JP2004028007A - Engine starter - Google Patents

Abstract

An engine starting performance is improved by a brushless motor having no rotor position detection sensor.
A forward / reverse control unit (34) starts the engine by first rotating the motor in the normal direction, subsequently rotating the motor in the reverse direction, and then rotating the motor in the positive direction. The motor rotation speed calculator 31 calculates the rotation speed of the motor based on the induced voltage of the motor. The speed judging unit 33 outputs a detection signal when the rotation speed drops to 75% or less of the maximum speed up to then. The forward / reverse control unit 34 reverses the motor according to the detection signal. By detecting a decrease in the rotation speed of the motor, it is possible to detect that the load on the engine has increased. By reversing from this load increasing position, the motor is rotated forward with greater inertia and accelerated to the cranking speed at a stretch.
[Selection diagram] Fig. 1

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an engine starting device, and more particularly to an engine starting device suitable for overcoming the load of a compression stroke of an engine and stably starting the engine.
[0002]
[Prior art]
A large torque is required to get over TDC during the compression stroke of the engine. For this reason, if the engine is started from around 90 degrees before the top dead center, it may not be possible to get over the top dead center due to a high load. Therefore, the motor of the starter (starter motor) is required to have an output torque that has a sufficient margin to overcome the high load region of the compression stroke.
[0003]
On the other hand, if starting in such a high load region or immediately before such a high load region can be avoided, the starter motor having a relatively small torque can survive the compression stroke. Japanese Patent Application Laid-Open No. 7-71350 discloses that the current position, that is, the starting position is checked by reading the crank angle of the engine, and a normal rotation corresponding to this position or a preliminary rotation consisting of reverse rotation for a predetermined time is instructed. A starter that commands normal rotation, or reads the crank angle of the engine to check the start position, determines the load torque decreasing direction from this position, and commands a preliminary rotation in the torque decreasing direction, and then commands a normal forward rotation. A starting device is disclosed.
[0004]
This starting device focuses on the fact that the friction surface becomes substantially a dynamic friction surface due to the reverse rotation, that is, the spread of oil due to the preliminary rotation, that is, the friction coefficient decreases, and the load torque decreases. It is trying to improve startability.
[0005]
[Problems to be solved by the invention]
In the conventional starting device described above, even when a starter motor having a not so large starting torque is used, a certain improvement in startability can be expected. However, it is still not sufficient from the viewpoint of overcoming the high load region of the compression stroke as described above.
[0006]
In addition, a starting start position detecting means is indispensable in order to confirm the starting start position and take a configuration in which the motor is preliminarily reverse-rotated by a rotation angle or a time corresponding to the start start position. From the viewpoint of use as a general-purpose starting device, Not preferred. In particular, when a brushless motor having no rotor position detecting sensor is used as a starter motor, it is necessary to provide an engine position detecting means as described in JP-A-7-71350.
[0007]
An object of the present invention is to solve the above-described problem, move a piston to a forward rotation start position where a large inertia force can be obtained without confirming a start start position, and start the engine with an engine start torque utilizing the large inertia force from that position. It is an object of the present invention to provide an engine starting device that can be operated.
[0008]
[Means for Solving the Problems]
According to the present invention, a forward / reverse rotatable motor for starting the engine is first driven in the forward rotation direction of the engine until the rotation speed drops below a predetermined value, and then the rotation speed in the reverse rotation direction becomes lower than the predetermined value. The first feature is that control means is provided for starting the engine by driving the engine to the normal rotation direction and thereafter driving the engine in the forward rotation direction.
[0009]
According to the first feature, first, by rotating the motor forward until the rotation speed of the motor decreases, the motor can be rotated to a high load position, that is, a position where the load becomes light during reverse rotation. Thereafter, the motor is rotated in the reverse direction, the motor is rotated in the reverse direction until the rotation speed again decreases to the predetermined value, and then the rotation is shifted to the normal rotation for starting.
[0010]
Regardless of the starting position of the motor, the position where the motor rotation speed has decreased to the predetermined value corresponds to the position where the engine load has increased. Therefore, the high load position can be detected without using the position detection sensor, and it is not necessary to confirm the start position of the motor.
