JP6239377B2 - Brushless motor and wiper device - Google Patents

Description

  The present invention relates to a brushless motor and a wiper device that include a stator and a rotor and can control the rotation speed of the rotor.

  Examples of conventional motors are described in Patent Documents 1 to 3. The motors described in Patent Documents 1 and 2 are motors with brushes, and include a magnet (stator) as a field fixed to a case, and a rotor as an armature provided rotatably in the case. I have. The rotor has a core around which the coil is wound and a commutator connected to the coil. Moreover, it has the common brush which contacts a commutator, the brush for low speed operation, and the brush for high speed operation.

  Each brush is arrange | positioned in a different phase with the rotation direction of a rotor, and the switching element is each provided in the path | route which supplies electric power to these brushes. Then, by turning on or off each switching element, the brush to be supplied with current is switched, and the rotational speed of the rotor is controlled at a low speed or a high speed.

  The motor described in Patent Document 3 does not include a brush, and includes a stator (stator) as an armature provided in a case, and a rotor as a field provided rotatably in the case. I have. The stator includes a stator core and a coil wound around the stator core. The coils have three coils to which three-phase excitation currents, that is, U-phase, V-phase, and W-phase excitation currents are supplied, and each coil is arranged with a phase shifted in the rotation direction of the rotor.

  In addition, a switching element connected to each coil is provided. By switching on / off of each switching element alternately and controlling the duty ratio, which is the ON ratio, current is supplied to all coils at different timings, and the rotational speed of the rotor is controlled. The

JP 2007-202391 A JP 2007-143278 A JP 2010-93977 A

  In the motors described in Patent Documents 1 to 3, there is a problem that torque ripple in the rotor increases depending on control conditions, not limited to those with brushes and without brushes.

  The objective of this invention is providing the brushless motor and wiper apparatus which can suppress the torque ripple in a rotor.

The brushless motor of the present invention is a brushless motor in which a current is supplied to a coil and a rotor rotates, and the coil is energized at a first timing and energized for a first period. The first energization control for continuously controlling the rotation speed of the rotor, the energization of the coil is started at a second timing advanced by an electrical angle from the first timing, and the first A control unit that switches between and executes a second energization control that controls energization over a second period that is longer than the first period, and the second timing is The electrical angle is advanced by 30 ° or more in electrical angle and 60 ° or less in electrical angle with respect to the first timing, the first period is 120 ° in electrical angle, and the second period is , The second timing with respect to the first timing The electrical angle is adjusted within the range of 135 ° or more and the electrical angle of 165 ° or less in accordance with the value to be advanced, and the second energization control is being performed rather than the first energization control being performed. reduce the sound pressure.

  The wiper device of the present invention includes the above-described brushless motor, and a wiper arm that operates by transmitting the power of the rotor of the brushless motor and wipes the windshield of the vehicle.

  The wiper device of the present invention is provided with a mode switching unit that switches between a low speed mode in which the wiper arm is operated at a predetermined speed and a high speed mode in which the wiper arm is operated at a higher speed than the low speed mode. The controller executes the second energization control when the high speed mode is selected.

  According to the brushless motor and wiper device of the present invention, torque ripple of the rotor can be suppressed.

It is a schematic diagram which shows the example which applied the brushless motor of this invention to the wiper apparatus of the vehicle. It is a typical top view which shows the brushless motor of this invention. It is a typical side view showing the brushless motor of the present invention. It is sectional drawing of the brushless motor of this invention. It is a conceptual diagram which shows the armature of the brushless motor of this invention. It is a conceptual diagram which shows the armature of the brushless motor of this invention. It is a block diagram which shows the control system of the brushless motor of this invention. (A)-(C) are figures which show an example of the 1st electricity supply control-3rd electricity supply control which can be performed with the brushless motor of this invention. It is a figure which shows the characteristic of the brushless motor of this invention. (A), (B) is a diagram which shows the relationship between the torque and rotation speed in the brushless motor of this invention. It is a figure which shows the torque ripple rate of the brushless motor of this invention. It is a figure which shows the sound pressure characteristic of the brushless motor of this invention. It is a figure which shows the waveform at the time of electricity supply of the brushless motor of this invention. It is a figure which shows the sound pressure characteristic of the brushless motor of this invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The vehicle 10 shown in FIG. 1 has a windshield 11. The vehicle 10 also includes a first wiper device 12 and a second wiper device 13 that wipe the windshield 11. The first wiper device 12 and the second wiper device 13 are arranged at different positions in the width direction of the vehicle 10. Since the first wiper device 12 and the second wiper device 13 have a substantially symmetrical structure, the first wiper device 12 will be described below for convenience. The first wiper device 12 includes a wiper arm 15 that swings about a pivot shaft 14, and a wiper blade 16 that is attached to the wiper arm 15. Further, the first wiper device 12 has a drive device 17 that drives the wiper arm 15. The drive device 17 includes a brushless motor 18 and a speed reduction mechanism 19 that transmits the power of the brushless motor 18 to the pivot shaft 14.

