Engine starting device

Abstract

To exactly determine that a crank angle of a crankshaft which is inverted by swing-back control reaches a crank angle before a compression top dead point, and to surely start an engine.SOLUTION: An engine starter 11 comprises an electric generator 12, an electromagnetic pickup 32 and a drive control circuit 35. A rotor case 14 of the electric generator 12 is non-rotatably connected to a crankshaft 5, index parts a to k are arranged at a peripheral wall part 16 of the rotor case 14, the electromagnetic pickup 32 detects that the index parts a to k have passed a detection reference position Pd, and the drive control circuit 35 performs swing-back control for inverting the crankshaft 5 by the electric generator 12, and forwardly rotating the crankshaft 5 when a crank angle reaches an inversion execution crank angle. The drive control circuit 35 recognizes that the crank angle of the crankshaft 5 has reached the inversion execution crank angle on the basis of a detection signal outputted from the electromagnetic pickup 32.SELECTED DRAWING: Figure 7

Description

[Technical field]

[0001] The present invention relates to an engine starting device that starts an engine by rotating a crankshaft with an electric motor. [Background technology]

[0002] An engine starting device is a device that uses an electric motor to generate a rotational force in the crankshaft of the engine that triggers the engine to start when the engine is started. Patent Document 1 listed below describes the drive control of the motor when the engine is started.

[0003] Swing-back control is also known as a type of control used in engine starting devices. In swing-back control, the crankshaft is rotated in the reverse direction at engine start and then in the forward direction to allow the crankshaft to gain a running distance to overcome the top dead center of compression stroke using the power of the electric motor.

[0004] In swing-back control, when the engine is started, the electric motor is first rotated in one direction to rotate the crankshaft in the reverse direction. Then, when the crank angle of the reverse-rotating crankshaft reaches the crank angle just before the compression top dead center, the rotation direction of the electric motor is reversed to rotate the crankshaft in the forward direction. When the crankshaft starts to rotate in the forward direction from the crank angle just before the compression top dead center, the crankshaft rotates approximately two times before it reaches the crank angle of the next compression top dead center. In this way, a rotational force sufficient to get over the compression top dead center can be generated in the crankshaft while the crankshaft rotates in the forward direction approximately two times. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Publication No. 2018 / 142578 Summary of the Invention [Problem to be solved by the invention]

[0006] In the swing-back control, when the crank angle of the reverse rotating crankshaft reaches the crank angle before the compression top dead center, the rotation direction of the electric motor is reversed to rotate the crankshaft in the forward direction. In the conventional swing-back control, it is determined that the crank angle of the reverse rotating crankshaft has reached the crank angle before the compression top dead center based on the moving average of the rotation speed of the electric motor.

[0007] That is, in the swing-back control, the electric motor is rotated in one direction to reverse the stopped crankshaft, but the rotational torque applied to the crankshaft from the electric motor to reverse the crankshaft is not large enough to allow the crankshaft to overcome the compression top dead center. As a result, when the crank angle of the reversed crankshaft approaches the crank angle before the compression top dead center, the pressure in the cylinder of the engine reduces the ascending speed of the piston, and the rotation speed of the crankshaft decreases accordingly. In the conventional swing-back control, the reduction in the rotation speed of the crankshaft is determined based on the moving average of the rotation speed of the rotor of the electric motor that rotates together with the crankshaft. Then, the rotation direction of the electric motor is reversed at the timing when it is determined that the crank angle of the reversed crankshaft has reached the crank angle before the compression top dead center.

[0008] However, the method of determining, based on the moving average of the motor rotation speed, that the crank angle of the crankshaft rotating in the reverse direction has reached the crank angle just before the compression top dead center has the following problems.

[0009] When starting an engine, the load applied to the electric motor when the crankshaft is reversed varies depending on the temperature of the engine at that time. For example, when the engine is warm immediately after stopping the engine and when it is cold after stopping for a long period of time, the load on the electric motor when the crankshaft is reversed at engine start is smaller when the engine is warm immediately after stopping the engine. Therefore, when the crankshaft is reversed at engine start, the moving average of the rotation speed of the electric motor changes depending on the engine temperature at that time. Therefore, in a method of determining that the crank angle of the reversely rotating crankshaft has reached the crank angle before the compression top dead center based on the moving average of the rotation speed of the electric motor, the determination that the crank angle of the crankshaft has reached the crank angle before the compression top dead center may be inaccurate depending on the engine temperature at that time. As a result, the timing of reversing the rotation direction of the electric motor may vary depending on the engine temperature at engine start. If the engine temperature is low when the engine is started and the timing for reversing the rotational direction of the electric motor is earlier than the specified timing, the crankshaft may not be able to generate sufficient rotational force to overcome the compression top dead center between the time when the rotational direction of the crankshaft is switched from reverse to forward and the time when the crank angle of the crankshaft reaches the crank angle of the next compression top dead center, which may result in failure to start the engine.

[0010] The present invention has been made in consideration of the problems such as those described above, and an object of the present invention is to provide an engine starting device that can accurately determine when the crank angle of a crankshaft that has been reversed during swing back control has reached the crank angle just before top dead center of compression, and can reliably start the engine using swing back control. [Means for solving the problem]

[0011] In order to solve the above problems, the present invention 1.The engine starting device starts a four-stroke engine having an engine case, a cylinder provided in the engine case, a crankshaft provided within the engine case, a piston provided within the cylinder, and a connecting rod connecting the crankshaft and the piston, and the engine starting device includes an electric motor, an electromagnetic pickup, and a control unit, the electric motor includes a rotor case fixed to the crankshaft and rotating together with the crankshaft, a rotor having a plurality of magnetic field generating portions fixed to the rotor case, a core fixed to the engine case, and a stator having three or more coils provided on the core, the rotor case is formed in a cylindrical shape with a bottom, has a bottom plate portion, a peripheral wall portion provided on the outer periphery side of the bottom plate portion, and an insertion hole provided in the center of the bottom plate portion, an end of the crankshaft is inserted into the insertion hole, and is coupled to the end of the crankshaft in a manner that prevents it from rotating relative to the crankshaft, and an outer surface of the peripheral wall portion or an outer surface of the outer periphery side portion of the bottom plate portion is formed of a magnetic material. n (n is an integer of 3 or more) The indicator portions are provided at predetermined intervals around the entire circumference of the rotor case on a circle centered at the center of the rotor case, n pieces The indicator portion may be a shape, a size, or the like. n pieces The distance between the indicator portions provided adjacent to one of the indicator portions in the circumferential direction of the rotor case is n piecesthe electromagnetic pickup is fixed to the engine case and disposed so as to face the orbits of the index parts during rotation of the rotor, and outputs a pulse-shaped detection signal indicating that the index parts have passed a predetermined detection reference position during rotation of the rotor; the control unit rotates the rotor in one direction relative to the stator to reverse the crankshaft, and when the crank angle of the crankshaft that is being reversed reaches a reverse execution crank angle, performs a swing-back control to reverse the rotation direction of the rotor to rotate the crankshaft in the forward direction, the reverse execution crank angle is set to one crank angle within a section in which the piston rises within the cylinder from the expansion bottom dead center toward the compression top dead center while the crankshaft is reversed, and the control unit, in the swing-back control, Based on the detection signal, it is determined whether or not an output level of the detection signal becomes equal to or lower than a predetermined reference output level during a period from a first time point at which the peculiar indicator portion passes the detection reference position after the crankshaft starts to rotate in reverse to a second time point at which m (m is an integer greater than or equal to 1 and less than or equal to n / 2) of the indicator portions subsequently pass the detection reference position, and if the output level of the detection signal becomes equal to or lower than the reference output level during a period from the first time point to the second time point, it is determined that the crank angle of the crankshaft which is rotating in reverse has reached the reverse execution crank angle at the second time point. It is characterized by: In order to solve the above-mentioned problems, a second engine starting device of the present invention is an engine starting device for starting a four-stroke engine including an engine case, a cylinder provided in the engine case, a crankshaft provided within the engine case, a piston provided within the cylinder, and a connecting rod connecting the crankshaft and the piston, the engine starting device including an electric motor, an electromagnetic pickup, and a control unit, the electric motor including a rotor case fixed to the crankshaft and rotating together with the crankshaft, a rotor having a plurality of magnetic field generating portions fixed to the rotor case, a core fixed to the engine case, and a stator having three or more coils provided on the core, the rotor case being formed in a cylindrical shape with a bottom, having a bottom plate portion, a peripheral wall portion provided on the outer periphery of the bottom plate portion, and an insertion hole provided in the center of the bottom plate portion, an end of the crankshaft is inserted into the insertion hole, the end of the crankshaft is non-rotatably coupled to the crankshaft, and a connecting rod is provided between the outer surface of the peripheral wall portion or the outer periphery of the bottom plate portion. On an outer surface of the rotor case, n (n is an integer of 3 or more) index parts formed of a magnetic material are provided at predetermined intervals around a circle centered at the center of the rotor case, the n index parts include one unique index part that is different from the other index parts among the n index parts in shape, size, or interval between an index part provided adjacent to one of the n index parts in the circumferential direction of the rotor case, the electromagnetic pickup is fixed to the engine case and arranged to face an orbit of each of the index parts during rotation of the rotor, and outputs a pulse-shaped detection signal indicating that each of the index parts has passed a predetermined detection reference position during rotation of the rotor, the control part rotates the rotor in one direction relative to the stator to reverse the crankshaft, and performs swing-back control to rotate the crankshaft forward by reversing the rotation direction of the rotor when the crank angle of the crankshaft that is reversed reaches a reverse execution crank angle, and the reverse execution crank angle is set to a value that is greater than or equal to the value while the crankshaft is reversed,The crank angle is set to one within a range in which the piston rises within the cylinder from the expansion bottom dead center toward the compression top dead center, and the control unit, in the swing back control, judges, based on the detection signal, whether or not the output level of the detection signal becomes equal to or lower than a predetermined reference output level at a point in time when the peculiar indicator portion passes the detection reference position after the crankshaft starts to rotate in reverse, and m (m is an integer equal to or greater than 1 and less than n) of the indicator portions subsequently pass the detection reference position, and if the output level of the detection signal becomes equal to or lower than the reference output level at that point in time, it is judged that the crank angle of the crankshaft which is rotating in reverse has reached the reverse execution crank angle at that point in time. In order to solve the above problems, a third engine starting device of the present invention is an engine starting device for starting a four-stroke engine including an engine case, a cylinder provided in the engine case, a crankshaft provided within the engine case, a piston provided within the cylinder, and a connecting rod connecting the crankshaft and the piston, the engine starting device including an electric motor, an electromagnetic pickup, and a control unit, the electric motor including a rotor case fixed to the crankshaft and rotating together with the crankshaft, a rotor having a plurality of magnetic field generating portions fixed to the rotor case, a core fixed to the engine case, and a stator having three or more coils provided on the core, the rotor case being formed in a cylindrical shape with a bottom, having a bottom plate portion, a peripheral wall portion provided on the outer periphery of the bottom plate portion, and an insertion hole provided in the center of the bottom plate portion, an end of the crankshaft is inserted into the insertion hole, the end of the crankshaft is non-rotatably coupled to the crankshaft, and a connecting rod is provided between the outer surface of the peripheral wall portion or the outer periphery of the bottom plate portion. On an outer surface of the rotor case, n (n is an integer of 3 or more) index parts formed of a magnetic material are provided at predetermined intervals around a circle centered at the center of the rotor case, the n index parts include one unique index part that is different from the other index parts among the n index parts in shape, size, or interval between an index part provided adjacent to one of the n index parts in the circumferential direction of the rotor case, the electromagnetic pickup is fixed to the engine case and arranged to face an orbit of each of the index parts during rotation of the rotor, and outputs a pulse-shaped detection signal indicating that each of the index parts has passed a predetermined detection reference position during rotation of the rotor, the control part rotates the rotor in one direction relative to the stator to reverse the crankshaft, and performs swing-back control to rotate the crankshaft forward by reversing the rotation direction of the rotor when the crank angle of the crankshaft that is reversed reaches a reverse execution crank angle, and the reverse execution crank angle is set to a value that is greater than or equal to the value while the crankshaft is reversed,The crank angle is set to one within a range in which the piston rises within the cylinder from the expansion bottom dead center toward the compression top dead center, and the control unit, in the swing back control, judges, based on the detection signal, whether or not the output level of the detection signal has become equal to or lower than a predetermined reference output level at a time point when the peculiar indicator portion passes the detection reference position after the crankshaft starts to rotate in reverse, and if the output level of the detection signal has become equal to or lower than the predetermined reference output level at that time point, it is characterized in that the crank angle of the crankshaft rotating in reverse has reached the reverse execution crank angle at that time point. Effect of the Invention