[0011]
When the motor is rotated from the high load position in the reverse direction, the load becomes light. Therefore, in the reverse rotation after the forward rotation, the motor can be rotated to a position where the engine load further increases. In this way, the motor is moved to a position where the engine can be started with a light load, and then the motor is rotated forward, so that the motor with a small torque at a stretch overcomes the high load region of the compression stroke and accelerates the engine to the cranking rotational speed. It becomes possible.
[0012]
Further, the present invention has a second feature in that the motor is driven by an initial excitation current in forward rotation and reverse rotation at the start of a start operation, and is driven by a current higher than the initial excitation current in subsequent forward rotation. There is.
[0013]
According to the second feature, by suppressing the rotation speed with a low initial exciting current, the motor can be easily stopped at the high load position during the forward rotation and the reverse rotation, and the reaction when the vehicle cannot cross the high load position can be prevented. It is possible to suppress the force (the reaction force is large when the rotation speed is high).
[0014]
Further, according to the present invention, the motor is speed-controlled in accordance with a first target speed in a forward rotation and a reverse rotation at the start of a start operation, and in a subsequent forward rotation, a second target speed which is higher than the first target speed. The third feature is that the speed is controlled in accordance with the third target speed which is the cranking speed.
[0015]
According to the third feature, when the starting operation is started, the motor is rotated forward and backward at a speed smaller than the speed after the starting operation, so that the motor can be accurately stopped at the high load position, and the starting current does not become excessive after the starting operation. Thus, it is possible to accelerate at a stretch to the cranking speed at a large speed while suppressing the above.
[0016]
Further, the present invention provides the motor according to the first aspect, wherein the motor is a brushless motor, and among the three-phase fixed windings, when a drive current is applied to two phases, a rotor is driven based on a voltage signal induced in a non-energized winding. The fourth feature is that the rotation speed detection means detects the rotation speed of the motor based on the rotation speed signal.
[0017]
Further, according to the present invention, the motor is a brushless motor, and based on a deviation between a current output value for energizing a fixed winding and a measured current value in the stator winding, a rotation position signal of a rotor and A fifth feature is that a rotation speed signal is formed, and the rotation speed detection means detects the rotation speed of the motor based on the rotation speed signal.
[0018]
According to the fourth and fifth features, the rotation speed of the motor, that is, the rotation speed of the engine at the time of starting is detected based on the induced voltage of the winding or the current supplied to the winding, and the rotation position sensor of the motor or the engine is detected. The reverse position of the normal rotation and the reverse rotation of the motor can be determined based on the rotation speed without providing the motor.
[0019]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 2 is a side view of an engine generator using a brushless motor as a starter motor, and FIG. 3 is a sectional view taken along line V-V of FIG. The engine generator 1 includes a four-cycle internal combustion engine (hereinafter simply referred to as “engine”) 2 and a generator 3 that is a magnet-type multipolar generator. The generator 3 is a generator motor, and also operates as a motor. Details will be described later. The crankshaft 4 of the engine 2 is drawn out of the engine 2 while being supported by a bearing 6 or the like provided on a side wall 5 a of the crankcase 5. An annular star core 7 is fixed to a peripheral boss portion of a side wall 5 a of the crankcase 5 surrounding the crankshaft 4 by a bolt 80. The iron core 7 includes an annular yoke portion 7a and 27 salient pole portions 7b radially protruding therefrom. A three-phase winding is sequentially and alternately wound around the salient pole portion 7b to form the stator 8.
[0020]
A forged hub 9 is fitted to the end of the crankshaft 4, and a flywheel 10 also serving as a rotor yoke is connected to the hub 9. The flywheel 10 includes a disk portion 10a and a cylindrical portion 10b formed by press-forming a high-tensile steel plate into a cup shape. The disk portion 10a is fixed to the hub 9, and the cylindrical portion 10b is attached so as to cover the outside of the salient pole portion 7b of the iron core 7.
[0021]
Eighteen neodymium-based magnets 11 having a high magnetic force are fixed to the inner peripheral surface of the cylindrical portion 10b of the flywheel 10 in the circumferential direction to form an outer rotor type magnet rotor 12. Such a rotor 12 can function as a flywheel by securing a sufficient mass (mass) by laying the magnet 11 on the inner peripheral surface of the cylindrical portion 10b.
