Driving device for driving motor of vacuum cleaner and vacuum cleaner comprising same

Abstract

A driving device disclosed herein comprises: a motor that rotationally drives a rotary brush or a rotary blade of a vacuum cleaner by means of the rotation of a rotor; and a voltage application unit that causes periodic changes in a magnetic field in the motor at a frequency corresponding to the applied frequency of a voltage to the motor. The motor is configured so that the rotation speed of the rotor changes according to a current value that is a time average value of the DC current flowing through the motor due to the application of the voltage to the motor, and is configured to emit an operation sound from the vibration of the rotor due to the periodic changes in the magnetic field at the frequency corresponding to the applied frequency. The driving device further includes an application control unit for controlling the voltage application unit so that the applied frequency changes while suppressing fluctuations in the current value on the condition that a predetermined change condition is satisfied.

Description

Drive device for driving a motor of a vacuum cleaner and a vacuum cleaner equipped with the drive device

[0001] The present disclosure relates to drive techniques for driving motors in vacuum cleaners.

[0002] Various vacuum cleaners are known that are equipped with a suction source that generates suction force to suck up dust by rotating a rotating blade with a suction motor. When a user uses the vacuum cleaner, the vacuum cleaner emits the sound of the suction motor operating or the sound of the rotating blades rotating. If the rotation frequency of the suction motor is constant, these sounds do not change and are perceived by the user as nothing more than monotonous noise.

[0003] To solve this problem, Patent Document 1 discloses a method for controlling the suction motor so that the operating sound emitted from the suction source plays the melody represented by the musical notes on a predetermined musical score by increasing or decreasing the rotation frequency of the suction motor in accordance with the pitch of the notes on the musical score. This control allows the user to perform cleaning work while listening to the sound emitted from the vacuum cleaner as music, rather than just noise.

[0004] The control disclosed in Patent Document 1 increases or decreases the rotation frequency of the suction motor in accordance with the pitch of the notes on a predetermined musical score. When the rotation speed of the suction motor is reduced, the suction power of the vacuum cleaner decreases. Conversely, when the rotation speed of the suction motor is increased, the suction power of the vacuum cleaner increases. Therefore, while the control disclosed in Patent Document 1 allows the user to enjoy the operating sound of the vacuum cleaner as music, it has the problem of changing the performance of the vacuum cleaner.

[0005] Japanese Patent Application Publication No. 4-28320

[0006] The present disclosure aims to provide a technique for changing the operating noise of a vacuum cleaner while suppressing changes in the performance of the vacuum cleaner.

[0007] The drive device disclosed herein is configured to drive a rotating brush that rolls on a floor surface to scrape dust off the floor surface, or a rotating blade that generates a suction force to suck in dust as it rotates. The drive device includes a motor having a rotor that rotates the rotating brush or the rotating blade, and a voltage application unit that applies a voltage of a predetermined magnitude to the motor intermittently, thereby causing a periodic change in the magnetic field within the motor at a frequency corresponding to the frequency of the voltage applied to the motor. The motor is configured so that the rotor rotates at a rotation speed corresponding to a current value that is the time average value of a direct current flowing through the motor as a result of the intermittent application of voltage to the motor, and vibrates in response to the periodic change in the magnetic field at a frequency corresponding to the applied frequency, thereby emitting an operating sound. The drive device further includes an application control unit that controls the voltage application unit to change the applied frequency while suppressing fluctuations in the current value, provided that a predetermined change condition is met.

[0008] The vacuum cleaner of the present disclosure includes a rotating brush that rolls on a floor surface to scrape off dust on the floor surface or a rotating blade configured to generate suction force for sucking in dust while rotating, the drive device described above, a storage battery that stores power for the motor, and a power detection unit that detects the remaining amount of power stored in the storage battery. The application control unit controls the voltage application unit to change the application frequency while suppressing fluctuations in the current value, on the condition that the power detection unit detects that the remaining amount of power stored in the storage battery has fallen below a predetermined power threshold.