[0012] According to the present invention, it is possible to accurately determine whether the crank angle of the crankshaft that has been reversed during swing back control has reached the crank angle just before the top dead center of compression, and to reliably start the engine using swing back control. [Brief description of the drawings]

[0013] [Figure 1] 1 is an explanatory diagram showing an engine provided with an engine starting device according to a first embodiment of the present invention; [Diagram 2] 2 is an exploded perspective view showing a crankshaft provided in the engine in FIG. 1 and a motor generator in the engine starting device according to the first embodiment of the present invention. FIG. [Diagram 3] 3 is an explanatory diagram showing the motor generator cut along the cutting line III-III in FIG. 1 as viewed from the right side in FIG. [Figure 4]1 is a circuit diagram showing a drive control circuit in an engine starting device according to a first embodiment of the present invention, and coils and the like connected to the drive control circuit. [Diagram 5] FIG. 11 is an explanatory diagram showing swing-back control when the crankshaft is stopped before exhaust top dead center in the forward rotation direction of the crankshaft immediately before the start of the engine. [Figure 6] FIG. 11 is an explanatory diagram showing swing-back control in a case where the crankshaft is stopped before the compression top dead center in the forward rotation direction of the crankshaft immediately before the start of the engine. [Figure 7] 4 is an explanatory diagram showing a state in which the crank angle of a crankshaft has reached a reverse rotation execution crank angle in the motor generator of the engine starting device according to the first embodiment of the present invention. FIG. [Figure 8] 4 is a flowchart showing a swing-back control in the engine starting device according to the first embodiment of the present invention. [Figure 9] FIG. 11 is a waveform diagram showing a detection signal output from an electromagnetic pickup during the period from the point at which the peculiar indicator portion passes the detection reference position for the first time after the crankshaft starts to rotate in reverse to the point at which two normal indicator portions subsequently pass the detection reference position in an engine starting device of a first embodiment of the present invention. [Figure 10] FIG. 4 is an explanatory diagram showing an engine starting device according to a second embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] An engine starting device according to an embodiment of the present invention is a device for starting a four-stroke engine. The engine includes an engine case, a cylinder provided in the engine case, a crankshaft provided within the engine case, a piston provided in the cylinder, and a connecting rod connecting the crankshaft and the piston.

[0015] An engine starting device according to an embodiment of the present invention includes an electric motor, an electromagnetic pickup, and a control unit.

[0016] The electric motor includes a rotor and a stator. The rotor has a rotor case fixed to the crankshaft and rotates together with the crankshaft, and a number of magnetic field generating units fixed to the rotor case. For example, a permanent magnet can be used as the magnetic field generating unit. The stator has a core fixed to the engine case, and three or more coils provided on the core. The rotor functions as a field magnet, and the stator functions as an armature.

[0017] The rotor case is formed in a cylindrical shape with a bottom. The rotor case has a bottom plate, a peripheral wall provided on the outer periphery of the bottom plate, and an insertion hole provided in the center of the bottom plate. An end of the crankshaft is inserted into the insertion hole, and the rotor case is connected to the end of the crankshaft so as to be non-rotatable relative to the crankshaft.

[0018] Furthermore, a plurality of indicator portions made of a magnetic material are provided on the outer surface of the peripheral wall portion of the rotor case or on the outer surface of the outer peripheral portion of the bottom plate portion at predetermined intervals around the entire circumference of the rotor case on a circle centered at the center of the rotor case. Note that the intervals between the indicator portions need only be predetermined, and may or may not be constant.

[0019] The plurality of index portions include one unique index portion that is different from the other index portions in shape, size, or distance from an adjacent index portion provided on one side of the plurality of index portions in the circumferential direction of the rotor case. Specifically, one of the following three configurations can be adopted as the configuration of the plurality of index portions. (1) Among the multiple indicator portions, the shapes of the indicator portions other than the unique indicator portion are identical to each other, and the shape of the unique indicator portion is different from the shapes of the indicator portions other than the unique indicator portion. (2) Among the multiple indicator portions, the sizes of the indicator portions other than the unique indicator portion are identical to each other, and the size of the unique indicator portion is different from the size of the indicator portions other than the unique indicator portion. (3) If the distance between one of the multiple indicator portions and another indicator portion provided adjacent to the one of the multiple indicator portions in the circumferential direction of the rotor case is defined as the “indicator portion spacing,” the indicator portion spacings for the multiple indicator portions other than the unique indicator portion are all identical to each other, and the indicator portion spacing for the unique indicator portion is different from the indicator portion spacing for the indicator portions other than the unique indicator portion.

[0020] The electromagnetic pickup is fixed to the engine case. The electromagnetic pickup is disposed so as to face the trajectory of each indicator part when the rotor rotates. Specifically, the electromagnetic pickup is disposed in the engine case at a location close to a predetermined detection reference position set at one point on the trajectory of each indicator part when the rotor rotates, so as to face the detection reference position. The electromagnetic pickup detects that each indicator part has passed the detection reference position when the rotor rotates, and outputs a pulse-shaped detection signal indicating that each indicator part has passed the detection reference position.

[0021] The control unit controls the driving of the electric motor. Specifically, the control unit controls the rotor to rotate relative to the stator. The control unit also rotates the rotor in one direction relative to the stator to reverse the crankshaft, and when the crank angle of the reversed crankshaft reaches a reverse execution crank angle, the control unit performs swing-back control to reverse the rotation direction of the rotor to rotate the crankshaft forward. The reverse execution crank angle is set to a crank angle within a range in which the piston rises in the cylinder from the expansion bottom dead center to the compression top dead center while the crankshaft is rotating in the reverse direction. Specifically, the crank angle at the compression top dead center is set to 0 degrees, the forward rotation direction of the crankshaft from that crank angle is set to a plus angle, and the reverse rotation direction of the crankshaft from that crank angle is set to a minus angle. The reverse execution crank angle is set to a crank angle within a range of -540 degrees or more and less than -720 degrees in the reverse direction of the crankshaft. This range includes the crank angle just before the compression top dead center in the reverse direction of the crankshaft. Furthermore, during swing back control, the control unit recognizes that the crank angle of the crankshaft undergoing reverse rotation has reached a reverse rotation execution crank angle based on a detection signal output from the electromagnetic pickup.

[0022] Hereinafter, the principle by which the control unit can recognize that the crank angle of the crankshaft undergoing reverse rotation has reached the reverse rotation execution crank angle based on the detection signal output from the electromagnetic pickup during swing back control will be described.

[0023] When starting the engine, the control unit first rotates the rotor of the electric motor in one direction to reverse the crankshaft. As the rotor rotates, a plurality of indicators provided on the rotor case move. Since the plurality of indicators are provided on a circle centered on the center of the rotor case, the orbit along which each indicator moves is the same circle. As the rotor rotates, each indicator sequentially passes through a detection reference position set at one point on the orbit. In addition, since each indicator is formed of a magnetic material, when an indicator passes through the detection reference position, the passage of the indicator by the detection reference position is detected by an electromagnetic pickup, and a pulse-shaped detection signal is output from the electromagnetic pickup. Based on the detection signal output from the electromagnetic pickup, the control unit can recognize that each indicator has passed through the detection reference position.

[0024] Moreover, the multiple indicator parts include one unique indicator part. When the shapes of the indicator parts other than the unique indicator part are the same as each other and the shape of the unique indicator part is different from the shape of the indicator parts other than the unique indicator part, the waveform of the detection signal output from the electromagnetic pickup when the unique indicator part passes the detection reference position is different from the waveform of the detection signal output from the electromagnetic pickup when the indicator part other than the unique indicator part passes the detection reference position. When the sizes of the indicator parts other than the unique indicator part are the same as each other and the size of the unique indicator part is different from the size of the indicator parts other than the unique indicator part, the waveform or amplitude of the detection signal output from the electromagnetic pickup when the unique indicator part passes the detection reference position is different from the waveform or amplitude of the detection signal output from the electromagnetic pickup when the indicator part other than the unique indicator part passes the detection reference position. Furthermore, when the indicator part intervals for the indicator parts other than the unique indicator parts are the same and the indicator part intervals for the unique indicator parts are different from the indicator part intervals for the indicator parts other than the unique indicator parts, the interval between two detection signals sequentially output from the electromagnetic pickup when adjacent unique indicator parts and an indicator part other than the unique indicator part sequentially pass the detection reference position is different from the interval between two detection signals sequentially output from the electromagnetic pickup when two indicator parts other than adjacent unique indicator parts sequentially pass the detection reference position. Therefore, the control unit can identify whether the indicator part that has passed the detection reference position is a unique indicator part or an indicator part other than the unique indicator part, based on the waveform, amplitude, or output interval of the detection signal.

[0025] Moreover, since the intervals between the indicator parts are predetermined and the number of the unique indicator part is one, the control part can recognize that the rotation angle of the rotor has become one angle in the range from 0 degrees to 360 degrees by recognizing, based on the detection signal output from the electromagnetic pickup, that the unique indicator part has passed the detection reference position or that an indicator part other than the unique indicator part provided at a position spaced a predetermined angle from the unique indicator part has passed the detection reference position. Furthermore, since the rotor case is coupled to the end of the crankshaft so as not to rotate with respect to the crankshaft, the control part can recognize that the rotation angle of the crankshaft has become one angle in the range from 0 degrees to 360 degrees by recognizing, based on the detection signal output from the electromagnetic pickup, that the unique indicator part has passed the detection reference position or that an indicator part other than the unique indicator part provided at a position spaced a predetermined angle from the unique indicator part has passed the detection reference position.

