JP2019044622A - Engine starting control device and engine starting method - Google Patents

Abstract

To provide an engine starting control device and an engine starting method for adjusting the opening of a throttle valve to a starting target opening appropriate for engine start at the engine start, actualizing more reliable engine start even when a battery deteriorates.SOLUTION: The engine starting control device for adjusting the opening of a throttle valve 2 to a starting target opening appropriate for engine start at the engine start with battery power changes a timing for setting the throttle valve 2 at the starting target opening according to the drop of battery voltage with cranking start.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an engine start control device and an engine start method.

  For example, as disclosed in Patent Document 1, a motorcycle or the like is provided with a throttle valve, and the intake amount to the engine is adjusted by adjusting the opening degree of the throttle valve. When starting such an engine from a stopped state, it is preferable to raise the engine speed early in order to stabilize the engine speed in a short time. For this reason, at the time of engine start, the opening degree of the throttle valve is set large (start target opening degree) so that more air is supplied to the engine than the intake amount required at the time of idling.

International Publication No. 2012/091014

  By the way, in order to stabilize the engine speed early, it is preferable to set the opening degree of the throttle valve to the target opening degree as early as possible. Therefore, it is conceivable to set the opening degree of the throttle valve to the start target opening degree when the ignition switch is turned on.

  However, when the ignition switch is turned on and the throttle valve starts to open at the target opening degree, the throttle valve becomes the target opening degree at the start of cranking. For this reason, a large amount of air flows into the cylinder of the engine at the start of cranking, and the torque of the crankshaft required for the compression of the air flowing into the cylinder increases. At this time, if the battery is deteriorated, for example, even if the charge level of the battery is high, the battery voltage may drop rapidly and the torque required to compress the air flowing into the cylinder may not be obtained. is there. In such a case, the startability of the engine may deteriorate or the engine may not start.

  The present invention has been made in view of the above-mentioned problems, and in an engine start control device and an engine start method for adjusting the opening degree of a throttle valve to a start target opening degree suitable for engine start at engine start, Even if, it aims to start the engine more reliably.

  The present invention adopts the following configuration as means for solving the above-mentioned problems.

  The first invention is an engine start control device that adjusts the opening degree of a throttle valve to a start target opening degree suitable for engine start at the time of engine start by battery power, and corresponds to a drop in battery voltage due to cranking start. A configuration is adopted in which the timing of setting the throttle valve to the start target opening degree is changed.

  According to a second aspect of the present invention, in the first aspect, a difference between the battery voltage before the start of cranking and the minimum value of the battery voltage in a predetermined period from the start of cranking is used as the drop amount of the battery voltage. Do.

  According to a third aspect of the present invention, in the first aspect, a difference between a battery voltage before the start of cranking and a minimum value of the battery voltage acquired before the battery voltage which has dropped from the start of the cranking starts to rise. Is adopted as the drop amount of the battery voltage.

  According to a fourth aspect of the present invention, in any one of the first to third aspects, timing of setting the value of the drop amount of the battery voltage and the throttle valve to the start target opening according to the battery voltage before the start of cranking Adopt a configuration that changes the relationship with the change amount of.

  According to a fifth invention, in any one of the first to fourth inventions, the timing of setting the throttle valve to the start target opening is delayed as the amount of decrease is larger.

  A sixth invention is an engine start method for adjusting the opening degree of the throttle valve to a start target opening degree suitable for engine start at the time of engine start by battery power, which corresponds to the above mentioned drop amount of battery voltage due to cranking start. A configuration is adopted in which the timing of setting the throttle valve to the start target opening is changed.

  According to the present invention, the timing for setting the throttle valve to the start target opening degree is changed according to the amount of drop of the battery voltage due to the start of cranking. As described above, in the present invention, the timing at which the throttle valve, which has conventionally been fixed, is set to the start target opening degree is made variable according to the drop amount of the battery voltage due to the start of cranking. Therefore, based on the amount of decrease in battery voltage due to the start of cranking, it is possible to set the throttle valve to the target start opening as soon as possible without causing compression loss in the cylinder. Therefore, according to the present invention, in the engine start control device and the engine start method for adjusting the opening degree of the throttle valve to the start target opening degree suitable for the engine start at the engine start, even a deteriorated battery can be more reliably It is possible to start the engine.