[0022]
A cooling fan 13 is attached to the disk portion 10a of the flywheel 10. The cooling fan 13 has a plurality of blades 13b erected in one circumferential direction on one side surface of an annular substrate 13a, and the substrate 13a is fixed to the outer surface of the disk portion 10a of the flywheel 10. The fan cover 14 that covers the cooling fan 13 forms a cooling air guide path 14 a that extends from the side of the flywheel 10 to the engine 2.
[0023]
FIG. 4 is a system diagram of the engine generator 1. The generator 3 is driven by the engine 2 to generate a three-phase alternating current. The output AC of the generator 3 is full-wave rectified by a converter 15 comprising a rectifier circuit in which semiconductor rectifiers are assembled in a bridge, and is converted to DC. The DC output from the converter 15 is smoothed by the capacitor smoothing circuit 16 and input to the inverter 17, where it is converted into AC of a predetermined frequency by a bridge circuit of FETs constituting the inverter 17. The alternating current output from the inverter 17 is input to the demodulation filter 18 and only low frequency components (for example, commercial frequency) pass. The alternating current that has passed through the demodulation filter 18 is connected to an output terminal 21 via a relay 19 and a fuse 20. The relay 19 is "open" when the engine 2 is started, and is "closed" after the engine 2 is started to a predetermined degree.
[0024]
The generator 3 of the engine generator 1 is a generator motor as described above, and can be used as a starter motor for starting the engine 2. Hereinafter, when used as a starter motor, the generator 3 will be described as a starter motor 3a. A starter driver 22 for the starter motor 3a is provided. In order to supply a current for starting the engine 2 to the starter driver 22, a rectifying circuit 23 and a smoothing circuit 24 are provided. The rectifier circuit 23 includes a harmonic filter 231 and a converter 232. The harmonic filter 231 is connected to the output terminal 21.
[0025]
The output side of the generator 3 is connected to, for example, a single-phase power supply 25 of AC 200 V, and AC is supplied from the power supply 25 when the engine is started. This alternating current is input to the harmonic filter 231 to remove the higher harmonics, converted into direct current by the converter 232, and further supplied to the starter driver 22 via the smoothing circuit 24 as control power.
[0026]
The output side of the starter driver 22 is connected to each phase of the three-phase winding of the generator 3 via the relay 26. The relay 26 is "closed" when the engine 2 is started, and is "open" after the engine 2 is started to a predetermined degree. In order to start the engine 2, current is sequentially supplied to each phase of the three-phase winding of the generator 3 in a predetermined order. A switching element (FET) 221 for sequentially supplying a current to each phase winding, a CPU 222, and a sensorless drive unit 223 that does not use a sensor for detecting the position of the rotor 12 are provided.
[0027]
FIG. 5 is a block diagram illustrating main functions of the sensorless driving unit 223. In the figure, an induced voltage detection unit 27 detects the voltage signal induced between the remaining one phase and the middle point when the rotor is rotated by conducting electricity between the two phases of the stator 8 by the inverter circuit, that is, the switching element 221. Detect the waveform. The position detector 28 determines the positional relationship between each phase of the stator 8 and each magnet of the rotor 12, that is, the rotational position, based on the detected voltage waveform. The drive calculation circuit 29 calculates a cycle for driving the switching element 221 based on the positional relationship between each phase of the stator 8 and each magnet of the rotor 12. The drive unit 30 supplies a conduction signal to the inverter circuit 221 based on the cycle calculated by the drive operation circuit 29.
[0028]
FIG. 6 is a time chart illustrating the overall operation of the start control of the engine power generator 1. At timing t1, an engine start command is input, the start signal of the control device (ECU) is turned on, and after a standby time (for example, 1 second), the relays 19 and 26 are switched for controlling the starter motor 3a, and at timing t2. The starter motor 3a is rotated forward. Then, the starter motor 3a is rotated in the reverse direction at timing t3 when the rotation speed falls to the predetermined value or less during the forward rotation, and reaches the high load region. In the forward rotation and the reverse rotation, the starter motor 3a is driven with an initial excitation current smaller than the current supplied during the steady operation. By suppressing the rotation speed by such an initial exciting current, the starter motor 3a can be easily stopped at the high load position, that is, at the position where a sufficient starting torque can be expected at the time of reverse rotation during the forward rotation and the reverse rotation. (When the rotation speed is high, the reaction force is high).