[0026] However, in a four-stroke engine, the crankshaft rotates 720 degrees in one engine cycle. Therefore, simply being able to recognize that the rotation angle of the crankshaft has reached one angle in the range from 0 degrees to 360 degrees does not allow the crankshaft angle to be recognized as one crank angle in one engine cycle. Therefore, there are cases where simply being able to recognize that the rotation angle of the crankshaft has reached one angle in the range from 0 degrees to 360 degrees does not allow the crankshaft angle to be recognized as having reached the reverse execution crank angle. Such a case is, for example, when the crankshaft is stopped before the compression top dead center in the forward rotation direction of the crankshaft immediately before the engine starts.

[0027] When the clutch is disengaged and the engine stops while the engine is running, the crankshaft continues to rotate in the forward direction due to inertia, but then the crankshaft stops when the piston stops rising because it cannot resist the pressure in the cylinder. The crankshaft stops at the compression top dead center or exhaust top dead center in the forward direction of the crankshaft. If the crankshaft stops before the compression top dead center in the forward direction of the crankshaft just before the engine starts, the crankshaft rotates more than 360 degrees from the start of reverse rotation of the crankshaft until the crank angle of the crankshaft reaches the reverse execution crank angle in the swing back control. For example, if the crank angle before the compression top dead center in the forward direction of the crankshaft is -45 degrees and the reverse execution crank angle is set to -675 degrees, the crankshaft rotates 630 degrees from the start of reverse rotation of the crankshaft until the crank angle of the crankshaft reaches the reverse execution crank angle. In this case, in order to recognize that the reverse rotating crankshaft has reached the reverse rotation execution crank angle, it is necessary to distinguish between the rotation angle of the reverse rotating crankshaft being -315 degrees and the rotation angle of the reverse rotating crankshaft being -675 degrees. Therefore, it is not possible to recognize that the crank angle of the crankshaft has reached the reverse rotation execution crank angle just by recognizing that the rotation angle of the crankshaft has reached one angle in the range from 0 degrees to 360 degrees. Therefore, the engine starting device of the embodiment of the present invention has the following configuration in addition to the configuration for recognizing that the rotation angle of the crankshaft has reached one angle in the range from 0 degrees to 360 degrees based on the detection signal output from the electromagnetic pickup as described above.

[0028] First, the arrangement and detection reference position of each indicator part are set so that the peculiar indicator part coincides with the detection reference position when the crank angle of the crankshaft is the reverse execution crank angle, or so that an indicator part other than a peculiar indicator part provided at a position spaced a predetermined angle from the peculiar indicator part coincides with the detection reference position. Hereinafter, a peculiar indicator part provided at a position that coincides with the detection reference position when the crank angle of the crankshaft is the reverse execution crank angle or an indicator part other than the peculiar indicator part is referred to as a "reverse determination indicator part." With this setting, for example, if the reverse rotation execution crank angle is set to -675 degrees, when the crankshaft is stopped, for example, before the compression top dead center in the forward rotation direction of the crankshaft immediately before the engine starts, the crankshaft crank angle is -315 degrees (crank angle 360 ​​degrees before the reverse rotation execution crank angle in the reverse direction of the crankshaft) when the reverse rotation judgment indicator unit passes the detection reference position for the first time after the crankshaft starts reverse rotation, and then when the reverse rotation judgment indicator unit passes the detection reference position again, the crankshaft crank angle is -675 degrees, reaching the reverse rotation execution crank angle. Also, when the crankshaft is stopped, for example, before the exhaust top dead center in the forward rotation direction of the crankshaft immediately before the engine starts, the crankshaft rotation angle is -675 degrees when the reverse rotation judgment indicator unit passes the detection reference position for the first time after the crankshaft starts reverse rotation, reaching the reverse rotation execution crank angle. Based on the detection signal output from the electromagnetic pickup, the control unit recognizes that the reversal judgment indicator unit has passed the detection reference position, and can thereby recognize that the crankshaft rotation angle has reached either -315 degrees or -675 degrees.

[0029] Secondly, the control unit judges whether the output level (amplitude) of the detection signal output from the electromagnetic pickup at the time when the reversal judgment indicator unit passes the detection reference position for the first time after the crankshaft starts to reverse is equal to or lower than a predetermined reference output level. If the output level of the detection signal is equal to or lower than the predetermined reference output level, the control unit judges that the reversed crankshaft has reached -675 degrees and has reached the reverse execution crank angle. On the other hand, if the output level of the detection signal output from the electromagnetic pickup at the time when the reversal judgment indicator unit passes the detection reference position for the first time after the crankshaft starts to reverse is not equal to or lower than the above reference output level, the control unit judges that the reversed crankshaft has not reached the reverse execution crank angle (the crankshaft's crank angle has only reached -315 degrees).

[0030] Here, the reason why it is possible to determine whether the reverse rotation of the crankshaft has reached the reverse execution crank angle based on whether the output level of the detection signal at the time when the reverse rotation determination indicator unit passes through the detection reference position for the first time after the start of reverse rotation of the crankshaft is equal to or lower than a predetermined reference output level is as follows.

[0031] For example, when comparing the pressure inside the cylinder when the crank angle of the reverse crankshaft is -315 degrees and when it is -675 degrees, the pressure inside the cylinder is higher when the crank angle of the reverse crankshaft is -675 degrees. This is because -315 degrees is the crank angle just before the exhaust top dead center in the reverse direction of the crankshaft, whereas -675 degrees is the crank angle just before the compression top dead center in the reverse direction of the crankshaft. Also, when the engine is stopped, the piston's rising speed decreases as the pressure inside the cylinder increases, so when comparing the rotation speed of the crankshaft when the crank angle of the reverse crankshaft is -315 degrees and when it is -675 degrees, the rotation speed of the crankshaft is lower when the crank angle of the reverse crankshaft is -675 degrees. Furthermore, the output level of the detection signal output from the electromagnetic pickup decreases as the moving speed of the indicator when passing through the detection reference position decreases. Since the moving speed of the indicator portion when passing the detection reference position becomes slower as the rotation speed of the crankshaft decreases, when comparing the output level of the detection signal output from the electromagnetic pickup when the crank angle of the crankshaft rotating in reverse becomes -315 degrees and when it becomes -675 degrees, the output level of the detection signal output from the electromagnetic pickup becomes smaller when the crank angle of the crankshaft rotating in reverse becomes -675 degrees. Therefore, it is possible to determine whether the crankshaft rotating in reverse has reached the reverse execution crank angle based on whether the output level of the detection signal at the time when the reverse determination indicator portion passes the detection reference position for the first time after the crankshaft starts rotating in reverse is equal to or lower than a predetermined reference output level.

[0032] The above is the principle by which the control unit can recognize, in swing back control, that the crank angle of the crankshaft undergoing reverse rotation has reached the reverse rotation execution crank angle, based on the detection signal output from the electromagnetic pickup.

[0033] If the control unit determines that the output level of the detection signal at the time when the reverse rotation judgment indicator unit passes the detection reference position for the first time after the reverse rotation of the crankshaft is equal to or lower than a predetermined reference output level and that the reverse rotation of the crankshaft has reached the reverse execution crank angle based on this, it reverses the rotation direction of the rotor at that time to rotate the crankshaft in the forward direction. On the other hand, if the control unit determines that the output level of the detection signal at the time when the reverse rotation judgment indicator unit passes the detection reference position for the first time after the reverse rotation of the crankshaft is not equal to or lower than the reference output level and that the reverse rotation of the crankshaft has not reached the reverse execution crank angle based on this, it subsequently recognizes based on the detection signal that the reverse rotation judgment indicator unit has passed the detection reference position again and reverses the rotation direction of the rotor at that time to rotate the crankshaft in the forward direction.

[0034] As described above, the engine starting device of the embodiment of the present invention determines that the crank angle of the reversed crankshaft reaches the reverse execution crank angle during swing back control based on the detection signal output from the electromagnetic pickup. This makes it possible to prevent the determination that the crank angle of the reversed crankshaft has reached the reverse execution crank angle from becoming inaccurate due to the temperature of the engine. In this way, the engine starting device of the embodiment of the present invention can accurately determine that the crank angle of the reversed crankshaft has reached the reverse execution crank angle during swing back control, and can reliably start the engine using swing back control. EXAMPLES

[0035] (engine) 1 shows an engine 1 provided with an engine starting device 11 according to a first embodiment of the present invention. Note that arrows Fd, Bd, Ld, and Rd in the drawing indicate the front, rear, left, and right, respectively, of a vehicle in which the engine 1 is provided.

[0036] In FIG. 1, engine 1 is a single-cylinder four-stroke engine, and is mounted on a vehicle such as a saddle-type vehicle. Engine 1 includes crankcase 2, cylinder 3, cylinder head 4, crankshaft 5, piston 6, and connecting rod 7. Cylinder 3 is provided in crankcase 2 so as to protrude substantially forward from the front of crankcase 2. Cylinder head 4 is provided on the front end side of cylinder 3. Crankshaft 5 is provided in crankcase 2. Crankshaft 5 extends in the left-right direction as a whole, and is supported rotatably by crankcase 2. Piston 6 is provided in cylinder 3 so as to be capable of reciprocating substantially in the front-rear direction. Piston 6 is connected to crankshaft 5 via connecting rod 7. When engine 1 is operating, piston 6 reciprocates in cylinder 3, causing crankshaft 5 to rotate. Crankcase 2 is a specific example of an engine case.

[0037] Further, the motor-generator 12 and the electromagnetic pickup 32, which are components of the engine starting device 11, are provided on the right side within the crankcase 2. Note that the electromagnetic pickup 32 is not shown in FIG. 1 because it is disposed in a position hidden by the motor-generator 12. Further, in the crankcase 2, a fan 8 that generates cooling air for cooling the engine 1 is provided to the right of the motor-generator 12. Also, a drive pulley 10 of the transmission 9 is connected to the left end portion of the crankshaft 5.

[0038] (Crankshaft) Fig. 2 shows the crankshaft 5 and the motor-generator 12 in an exploded state. The upper right side of Fig. 2 shows the crankshaft 5 cut along the cutting line II-II in Fig. 2 as viewed from the upper left side of Fig. 2 (the right side of the vehicle).

[0039] As shown in FIG. 2, the crankshaft 5 includes a crank journal 5A extending in the left-right direction, a crank arm 5B extending radially from the crank journal 5A, and a crank pin 5C provided at the tip of the crank arm 5B. The crank journal 5A is rotatably supported by the crankcase 2 via a bearing. A piston 6 is connected to the crank pin 5C via a connecting rod 7. A counterweight 5D is provided on the radial opposite side of the crank journal 5A to the crank pin 5C. As shown in the upper right side of FIG. 2, the axis of the crank journal 5A is the rotation axis Q of the crankshaft 5. The crankshaft 5 can rotate around the rotation axis Q.

[0040] A tapered portion 5E having a diameter that decreases as it extends to the right is provided on the right end side of the crank journal 5A. A key groove 5F is formed on the outer peripheral surface of the tapered portion 5E. As shown in the upper right side of Fig. 2, when the crankshaft 5 is viewed from the right side of the vehicle, the key groove 5F is formed on the outer peripheral surface of the tapered portion 5E at a position facing the axis Cp of the crank pin 5C.