  The brushless motor 18 is configured as shown in FIGS. The brushless motor 18 in this embodiment has a bottomed cylindrical motor case 20, and an armature 21 as a stator is provided on the inner periphery of the motor case 20. The armature 21 includes a stator core 22 and armature coils V1, V2, U1, U2, W1, and W2 wound around the stator core 22. The stator core 22 is formed by stacking conductive metal plates, and a plurality of, specifically, six teeth 23 are provided on the inner periphery of the stator core 22 at intervals in the circumferential direction. The armature coils V1, V2, U1, U2, W1, and W2 are separately wound around the six teeth 23.

  The armature coils V1, V2 correspond to the V phase, the armature coils U1, U2 correspond to the U phase, and the armature coils W1, W2 correspond to the W phase. In FIG. 4, the armature coil U1, the armature coil V1, the armature coil W1, the armature coil U2, the armature coil V2, and the armature coil W2 are provided in the order of the armature 21 in the clockwise direction. . The armature coils V1 and V2, the armature coils U1 and U2, and the armature coils W1 and W2 have mutually different phases of the energization period.

  Further, as shown in FIGS. 5 and 6, the end portion Ua of the armature coil U <b> 1 and the end portion Ub of the armature coil W <b> 2 are connected by a terminal 24. Further, the end portion Vb of the armature coil U2 and the end portion Va of the armature coil V1 are connected by a terminal 25. Further, the end portion Wa of the armature coil W1 and the end portion Wb of the armature coil V2 are connected by a terminal 26. Thus, the brushless motor 18 employs a delta connection as a connection structure of six armature coils.

  On the other hand, the brushless motor 18 has a rotor 27, and the rotor 27 is provided inside the armature 21. The brushless motor 18 has an inner rotor type structure in which a rotor 27 is disposed inside an armature 21 as a stator. The rotor 27 includes a rotor shaft 28 and four-pole permanent magnets 29N and 29S fixed to the outer periphery of the rotor shaft 28 via a rotor core 30. The polarities of the two permanent magnets 29N are N poles, the polarities of the two permanent magnets 29S are S poles, and the permanent magnets 29N and the permanent magnets 29S are alternately arranged along the circumferential direction of the rotor shaft 28. Has been placed. The brushless motor 18 has a 4-pole 6-slot structure with 4 permanent magnets and 6 armature coils.

  Thus, the brushless motor 18 has an SPM (Surface Permanent Magnet) structure. In the SPM structure, permanent magnets 29 </ b> N and 29 </ b> S are fixed to the outer peripheral surface of the rotor core 30. The rotor core 30 is formed of an iron-based magnetic material. The rotor shaft 28 is rotatably supported by a plurality of bearings 49.

  On the other hand, the drive device 17 includes a gear case 31 that houses the speed reduction mechanism 19, and the gear case 31 and the motor case 20 are fixed by a fastening member (not shown). A part of the rotor shaft 28 in the length direction is disposed inside the motor case 20, and the remaining part is disposed in the gear case 31. A worm 32 is formed on the outer periphery of a portion of the rotor shaft 28 disposed in the gear case 31. A worm wheel 33 is provided in the gear case 31. A gear 33a is formed on the outer periphery of the worm wheel 33, and the gear 33a and the worm 32 are engaged with each other.

  The pivot shaft 14 is disposed concentrically with the worm wheel 33, and the pivot shaft 14 rotates integrally with the worm wheel 33. The worm 32 and the gear 33a are the speed reduction mechanism 19 in the present embodiment. The speed reduction mechanism 19 is a mechanism that, when transmitting the power of the rotor 27 to the pivot shaft 14, makes the rotation speed (output rotation speed) of the pivot shaft 14 lower than the rotation speed (input rotation speed) of the rotor 27. is there. The rotation speed in the present embodiment is the rotation speed per unit time and is synonymous with the rotation speed.