[0029]
When the starter motor 3a is rotated forward and reverse to position the crankshaft 4 at a position where a sufficient starting torque can be expected, acceleration is started in the forward rotation direction at timing t4. In this forward rotation, a starting current higher than the initial exciting current is supplied to the starter motor 3a.
[0030]
When the starter motor 3a reaches the cranking target rotation speed at timing t5, this rotation speed is maintained during cranking. Then, after the initial explosion of the engine at the ignition timing t6, the rotation speed of the engine starts to increase, and at the timing t7, the relay 19 is closed, the relay 26 is opened, and the control of the generator 3 is switched. The start signal is maintained until the timing t8 (for example, 10 seconds from the timing t1), but if the specified rotation speed (for example, 1500 rpm) is not reached by the timing t8, the start has failed. Judgment is made, and the start signal is turned on again after a predetermined time (for example, 10 seconds).
[0031]
The stop positions of the forward rotation and the reverse rotation for moving the starter motor 3a to a position where a sufficient starting torque can be expected are determined based on the fact that the rotation speed of the starter motor 3a has fallen below a predetermined value. The rotation speed of the starter motor 3a can be calculated based on, for example, the period of the induced voltage waveform.
[0032]
7 and 8 are flowcharts of the start control of the engine generator 1, and FIG. 9 is a time chart of the start control. In step S1 of FIG. 7, it is determined whether or not there is an engine start command. If an engine start command has been input, the process proceeds to step S2, and the starter motor 3a is driven in the forward direction, that is, in the forward direction of the engine 2. In step S3, it is determined whether time T1 (for example, 0.3 seconds) has elapsed from the start of the forward rotation operation in step S2. Time T1 is a time for determining whether or not driving in the normal rotation direction is possible. In step S4, it is determined whether or not the rotation speed of the starter motor 3a is equal to or higher than the start completion speed (for example, 33 rpm). Thus, it is determined whether or not starter motor 3a has started to rotate. If the rotation speed does not become equal to or higher than the start completion speed before the time T1 elapses, the process proceeds to step S11 to start reverse rotation (FIG. 9 (1)).
[0033]
When the starter motor 3a becomes equal to or higher than the start completion speed, step S4 becomes affirmative and the process proceeds to step S5, in which forward rotation with speed control is performed so as to converge to the forward rotation target speed (for example, 230 rpm) for alignment. In step S6, it is determined whether time T2 (for example, 0.5 seconds) has elapsed from the start of the forward rotation operation in step S5. The time T2 is a time for determining the necessity of the alignment and the transition to the reverse operation. The process proceeds to step S7 until the time T2 elapses.
[0034]
In step S7, it is determined whether the rotation speed of the starter motor 3a has decreased to the reversal determination speed (for example, 75% of the maximum speed up to that point). Thus, it is determined whether or not the crank angle has decreased near the high load position before the top dead center. Even if the time T2 has elapsed (Yes at Step S6), if the rotational speed does not decrease (No at Step S7), it is determined that the engine is in the light load region after the top dead center. Instead, the process proceeds to step S23 (FIG. 8) for positive acceleration rotation (FIG. 9 (2)).
[0035]
If the rotation speed has decreased to the reversal determination speed, step S7 becomes affirmative, and the process proceeds to step S8 to stop the forward rotation of the starter motor 3a by brake control. When the time T3 (for example, 0.2 seconds) for the stop determination elapses (Yes in step S9), or when the speed becomes equal to or less than the speed (for example, 23 rpm (FIG. 9-4)) regarded as the rotation stop (Yes in step S10). Then, it is determined that the starter motor 3a does not rotate forward any more, and the process proceeds to step S11.
[0036]
In step S11, the starter motor 3a is rotated in the reverse direction to rotate the engine 2 in the reverse direction. In step S12, it is determined whether time T4 (for example, 0.3 seconds) has elapsed from the start of the reverse rotation operation in step S11. Time T4 is a determination time for shifting to the reverse rotation operation with speed control. If the starting completion speed (for example, 33 rpm) has been reached before the time T4 has elapsed, the result of the determination in step S13 becomes affirmative, and the process proceeds to step S14. If the speed does not exceed the start completion speed even after the elapse of the time T4, the process proceeds to step S20 ((3) in FIG. 9).