[0041] Here, when the crankshaft 5 is viewed from the right side of the vehicle, the direction in which the axis Cp of the crankpin 5C is located as viewed from the rotation axis Q of the crankshaft 5 is referred to as the "direction of the crankpin 5C as viewed from the axis of the crankshaft 5." The dashed line Dc on the upper right side of Fig. 2 indicates the direction of the crankpin 5C as viewed from the axis of the crankshaft 5 when the crank angle of the crankshaft 5 becomes 0 degrees, that is, when the piston 6 reaches the top dead center of compression. When the crankshaft 5 is viewed from the right side of the vehicle, the direction of the key groove 5F as viewed from the axis of the crankshaft 5 coincides with the direction of the crankpin 5C as viewed from the axis of the crankshaft 5.

[0042] (Engine starting device) Fig. 3 shows the motor-generator 12 cut along line III-III in Fig. 1 as viewed from the right side in Fig. 1. In addition, Fig. 3 also shows a schematic diagram of an electromagnetic pickup 32 and a drive control circuit 35.

[0043] The engine starting device 11 is a device that, when starting the engine 1, generates a rotational force in the crankshaft 5 by an electric motor, which serves as a trigger for starting the engine 1. As shown in FIG. 3, the engine starting device 11 includes a motor-generator 12 as an electric motor, an electromagnetic pickup 32, and a drive control circuit 35 as a control unit. When starting the engine 1, the motor-generator 12 functions as an electric motor (specifically, a brushless motor) that rotates the crankshaft 5, and after starting the engine 1, functions as a generator that generates electricity by utilizing the rotation of the crankshaft 5 caused by the operation of the engine 1. As described above, the motor-generator 12 is provided on the right side inside the crankcase 2.

[0044] The electromagnetic pickup 32 has a function of detecting the positions of the magnetic field generating units 21A-24L provided in the motor generator 12, and a function of detecting the crank angle of the crankshaft 5. The electromagnetic pickup 32 is provided on the right side of the crankcase 2, at a position facing the outer surface of the peripheral wall portion 16 of the rotor case 14 of the motor generator 12. The electromagnetic pickup 32 is fixed to the crankcase 2 via, for example, a bracket or the like.

[0045] The drive control circuit 35 is a circuit that performs drive control and swing back control of the motor generator 12. When the vehicle in which the engine 1 and the engine starting device 11 are provided is a saddle-ride type vehicle, the drive control circuit 35 is housed in, for example, a protective case and disposed in a location in the saddle-ride type vehicle that is unlikely to be exposed to rain, etc., such as under the seat of the saddle-ride type vehicle or inside the front cowl.

[0046] (Motor Generator) As shown in Fig. 3, the motor generator 12 includes a rotor 13 and a stator 25. The rotor 13 is fixed to the crankshaft 5 and rotates together with the crankshaft 5. On the other hand, the stator 25 is fixed to the crankcase 2. The rotor 13 functions as a field magnet, and the stator 25 functions as an armature. When the engine is started, the motor generator 12 rotates the rotor 13 relative to the stator 25, thereby rotating the crankshaft 5.

[0047] As shown in FIG. 2, the rotor 13 includes a rotor case 14, twelve magnetic field generating units 21A to 21L, and a magnet support member .

[0048] The rotor case 14 is formed into a cylindrical shape with a bottom and is made of a magnetic material such as steel. The rotor case 14 includes a disk-shaped bottom plate portion 15, a peripheral wall portion 16 provided on the outer periphery of the bottom plate portion 15, and a boss portion 17 provided in the center of the bottom plate portion 15. An insertion hole 18 into which the right end portion of the crankshaft 5 is inserted is provided in the center of the boss portion 17. A key groove 19 is formed on the inner periphery of the insertion hole 18.

[0049] 3, the right end of the crankshaft 5, specifically the tapered portion 5E, is inserted into the insertion hole 18 of the rotor case 14. The rotor case 14 is positioned relative to the crankshaft 5 such that a key groove 5F formed on the outer circumferential surface of the tapered portion 5E and a key groove 19 formed on the inner circumferential surface of the insertion hole 18 face each other within the insertion hole 18, and the positions of these key grooves 5F, 19 coincide with each other in the circumferential direction of the rotor case 14. The rotor case 14 is coupled and fixed to the crankshaft 5 so as not to rotate relative to the crankshaft 5 by fitting a key into these two key grooves 5F, 19. The center of the rotor case 14 coincides with the rotation axis Q of the crankshaft 5.

[0050] 2, and indicates the direction of the crank pin 5C seen from the axis of the crankshaft 5 when the crank angle of the crankshaft 5 becomes 0 degrees. When the rotor case 14 connected to the crankshaft 5 is seen from the right side of the vehicle, the direction of the key groove 19 seen from the rotation axis Q of the crankshaft 5 coincides with the direction of the crank pin 5C seen from the axis of the crankshaft 5.

[0051] The magnetic field generating units 21A to 21L are magnets that generate a magnetic field within the rotor case 14. As shown in FIG. 3, the twelve magnetic field generating units 21A to 21L are arranged within the rotor case 14 on the outer circumferential side of the bottom plate portion 15 and the inner circumferential side of the peripheral wall portion 16, along a circle centered at the center of the rotor case 14 (the rotation axis Q of the crankshaft 5). The magnetic field generating units 21A to 21L are arranged at equal intervals around the entire circumference of the rotor case 14. The intervals between the magnetic field generating units 21A to 21L are 30 degrees. The magnetic field generating units 21A to 21L are arranged such that the magnetic poles of two adjacent magnetic field generating units in the circumferential direction of the rotor case 14 are different from each other. Specifically, magnetic field forming sections 21A, 21C, 21E, 21G, 21I, and 21K, whose magnetic poles are set so that the inner circumferential side is a north pole, and magnetic field forming sections 21B, 21D, 21F, 21H, 21J, and 21L, whose magnetic poles are set so that the inner circumferential side is a south pole, are arranged alternately one by one in the circumferential direction within rotor case 14.

[0052] As shown in FIG. 2, the magnetic field generating units 21A to 21L are formed by four magnet plates 22A to 22D. Each of the magnet plates 22A to 22D is a permanent magnet such as a ferrite magnet or a neodymium magnet, and is formed in a plate shape curved in an arc. The magnet plates 22A and 22C are magnetized so that the inner circumferential sides of both end portions are N poles, and the inner circumferential side of the center portion is S poles. The magnet plates 22B and 22D are magnetized so that the inner circumferential sides of both end portions are S poles, and the inner circumferential side of the center portion is N poles. A magnet support member 23 formed in a cylindrical shape from a magnetic material such as metal is attached to the rotor case 14. The magnet plates 22A to 22D are held between the rotor case 14 and the magnet support member 23. The magnetic field generating units 21A to 21L are fixed to the rotor case 14 in this way and rotate together with the rotor case 14.

[0053] As shown in FIG. 3, the stator 25 includes a core 26 and a total of 18 coils 31U to 31W through which three-phase drive currents, U-phase, V-phase, and W-phase, flow. The core 26 includes a base portion 27 formed in a disk shape from, for example, a metal material. The base portion 27 is fixed to the crankcase 2. An insertion hole 28 is formed in the center of the base portion 27 for inserting the boss portion 17 of the rotor case 14. Furthermore, 18 teeth 29 formed from a magnetic material such as steel are provided on the outer periphery of the base portion 27. Each tooth 29 protrudes from the outer periphery of the base portion 27 in the radial direction of the base portion 27. The 18 teeth 29 are arranged at equal intervals (20 degrees) from each other all around the outer periphery of the base portion 27.

[0054] The 18 coils 31U to 31W are composed of six coils 31U through which a U-phase driving current flows, six coils 31V through which a V-phase driving current flows, and six coils 31W through which a W-phase driving current flows. The 18 coils 31U to 31W are formed by winding wire around the 18 teeth 29. These coils 31U to 31W are arranged in the reverse rotation direction R of the crankshaft 5 in the order of coil 31U, coil 31V, coil 31W.

[0055] Stator 25 is arranged coaxially with rotor case 14 on the inner circumferential side of the arrangement of magnetic field generating portions 21A to 21L. Boss portion 17 of rotor case 14 is inserted into insertion hole 28 of core 26. Stator 25 is arranged in rotor case 14 at a distance from rotor 13 so that rotor 13 can rotate relative to stator 25.

[0056] (Indicator part) Further, n (n is an integer of 3 or more) indicator parts are provided on the outer surface of the peripheral wall part 16 of the rotor case 14. Each indicator part is made of a magnetic material. Moreover, the n indicator parts are provided at predetermined intervals around the entire circumference of the rotor case 14 on a circle centered on the center (rotation axis Q) of the rotor case 14. Moreover, the n indicator parts include (n-1) normal indicator parts and one peculiar indicator part. Moreover, the interval between each normal indicator part and another indicator part among the n indicator parts provided adjacent to the normal indicator part in the reverse direction R of the crankshaft 5 is set to 360 / (n+1) degrees. Moreover, the interval between the peculiar indicator part and an indicator part among the n indicator parts provided adjacent to the peculiar indicator part in the reverse direction R of the crankshaft 5 is set to 180 / (n+1) degrees. In addition, in the swing-back control described later, when the crank angle of the crankshaft 5 is the reverse execution crank angle, the arrangement of n indicator parts is set so that, among the (n-1) normal indicator parts, the position of a normal indicator part that is X degrees away from the peculiar indicator part in the forward rotation direction of the crankshaft 5 coincides with the detection reference position Pd, and the following mathematical formula is established for X degrees. X={360 / (n+1)}·m

[0057] To explain the indicators in detail, in this embodiment, as shown in Fig. 3, eleven indicators a-k are provided on the outer surface of the peripheral wall portion 16 of the rotor case 14. That is, in this embodiment, the above n is 11. Each of the indicators a-k is a protrusion (convex portion) protruding in the radial direction from the outer surface of the peripheral wall portion 16 of the rotor case 14. Each of the indicators a-k is integrally formed with the peripheral wall portion 16 of the rotor case 14 by, for example, pressing or molding. Note that the indicators a-k may be formed by attaching eleven cylindrical pieces made of a magnetic material to the peripheral wall portion 16 of the rotor case 14 by means of welding, screwing, or the like.

[0058] In this embodiment, the eleven indicator portions a to k are provided around the entire circumference of the rotor case 14 on a circle centered at the center (rotation axis Q) of the rotor case 14. Of the indicator portions a to k, the indicator portion a is a peculiar indicator portion, and the other indicator portions b to k are normal indicator portions. The interval between each normal indicator portion b to k and another indicator portion among the indicator portions a to k that is provided adjacent to the normal indicator portion in the reverse direction R of the crankshaft 5 is set to 30 degrees. In addition, the interval between the peculiar indicator portion a and the indicator portion (normal indicator portion k) among the indicator portions a to k that is provided adjacent to the peculiar indicator portion in the reverse direction R of the crankshaft 5 is set to 60 degrees.

[0059] Furthermore, as shown in FIG. 3, when the rotor case 14 connected to the crankshaft 5 is viewed from the right of the vehicle, if a position on the peripheral wall portion 16 of the rotor case 14 that is located in the direction of the key groove 19 as viewed from the rotation axis Q of the crankshaft 5 is defined as the “rotor rotation reference position Pa,” the unique indicator portion a is located at a position 40 degrees away from the rotor rotation reference position Pa in the reverse direction R of the crankshaft 5.