[0009] Another vacuum cleaner of the present disclosure includes a rotating brush that rolls on a floor surface to scrape off dust on the floor surface or a rotating blade configured to generate suction force for sucking in dust as it rotates, the drive device described above, a dust storage unit that stores the dust scraped by the rotating brush or dust sucked in by the suction force generated by the rotation of the rotating blade, and a dust storage detection unit that detects the amount of dust in the dust storage unit. The application control unit controls the voltage application unit to change the applied frequency while suppressing fluctuations in the current value, on the condition that it detects that the amount of dust in the dust storage unit has exceeded a predetermined dust storage threshold.

[0010] Another vacuum cleaner according to the present disclosure includes a rotating brush that rolls on a floor surface to scrape off dust or rotating blades that are configured to generate a suction force for sucking in dust as they rotate, the drive device described above, and a dust detection unit that detects the amount of dust being scraped off by the rotating brush or the amount of dust being sucked in by the suction force generated by the rotation of the rotating blades. The application control unit controls the voltage application unit to change the application frequency while suppressing fluctuations in the current value, on the condition that the amount of dust detected by the dust detection unit exceeds a predetermined dust threshold.

[0011] The present disclosure also provides a vacuum cleaner including a rotating brush that rolls on a floor surface to scrape off dust or a rotating blade configured to generate suction force for sucking in dust as it rotates, the drive device described above, and a motor housing that houses a motor so that vibrations of the rotor are transmitted. The application control unit controls the voltage application unit so that the application frequency approaches the resonant frequency of the motor housing while suppressing fluctuations in the current value, provided that a change condition is satisfied.

[0012] Another drive device according to the present disclosure is configured to drive a first rotating brush and a second rotating brush that roll on a floor surface to scrape off dust. The drive device includes a first motor having a first rotor that rotatably drives the first rotating brush, a second motor having a second rotor that rotatably drives the second rotating brush, a first voltage application unit that applies a predetermined voltage to the first motor intermittently to cause a periodic change in the magnetic field within the first motor at a frequency corresponding to the frequency of the voltage applied to the first motor, and a second voltage application unit that applies a predetermined voltage to the second motor intermittently to cause a periodic change in the magnetic field within the second motor at a frequency corresponding to the frequency of the voltage applied to the second motor. The first motor is configured such that the first rotor rotates at a rotation speed corresponding to a current value that is a time average value of a direct current flowing through the first motor as a result of the intermittent application of the voltage to the first motor, and vibrates in response to the periodic change in the magnetic field at a frequency corresponding to the frequency of the voltage applied to the first motor, thereby emitting an operating sound. The second motor is configured such that the second rotor rotates at a rotation speed corresponding to a current value, which is a time average value of a direct current flowing through the second motor, in response to intermittent application of a voltage to the second motor, and the second rotor vibrates in response to a periodic change in the magnetic field at a frequency corresponding to the applied frequency to the second motor, thereby emitting an operating sound. The drive device further includes an application control unit that controls the first voltage application unit and the second voltage application unit. The application control unit, on the condition that a predetermined change condition is satisfied, controls the first voltage application unit to change the applied frequency to the first motor while suppressing fluctuations in the current value to the first motor, and controls the second voltage application unit to make the applied frequency to the second motor different from the applied frequency of the voltage to the first motor while suppressing fluctuations in the current value to the second motor, thereby generating a discordant or consonant sound by the operating sounds of the first motor and the second motor.

[0013] Yet another vacuum cleaner according to the present disclosure includes a first rotating brush and a second rotating brush that roll over a floor surface to scrape off dust from the floor surface, the drive device described above, a storage battery that stores power for the first motor and the second motor, and a power detection unit that detects the remaining amount of power stored in the storage battery. The application control unit controls the first voltage application unit and the second voltage application unit so as to suppress fluctuations in the current values ​​for the first motor and the second motor and to generate a discordant sound from the operating sounds of the first motor and the second motor, on the condition that the power detection unit detects that the remaining amount of power stored in the storage battery has fallen below a predetermined power threshold.

[0014] Yet another vacuum cleaner according to the present disclosure includes a first rotating brush and a second rotating brush that roll over a floor surface to scrape off dust from the floor surface, the drive device described above, a dust storage unit that stores the dust scraped by the first rotating brush and the second rotating brush, and a dust accumulation detection unit that detects the amount of dust in the dust storage unit. When the application control unit detects that the amount of dust in the dust storage unit has exceeded a predetermined dust accumulation threshold, the application control unit controls the first voltage application unit and the second voltage application unit to suppress fluctuations in the current values ​​applied to the first motor and the second motor and to generate a discordant sound from the operating sounds of the first motor and the second motor.