[0037]
In step S14, a reverse rotation operation involving speed control is performed. In step S15, it is determined whether time T5 (for example, 0.5 seconds) has elapsed from the start of the reverse rotation operation in step S14. Time T5 is a time for determining the reverse rotation stop. The process proceeds to step S16 until the time T5 has elapsed. In step S16, it is determined whether the rotation speed of the starter motor 3a has decreased to the reversal determination speed (for example, 75% of the maximum speed up to that point). As a result, it is determined whether the engine load has increased and the crank angle has reached the high load position before the top dead center (corresponding to after the top dead center in the normal rotation direction).
[0038]
When the time T5 has elapsed (Yes at Step S15) or when the rotation speed has decreased (Yes at Step S16), the process proceeds to Step S17 to stop the reverse rotation of the starter motor 3a by brake control. When the time T6 (for example, 0.2 seconds) for the stop determination has elapsed (Yes in step S18), or when the speed is considered to be the rotation stop (for example, 23 rpm (5 in FIG. 9)) or less (Yes in step S19). Then, the process proceeds to step S20 (FIG. 8) to cause the starter motor 3a to accelerate forward rotation.
[0039]
In step S20 in FIG. 8, acceleration forward rotation is performed. In the forward rotation after the positioning, first, the current value is fixed and the forward rotation is accelerated without performing the speed control. When the rotation speed of the starter motor 3a reaches the control start speed (for example, 198 rpm (FIG. 9 6)), the rotation is switched to forward rotation with speed control, and the initial control target value is, for example, 331 pm. The target value is changed at a predetermined acceleration (for example, 3300 rpm / sec).
[0040]
That is, in step S21, it is determined whether the acceleration limit time T7 at a constant current has elapsed. In step S22, it is determined whether the speed has become equal to or higher than the control start speed. When the time T6 has elapsed or when the rotation speed of the starter motor 3a has become equal to or higher than the control start speed, the process proceeds to step S23, and speed control is performed according to the control target value. Since the control target value is gradually increased, the actual rotation speed also increases. In step S24, it is determined whether or not the rotation speed has reached a cranking speed (for example, 800 rpm). If the rotation speed increases and the result of step S24 becomes affirmative, the control target value is set to the cranking speed in order to maintain the rotation speed at the cranking speed, and the startup sequence is ended. In addition, when the target speed is not reached even after the elapse of the predetermined time T8 since the start of the speed control in step S23, it is preferable to determine that a failure has occurred and stop the starting operation. That is, if step S23a is affirmative, the starting operation is stopped and the processing of this flowchart is terminated.
[0041]
FIG. 1 is a functional block diagram of a main part of engine start positioning. The waveform of the induced voltage detected by the induced voltage detector 27 is input to the motor rotation speed calculator 31. The motor rotation speed calculator 31 calculates the rotation speed of the starter motor 3a based on the period of the induced voltage. The maximum speed storage unit 32 latches the maximum speed of the starter motor 3a detected so far in the start control. The maximum speed is cleared when the direction of rotation changes. The speed determination unit 33 compares the current rotation speed of the starter motor 3a with a scheduled reversal determination speed (for example, 75% of the maximum speed). If the current rotation speed is equal to or less than the reversal determination speed, A speed reduction detection signal is output to the forward / reverse control unit 34.
[0042]
In response to the speed reduction detection signal, the forward / reverse control unit 34 supplies the drive unit 30 with a reversal instruction for stopping and reversing the starter motor 3a. The forward / reverse control unit 34 inputs the control target values for the forward rotation and the reverse rotation together with the reversal instruction to the drive operation circuit 29, and the drive operation circuit 29 controls the rotation speed of the starter motor to the control target value. A cycle for driving the switching element 221 is calculated. The starter motor 3a is controlled to rotate at a speed determined by the driving cycle of the switching element 221. The current supply unit 35 supplies the initial excitation current and the starting current to the starter motor 3a at the time of positioning and thereafter at the time of positive acceleration.
[0043]
According to the present embodiment, the engine is first rotated forward to a position where the engine load is increased, and then rotated in the reverse direction and stopped again at the position where the engine load is increased. Then, it accelerates from that position to a speed at which it can crank at a stretch. By stopping the engine at a position where the engine load becomes large, the load becomes light at the time of subsequent reversal, so that acceleration is easy. Therefore, the inertia force can be used by supplying the starting current after the positioning by the forward / reverse rotation, and the cranking operation can be easily performed over the compression stroke.
