, it is only necessary to store and hold the cranking stop rotational speed Nsc, and it is not necessary to store and hold a lot of start history information in the nonvolatile memory as in the conventional case, and start control is also possible. It won't be complicated.

Further, in the engine start control device of the present embodiment, since the memory for storing the stop condition is configured by a static RAM, the update process of the cranking stop rotation speed Nsc can be executed quickly, and the existing Since the static RAM normally mounted on the engine control unit or the like can be used, the cost is not increased. In addition, when the memory for storing the stop condition is an EEPROM, even if the battery is disconnected, the stored information of the updated cranking stop rotational speed Nsc can be retained.
In the above-described embodiment, the engine ECU 20 is equipped with a main control function. However, the stop condition storage means, maximum speed measurement means, comparison means, cranking stop speed update means, and Needless to say, some or all of the functions of the update lower limit determination means can be mounted in the power management ECU, and in this case, the same effect as described above can be obtained.

  As described above, the present invention learns that when the cranking stop rotational speed exceeds the measured maximum blow-up rotational speed Np, it is updated to a new low rotational speed. Is reflected in the cranking stop rotational speed Nsc at the next restart, so that there is a lot of history information and a work process for setting the optimum cranking stop rotational speed suitable for each vehicle type is provided. In addition, it is possible to reliably suppress the starter motor overrun because the maximum blow-up rotation speed Np does not exceed the cranking stop rotation speed Nsc, and to ensure reliable startability. The control device can be provided, and is useful for all engine start control devices that execute learning control in order to improve engine startability.

1 is a schematic block configuration diagram showing an engine start control device according to a first embodiment of the present invention. It is a flowchart which shows the general | schematic process sequence of cranking hold control of the engine starting control apparatus which concerns on 1st Embodiment. (A) is a graph showing the engine speed change at the normal start by the engine start control device according to the first embodiment, and (b) is a graph showing the engine speed change at a high temperature restart by the engine start control device. The vertical axis represents the engine speed and the horizontal axis represents time. 3 is a graph similar to the graph of FIG. 3 for explaining the conventional problem, in which (a) shows a change in the engine speed at the normal start, and (b) shows a change in the engine speed at the high temperature restart.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Engine 1c Crankshaft 1w Flywheel 11 Starter switch 11a Start button 11b Contact part 12 Starter motor 12a Output shaft 13 Rotational speed sensor 20 Engine ECU (Stop condition storage means, maximum rotational speed measuring means, comparison means, cranking stop rotational speed Update means, update lower limit judgment means)
21 CPU
22 ROM
23 RAM
24 B-RAM (memory, stop condition storage means)
26 Input Interface Circuit 27 Output Interface Circuit 28 Constant Voltage Power Supply Circuit 31 Relay Switch Circuit 31a Relay Coil Part 31b Contact Part

Claims (6)

A starter switch operated to start the engine;
A starter motor that performs cranking of the engine by energization;
A rotational speed sensor for detecting an engine rotational speed of the engine;
Stop condition storage means for storing a stop condition for stopping the cranking;
In an engine start control device comprising: an energization control unit that controls energization to the starter motor based on the engine speed, the operation state of the starter switch, and the stop condition;
The stop condition storage means has a non-volatile memory for rewritably storing a cranking stop rotational speed for stopping the cranking;
The energization control unit is
Based on the detection information of the rotational speed sensor, maximum rotational speed measuring means for measuring the maximum value of the engine rotational speed due to the complete explosion of the engine,
A comparison means for comparing the cranking stop rotational speed with a maximum value of the engine rotational speed when the starter switch is operated continuously for a predetermined time or more;
Based on the comparison result of the comparison means, when the maximum value of the engine rotational speed does not exceed the cranking stop rotational speed, the cranking stop rotational speed stored in the memory is newly set lower than the rotational speed. An engine start control device comprising: cranking stop rotation number updating means for updating by rewriting to a different rotation number.   2. The engine start according to claim 1, wherein the cranking stop rotational speed update unit determines the new rotational speed by subtracting a predetermined rotational speed from the cranking stop rotational speed stored in the memory. Control device. The energization control unit includes an update lower limit determination unit that determines whether or not the new rotational speed is equal to or higher than a preset lower limit guard value,
The cranking stop rotational speed update means is based on the determination result of the update lower limit determination means,
3. The engine start control device according to claim 2, wherein the cranking stop rotational speed stored in the memory is updated only when the new rotational speed is equal to or greater than the lower limit guard value.   The energization control unit prohibits the cranking by stopping energization to the starter motor regardless of the operation of the starter switch when the engine speed exceeds the cranking stop speed. The engine start control device according to any one of claims 1 to 3, characterized in that:   The engine start control device according to claim 1, wherein the memory is configured by a static RAM.   2. The engine start control device according to claim 1, wherein the memory comprises an EEPROM.

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