[0015] Still another vacuum cleaner according to the present disclosure includes a first rotating brush and a second rotating brush that roll over a floor surface to scrape off dust on the floor surface, the drive device described above, a dust storage unit that stores the dust scraped by the first rotating brush and the second rotating brush, and a dust detection unit that detects the amount of dust scraped by the first rotating brush and the second rotating brush. The application control unit controls the first voltage application unit and the second voltage application unit so as to suppress fluctuations in the current values ​​applied to the first motor and the second motor and to produce a consonant sound from the operating sounds of the first motor and the second motor, on the condition that the amount of dust detected by the dust detection unit exceeds a predetermined dust threshold.

[0016] Another driving device according to the present disclosure is configured to drive a rotating brush that rolls on a floor surface to scrape dust off the floor surface, or a rotating blade configured to generate a suction force for sucking in dust as it rotates. The driving device includes a motor having a rotor that rotates the rotating brush or the rotating blade, and a voltage application unit that applies a voltage of a predetermined magnitude to the motor intermittently, thereby causing a periodic change in the magnetic field within the motor at a frequency corresponding to the frequency of the voltage applied to the motor. The motor is configured such that the rotor rotates at a rotation speed corresponding to a current value that is the time average value of a direct current flowing through the motor as a result of the intermittent application of the voltage to the motor, and vibrates in response to the periodic change in the magnetic field at a frequency corresponding to the applied frequency, thereby emitting an operating sound. The driving device further includes an application control unit that controls the voltage application unit so that the applied frequency increases or decreases in accordance with the pitch of the notes on a predetermined musical score, while suppressing fluctuations in the current value.

[0017] The above-described technology can change the operating noise of the vacuum cleaner while suppressing changes in the performance of the vacuum cleaner.

[0018] The objects, features, and advantages of the present disclosure will become more apparent from the following detailed description and the accompanying drawings.

[0019] Longitudinal cross-sectional view of a vacuum cleaner (first embodiment) Front view of a vacuum cleaner Schematic diagram of the internal structure of the vacuum cleaner's motor Diagram showing the form of DC current input to the motor Functional configuration diagram of a control circuit that controls the motor Longitudinal cross-sectional view of a vacuum cleaner (second embodiment) Functional configuration diagram of a control circuit that controls the vacuum cleaner's motor Longitudinal cross-sectional view of a vacuum cleaner (third embodiment) Functional configuration diagram of a control circuit that controls the vacuum cleaner's motor Musical score showing a melody that can be played by the operating sound of a vacuum cleaner Schematic diagram showing the structure of a vacuum cleaner's suction nozzle (fourth embodiment) Exploded perspective view of a suction nozzle Functional configuration diagram of a control circuit that controls the suction nozzle motor Functional configuration diagram of a control circuit that controls the suction nozzle motor Functional configuration diagram of a control circuit that controls the suction nozzle motor

[0020] Hereinafter, first to fourth embodiments of the vacuum cleaner will be described in detail with reference to the drawings. However, to facilitate understanding by those skilled in the art, for example, detailed descriptions of well-known matters or redundant descriptions of substantially identical configurations may be omitted. Note that the accompanying drawings and the following description are provided to enable those skilled in the art to fully understand the present disclosure, and are not intended to limit the subject matter recited in the claims.

[0021] First Embodiment In a first embodiment, a drive device is incorporated into a vacuum cleaner and is used to generate suction force for sucking dust.

[0022] (Overall Structure of Vacuum Cleaner) Fig. 1 is a schematic cross-sectional view of a stick-type vacuum cleaner 100. Fig. 2 is a front view of the vacuum cleaner 100. The vacuum cleaner 100 will be described with reference to Figs. 1 and 2.

[0023] The vacuum cleaner 100 comprises a suction nozzle 130 that sucks up dust on the floor, a vacuum cleaner body 110 attached to the suction nozzle 130 so as to be tiltable forward and backward relative to the suction nozzle 130, and a grip 140 extending upward from an upper end 112 of the vacuum cleaner body 110. The vacuum cleaner body 110 and the grip 140 shown in Figures 1 and 2 are in an upright position relative to the suction nozzle 130. When the vacuum cleaner 100 is in use, the vacuum cleaner body 110 and the grip 140 are held by the user in a position tilted backward relative to the suction nozzle 130.