[0044]
In the above description, the rotation speed of the motor is calculated based on the period of the induced voltage of the starter motor. However, when the starter motor is controlled by the following method, the rotation speed can be calculated by the current supplied to the stator winding of the starter motor.
[0045]
FIG. 10 is a block diagram illustrating a configuration of a starter motor control device according to a modification. In the following description, the axis through which the magnetic flux formed by the magnet 11 provided along the outer periphery of the rotor 12 of the starter motor 3a passes through the rotor 12 in the radial direction is referred to as the d-axis. The axis through which the magnetic flux formed by the stator coil passes through the rotor 12 in the radial direction is called the q-axis. The operation of the starter motor 3a is grasped by vector-decomposing the current of each layer on the d-axis and the q-axis, and control is performed based on the result.
[0046]
10, a starter motor control device includes a current target value calculation unit 41, a two-phase / 3-phase conversion unit 42, a PWM control unit 43, an inverter circuit, that is, a switching element 221, a three-phase / 2-phase conversion unit 44, and a rotation angle. An estimation unit 45 is provided. The current target value calculator 41 calculates the q-axis current output value based on the q-axis current target value determined based on the rotation speed target value and the current (q-axis current measured value) actually supplied to the starter motor 3a. In addition to the calculation, a d-axis current output value is calculated based on the d-axis current measurement value and the rotation speed estimated by the rotation angle estimation unit 45. The q-axis current output value and the d-axis current output value are input to the two-phase / 3-phase converter 42 and the rotation angle estimator 45.
[0047]
The two-phase / three-phase converter 42 converts the input into three-phase PWM data and outputs the PWM data to the PWM controller 43. The PWM control unit 43 calculates the on / off duty of each switching element of the inverter circuit 221 based on the PWM data, and inputs an on / off signal to the inverter circuit 221. The inverter circuit 221 detects the current of each phase and inputs the current to the three-phase / two-phase conversion unit 44. The measured q-axis current and the measured d-axis current output from the three-phase / two-phase converter 44 are input to the rotation angle estimator 45 and the current target value calculator 41.
[0048]
The rotation angle estimation unit 45 calculates the rotation angle (rad) and the rotation speed (rad / sec) based on the deviation between the previous q-axis current output value and d-axis current output value and the current q-axis current measurement value and d-axis current measurement value. ). The rotation angle is supplied to a two-phase / 3-phase conversion unit 42 and a three-phase / 2-phase conversion unit 44, and the rotation speed is supplied to a current target value calculation unit 41. The rotation angle estimating unit 45 can have a configuration disclosed in, for example, Japanese Patent Application Laid-Open No. 8-308286.
[0049]
In the start control according to the present embodiment, the rotation speed information of the starter motor 3 a used in the forward / reverse rotation for positioning the crankshaft 4 and the acceleration forward rotation for the start is estimated by the rotation angle estimating unit 45. Can be determined based on the rotation speed.
[0050]
FIG. 11 is a flowchart of the rotation speed control using the q-axis current. In FIG. 11, in step S30, a difference between the target value of the motor rotation speed and the estimated rotation speed is calculated. In step S31, a q-axis current output value is calculated based on the speed difference calculated in step S30. A calculation formula set so that the q-axis current output value increases as the speed difference increases. In step S32, a d-axis current output value is calculated based on the q-axis current measurement value and the current rotation speed. A calculation formula that is set so that the d-axis current output value increases as the q-axis current measurement value and the current rotation speed increase. In step S33, a PWM signal for controlling the inverter circuit 221 determined by the q-axis current output value and the d-axis current output value is output. In this control, a phase shift of the q-axis current occurs due to the d-axis current value. The phase shift causes a demagnetization effect due to the armature reaction effect, and the field of the starter motor 3a decreases. Therefore, the rotation speed of the starter motor 3a is controlled to the target rotation speed.
[0051]
【The invention's effect】
As apparent from the above description, according to the first to fifth aspects of the present invention, it is detected that the rotation speed of the motor has decreased, and that the engine state is in the high load region near the compression top dead center. Can be detected. Then, by rotating from the high load region, the inertia force of rotation can be used to move to the high load region on the reversing side, so that it can be moved to a position where the inertia force for forward rotation is sufficiently obtained. Therefore, in the next normal rotation, the engine can be accelerated to the cranking speed by using the large inertia in combination with the starting current to quickly overcome the high load region before the top dead center of the compression stroke. In particular, regardless of the position detection sensor, the high load position can be accurately determined when the motor rotation speed has decreased to a predetermined value, and there is no need to confirm the start position of the motor.