[0060] The indicator units a-k are assigned two roles. The first role of the indicator units a-k is to allow the rotation control unit 42 of the microcomputer 41 of the drive control circuit 35 to recognize the positions of the 12 magnetic field generating units 21A-21L relative to the 18 coils 31U-31W in order to control the rotation of the motor generator 12. The second role of the indicator units a-k is to allow the swing-back control unit 43 of the microcomputer 41 of the drive control circuit 35 to recognize that the crank angle of the crankshaft 5 has reached a reverse execution crank angle in order to control the swing-back.

[0061] Normally, the interval (30 degrees) between the indicator portions b to k is equal to the interval (30 degrees) between the magnetic field generating portions 21A to 21L. Also, each of the indicator portions a to k is arranged at a position facing the boundary between two adjacent magnetic field generating portions in the magnetic field generating portions 21B to 21L. This configuration of the indicator portions a to k allows the indicator portions a to k to fulfill the first role described above. Although no indicator portion is arranged at a position facing the boundary between the magnetic field generating portion 21A and the magnetic field generating portion 21B, each of the indicator portions a to k can fulfill the first role described above.

[0062] The eleven indicator portions a to k include ten normal indicator portions b to k and one peculiar indicator portion a, and the interval between each of the normal indicator portions b to k and another indicator portion among the indicator portions a to k that is provided adjacent to the normal indicator portion in the reverse direction R of the crankshaft 5 is set to 30 degrees, and the interval between the peculiar indicator portion a and an indicator portion among the indicator portions a to k that is provided adjacent to the peculiar indicator portion a in the reverse direction R of the crankshaft 5 is set to 60 degrees. Furthermore, as will be described later, the peculiar indicator portion a is disposed at a position 40 degrees away from the rotor rotation reference position Pa in the reverse direction R of the crankshaft 5, so that in the swing-back control, when the crank angle of the crankshaft 5 is the reverse execution crank angle, the position of the normal indicator portion c (the second normal indicator portion counting from the peculiar indicator portion a in the forward rotation direction of the crankshaft 5) that is 60 degrees away from the peculiar indicator portion a in the forward rotation direction of the crankshaft 5, among the normal indicator portions b to k, coincides with the detection reference position Pd. This configuration of the indicator portions a to k enables the indicator portions a to k to fulfill the second role described above.

[0063] (electromagnetic pickup) 3, the electromagnetic pickup 32 is disposed on the outer periphery of the rotor case 14 at a position spaced a predetermined distance radially from the rotor case 14. The electromagnetic pickup 32 is disposed so as to face the trajectory E of the indicator portions a to k during rotation of the rotor 13. The electromagnetic pickup 32 is fixed to the crankcase 2 as described above.

[0064] The electromagnetic pickup 32 detects that each of the indicator parts a to k has passed a predetermined detection reference position Pd during rotation of the rotor 13. The detection reference position Pd is set at one location on the trajectory E of the indicator parts a to k during rotation of the rotor 13. The electromagnetic pickup 32 is disposed in a location close to the detection reference position Pd so as to face the detection reference position Pd, so that the electromagnetic pickup 32 can detect that each of the indicator parts a to k has passed the detection reference position Pd during rotation of the rotor 13.

[0065] In addition, in order to enable the swing-back control unit 43 of the microcomputer 41 of the drive control circuit 35 to recognize that the crank angle of the crankshaft 5 has reached the reverse execution crank angle during swing-back control, the detection reference position Pd is set so that when the crankshaft 5, the motor generator 12 and the electromagnetic pickup 32 are viewed from the right side of the vehicle, the direction in which the detection reference position Pd is viewed from the rotation axis Q of the crankshaft 5 coincides with the direction of the crank pin 5C viewed from the axis of the crankshaft 5 when the crank angle of the crankshaft 5 becomes 65 degrees (or 425 degrees).

[0066] Moreover, the electromagnetic pickup 32 outputs a pulsed detection signal indicating that each of the indicators a to k has passed the detection reference position Pd when the rotor 13 rotates. That is, the electromagnetic pickup 32 has a built-in magnet and a pickup coil. When the rotor 13 rotates, the magnetic field formed by the magnet built in the electromagnetic pickup 32 changes as the indicators a to k approach and move away from each other, and a voltage is generated in the pickup coil accordingly. The electromagnetic pickup 32 outputs a signal corresponding to the voltage as a detection signal. The electromagnetic pickup 32 is connected to a microcomputer 41 of the drive control circuit 35 (see FIG. 4). The detection signal output from the electromagnetic pickup 32 is input to a rotation control unit 42 and a swing-back control unit 43 of the microcomputer 41, respectively.

[0067] (Drive control circuit) Fig. 4 shows the drive control circuit 35 and the coils 31U, 31V, 31W, etc. connected to the drive control circuit 35. Note that in Fig. 4, the coils 31U, 31V, 31W are shown diagrammatically from an electrical point of view.

[0068] 4, the drive control circuit 35 includes a drive current supply circuit 36 ​​and a microcomputer 41. The microcomputer 41 also includes a rotation control unit 42 and a swing-back control unit 43. The rotation control unit 42 and the swing-back control unit 43 are realized by the microcomputer 41 executing a computer program.

[0069] The drive current supply circuit 36 ​​and the rotation control unit 42 are circuits that control the rotation of the motor generator 12 by controlling the drive currents flowing through the coils 31U, 31V, and 31W, respectively. A DC voltage Vb of, for example, 12V output from a battery mounted on the vehicle is applied to an input terminal 37 of the drive current supply circuit 36, and a DC current is supplied to the drive current supply circuit 36. The coils 31U, 31V, and 31W are connected to the output side of the drive current supply circuit 36 ​​via a current detection resistor 39. The drive current supply circuit 36 ​​also includes six FETs (field effect transistors) 38A to 38F. The drive currents supplied to the coils 31U, 31V, and 31W are switched by turning the FETs 38A to 38F on and off. The microcomputer 41 is connected to gate terminals G1 to G6 of the FETs 38A to 38F of the drive current supply circuit 36, respectively. A rotation control unit 42 of the microcomputer 41 controls the drive current flowing through each of the coils 31U, 31V, and 31W by switching on and off the FETs 38A to 38F of the drive current supply circuit 36, thereby controlling the rotation direction and number of rotations (rotational speed) of the rotor 13 relative to the stator 25. The electromagnetic pickup 32 is also connected to the microcomputer 41. The microcomputer 41 is also connected to a main controller provided in the vehicle.

[0070] The microcomputer 41 performs two types of control, open loop control and closed loop control, to rotate the rotor 13. The open loop control controls the timing of flowing the drive current to each of the coils 31U, 31V, and 31W by switching on and off the FETs 38A to 38F according to a preset control sequence. On the other hand, the closed loop control is, for example, vector control, and controls the timing of flowing the drive current to each of the coils 31U, 31V, and 31W by switching on and off the FETs 38A to 38F based on a detection signal output from the electromagnetic pickup 32. In addition, although a detailed description is omitted, when the rotor 13 rotates, a no-load induced voltage is generated in a specific coil 31 according to the rotation angle. In the closed loop control, the drive current to be flowed to each of the coils 31U, 31V, and 31W is controlled based on the no-load induced voltage in addition to the detection signal from the electromagnetic pickup 32.

[0071] Further, a current detection resistor 39 is connected between the drive current supply circuit 36 ​​and the coils 31U, 31V, and 31W. Although a detailed description will be omitted, the microcomputer 41 can use the current detection resistor 39 to detect the drive current flowing through each of the coils 31U, 31V, and 31W.

[0072] The swing-back control unit 43 performs swing-back control by first rotating the crankshaft 5 in the reverse direction and then in the forward direction when the engine 1 is started, thereby increasing the running distance for the crankshaft 5 to overcome the top dead center of compression using the power of the motor-generator 12.

[0073] (Swing back control) FIG. 5 shows the swing-back control in the case where the crankshaft 5 stops before the exhaust top dead center in the forward rotation direction of the crankshaft 5 just before the start of the engine 1. FIG. 6 shows the swing-back control in the case where the crankshaft 5 stops before the compression top dead center in the forward rotation direction of the crankshaft 5 just before the start of the engine 1. In FIG. 5 and FIG. 6, the characteristic diagram in the upper part of the figure shows the relationship between the crank angle of the crankshaft 5 and the pressure in the cylinder 3. In FIG. 5 and FIG. 6, a to k immediately below the characteristic diagram show the timing when the indicator parts a to K pass the detection reference position in correspondence with the crank angle of the crankshaft 5. In FIG. 5 and FIG. 6, t1, t2, etc. in the lowermost part of the figure show the timing when each process in the swing-back control is executed in correspondence with the crank angle of the crankshaft 5. In addition, as shown in FIG. 5 and FIG. 6, the time when the piston 6 reaches the compression top dead center is set to 0 degrees of the crank angle of the crankshaft 5.

[0074] In the swing-back control, the swing-back control unit 43 rotates the rotor 13 of the motor generator 12 relative to the stator 25 in the reverse direction R of the crankshaft 5 to reverse the rotation of the crankshaft 5, and when the crank angle of the reversed crankshaft 5 reaches a reverse execution crank angle, reverses the rotation direction of the rotor 13 to rotate the crankshaft 5 in the forward direction. In addition, the swing-back control unit 43 recognizes that the crank angle of the reversed crankshaft 5 has reached the reverse execution crank angle in the swing-back control based on the detection signal output from the electromagnetic pickup 32.

[0075] The reverse rotation execution crank angle is a crank angle at which the rotation direction of the reversed crankshaft 5 is switched from reverse to normal rotation in the swing back control. The reverse rotation execution crank angle is set to one crank angle within a section where the piston 6 rises in the cylinder 3 from the expansion bottom dead center to the compression top dead center while the crankshaft 5 is rotating in the reverse direction. In other words, the reverse rotation execution crank angle is set to an angle equal to or greater than -540 degrees and less than -720 degrees in the reverse direction of the crankshaft 5. In this embodiment, the reverse rotation execution crank angle is set to -675 degrees.

[0076] In the swing-back control, as shown in FIG. 5, the swing-back control unit 43 rotates the rotor 13 of the motor generator 12 in the reverse direction R of the crankshaft 5 to start the reverse rotation of the crankshaft 5, and then, based on the detection signal output from the electromagnetic pickup 32, judges whether the output level (amplitude) of the detection signal becomes equal to or lower than a predetermined reference output level during the period from time t1 when the peculiar indicator portion a passes the detection reference position Pd for the first time after time t0 when the crankshaft 5 starts the reverse rotation to time t2 when m (m is an integer of 1 to n / 2) normal indicator portions pass the detection reference position. In this embodiment, m is set to 2 (note that m is limited to an integer of 1 to n / 2, as will be described later). Therefore, the swing-back control unit 43 judges whether the output level of the detection signal becomes equal to or lower than the reference output level during the period from time t1 when the peculiar indicator portion a passes the detection reference position Pd for the first time after time t0 when the crankshaft 5 starts the reverse rotation to time t2 when two normal indicator portions pass the detection reference position Pd.