FIG. 1 is a block diagram showing a schematic configuration of an engine control system including a function as an engine start control device according to an embodiment of the present invention. It is a timing chart which shows the injection timing of the fuel in an injector, the ignition timing by an ignition coil, the opening degree of a throttle valve, the on-off state of an ignition switch, and the on-off state of a starter switch. It is a graph which shows the time-sequential change of the battery voltage at the time of engine starting. It is a flowchart which shows the processing flow at the time of the engine start of ECU which the engine control system containing the function as an engine start control apparatus of one Embodiment of this invention has.

  Hereinafter, an embodiment of an engine start control device and an engine start method according to the present invention will be described with reference to the drawings. In the following drawings, the scale of each member is appropriately changed in order to make each member have a recognizable size.

  FIG. 1 is a block diagram showing a schematic configuration of an engine control system 1 including a function as an engine start control device of the present embodiment. The engine control system 1 is a system for controlling the number of revolutions of an engine 20 mounted on a motorcycle or the like. The engine 20 in the present embodiment is a reciprocating engine having three cylinders (a first cylinder 21, a second cylinder 22 and a third cylinder 23). Such an engine 20 includes, for each cylinder, an injector for injecting fuel and an ignition coil for igniting a mixture containing fuel. In the following description, the injector and the ignition coil installed in the first cylinder 21 will be referred to as the first injector 21a and the first ignition coil 21b, if necessary, and the injector and the ignition coil installed in the second cylinder 22 Are referred to as a second injector 22a and a second ignition coil 22b, and an injector and an ignition coil installed in the third cylinder 23 are referred to as a third injector 23a and a third ignition coil 23b. The first injector 21a, the second injector 22a, and the third injector 23a are disposed, for example, at ports connected to the combustion chambers of the respective cylinders, and the first ignition coil 21b, the second ignition coil 22b, and the third ignition The coil 23 b is disposed in the combustion chamber of each cylinder.

  The first cylinder 21, the second cylinder 22, and the third cylinder 23 each have an intake stroke for taking air into the cylinder, a compression stroke for compressing the air, an explosion stroke for burning the air and fuel, and a combustion. The exhaust stroke for exhausting the gas from the cylinders is sequentially performed. The same stroke in each cylinder is started at different crank angles. For example, the intake stroke of the first cylinder 21, the intake stroke of the second cylinder 22, and the intake stroke of the third cylinder 23 are started at different timings (that is, different crank angles) in time series.

  A fuel pump 30 is connected to the first injector 21a, the second injector 22a, and the third injector 23a. The fuel pump 30 pressurizes the fuel and supplies the boosted fuel to the first injector 21a, the second injector 22a, and the third injector 23a.

  Further, for the engine 20, a temperature sensor 24 and a crank angle sensor 25 are installed. The temperature sensor 24 measures the temperature of the cooling water of the engine 20, and outputs a signal indicating the measurement result. The crank angle sensor 25 outputs a pulse signal indicating passage of a rotor tooth fixed to the crankshaft of the engine 20 and rotated with the crankshaft. The pulse interval of such a pulse signal indicates the number of revolutions of the engine 20. That is, the crank angle sensor 25 outputs a signal including the number of revolutions of the engine 20.

  Further, in the present embodiment, the rotor has a plurality of teeth arranged in the circumferential direction at equal intervals, but has a missing tooth region (a region where no teeth are provided) at one location in the circumferential direction. There is. The non-toothed area is arranged so that the crankshaft is located within the measurement range of the crank angle sensor 25 when the first cylinder 21 has a crank angle at the initial stage of the intake stroke. That is, in the pulse signal output from the crank angle sensor 25, when the first cylinder 21 reaches the crank angle at the initial stage of the intake stroke, pulses at substantially equal intervals are lost. In the present embodiment, a crank angle at which a pulse is lost in a pulse signal output from the crank angle sensor 25 is used as a reference angle.

  As shown in FIG. 1, the engine control system 1 of the present embodiment includes a throttle valve 2, a valve drive motor 3, a cell motor 4, a relay 5, a starter switch 6, an ignition switch 7, and a battery 8. An engine start control device 9 is provided.