  Further, in FIG. 3, a shaft hole (not shown) is provided in the upper part of the gear case 31. The end of the pivot shaft 14 opposite to the end to which the worm wheel 33 is fixed is exposed to the outside through the shaft hole of the gear case 31. The wiper arm 15 is connected to a portion of the pivot shaft 14 exposed to the outside of the gear case 31.

  On the other hand, a sensor magnet 34 is attached to a portion of the rotor shaft 28 disposed in the gear case 31. The sensor magnet 34 rotates integrally with the rotor shaft 28. The sensor magnet 34 has a cylindrical shape, and the sensor magnet 34 is magnetized so that N poles and S poles are alternately arranged along the circumferential direction of the rotor shaft 28.

  An opening is provided in a portion of the gear case 31 opposite to the shaft hole. The opening is formed to insert the worm wheel 33, the pivot shaft 14 and the like into the gear case 31. An under cover 35 that closes the opening is provided. The under cover 35 has a tray shape, and a control board 36 is provided in a space surrounded by the under cover 35 and the gear case 31.

  The control board 36 is provided with a drive circuit 37 for controlling the brushless motor 18 as shown in FIG. The drive circuit 37 has an inverter circuit 38 that controls energization of the six armature coils V1, V2, U1, U2, W1, and W2. The inverter circuit 38 is connected to the terminals 24, 25 and 26. In addition, the under cover 35 is provided with a connector 39. By connecting a power cable connected to the external power source 40 to the connector 39, the external power source 40 and the inverter circuit 38 are connected. The external power supply 40 includes a battery or a capacitor mounted on the vehicle 10.

  In addition, the inverter circuit 38 includes a plurality of switching elements 38a that separately connect or disconnect the external power source 40 and the six armature coils V1, V2, U1, U2, W1, and W2. The plurality of switching elements 38a are constituted by semiconductor elements such as FETs, for example. More specifically, three positive-side switching elements connected to the positive electrode of the external power supply 40 corresponding to the U phase, V phase, and W phase, and corresponding to the U phase, V phase, and W phase, the external power supply And 40 negative electrode side switching elements connected to the negative electrode side of 40. A total of six switching elements 38a are provided.

  When the switching element 38a is connected (turned on), current is supplied from the external power supply 40 to the armature coil. On the other hand, when the switching element 38a is cut off (turned off), no current is supplied from the external power supply 40 to the armature coil. Further, a control circuit (controller) 50 for switching on and off of the plurality of switching elements 38 a is connected to the inverter circuit 38.

  The control circuit 50 is a known microcomputer provided with a CPU, RAM, ROM and the like. The drive circuit 37 has a PWM signal generation circuit 51, and the signal of the PWM signal generation circuit 51 is input to the control circuit 50. The control circuit 50 outputs a drive signal for controlling the three negative-side switching elements, and a PWM signal is superimposed on the drive signal. That is, the three negative-side switching elements are driven by PWM control and are intermittently turned on in each energization period. The current value supplied to the six armature coils V1, V2, U1, U2, W1, and W2 is controlled by controlling the rate at which the three negative side switching elements are individually turned on, that is, the duty ratio. Is done. That is, the energization period for supplying power to the six armature coils V1, V2, U1, U2, W1, and W2 can be increased or decreased between 0% and 100% with respect to the entire energizable period. Further, the control circuit 50 stores data, a program, and the like for controlling the rotational speed of the rotor 27 of the brushless motor 18.

  Furthermore, the brushless motor 18 in the present embodiment switches on and off of the switching element 38a to reverse the direction of energization to the six armature coils V1, V2, U1, U2, W1, and W2. The rotor 27 can be rotated forward and backward. When the switching element 38a is turned on, the external power supply 40 and the armature coils V1, V2, U1, U2, W1, W2 are separately connected, and when the switching element 38a is turned off, the external power supply 40 and the armature coil V1, V2, U1, U2, W1, and W2 are blocked separately.

  The control board 36 is disposed along a plane direction perpendicular to the first axis A1 of the pivot shaft 14. The first axis A1 is the center when the pivot shaft 14 rotates. Three detection sensors 41, 42, and 43 are attached to the control board 36. The three detection sensors 41, 42, and 43 are all Hall ICs, and the three detection sensors 41, 42, and 43 are fixed to the control board 36 without contact with the sensor magnet 34. The three detection sensors 41, 42, 43 are arranged in a direction intersecting the second axis B1 of the rotor shaft 28 as shown in FIG. The second axis B1 is the center when the rotor shaft 28 rotates.