[0077] 5, if the output level of the detection signal becomes equal to or lower than the reference output level between time t1 and time t2, the swing-back control unit 43 determines that the crank angle of the reverse rotating crankshaft 5 reaches the reverse execution crank angle at time t2. On the other hand, if the output level of the detection signal does not become equal to or lower than the reference output level between time t1 and time t2, the swing-back control unit 43 determines that the crank angle of the reverse rotating crankshaft reaches the reverse execution crank angle at time t3 when the peculiar indicator portion a passes the detection reference position Pd again after time t2 and m (two) indicator portions subsequently pass the detection reference position Pd, as shown in FIG.

[0078] Time t2 is the time when the peculiar indicator portion a passes the detection reference position Pd for the first time after the crankshaft 5 starts reverse rotation and the second normal indicator portion passes the detection reference position Pd. Time t3 is the time when the peculiar indicator portion a passes the detection reference position Pd again after the crankshaft 5 starts reverse rotation and the second normal indicator portion passes the detection reference position Pd. When the crankshaft 5 is rotating in reverse, the second normal indicator portion that passes the detection reference position Pd after the peculiar indicator portion a passes the detection reference position Pd is the normal indicator portion c. That is, the timing at which the swing-back control portion 43 determines that the crank angle of the crankshaft 5 rotating in reverse has reached the reverse execution crank angle is when the normal indicator portion c passes the detection reference position Pd, both in the case of FIG. 5 and in the case of FIG. 6.

[0079] When the crank angle of the crankshaft 5, which is being reversed, reaches the reverse execution crank angle, the swing-back control unit 43 reverses the rotation direction of the rotor 13, and switches the rotation direction of the crankshaft 5 from reverse to forward. After that, when the intake, compression, expansion, and exhaust processes are initiated in the engine 1 and the engine 1 starts, the microcomputer 41 switches the control of the motor-generator 12 to power generation control.

[0080] FIG. 7 shows a state in which the crank angle of the crankshaft 5 reaches −675 degrees in the motor generator 12, which is set as the reverse rotation execution crank angle. As described above, the motor generator 12 has a configuration in which, among the eleven indicator parts a to k, the interval between each of the normal indicator parts b to k and another indicator part among the indicator parts a to k that is provided adjacent to the normal indicator part in the reverse rotation direction R of the crankshaft 5 is set to 30 degrees, the interval between the peculiar indicator part a and an indicator part among the indicator parts a to k that is provided adjacent to the peculiar indicator part a in the reverse rotation direction R of the crankshaft 5 is set to 60 degrees, and the peculiar indicator part a is disposed at a position 40 degrees away from the rotor rotation reference position Pa in the reverse rotation direction R of the crankshaft 5. In the motor generator 12 having such a configuration, as shown in FIG. 7, when the crank angle of the crankshaft 5 reaches the reverse rotation execution crank angle, the position of the normal indicator part c, among the normal indicator parts b to k, that is 60 degrees away from the peculiar indicator part a in the forward rotation direction of the crankshaft 5, coincides with the detection reference position Pd. The normal indicator portion c, which is 60 degrees away from the peculiar indicator portion a in the forward rotation direction of the crankshaft 5, corresponds to the second normal indicator portion that passes through the detection reference position Pd after the peculiar indicator portion a passes through the detection reference position Pd when the crankshaft 5 is rotating in the reverse direction. Moreover, the normal indicator portion c in this embodiment corresponds to the reversal determination indicator portion in the above-mentioned embodiment of the present invention.

[0081] Fig. 8 shows a specific flow of the swing-back control. In a state where the engine 1 is stopped and the crankshaft 5 and the rotor 13 are stopped, for example, when an engine start signal is output from a main controller provided in the vehicle to the microcomputer 41, the swing-back control shown in Fig. 8 is started. Note that the main controller provided in the vehicle outputs the engine start signal to the microcomputer 41 when the engine start switch of the vehicle is turned on or when the throttle is turned on after idling stop.

[0082] In the swing-back control, the swing-back control unit 43 first rotates the rotor 13 of the motor generator 12 in the reverse direction R of the crankshaft 5 to start reverse rotation of the crankshaft 5 (step S1).

[0083] Next, the swing-back control unit 43 judges whether the peculiar indicator portion a has passed the detection reference position Pd for the first time based on the detection signal output from the electromagnetic pickup 32 (step S2). Since the interval between the peculiar indicator portion a and an indicator portion provided adjacent to the peculiar indicator portion in the reverse direction R of the crankshaft 5 is different from the interval between each of the normal indicator portions b to k and another indicator portion provided adjacent to the normal indicator portion in the reverse direction R of the crankshaft 5, the swing-back control unit 43 can judge whether the indicator portion that has passed the detection reference position Pd is the peculiar indicator portion a or the normal indicator portion b to k based on the interval of the detection signal output from the electromagnetic pickup 32.

[0084] If the peculiar indicator portion a passes through the detection reference position Pd for the first time (step S2: YES), then the swing-back control portion 43 determines whether or not the output level of the detection signal becomes equal to or lower than the reference output level during the period from time t1 when the peculiar indicator portion a passes through the detection reference position Pd for the first time after the crankshaft 5 starts reverse rotation to time t2 when the two normal indicator portions subsequently pass through the detection reference position Pd (step S3).

[0085] Here, Fig. 9 shows the waveform of the detection signal output from the electromagnetic pickup 32 from the time t1 to the time t2. As shown in Fig. 5, when the crank angle of the reverse rotating crankshaft 5 is a crank angle before the compression top dead center in the reverse direction of the crankshaft 5 at the time t1 when the peculiar indicator portion a passes the detection reference position Pd for the first time after the crankshaft 5 starts reverse rotation, as shown in Fig. 9(A), the output level of the detection signal, for example, on the positive side, output from the electromagnetic pickup 32 becomes equal to or lower than the reference output level Vt. On the other hand, as shown in Fig. 6, when the crank angle of the reverse rotating crankshaft 5 is a crank angle before the exhaust top dead center in the reverse direction of the crankshaft 5 at the time t1 when the peculiar indicator portion a passes the detection reference position Pd for the first time after the crankshaft 5 starts reverse rotation, as shown in Fig. 9(b), the output level of the detection signal, for example, on the positive side, output from the electromagnetic pickup 32 becomes higher than the reference output level Vt. The reason why the output level of the detection signal differs between time t1 and time t2 when the crank angle of the reverse rotating crankshaft 5 is just before top dead center of compression stroke and just before top dead center of exhaust stroke is as described in the explanation of the embodiment of the present invention. (Strictly speaking, the explanation of the embodiment of the present invention describes the reason why the output level of the detection signal differs between time t2 when the crank angle of the reverse rotating crankshaft 5 is just before top dead center of compression stroke and just before top dead center of exhaust stroke, but this also applies to the case where the output level of the detection signal differs between time t1 and time t2 when the crank angle of the reverse rotating crankshaft 5 is just before top dead center of compression stroke and just before top dead center of exhaust stroke.) In step S3, the swing-back control unit 43 determines whether the positive output level of the detection signal output from the electromagnetic pickup 32 becomes equal to or lower than the reference output level Vt during the period from the point when the peculiar indicator portion a passes through the detection reference position Pd for the first time after the crankshaft 5 starts to rotate reverse to the point when the two normal indicator portions subsequently pass through the detection reference position Pd.

[0086] In addition, in step S3, the swing-back control unit 43 may determine whether the output level of the detection signal output from the electromagnetic pickup 32 at the time t1 when the unique indicator portion a passes the detection reference position Pd for the first time is below the reference output level, or may determine whether the output level of the detection signal output from the electromagnetic pickup 32 at the time when one normal indicator portion subsequently passes the detection reference position Pd after the unique indicator portion a passes the detection reference position Pd for the first time is below the reference output level, or may determine whether the output level of the detection signal output from the electromagnetic pickup 32 at the time t2 when two normal indicator portions subsequently pass the detection reference position Pd after the unique indicator portion a passes the detection reference position Pd for the first time is below the reference output level.

[0087] If the output level of the detection signal becomes equal to or lower than the reference output level during the period from time t1 when the peculiar indicator portion a passes the detection reference position Pd for the first time after the crankshaft 5 starts to rotate in reverse to time t2 when two subsequent normal indicator portions pass the detection reference position Pd (step S3: YES), the swing-back control portion 43 then determines whether or not the second normal indicator portion has passed the detection reference position Pd since the peculiar indicator portion a passed the detection reference position Pd for the first time (step S4) based on the detection signal output from the electromagnetic pickup 32. This determination can be made by counting the number of normal indicator portions passing the detection reference position Pd based on the detection signal output from the electromagnetic pickup 32 after it is recognized that the peculiar indicator portion a has passed the detection reference position Pd.

[0088] Then, when the second normal indicator portion passes through the detection reference position Pd after the peculiar indicator portion a passes through the detection reference position Pd for the first time (step S4: YES), the swing-back control portion 43 reverses the rotation direction of the rotor 13 and switches the rotation direction of the crankshaft 5 from reverse to normal (step S7). After that, when the intake, compression, expansion, and exhaust processes are initiated in the engine 1 and the engine 1 starts (step S8: YES), the microcomputer 41 switches the control of the motor-generator 12 to power generation control (step S9).

[0089] On the other hand, if the result of the judgment in step S3 is that the output level of the detection signal does not become below the reference output level between time t1 when the peculiar indicator portion a passes the detection reference position Pd for the first time after the crankshaft 5 starts reverse rotation and time t2 when the two normal indicator portions subsequently pass the detection reference position Pd (step S3: NO), then the swing-back control portion 43 judges, based on the detection signal output from the electromagnetic pickup 32, whether or not the peculiar indicator portion a has passed the detection reference position Pd again after time t2 (step S5).

[0090] If the unique indicator portion a has passed the detection reference position Pd again (step S5: YES), then, based on the detection signal output from the electromagnetic pickup 32, the swing-back control portion 43 determines whether or not a second normal indicator portion has passed the detection reference position Pd after the unique indicator portion a has passed the detection reference position Pd again (step S6).

[0091] Then, when the second normal indicator portion passes through the detection reference position Pd after the peculiar indicator portion a passes through the detection reference position Pd again (step S6: YES), the swing-back control portion 43 reverses the rotation direction of the rotor 13 and switches the rotation direction of the crankshaft 5 from reverse to normal (step S7). After that, when the intake, compression, expansion, and exhaust processes are initiated in the engine 1 and the engine 1 starts (step S8: YES), the microcomputer 41 switches the control of the motor-generator 12 to power generation control (step S9).

[0092] As described above, n (n is an integer equal to or greater than 3) indicator portions are provided on the outer surface of the peripheral wall portion 16 of the rotor case 14, and in the swing-back control, the swing-back control portion 43 judges, based on the detection signal, whether or not the output level of the detection signal becomes equal to or less than the reference output level between time t1 when the peculiar indicator portion passes the detection reference position Pd for the first time after the crankshaft starts reverse rotation, and time t2 when m (m is an integer equal to or greater than 1 and equal to or less than n / 2) indicator portions subsequently pass the detection reference position Pd. If the output level of the detection signal becomes equal to or less than the reference output level between time t1 and time t2, it is judged that the crank angle of the crankshaft 5 which is rotating in the reverse direction has reached the reverse execution crank angle at time t2. On the other hand, if the output level of the detection signal does not become equal to or less than the reference output level between time t1 and time t2, it is judged that the crank angle of the crankshaft 5 which is rotating in the reverse direction has reached the reverse execution crank angle at time t3 when the peculiar indicator portion passes the detection reference position Pd again after time t2, and m indicator portions subsequently pass the detection reference position Pd. Thus, in the embodiment of the present invention, n is limited to 3 or more, and m is limited to 1 or more and n / 2 or less. The reason for setting these limitations is that, when swing-back control is performed in a state in which the crankshaft 5 is stopped before the compression top dead center in the forward rotation direction of the crankshaft 5 immediately before the start of the engine 1, as shown in Fig. 6, the rotation speed of the crankshaft 5 is made sufficiently large from the start of reverse rotation of the crankshaft 5 until the peculiar indicator portion a passes the detection reference position Pd for the first time, so that the output level of the detection signal output from the electromagnetic pickup 32 surely exceeds the reference output level at the time when the peculiar indicator portion a passes the detection reference position Pd for the first time.