  The throttle valve 2 is a valve for adjusting the intake amount of the engine 20. The throttle valve 2 is provided with a disc-shaped valve element capable of changing its attitude, and adjusts the passing amount of air (that is, the intake amount of the engine 20) by changing the inclination angle with respect to the flow direction of the valve element. . The valve drive motor 3 is, for example, a three-phase brushless motor, and the output shaft is coupled to the valve body of the throttle valve 2 via a reduction gear (not shown). The valve drive motor 3 is rotated in response to a three-phase drive signal input from a throttle valve controller 9 b of the engine start control device 9 described later.

  The cell motor 4 is a DC motor that generates rotational power by DC power supplied from the battery 8, and is connected to the crankshaft of the engine 20. The cell motor 4 is connected to the battery 8 through the relay 5 and the ignition switch 7 and is electrically connected to the battery 8 when the ignition switch 7 is on and the relay 5 can be energized. Ru. Such a cell motor 4 performs so-called cranking by converting DC power supplied from the battery 8 into rotational power and transmitting it to the crankshaft of the engine 20 when connected to the battery 8.

  The relay 5 is disposed between the cell motor 4 and the ignition switch 7 and electrically connects the battery 8 and the cell motor 4 via the ignition switch 7 while the starter switch 6 is pressed. The starter switch 6 is installed, for example, on the handle portion of the motorcycle, and is a switch that enables the relay 5 to be energized while being pressed by an occupant. The ignition switch 7 is, for example, a switch connected by inserting and rotating a key (not shown). When the ignition switch 7 is turned on, the electric power of the battery 8 is supplied to an ECU 9a and a throttle valve controller 9b which will be described later of the engine start control device 9. When the ignition switch 7 is turned on, the electric power of the battery 8 can be supplied to the cell motor 4 through the relay 5. The battery 8 is connected to the engine start control device 9 via the ignition switch 7. Also, the battery 8 is connected to the cell motor 4 via the ignition switch 7 and the relay 5.

  The engine start control device 9 includes an ECU (Engine Control Unit) 9 a and a throttle valve controller 9 b which generates a three-phase drive signal from battery power and supplies it to the valve drive motor 3 under the control of the ECU 9 a. The ECU 9a centrally controls the operating state of the engine 20, and includes an MPU (Micro-processing unit) that performs arithmetic processing, a memory that stores various data, programs, and the like. Further, as shown in FIG. 1, the ECU 9 a includes a battery voltage detection circuit 9 a 1 for detecting the voltage (battery voltage) of the battery 8.

  Such an ECU 9a calculates, for example, the opening degree of the throttle valve 2 based on the input from the temperature sensor 24, the crank angle sensor 25 or the like, and outputs a control signal indicating the calculated opening degree of the throttle valve 2 to the throttle valve controller Enter 9b. Further, the ECU 9a controls the first injector 21a, the first ignition coil 21b, the second injector 22a, the second ignition coil 22b, the third injector 23a, the third ignition coil 23b, based on the input from the temperature sensor 24, the crank angle sensor 25 and the like. Do also. The ECU 9a not only controls the engine start but also controls the operation of the engine 20 after the start.

  Further, the ECU 9a controls the opening degree of the throttle valve 2 in the control of starting the engine 20 from the stop state (engine start control). In the present embodiment, the ECU 9a sets a timing at which the throttle valve 2 is set to the target start opening degree in accordance with the amount of decrease in the battery voltage due to the start of cranking in the engine start control. The start target opening degree is an opening degree set so that the rotation speed of the engine 20 is stabilized early to the target rotation speed at idling, and is stored in the memory after being obtained in advance by experiments or simulations. Note that it is preferable to change the start target opening degree according to the temperature of the engine 20 (temperature of cooling water) before the start. For this reason, in the present embodiment, a table (target opening degree table) indicating the relationship between the temperature of the cooling water and the start target opening degree is stored in the memory of the ECU 9a.

  Further, the ECU 9a stores the minimum opening (control zero opening) of the throttle valve 2 at which the engine 20 can idle. The control zero opening is an opening that allows the engine 20 to take in air to such an extent that idling is possible, and is different from an opening where the throttle valve 2 is fully closed mechanically. Such a control zero opening degree is an opening degree which is zero in control of the engine 20, and is stored in the memory after being obtained in advance by experiments and simulations. That is, with the control zero opening as zero, the target value and the detection value of the opening of the throttle valve 2 are determined.