  In the direction along the second axis B1, the arrangement range of the three detection sensors 41, 42, and 43 and the arrangement range of the sensor magnet 34 overlap at least partially. Assuming that the control board 36 is horizontally disposed, as shown in FIG. 3, one detection sensor 42 is disposed immediately below the second axis B1. The three detection sensors 41, 42, 43 are arranged at equal intervals in the direction intersecting the second axis B1. The detection sensor 42 is disposed between the detection sensor 41 and the detection sensor 43.

  The three detection sensors 41, 42, and 43 are switched when the rotor 27 rotates and the magnetic pole of the sensor magnet 34 moves, and the three detection sensors 41, 42, and 43 are each switched to a switching signal (ON / OFF). Signal) is generated separately. The control circuit 50 can detect the rotation angle and the number of rotations of the rotor 27 based on the switching signals of the three detection sensors 41, 42, and 43. Further, a wiper switch 44 is provided in the vehicle 10. When the driver operates the wiper switch 44 to select the low speed mode or the high speed mode, an operation signal of the wiper switch 44 is input to the control circuit 50. . Further, a vehicle speed sensor 45 that detects the traveling speed of the vehicle 10 is provided, and a detection signal of the vehicle speed sensor 45 is input to the control circuit 50.

  The control circuit 50 includes a timing for turning on / off the switching element 38a of the inverter circuit 38 based on various conditions such as an operation signal of the wiper switch 44, a detection signal of the vehicle speed sensor 45, and an operating load of the wiper arm 15. Data for controlling the duration time during which 38a is turned on, arithmetic expressions, and the like are stored in advance. Specifically, the operating load of the wiper arm 15 can be estimated from the signals of the detection sensors 41, 42, and 43.

  For example, the high speed mode is selected, the target rotation speed of the rotor 27 that should achieve the target wiping speed of the wiper arm 15 in the high speed mode is obtained, and energization is performed so that the actual rotation speed of the rotor 27 becomes the target rotation speed. Suppose that control is performed. Here, when the actual rotational speed of the rotor 27 does not reach the target rotational speed, it is possible to estimate that the operating resistance of the wiper arm 15, that is, the operating load of the wiper arm 15 is increased due to snow or the like.

  Moreover, since the wind pressure which the wiper arm 15 receives will change if vehicle speeds differ, the operating load of the wiper arm 15 differs. Further, when the inclination angle of the windshield 11 is different, the wind pressure received by the wiper arm 15 is changed, so that the operation load of the wiper arm 15 is different. The inclination angle of the windshield 11 is represented by the inclination angle on the acute angle side of the windshield 11 with respect to the horizontal plane. Furthermore, when the length of the wiper blade 16 is different, the operating load of the wiper arm 15 is different.

  The gear case 31 is provided with a plurality of attachment portions 46, for example, three locations, and the attachment portions 46 are each provided with a shaft hole. In addition, a buffer material 47 is attached to each of the shaft holes of the attachment portion 46. The buffer material 47 is a synthetic rubber formed in an annular shape. A screw member is inserted into the hole 47 a of the buffer material 47, and the drive device 17 is attached to the vehicle body 48.

  Next, an example of control that can be executed by the brushless motor 18 in each of the first wiper device 12 and the second wiper device 13 will be described. On / off of the plurality of switching elements 38a is controlled by conditions other than the operation signal of the wiper switch 44 or the operation signal of the wiper switch 44. Further, the control circuit 50 estimates the rotational position of the rotor 27, that is, the angle in the rotational direction, based on the detection signals of the three detection sensors 41, 42, and 43, and energizes based on the rotational position of the rotor 27. Take control. In other words, the positive-side switching elements of each phase are sequentially turned on by a predetermined angle in terms of electrical angle, that is, the energization angle, and the negative-side switching elements of phases different from the positive-side switching elements are sequentially turned on by a predetermined energization angle. The armature coils U1, U2, V1, V2, W1, and W2 are switched to energize and phase current is commutated.

  When the above control is repeated, a rotating magnetic field is formed by the armature 21, and the rotor 27 rotates. The brushless motor 18 controls switching of the switching element 38a on and off, and reverses the direction of energization to the armature coils U1, U2, V1, V2, W1, and W2, thereby rotating the rotor 27 forward and stop.・ Can be rotated in reverse. When the power of the rotor 27 is transmitted to the pivot shaft 14 via the speed reduction mechanism 19, the wiper arm 15 reciprocates within a predetermined angle range, and the windshield 11 is wiped by the wiper blade 16.