[0093] Specifically, as described above, in this embodiment, when the crank angle of the crankshaft 5 is the reverse execution crank angle, the arrangement of the indicator portions a to k and the detection reference position Pd are set so that the position of a normal indicator portion among the (n-1) normal indicator portions that is away from the peculiar indicator portion by X degrees in the forward rotation direction of the crankshaft 5 coincides with the detection reference position Pd, and the following mathematical formula holds for X degrees. X={360 / (n+1)}·m Therefore, as can be seen from the above formula, when m becomes larger, X becomes larger. As a result, in the case of FIG. 6, that is, immediately before the start of the engine 1, when the swing-back control is performed in a state in which the crankshaft 5 is stopped before the compression top dead center in the forward rotation direction of the crankshaft 5, the crank angle of the crankshaft 5 approaches 0 degrees at the time when the peculiar indicator portion a passes the detection reference position Pd for the first time after the crankshaft 5 starts reverse rotation. Therefore, in the case of FIG. 6, there is a possibility that the number of rotations of the crankshaft 5 does not increase during the period from the start of reverse rotation to the time when the peculiar indicator portion a passes the detection reference position Pd for the first time, and the output level of the detection signal output from the electromagnetic pickup 32 does not exceed the reference output level at the time when the peculiar indicator portion a passes the detection reference position Pd for the first time. If such a situation occurs, the swing-back control shown in FIG. 8 will not be performed normally. In order to prevent such a situation from occurring, when n is an integer of 3 or more, m is limited to an integer of 1 to n / 2. When n is an integer of 3 or more, m may be limited to an integer of 1 or more and less than n / 2, or an integer of 1 or more and n / 3 or less. When n is an integer of 4 or more, m may be limited to an integer of 1 or more and n / 4 or less.

[0094] In this embodiment, the reversing crank angle is −675 degrees, n is 11, m is 2, and the interval between the normal index portions is 30 degrees, so that in the case of FIG. 6, the crank angle of the crankshaft 5 at the time when the peculiar index portion a passes through the detection reference position Pd for the first time is −255 degrees, as calculated below. -675+360+30×2=-255 Furthermore, m is limited to an integer between 1 and n / 2, and when n is 11, the maximum value of m is 5. When the reversing crank angle is -675 degrees, n is 11, m is 5, and the interval between normal index portions is 30 degrees, the crank angle of crankshaft 5 at the time when peculiar index portion a passes through the detection reference position for the first time in the case of Figure 6 is -165 degrees, as calculated below. -675+360+30×5=-165

[0095] As described above, the engine starting device 11 of the first embodiment of the present invention judges whether or not the second normal indicator part has passed the detection reference position Pd after the crankshaft 5 has been rotated in the reverse direction based on the detection signal output from the electromagnetic pickup 32, and when the second normal indicator part has passed the detection reference position Pd, it judges that the crank angle of the crankshaft 5 has reached the reverse rotation execution crank angle, and switches the rotation direction of the crankshaft 5 from reverse rotation to forward rotation. In this way, the engine starting device 11 of the present embodiment recognizes that the crank angle of the reversed crankshaft 5 has reached the reverse rotation execution crank angle based on the detection signal output from the electromagnetic pickup 32 in the swing back control. Therefore, it is possible to prevent the recognition that the crank angle of the reversed crankshaft 5 has reached the reverse rotation execution crank angle from becoming inaccurate due to the temperature of the engine 1. According to the engine starting device 11 of this embodiment, it is possible to accurately recognize that the crank angle of the reversed crankshaft 5 has reached the reverse execution crank angle during swing back control, and the engine 1 can be reliably started by swing back control.

[0096] Furthermore, according to the engine starting device 11 of this embodiment, in the swing back control, it is possible to determine whether the crank angle of the reversed crankshaft 5 has reached the reverse execution crank angle by utilizing the indicators a-k provided for the rotation control of the motor generator 12. By using the indicators a-k for both the rotation control and the swing back control of the motor generator 12, the structure of the motor generator 12 can be simplified.

[0097] In addition, in the swing back control, the engine starting device 11 of this embodiment judges whether the output level of the detection signal becomes equal to or lower than a predetermined reference output level during the period from time t1 when the peculiar indicator portion passes the detection reference position Pd after the crankshaft 5 starts reverse rotation to time t2 when m (two) indicator portions pass the detection reference position Pd, and judges that the crank angle of the reversed crankshaft 5 has reached the reverse execution crank angle at time t2 if the output level of the detection signal becomes equal to or lower than the reference output level during the period from time t1 to time t2, and judges that the crank angle of the reversed crankshaft 5 has not reached the reverse execution crank angle at time t2 if the output level of the detection signal does not become equal to or lower than the reference output level during the period from time t1 to time t2. With this configuration, it is possible to accurately judge that the crank angle of the crankshaft 5 has reached the reverse execution crank angle in both cases, that is, when the crankshaft 5 is stopped just before the compression top dead center in the normal rotation direction of the crankshaft 5 and when the crankshaft 5 is stopped just before the exhaust top dead center, immediately before the engine starts.

[0098] In the engine starting device 11 of the first embodiment, n (n is an integer of 3 or more) indicator parts are provided, one of the n indicator parts is a peculiar indicator part, and in the swing-back control, the swing-back control part 43 detects, based on the detection signal output from the electromagnetic pickup 32, when the output level of the detection signal becomes equal to or lower than a predetermined reference output level at a first time point when the peculiar indicator part passes the detection reference position Pd for the first time after the crankshaft 5 starts to rotate in reverse and m (m is an integer of 1 or more and less than n) indicator parts subsequently pass the detection reference position. If the output level of the detection signal becomes equal to or lower than the reference output level at the first time point, it is determined that the crank angle of the crankshaft 5 rotating in the reverse direction has reached the reverse execution crank angle at the first time point. On the other hand, if the output level of the detection signal does not become equal to or lower than the reference output level at the first time point, it may be determined that the crank angle of the crankshaft 5 rotating in the reverse direction has reached the reverse execution crank angle at the second time point when the peculiar indicator portion passes the detection reference position again after the first time point and m indicator portions subsequently pass the detection reference position. This configuration limits the timing for determining whether the output level of the detection signal has become equal to or lower than the predetermined reference output level to the time point when the peculiar indicator portion passes the detection reference position Pd for the first time after the crankshaft 5 starts to rotate in the reverse direction and m indicator portions subsequently pass the detection reference position. This configuration allows the restriction on m to be relaxed.

[0099] Also, the engine starting device 11 of the first embodiment may be provided with n (n is an integer of 3 or more) indicator parts, one of the n indicator parts being a peculiar indicator part, and the swing-back control part 43 may determine, in the swing-back control, whether or not the output level of the detection signal becomes equal to or lower than a predetermined reference output level at the time point when the peculiar indicator part passes the detection reference position Pd after the crankshaft 5 starts reverse rotation, based on the detection signal output from the electromagnetic pickup 32, and if the output level of the detection signal becomes equal to or lower than the predetermined reference output level at that time point, determine that the crank angle of the crankshaft 5, which is reverse rotating, has reached the reverse execution crank angle at that time point. In this configuration, the determination of whether or not the output level of the detection signal has become equal to or lower than the predetermined reference output level and the determination of whether or not the crank angle of the crankshaft 5 has reached the reverse execution crank angle are performed at the time point when the peculiar indicator part passes the detection reference position Pd. According to this configuration, the timing for determining whether the output level of the detection signal has fallen below a predetermined reference output level and the timing for determining whether the crank angle of the crankshaft 5 has reached the reverse execution crank angle can be easily determined based on the peculiar indicator portion. EXAMPLES

[0100] FIG. 10 shows an engine starting device 51 according to a second embodiment of the present invention. In the engine starting device 51 according to the second embodiment, n indicator parts are provided on the outer surface of the peripheral wall of the rotor case 14 of the motor generator 52. The n indicator parts include (n-1) normal indicator parts and one peculiar indicator part. The n indicator parts are provided at equal intervals in the circumferential direction of the rotor case 14. The (n-1) normal indicator parts are identical in shape or size, and the peculiar indicator part is different in shape or size from each of the normal indicator parts. When the crank angle of the crankshaft 5 is the reverse execution crank angle, the arrangement of the multiple indicator parts and the detection reference position are set so that the position of a normal indicator part that is X degrees away from the peculiar indicator part in the forward rotation direction of the crankshaft 5 among the (n-1) normal indicator parts and the detection reference position coincide with each other, and the following formula is established for X degrees. X = (360 / n) m

[0101] Specifically, as shown in FIG. 10, twelve indicator portions a to l are provided on the outer surface of the peripheral wall of the rotor case 14. The indicator portions a to l include eleven normal indicator portions b to l and one peculiar indicator portion a. The indicator portions a to l are provided at equal intervals in the circumferential direction of the rotor case 14. The normal indicator portions b to l have the same shape or size, and the peculiar indicator portion a has a different shape or size from each of the normal indicator portions b to l. More specifically, the peculiar indicator portion a is longer than each of the normal indicator portions b to l in the circumferential direction of the rotor case 14. The arrangement of the indicator portions a to l and the detection reference position Pd are set so that, when the crank angle of the crankshaft 5 is the reverse execution crank angle, the position of the normal indicator portion c, which is 60 degrees away from the peculiar indicator portion a in the forward rotation direction of the crankshaft 5, coincides with the detection reference position.

[0102] The engine starting device 51 of the second embodiment also provides the same operational effects as the engine starting device 11 of the first embodiment.

[0103] In the above embodiments, the number of magnetic field generating parts is 12, the number of coils is 18, and the number of indicator parts is 11 or 12, but the numbers of magnetic field generating parts, coils, and indicator parts are not limited to these. In addition, the engine to which the engine starting device of the present invention is applied is not limited to that for a vehicle.