[0052]
According to the second aspect of the present invention, by suppressing the rotation speed with a small initial exciting current, it is possible to easily stop the motor in the high load region during the forward rotation and the reverse rotation, and cannot cross the high load position. The reaction force at that time (the larger the rotation speed, the larger the reaction force) can be suppressed.
[0053]
According to the invention of claim 3, at the start of the start operation, the motor is rotated forward and reverse at a speed smaller than the speed after the start operation, and the motor can be accurately stopped at the high load position. It is possible to accelerate at a stretch to a cranking speed at a large speed while controlling so as not to become so.
[0054]
Further, according to the present invention, the rotation speed of the motor, that is, the rotation speed of the engine at the time of starting is detected based on the induced voltage of the winding or the current supplied to the winding, and the rotation of the motor or the engine is detected. Without providing a position sensor, it is possible to determine the reverse position of the forward rotation and the reverse rotation of the motor based on the rotation speed.
[Brief description of the drawings]
FIG. 1 is a functional block diagram of a main part of an engine starting device according to an embodiment of the present invention.
FIG. 2 is a side view of an engine generator using a brushless motor as a starter motor.
FIG. 3 is a sectional view taken along line VV of FIG. 2;
FIG. 4 is a system diagram of an engine power generator.
FIG. 5 is a block diagram illustrating a main function of a sensorless driving unit.
FIG. 6 is a time chart showing the overall operation of the start control of the engine generator.
FIG. 7 is a flowchart (part 1) of start control of the engine generator.
FIG. 8 is a flowchart (part 2) of the start control of the engine generator.
FIG. 9 is a time chart of a main part of the start control.
FIG. 10 is a block diagram illustrating a configuration of a starter motor control device according to a modification.
FIG. 11 is a flowchart of a rotation speed control.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 3 ... Generator, 3a ... Motor, 4 ... Crankshaft, 8 ... Stator, 19, 26 ... Relay, 22 ... Starter driver, 23 ... Rectifier circuit, 27 ... Induction voltage detection part, 28 ... Position detection part, 29 ... Drive Arithmetic circuit, 30: drive unit, 31: motor rotation speed calculation unit, 32: maximum speed storage unit, 33: speed determination unit, 34: forward / reverse rotation control unit, 35: current supply unit, 221: switching element (inverter)

Claims (5)

A forward / reverse motor that starts the engine,
Rotation speed detection means for detecting the rotation speed of the motor,
The motor is first driven in the forward rotation direction of the engine until the rotation speed is reduced to a predetermined value or less, then driven in the reverse rotation direction until the rotation speed is reduced to a predetermined value or less, and then driven in the forward rotation direction. An engine starting device, comprising: control means for starting the engine by means of the engine. 2. The engine start according to claim 1, wherein the motor is driven by an initial excitation current in forward rotation and reverse rotation at the start of a start operation, and is driven by a current higher than the initial excitation current in subsequent forward rotation. 3. apparatus. The speed of the motor is controlled in accordance with a first target speed in the forward rotation and the reverse rotation at the start of the start operation, and in the subsequent forward rotation, the motor is driven to a second target speed higher than the first target speed. 3. The engine starting device according to claim 1, wherein the speed is controlled in accordance with a third target speed that is a cranking speed. The motor is a brushless motor,
The three-phase fixed winding is configured to generate a rotation position signal and a rotation speed signal of the rotor based on a voltage signal induced in a winding that is not energized when the two phases are energized for driving. ,
The engine starting device according to any one of claims 1 to 3, wherein the rotation speed detection means detects a rotation speed of the motor based on the rotation speed signal. The motor is a brushless motor,
It is configured to form a rotation position signal and a rotation speed signal of the rotor based on a deviation between a current output value for supplying current to the fixed winding and a current measurement value in the stator winding,
The engine starting device according to any one of claims 1 to 3, wherein the rotation speed detection means detects a rotation speed of the motor based on the rotation speed signal.

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