  The brushless motor 18 has a characteristic that the rotational speed of the rotor 27 increases as the current value increases. Further, the brushless motor 18 has a characteristic that the torque of the rotor 27 decreases as the rotational speed of the rotor 27 increases.

  Further, the brushless motor 18 according to the present embodiment can switch between the first energization control, the field weakening control, and the second energization control when controlling the output of the rotor 27, that is, the rotation speed and torque. The first energization control, the field weakening control, and the second energization control are switched according to various conditions such as a detection signal of the wiper switch 44, a detection signal of the vehicle speed sensor 45, and a load of the wiper arm 15. In particular, the field weakening control is executed when there is a request to increase the rotational speed of the rotor 27 compared to the first energization control. On the other hand, the second energization control is executed when there is a request to increase the torque of the rotor 27 as compared to the first energization control.

  The first energization control, field weakening control, and second energization control will be described with reference to FIG. The angle of 0 ° to 360 ° shown in FIG. 8 is an energization angle representing an energization period within one cycle of the electric signal. Positive represents that the armature coils V1, V2, U1, U2, W1, and W2 are energized from the positive electrode, and negative represents that the armature coils V1, V2, U1, U2, W1, and W2 are energized from the negative electrode. The energization control shown in FIG. 8 exemplifies the energization state for a predetermined one armature coil.

  FIG. 8A shows the first energization control. In the first energization control, energization is started from a positive electrode to a predetermined armature coil at an energization angle of 30 ° with respect to an energization angle of 0 °, and energization is maintained within a range of an energization angle of 120 °. Energization from the positive electrode ends. In the first energization control, energization is started from the negative electrode to a predetermined armature coil after the energization from the positive electrode is completed, and the energization angle is 120 °. After being maintained in the range, energization ends.

  FIG. 8B shows field-weakening control. With respect to a predetermined armature coil, energization from the positive electrode is started at a position of an energization angle of 15 ° with an energization angle of 0 ° as a reference, and energization from the positive electrode is maintained within a range of an energization angle of 120 °, Is turned off. In addition, after energization from the positive electrode is completed, the energization angle is set to 60 °, the energization from the negative electrode is started, the energization from the negative electrode is maintained in the energization angle range of 120 °, and then the energization from the negative electrode is performed. Ends. In this way, the position at the energization angle of 15 ° where the energization from the positive electrode is started in FIG. 8B is earlier than the position at the energization angle of 30 ° shown in FIG. The position at the energization angle of 15 ° is advanced by the energization angle of 15 ° relative to the position at the energization angle of 30 °.

  The second energization control will be described with reference to FIG. With respect to a predetermined armature coil, energization from the positive electrode is started at an energization angle of 15 ° with respect to an energization angle of 0 °, and the energization from the positive electrode is maintained in the range of the energization angle of 120 ° + α and then energized. Energization from the positive electrode is terminated at a position of an angle of 165 °. After the energization from the positive electrode is completed, the energization from the negative electrode is started at an energization angle of 195 °, and the energization from the negative electrode is maintained in the range of the energization angle of 120 ° + α, and then the energization from the negative electrode is terminated. As described above, the energization start timing in the second energization control is earlier than the energization start timing in the first energization control by a range of the energization angle of 15 °, and the energization angle at which energization is continued in the second energization control. The range of 120 ° + α is wider than the range of the energization angle of 120 ° in which energization is continued in the first energization control. Here, the range of the conduction angle of 120 ° is the first period in the present invention, and the range of the conduction angle of 120 ° + α is the second period in the present invention.

  The first energization control is executed when, for example, the low speed mode is selected. In the first energization control, the actual rotation speed of the rotor 27 is brought close to the requested target rotation speed by controlling the duty ratio without performing the field weakening control. Further, when the first energization control is performed, the energization start timing for the armature coils U1, U2, V1, V2, W1, and W2 is a predetermined fixed value, that is, a position at an energization angle of 30 °. .

  The field weakening control or the second energization control is executed, for example, when the high speed mode is selected. The field weakening control is executed without changing the current value supplied to the armature coils U1, U2, V1, V2, W1, and W2. The field weakening control is a control that weakens the magnetic field formed by the armature 21 by supplying current to the armature coils U1, U2, V1, V2, W1, and W2. When this field weakening control is performed, the counter electromotive force generated in the armature coils U1, U2, V1, V2, W1, and W2 decreases, and the rotational speed of the rotor 27 increases. In the second energization control, in addition to the field weakening control, the energization period is made longer than the first energization control and the second energization control.