  Further, the ECU 9a stores a first battery voltage drop amount V1 and a second battery voltage drop amount V2 for determining the timing of setting the throttle valve 2 to the target opening degree for start. The first battery voltage drop amount V1 and the second battery voltage drop amount V2 are stored in the memory after being obtained in advance by experiments and simulations. The first battery voltage drop amount V1 is a threshold value indicating that sufficient electric power can be supplied to the cell motor 4 at the time of cranking because the amount of drop of the battery voltage due to the start of cranking is smaller than this. Here, "sufficient electric power can be supplied to the cell motor 4" means that even if engine friction increases due to low temperature and so on and the throttle valve 2 has a target start opening degree at the start of cranking, the crankshaft It means that electric power capable of generating a torque for rotating the electric motor is supplied to the cell motor 4. That is, when the battery voltage is applied to the cell motor 4 in a state where the battery voltage drop amount due to the start of cranking is equal to or less than the first battery voltage drop amount V1, engine friction increases due to low temperature etc. and cranking starts At the same time, even when the throttle valve 2 is at the start target opening degree, the torque for rotating the crankshaft can be generated by the cell motor 4.

  The second battery voltage drop amount V2 is larger than the first battery voltage drop amount V1 and is a threshold value indicating that the battery voltage may exceed the first battery voltage drop amount V1 and that the cell motor 4 may be supplied with minimal power at the time of cranking. is there. Here, "only minimum power can be supplied to the cell motor 4" means that power can be supplied to the cell motor 4 for which the torque for rotating the crankshaft can not be obtained unless the throttle valve 2 has a control zero opening at the start of cranking It means that. That is, when the battery voltage is applied to the cell motor 4 in a state where the battery voltage drop amount due to the start of cranking exceeds the second battery voltage drop amount V2, the crankshaft is rotated if the throttle valve 2 is not at control zero opening. There is a possibility that the cell motor 4 can not generate torque to move.

  In the present embodiment, the ECU 9a detects the battery voltage drop amount due to the start of cranking by the battery voltage detection circuit 9a1, and the timing for setting the throttle valve 2 to the target opening degree based on the detected battery voltage drop amount. Change For example, when the battery voltage drop amount is equal to or less than the first battery voltage drop amount V1, the ECU 9a sets the timing for setting the throttle valve 2 to the start target opening degree immediately after the start of cranking. Further, for example, when the battery voltage drop amount is larger than the first battery voltage drop amount V1 and not more than the second battery voltage drop amount V2, the ECU 9a cranks the timing for setting the throttle valve 2 to the start target opening degree. The timing when the first missing tooth is detected by the angle sensor 25 is set. Further, for example, when the drop amount of the battery voltage is larger than the second battery voltage drop amount V2, the ECU 9a makes the timing for setting the throttle valve 2 to the start target opening degree after the complete explosion (ignition to air-fuel mixture) Do. That is, the ECU 9a delays the timing of setting the throttle valve 2 to the target opening degree as the amount of drop of the battery voltage due to the start of cranking is larger.

  Further, the ECU 9a uses the difference between the battery voltage before the start of cranking and the minimum value of the battery voltage acquired during the period from the start of the cranking to the rise of the battery voltage as the battery voltage drop amount.

  Subsequently, an engine start method by the engine control system 1 of the present embodiment will be described with reference to the timing chart of FIG. 2, the graph of FIG. 3 and the flowchart of FIG. Note that FIG. 2 shows the injection timing of fuel in each injector (the first injector 21a, the second injector 22a, and the third injector 23a), and each ignition coil (the first ignition coil 21b, the second ignition coil 22b, and the third ignition) 5 is a timing chart showing the ignition timing by the coil 23b), the opening degree of the throttle valve 2, the on / off state of the ignition switch 7, and the on / off state of the starter switch 6. FIG. FIG. 3 is a graph showing time-series changes in battery voltage at engine start. Moreover, FIG. 4 is a flowchart which shows the processing flow of ECU9a at the time of engine starting.