[0104] Furthermore, the present invention can be modified as appropriate within the scope that does not contradict the gist or concept of the invention that can be read from the claims and the entire specification, and an engine starting device involving such modifications is also included in the technical concept of the present invention. [Explanation of symbols]

[0105] 1 Engine 2 Crankcase (engine case) 3 Cylinder 5 Crankshaft 6 Piston 7 Connecting rod 11, 51 Engine starting device 12, 52 Motor generator (electric motor) 13 Rotor 14 Rotor case 15 Bottom plate part 16 Peripheral wall section 18 Crankshaft insertion hole (insertion hole) 21A~21L Magnetic field generating section a~l Index part a Singular indicator part 25 Stator 26 cores 31U~31W coil 32 Electromagnetic Pickup 35 Drive control circuit (control unit)

Claims

1. An engine starting device for starting a four-stroke engine including an engine case, a cylinder provided in the engine case, a crankshaft provided within the engine case, a piston provided within the cylinder, and a connecting rod connecting the crankshaft and the piston, The device includes an electric motor, an electromagnetic pickup, and a control unit. The electric motor is a rotor having a rotor case fixed to the crankshaft and rotating together with the crankshaft, and a rotor having a plurality of magnetic field generating portions fixed to the rotor case; a core fixed to the engine case, and a stator having three or more coils provided on the core, the rotor case is formed in a cylindrical shape with a bottom, and has a bottom plate portion, a peripheral wall portion provided on an outer periphery side of the bottom plate portion, and an insertion hole provided in a center of the bottom plate portion, an end portion of the crankshaft is inserted into the insertion hole, and the rotor case is coupled to the end portion of the crankshaft so as to be non-rotatable with respect to the crankshaft, an outer surface of the peripheral wall portion or an outer surface of an outer peripheral portion of the bottom plate portion, n (n is an integer of 3 or more) indicator portions made of a magnetic material are provided at predetermined intervals around a circle centered at the center of the rotor case, the n number of index portions include one unique index portion that is different from other index portions among the n number of index portions in terms of shape, size, or distance between the unique index portion and an index portion that is provided adjacent to one of the n number of index portions in the circumferential direction of the rotor case, the electromagnetic pickup is fixed to the engine case, and is disposed so as to face the trajectory of each of the indicator portions during rotation of the rotor, and outputs a pulse-like detection signal indicating that each of the indicator portions has passed a predetermined detection reference position during rotation of the rotor; the control unit rotates the rotor in one direction relative to the stator to reverse the rotation of the crankshaft, and when a crank angle of the crankshaft that is being reversed reaches a reverse execution crank angle, performs a swing-back control to reverse the rotation direction of the rotor to rotate the crankshaft in the forward direction; the reverse rotation execution crank angle is set to one crank angle within a section in which the piston rises in the cylinder from the expansion bottom dead center toward the compression top dead center while the crankshaft is rotating in the reverse direction, The control unit, in the swing back control, determines, based on the detection signal, whether or not the output level of the detection signal becomes equal to or lower than a predetermined reference output level between a first point in time when the peculiar indicator portion passes the detection reference position after the crankshaft starts reverse rotation and a second point in time when m (m is an integer greater than or equal to 1 and less than or equal to n / 2) of the indicator portions subsequently pass the detection reference position, and if the output level of the detection signal becomes equal to or lower than the reference output level between the first point in time and the second point in time, determines that the crank angle of the crankshaft, which is reverse rotating, has reached the reverse execution crank angle at the second point in time.

2. The engine starting device of claim 1, characterized in that, in the swing back control, the control unit determines, based on the detection signal, whether or not the output level of the detection signal has become below the reference output level between a first time point when the peculiar indicator portion passes the detection reference position for the first time after the crankshaft starts reverse rotation and a second time point when the m indicator portions subsequently pass the detection reference position, and if the output level of the detection signal has become below the reference output level between the first time point and the second time point, determines that the crank angle of the crankshaft which is reversed has reached the reverse execution crank angle at the second time point, and on the other hand, if the output level of the detection signal has not become below the reference output level between the first time point and the second time point, determines that the crank angle of the crankshaft which is reversed has reached the reverse execution crank angle at a third time point when the peculiar indicator portion passes the detection reference position again after the second time point and then the m indicator portions subsequently pass the detection reference position.

3. An engine starting device for starting a four-stroke engine including an engine case, a cylinder provided in the engine case, a crankshaft provided within the engine case, a piston provided within the cylinder, and a connecting rod connecting the crankshaft and the piston, The device includes an electric motor, an electromagnetic pickup, and a control unit. The electric motor is a rotor having a rotor case fixed to the crankshaft and rotating together with the crankshaft, and a rotor having a plurality of magnetic field generating portions fixed to the rotor case; a core fixed to the engine case, and a stator having three or more coils provided on the core, the rotor case is formed in a cylindrical shape with a bottom, and has a bottom plate portion, a peripheral wall portion provided on an outer periphery side of the bottom plate portion, and an insertion hole provided in a center of the bottom plate portion, an end portion of the crankshaft is inserted into the insertion hole, and the rotor case is coupled to the end portion of the crankshaft so as to be non-rotatable with respect to the crankshaft, an outer surface of the peripheral wall portion or an outer surface of an outer peripheral portion of the bottom plate portion, n (n is an integer of 3 or more) indicator portions made of a magnetic material are provided at predetermined intervals around a circle centered at the center of the rotor case, the n number of index portions include one unique index portion that is different from other index portions among the n number of index portions in terms of shape, size, or distance between the unique index portion and an index portion that is provided adjacent to one of the n number of index portions in the circumferential direction of the rotor case, the electromagnetic pickup is fixed to the engine case, and is disposed so as to face the trajectory of each of the indicator portions during rotation of the rotor, and outputs a pulse-like detection signal indicating that each of the indicator portions has passed a predetermined detection reference position during rotation of the rotor; the control unit rotates the rotor in one direction relative to the stator to reverse the rotation of the crankshaft, and when a crank angle of the crankshaft that is being reversed reaches a reverse execution crank angle, performs a swing-back control to reverse the rotation direction of the rotor to rotate the crankshaft in the forward direction; the reverse rotation execution crank angle is set to one crank angle within a section in which the piston rises in the cylinder from the expansion bottom dead center toward the compression top dead center while the crankshaft is rotating in the reverse direction, The control unit, in the swing back control, determines, based on the detection signal, whether or not the output level of the detection signal becomes equal to or lower than a predetermined reference output level at a point in time when the unique indicator portion passes the detection reference position after the crankshaft starts to rotate in reverse, and m (m is an integer greater than 1 and less than n) of the indicator portions subsequently pass the detection reference position, and if the output level of the detection signal becomes equal to or lower than the reference output level at that point in time, it determines that the crank angle of the crankshaft which is rotating in reverse has reached the reverse execution crank angle at that point in time.

4. The engine starting device of claim 3, characterized in that in the swing back control, the control unit determines, based on the detection signal, whether or not the output level of the detection signal has become below the reference output level at a first time point when the peculiar indicator unit passes the detection reference position for the first time after the crankshaft starts reverse rotation and the m indicator units subsequently pass the detection reference position, and if the output level of the detection signal has become below the reference output level at the first time point, determines that the crank angle of the crankshaft which is reverse rotating has reached the reverse execution crank angle at the first time point, and on the other hand, if the output level of the detection signal has not become below the reference output level at the first time point, determines that the crank angle of the crankshaft which is reverse rotating has reached the reverse execution crank angle at a second time point when the peculiar indicator unit passes the detection reference position again after the first time point and the m indicator units subsequently pass the detection reference position.

5. the n index portions include (n-1) normal index portions and one of the specific index portions, an interval between each normal indicator portion and another indicator portion among the n indicator portions that is provided adjacent to the normal indicator portion in the reverse rotation direction of the crankshaft is set to 360 / (n+1) degrees; a distance between the unique index portion and one of the n index portions that is adjacent to the unique index portion in the reverse rotation direction of the crankshaft is set to 180 / (n+1) degrees; an arrangement of the n indicator portions and the detection reference position are set such that, when the crank angle of the crankshaft is the reverse execution crank angle, a position of a normal indicator portion, among the (n-1) normal indicator portions, that is separated by X degrees from the peculiar indicator portion in the forward rotation direction of the crankshaft, coincides with the detection reference position; X={360 / (n+1)}・m 5. The engine starting device according to claim 1, wherein

6. the n index portions include (n-1) normal index portions and one of the specific index portions, The n indicator portions are provided at equal intervals, the (n-1) normal indicator portions are identical in shape or size to one another, The specific indicator portion has a shape or size different from each of the normal indicator portions, an arrangement of the n indicator portions and the detection reference position are set such that, when the crank angle of the crankshaft is the reverse execution crank angle, a position of a normal indicator portion, among the (n-1) normal indicator portions, that is separated by X degrees from the peculiar indicator portion in the forward rotation direction of the crankshaft coincides with the detection reference position; X=(360 / n)・m 5. The engine starting device according to claim 1, wherein

7. An engine starting device for starting a four-stroke engine including an engine case, a cylinder provided in the engine case, a crankshaft provided within the engine case, a piston provided within the cylinder, and a connecting rod connecting the crankshaft and the piston, The device includes an electric motor, an electromagnetic pickup, and a control unit. The electric motor is a rotor having a rotor case fixed to the crankshaft and rotating together with the crankshaft, and a rotor having a plurality of magnetic field generating portions fixed to the rotor case; a core fixed to the engine case, and a stator having three or more coils provided on the core, the rotor case is formed in a cylindrical shape with a bottom, and has a bottom plate portion, a peripheral wall portion provided on an outer periphery side of the bottom plate portion, and an insertion hole provided in a center of the bottom plate portion, an end portion of the crankshaft is inserted into the insertion hole, and the rotor case is coupled to the end portion of the crankshaft so as to be non-rotatable with respect to the crankshaft, an outer surface of the peripheral wall portion or an outer surface of an outer peripheral portion of the bottom plate portion, n (n is an integer of 3 or more) indicator portions made of a magnetic material are provided at predetermined intervals around a circle centered at the center of the rotor case, the n number of index portions include one unique index portion that is different from other index portions among the n number of index portions in terms of shape, size, or distance between the unique index portion and an index portion that is provided adjacent to one of the n number of index portions in the circumferential direction of the rotor case, the electromagnetic pickup is fixed to the engine case, and is disposed so as to face the trajectory of each of the indicator portions during rotation of the rotor, and outputs a pulse-like detection signal indicating that each of the indicator portions has passed a predetermined detection reference position during rotation of the rotor; the control unit rotates the rotor in one direction relative to the stator to reverse the rotation of the crankshaft, and when a crank angle of the crankshaft that is being reversed reaches a reverse execution crank angle, performs a swing-back control to reverse the rotation direction of the rotor to rotate the crankshaft in the forward direction; the reverse rotation execution crank angle is set to one crank angle within a section in which the piston rises in the cylinder from the expansion bottom dead center toward the compression top dead center while the crankshaft is rotating in the reverse direction, The control unit, in the swing back control, determines based on the detection signal whether or not the output level of the detection signal has become equal to or lower than a predetermined reference output level at the point in time when the peculiar indicator portion passes the detection reference position after the crankshaft starts reverse rotation, and if the output level of the detection signal has become equal to or lower than the predetermined reference output level at that point in time, determines that the crank angle of the crankshaft which is reverse rotating has reached the reverse execution crank angle at that point in time.

8. the plurality of magnetic field generating portions are arranged on the rotor case on an outer circumferential side of the bottom plate portion and an inner circumferential side of the peripheral wall portion over an entire periphery of the rotor case, the stator is disposed on the inner circumferential side of the arrangement of the plurality of magnetic field generating units, 8. The engine starting device according to claim 1, wherein the control unit rotates the rotor relative to the stator by controlling the current flowing through each of the coils based on the detection signal.

Images