  FIG. 9 is a diagram showing the characteristics of the brushless motor 18. In FIG. 9, the rotation speed of the brushless motor 18 is shown on the vertical axis, and the torque of the brushless motor 18 is shown on the horizontal axis. FIG. 9 shows an example of the low-speed mode characteristic and an example of the high-speed mode characteristic.

  The brushless motor 18 of this embodiment has a single characteristic at a position indicated by a solid line, for example, so that the rotation speed and torque corresponding to the low speed mode characteristic of FIG. 9 can be obtained when setting the rating. Yes. For this reason, when the low speed mode is selected, the required rotation speed and torque can be obtained within the range of the single characteristic or less by executing the first energization control.

  The single unit characteristic is a characteristic that satisfies the target output when the actual vehicle speed of the vehicle 10 is equal to or lower than the reference vehicle speed, that is, the low speed mode. The apparent characteristic is a characteristic that satisfies the target output when the actual vehicle speed of the vehicle 10 exceeds the reference vehicle speed, that is, the high-speed mode characteristic. The target output is represented by the rotation speed and torque of the rotor 27. Conditions for determining the target output include various conditions such as a detection signal of the wiper switch 44, a detection signal of the vehicle speed sensor 45, and a load of the wiper arm 15.

  On the other hand, for example, when the high speed mode is selected and the torque and the rotational speed required for the rotor 27 exceed the single unit characteristics, the control circuit 50 executes the field weakening control or the second energization control. By doing so, it is possible to obtain a rotational speed and torque exceeding the single unit characteristics. Thus, the characteristics of the brushless motor 18 are apparently equivalent to being at the position indicated by the alternate long and short dash line in FIG.

  That is, the design of the brushless motor 18 can be determined with reference to the low speed mode, and the physique of the brushless motor 18 can be made as small as possible. The fact that the torque can be increased by increasing the rotational speed of the brushless motor 18 without changing the current value means that the torque constant becomes relatively large. In other words, the brushless motor 18 of the present embodiment can generate as much torque as possible with less power consumption, and the motor efficiency is improved.

  The characteristics of the brushless motor 18 when the field weakening control or the second energization control is performed will be described based on the characteristic diagram of FIG. In the characteristic diagram of FIG. 10, the horizontal axis represents torque, and the vertical axis represents the rotational speed. The characteristic diagram of FIG. 10A is a characteristic of the brushless motor 18 when the second energization control is executed. The solid line is a characteristic with an advance angle of 30 °, the broken line is a characteristic with an advance angle of 45 °, and the alternate long and short dash line is a characteristic with an advance angle of 60 °. The advance angle of 30 °, advance angle of 45 °, and advance angle of 60 ° are an advance angle of 30 ° relative to the position of the energization angle of 30 °, which is the timing at which energization of the armature coil is started in the first energization control. This means that energization of the armature coil is started at an early timing of advance angle 45 ° and advance angle 60 °.

  The energization period to the armature coil is continued over a range of an energization angle of 120 ° regardless of the advance angle. According to FIG. 10 (A), it can be seen that even if the torque of the rotor is the same, the rotational speed of the rotor increases relatively as the advance angle increases. The three characteristics are that the rotational speed decreases as the torque of the rotor increases. Further, as the rotor torque increases, the rotor speed difference in the three characteristics decreases.

  The characteristics of the brushless motor 18 when the second energization control is performed will be described with reference to FIG. The solid line is a characteristic of an advance angle of 30 ° and a conduction angle of 120 °, the broken line is a characteristic of an advance angle of 37.5 ° and a conduction angle of 135 °, and the alternate long and short dash line is an advance angle of 45 ° and a conduction angle of 150 °. The two-dot chain line is a characteristic having an advance angle of 52.5 ° and a conduction angle of 165 °. The basic characteristics of the brushless motor 18 shown in FIG. 10B are the same as the basic characteristics of the brushless motor 18 shown in FIG. The difference in the rotational speed in the high torque region is greater in the characteristics of the brushless motor 18 shown in FIG. 10B than in the characteristics of the brushless motor 18 shown in FIG.