  When the ignition switch 7 is turned on by the occupant, the battery 8 and the engine start control device 9 are energized, and power is supplied from the battery 8 to the ECU 9a and the throttle valve controller 9b. When the ECU 9a is activated by being supplied with power from the battery 8, as shown in FIG. 4, the ECU 9a determines whether the engine 20 is stopped (step S1). Here, the ECU 9a determines whether the engine 20 is stopped based on the signal input from the crank angle sensor 25. When it is determined in step S1 that the engine 20 is not stopping, the ECU 9a ends the start control of the engine 20.

  When the ECU 9a determines that the engine 20 is stopped, the ECU 9a performs a process (step S2) of adjusting the opening degree of the throttle valve 2 to the control zero opening degree. In step S2, the ECU 9a outputs a control signal indicating that the opening degree of the throttle valve 2 should be the control zero opening degree. The control signal indicating the control zero opening degree output from the ECU 9a is input to the throttle valve controller 9b. The throttle valve controller 9 b generates a drive signal for setting the opening degree of the throttle valve 2 to the control zero opening degree from the power of the battery 8 and supplies the generated signal to the valve drive motor 3. As a result, as shown in FIG. 2, the opening degree of the throttle valve 2 becomes the control zero opening degree TH0.

  Subsequently, when the starter switch 6 is turned on by the occupant, power is supplied from the battery 8 to the cell motor 4 and cranking is started in which the crankshaft of the engine 20 is rotated by the cell motor 4. When cranking is started and the crankshaft of the engine 20 is rotated by the cell motor 4, a pulse signal is input from the crank angle sensor 25 to the ECU 9a. Then, the ECU 9a determines whether cranking is in progress based on the pulse signal input from the crank angle sensor 25 (step S3).

  If it is determined in step S3 that the cranking is not in progress, the ECU 9a acquires the detected battery voltage as the high battery voltage value Vmax (step S4). That is, the ECU 9a acquires the battery voltage before the start of cranking as the high battery voltage value Vmax.

  When the ECU 9a determines that cranking is in progress in step S3, the ECU 9a acquires the detected battery voltage as the low battery voltage value Vmin (step S5). Furthermore, the ECU 9a determines whether the battery voltage has risen (step S6), and updates the low battery voltage value Vmin until the battery voltage rises (step S7). That is, the ECU 9a sets the minimum value of the battery voltage acquired before the battery voltage dropped from the start of cranking to the rise becomes the low battery voltage value Vmin.

  When the ECU 9a determines in step S6 that the battery voltage has risen, it calculates the battery voltage drop amount Vd due to the start of cranking (step S8). Here, the ECU 9a calculates the difference between the high battery voltage value Vmax and the low battery voltage value Vmin as the drop amount Vd. That is, as shown in FIG. 3, the difference between the battery voltage before the start of cranking and the minimum value of the battery voltage acquired during the time the battery voltage dropped from the start of cranking starts to rise is the drop amount Vd. Become.

  Subsequently, the ECU 9a determines whether the drop amount Vd is equal to or less than the first battery voltage drop amount V1 (step S9). If the ECU 9a determines that the drop amount Vd is equal to or less than the first battery voltage drop amount V1, the ECU 9a sets a start target opening degree of the throttle valve 2 (step S10). Here, the ECU 9a sets the start target opening based on the target opening degree table that defines the relationship between the coolant temperature of the engine 20 and the start target opening degree, and the measurement result input from the temperature sensor 24. . Then, when the start target opening degree is set, the ECU 9a outputs a control signal indicating that the opening degree of the throttle valve 2 is to be the start target opening degree (step S11). The control signal indicating the start target opening degree output from the ECU 9a in this manner is input to the throttle valve controller 9b. The throttle valve controller 9 b generates a drive signal for setting the opening degree of the throttle valve 2 to the start target opening degree from the power of the battery 8 and supplies the generated signal to the valve drive motor 3. As a result, the opening degree of the throttle valve 2 becomes the start target opening degree THM. That is, in the present embodiment, as shown by the throttle valve opening degree (a) in FIG. 2, the ECU 9a sets the throttle immediately after cranking is started so that the drop amount Vd is equal to or less than the first battery voltage drop amount V1. Let the opening degree of the valve 2 be the start target opening degree THM.