  FIG. 11 is a graph showing the relationship between the advance angle, the conduction angle, and the torque ripple rate. The conduction angle is shown on the horizontal axis. Torque ripple means that the torque of the rotor changes, that is, pulsates. The torque ripple rate is the ratio of the torque pulsation width to the average torque. Here, the torque ripple rate of the rotor is shown for each of an advance angle of 0 °, an advance angle of 15 °, and an advance angle of 30 °. The advance angle 0 ° corresponds to the first timing in the present invention, and the advance angle 15 ° and the advance angle 30 ° correspond to the second timing in the present invention. That is, an advance angle of 15 ° means that the energization start timing is advanced by an energization angle of 15 ° relative to an advance angle of 0 °, and an advance angle of 30 ° energizes the energization start timing relative to an advance angle of 0 °. This means that the angle is advanced by 30 °.

  From the graph of FIG. 11, it can be seen that the torque ripple rate decreases as the advance angle increases when the energization angle is constant. On the other hand, when the advance angle is constant, the torque ripple rate tends to decrease as the energization angle increases. Specifically, it can be seen that when the brushless motor 18 is controlled at a conduction angle of 150 ° and an advance angle of 30 °, the torque ripple rate is the lowest. When comparing the first energization control and the second energization control, if the energization angle is 135 ° or more and the energization angle is 165 °, than the torque ripple rate when the first energization control is executed, The torque ripple rate when the second energization control is executed can be reduced.

  FIG. 12 shows a case where the current waveform is controlled as a rectangular wave and a case where the current waveform is controlled as a smoother waveform than the rectangular wave when the energization control to the armature coil of the brushless motor 18 is executed. It is the example which compared the emitted sound (sound pressure) which arises. When the first energization control is executed, the current waveform becomes a rectangular wave, and when the second energization control is executed, the current waveform becomes a smooth waveform. As can be seen from FIG. 12, the sound pressure when the second energization control is executed is lower than the sound pressure when the first energization control is executed.

  FIG. 13 is a waveform showing the relationship between the current and the electrical angle when the energization control to the armature coil of the brushless motor 18 is executed. A waveform with an advance angle of 60 ° and a conduction angle of 165 ° is shown by a solid line, a waveform with an advance angle of 0 ° and a conduction angle of 120 ° is shown by a two-dot chain line, and a waveform with an advance angle of 30 ° and a conduction angle of 150 ° is a broken line. A waveform having an advance angle of 15 ° and a conduction angle of 120 ° is indicated by a one-dot chain line. In the waveform shown in FIG. 13, the waveform having an advance angle of 60 ° and a conduction angle of 165 ° changes the current most smoothly, and approximates a sine wave. That is, the waveform of the advance angle of 60 ° and the energization angle of 165 ° has the lowest radiated sound (sound pressure) generated around the brushless motor, and the operating noise of the brushless motor 18 can be reduced.

  FIG. 14 is a graph showing the relationship between the advance angle and the conduction angle and the sound pressure. FIG. 14 shows the sound pressure at an energization angle of 120 ° at an advance angle of 0 °, an advance angle of 15 °, and an advance angle of 30 °, and the sound pressure at an energization angle of 150 ° at an advance angle of 15 ° and an advance angle of 30 °. The sound pressure at an advance angle of 60 ° and an energization angle of 165 ° is shown. FIG. 14 shows that the sound pressure at the advance angle of 15 ° and the conduction angle of 150 ° and the sound pressure at the advance angle of 60 ° and the conduction angle of 165 ° are lower than the sound pressure at the other advance and conduction angles.

  Here, the advance angle 0 ° is the first timing, and the advance angle 15 ° and the advance angle 30 ° are the second timing. Furthermore, the advance angle 60 ° is a second timing obtained by advancing the energization start timing by the energization angle 60 ° with respect to the first advance angle 0 °.

  When the trends shown in FIGS. 12 to 14 are summarized, it can be seen that if the conduction angle is constant, the sound pressure tends to decrease as the advance angle increases. It can also be seen that if the advance angle is constant, the sound pressure tends to decrease as the energization angle increases.

  In the present embodiment, in controlling the energization to the armature coil of the brushless motor 18, according to various conditions such as the selected mode, the vehicle speed, the load of the wiper arm 15 and the like so that the torque ripple rate is reduced, The advance angle and energization angle can be controlled. Further, in controlling energization of the armature coil of the brushless motor 18, the advance angle and energization angle can be controlled according to various conditions so that the sound pressure is lowered.

  Furthermore, the rigidity, attachment position, and the like of the vehicle body 48 to which the driving device 17 is attached differ for each vehicle type, and the resonance frequency when the brushless motor 18 is operated differs for each vehicle type. For this reason, the advance angle and the energization angle can be tuned for each vehicle type so that the sound pressure generated around the brushless motor 18 is lowered.

  Needless to say, the drive device of the present invention is not limited to the above-described embodiment, and various changes can be made without departing from the scope of the present invention. For example, the brushless motor of the present invention includes a star connection structure in which armature coils are connected in a Y shape. The brushless motor of the present invention includes a motor whose rotor has an IPM (Interior Permanent Magnet) structure. The IPM structure has a permanent magnet embedded in the rotor core. The first period is not limited to the conduction angle of 120 °, and may be less than the conduction angle of 120 ° or may exceed the conduction angle of 120 °.

  The brushless motor of the present invention includes an inner rotor type structure in which the rotor is disposed inside the stator, and an outer rotor type structure in which the rotor is disposed outside the stator.

  The wiper device of the present invention includes a wiper blade that wipes the rear glass. That is, the window glass in the wiper device of the present invention includes a windshield and a rear glass. In addition, the wiper device of the present invention includes a configuration in which two wiper arms are independently driven by one brushless motor.

  The brushless motor according to the present embodiment is provided for operating an operation member such as a door, a roof, and a glass in a power slide door device, a sunroof device, a power window device, and the like provided in a vehicle in addition to a wiper motor that operates the wiper device. Including a brushless motor. The drive circuit 37 corresponds to the control unit and the mode switching unit of the present invention.

DESCRIPTION OF SYMBOLS 10 Vehicle 11 Windshield 12 1st wiper apparatus 13 2nd wiper apparatus 14 Pivot shaft 15 Wiper arm 16 Wiper blade 17 Drive apparatus 18 Brushless motor 19 Reduction mechanism 20 Motor case 21 Armature 22 Stator core 23 Teeth 24, 25, 26 Terminal 27 Rotation Child 28 Rotor shaft 29N, 29S Permanent magnet 30 Rotor core 31 Gear case 32 Worm 33 Worm wheel 33a Gear 34 Sensor magnet 35 Under cover 36 Control board 37 Drive circuit 38 Inverter circuit 38a Switching element 39 Connector 40 External power supply 41, 42, 43 Detection sensor 44 Wiper Switch 45 Vehicle Speed Sensor 46 Mounting Portion 47 Buffer Material 47a Hole 48 Car Body 49 Bearing 50 Control Circuit 51 PWM Signal Generation Circuit A1 First Axis B1 Second Axis U1, U2, V1, V2, W1, W2 Armature coils Ua, Ub, Va, Vb, Wa, Wb Ends

Claims (4)

A brushless motor in which current is supplied to the coil and the rotor rotates.
First energization control for starting energization of the coil at a first timing and continuing energization for a first period to control the rotation speed of the rotor;
Energization of the coil is started at a second timing advanced by an electrical angle from the first timing, and energization is continued for a second period longer than the first period. A second energization control for controlling the rotational speed of the rotor;
By switching a control unit for executing,
The second timing is advanced at an electrical angle of 30 ° or more and an electrical angle of 60 ° or less with respect to the first timing,
The first period is 120 ° in electrical angle,
The second period is adjusted within a range of 135 ° or more in electrical angle and 165 ° or less in electrical angle according to a value for advancing the second timing with respect to the first timing,
Said first than running the energization control, reduce sound pressure in executing the second power supply control, the brushless motor. The brushless motor according to claim 1,
The rotor is
A rotor shaft having a rotor core attached to the outer peripheral surface;
A four-pole permanent magnet disposed on the outer peripheral surface of the rotor core along the circumferential direction of the rotor shaft;
With
A stator provided with a plurality of the coils on the outside of the rotor;
The stator is provided with six teeth at intervals in the circumferential direction of the rotor shaft,
The plurality of coils are separately wound around the six teeth and provided with six slots,
The plurality of coils are brushless motors wound around the six teeth and delta-connected . A wiper device comprising: the brushless motor according to claim 1; and a wiper arm that operates by transmitting power of a rotor of the brushless motor and wipes a windshield of the vehicle . The wiper device according to claim 3 .
A mode switching unit is provided that switches between a low-speed mode for operating the wiper arm at a predetermined speed and a high-speed mode for operating the wiper arm at a higher speed than the low-speed mode.
The said control part is a wiper apparatus which performs a said 2nd electricity supply control, if the said high speed mode is selected .

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