  If the ECU 9a determines in step S9 that the drop amount Vd is larger than the first battery voltage drop amount V1, it determines whether the drop amount Vd is larger than the second battery voltage drop amount V2 (step S12) . If the ECU 9a determines that the drop amount Vd is not larger than the second battery voltage drop amount V2, the ECU 9a stands by until the first missing tooth is detected by the crank angle sensor 25 (step S13). The ECU 9a determines that the first missing tooth is detected when there is a pulse defect in the pulse signal input from the crank angle sensor 25 and this is the first time after step S3. When the ECU 9a determines that the first missing tooth has been detected, the ECU 9a proceeds to step S10. That is, in the present embodiment, as shown by the throttle valve opening degree (b) in FIG. 2, the ECU 9a makes the drop amount Vd larger than the first battery voltage drop amount V1 and not more than the second battery voltage drop amount V2. It is waited to start the cranking and set the opening degree of the throttle valve 2 as the start target opening degree THM until the first missing tooth is detected.

  When the step S11 is completed, the ECU 9a stands by until the second missing tooth is detected by the crank angle sensor 25 (step S14). If there is a missing pulse in the pulse signal input from the crank angle sensor 25 and this is the second time after step S3, it is determined that the second missing tooth has been detected. When the ECU 9a determines that the second missing tooth has been detected, it determines the stroke of each cylinder (step S15). The ECU 9a determines the stroke of each cylinder based on, for example, an input from an intake pressure sensor (not shown). Then, after the detection of the second missing tooth, the ECU 9a repeatedly injects fuel from the injector and supplies electric power to the ignition coil at predetermined timing based on the engine rotational speed, the accelerator opening degree, and the like. In addition, after the engine 20 completely detonates (ignition to the air-fuel mixture) in any of the cylinders, it continues to operate continuously by injecting fuel from the above-described injector and supplying power to the ignition coil.

  When the ECU 9a determines in step S12 that the drop amount Vd is larger than the second battery voltage drop amount V2, the ECU 9a stands by until the second missing tooth is detected by the crank angle sensor 25 (step S16). Furthermore, the ECU 9a stands by until the complete explosion, which is a state in which the air-fuel mixture is ignited in any of the cylinders (step S17). Here, the ECU 9a determines based on the pulse interval of the pulse signal input from the crank angle sensor 25 whether or not the complete explosion has occurred.

  If the ECU 9a determines in step S17 that the explosion is complete, the stroke of each cylinder is determined (step S18), and then the start target opening THM of the throttle valve 2 is set (step S19). A control signal indicating that the opening degree of the vehicle is set to the start target opening degree THM is output (step S20). Step S18 is the same process as step S15 described above, step S19 is the same process as step S10 described above, and step S20 is the same process as step S11 described above. That is, in the present embodiment, as shown by the throttle valve opening degree (c) in FIG. 2, the ECU 9a completely detonates in any cylinder if the drop amount Vd is larger than the second battery voltage drop amount V2. It is waited until the opening degree of the throttle valve 2 becomes the start target opening degree THM.

  It should be noted that, when designing the engine 20, as the number of cylinders increases, it is easy to set one of the cylinders as the intake stroke at all crank angles (360 °). Air can be supplied to any cylinder. In this case, it is possible to supply a large amount of air to the cylinder immediately after a period in which compression loss may occur immediately after the start of cranking, and it is possible to stabilize the engine rotation speed earlier.

  According to the engine control system 1 provided with the engine start control device 9 of the present embodiment as described above, the timing at which the throttle valve 2 is made the start target opening degree THM is changed according to the drop amount of the battery voltage due to the start of cranking. Do. As described above, in the engine control system 1 including the engine start control device 9 of the present embodiment, the timing at which the throttle valve 2 conventionally fixed is set to the start target opening degree is the drop amount of the battery voltage due to the start of cranking. Is made variable. Therefore, based on the amount of decrease in battery voltage due to the start of cranking, it is possible to set the throttle valve to the target start opening as soon as possible without causing compression loss in the cylinder. Therefore, according to the engine control system 1 provided with the engine start control device 9 of the present embodiment, it is possible to start the engine 20 more reliably even with the deteriorated battery 8.

  Further, in the engine control system 1 provided with the engine start control device 9 of the present embodiment, the battery voltage before the start of cranking and the battery voltage acquired during the time when the battery voltage dropped from the start of cranking starts to rise. The difference with the minimum value of V is the battery voltage drop Vd. Therefore, the amount of decrease Vd can be determined based on the first bottom peak value of the voltage drop from the start of cranking, and the amount of decrease Vd can be determined in a short time.

  Further, in the engine control system 1 including the engine start control device 9 of the present embodiment, as the descent amount Vd is larger, the timing of setting the throttle valve 2 to the start target opening degree THM is delayed. The torque which needs to be generated by the cell motor 4 at the time of engine start decreases with the increase of the engine speed. Therefore, the compression loss in the cylinder can be more reliably prevented by delaying the timing of setting the throttle valve 2 to the start target opening THM as the descent amount Vd is large, that is, as the deterioration of the battery 8 progresses. .

  Although the preferred embodiments of the present invention have been described above with reference to the accompanying drawings, it goes without saying that the present invention is not limited to the above embodiments. The shapes, combinations, and the like of the constituent members shown in the above-described embodiment are merely examples, and various changes can be made based on design requirements and the like without departing from the spirit of the present invention.

  For example, in the above embodiment, the difference between the battery voltage before the start of cranking and the minimum value of the battery voltage acquired during the period from when the battery voltage dropped from the start of cranking starts to rise is the battery voltage drop amount We adopted Vd configuration. However, the present invention is not limited to this, and the difference between the battery voltage before the start of cranking and the minimum value of the battery voltage in a predetermined period from the start of cranking may be used as the drop amount Vd of the battery voltage. In such a case, even if a plurality of bottom peaks occur in the battery voltage during a predetermined period, the battery voltage drop Vd can be determined based on the smallest value.

  Further, depending on the charge amount of the battery 8 before the start of cranking, the drop amount Vd may be different even in the same deterioration state. Therefore, in the above embodiment, the relationship between the value of the drop amount Vd of the battery voltage and the change amount of the timing at which the throttle valve 2 starts the target opening degree is changed according to the battery voltage before the start of cranking. It is good. That is, the first battery voltage drop amount V1 and the second battery voltage drop amount V2 may be changed according to the battery voltage before the start of cranking. As a result, it is possible to optimize the timing for setting the throttle valve 2 to the target opening degree with consideration of the charge level of the battery 8.

  Moreover, in the said embodiment, the engine 20 demonstrated the structure provided with three cylinders (The 1st cylinder 21, the 2nd cylinder 22, and the 3rd cylinder 23). However, the present invention is not limited to this, and can also be applied to start a multi-cylinder engine other than a single cylinder or three cylinders.

  DESCRIPTION OF SYMBOLS 1 ...... Engine control system, 2 ...... Throttle valve, 3 ...... Valve drive motor, 4 ...... Cell motor, 5 ...... Relay, 6 ...... Starter switch, 7 ...... Ignition switch, 8 ...... Battery, 9 ...... Engine start control device 9a: ECU 9b: throttle valve controller 20: engine 21: first cylinder 22: second cylinder 23: third cylinder 24: temperature sensor , 25 ... crank angle sensor, 30 ... fuel pump

Claims (6)

An engine start control device that adjusts an opening degree of a throttle valve to a start target opening degree suitable for engine start at the time of engine start by battery power,
An engine start control device, comprising: changing a timing of setting the throttle valve to the start target opening degree in accordance with a drop amount of battery voltage due to the start of cranking.   2. The engine start control device according to claim 1, wherein a difference between a battery voltage before the start of cranking and a minimum value of the battery voltage in a predetermined period from the start of cranking is used as a drop amount of the battery voltage.   A difference between the battery voltage before the start of cranking and the minimum value of the battery voltage acquired during the period from the start of the cranking to the rise of the battery voltage is defined as a drop amount of the battery voltage. The engine start control device according to claim 1.   The relationship between the value of the drop amount of the battery voltage and the change amount of the timing at which the throttle valve is set to the start target opening degree is changed according to the battery voltage before the start of cranking. 3. The engine start control device according to any one of the above.   The engine start control device according to any one of claims 1 to 4, wherein the timing of setting the throttle valve to the start target opening is delayed as the amount of decrease is larger. An engine start method for adjusting an opening degree of a throttle valve to a start target opening degree suitable for engine start at the time of engine start by battery power,
An engine start method, comprising: changing a timing of setting the throttle valve to the start target opening degree according to a drop amount of battery voltage due to the start of cranking.

Images