[0024] Suction nozzle 130 is equipped with nozzle case 132 that is wider than vacuum cleaner body 110 so as to form wide suction space 131 into which dust on the floor flows. Suction space 131 opens toward the floor at the front portion of nozzle case 132. Behind this opening, suction space 131 is closed by bottom 134 of nozzle case 132. A rotating brush 133 rotatably held by nozzle case 132 is disposed in suction space 131, and rotating brush 133 is exposed from nozzle case 132 through the opening of suction space 131 so as to be able to contact the floor surface.

[0025] The vacuum cleaner body 110 has a cylindrical housing 111 that is elongated in the vertical direction. The upper part of the housing 111 tapers toward an upper end 112 of the housing 111, and a grip part 140 extends upward from the upper end 112. The grip part 140 is a rod-shaped part that is thick enough to be gripped by a user. As shown in FIG. 2 , the grip part 140 is provided with an operating part 141 that is operated by the user.

[0026] The housing 111 is configured to house various components for sucking up dust on the floor surface and storing the sucked up dust. Specifically, as shown in FIG. 1, a suction pipe 113 extending in the vertical direction is disposed inside the lower part of the housing 111. A check valve 114 is attached to the upper end of the suction pipe 113. The check valve 114 shown in FIG. 1 closes the upper end of the suction pipe 113, but can rotate upward when subjected to an upward external force. When the check valve 114 rotates upward, the upper end of the suction pipe 113 is opened.

[0027] The lower end of the suction tube 113 is connected to the rear of the suction nozzle 130. The connection between the suction tube 113 and the suction nozzle 130 is configured to allow the suction tube 113 to tilt rearward together with the vacuum cleaner body 110 from the upright position (the position shown in FIG. 1 ). When the suction tube 113 and the vacuum cleaner body 110 are in the upright position, the lower end of the suction tube 113 abuts against the bottom 134 of the nozzle case 132. That is, when the suction tube 113 and the vacuum cleaner body 110 are in the upright position, the lower end of the suction tube 113 is closed by the bottom 134 of the nozzle case 132. When the vacuum cleaner body 110 tilts rearward from the upright position, the lower end of the suction tube 113 moves in the direction indicated by arrow A in FIG. 1 . As a result, the flow path within the suction tube 113 is connected to the suction space 131 of the nozzle case 132.

[0028] The space above the suction tube 113 is divided into upper and lower sections by the filter section 115. In the following description, the space below the filter section 115 will be referred to as the "dust storage chamber 152." In addition, in the following description, the space above the filter section 115 will be referred to as the "drive chamber 153." The portion of the housing 111 that constitutes the drive chamber 153 will be referred to as the "motor housing section 172."

[0029] Drive chamber 153 is provided with rotating blades 143 that generate a suction force for sucking in dust. Rotation of rotating blades 143 generates an upward suction force. This suction force causes check valve 114 at the upper end of suction pipe 113 to rotate upward, opening the opening at the upper end of suction pipe 113. In this state, a suction airflow is generated that flows from the floor surface through suction nozzle 130 and suction pipe 113 into dust storage chamber 152, and dust on the floor surface is carried by this suction airflow into dust storage chamber 152. The suction airflow then passes through filter unit 115 and flows into drive chamber 153, while dust contained in this suction airflow is captured by filter unit 115 and retained in dust storage chamber 152.

[0030] A drive unit 101 that drives the rotary vanes 143 is configured inside the drive chamber 153. The drive unit 101 has a motor 142 that drives the rotary vanes 143 to rotate, and a control circuit 170 that controls the motor 142. The drive chamber 153 also contains a storage battery 117 that stores power for the motor 142. The storage battery 117 is electrically connected to the motor 142 via the control circuit 170, and the power of the storage battery 117 is supplied to the motor 142 via the control circuit 170.

[0031] A so-called brushed motor can be used as the motor 142. For example, as shown in Fig. 3, the motor 142 has a substantially cylindrical motor case 121 and a motor shaft 122 that protrudes from the motor case 121 and is rotatably supported by the motor case 121. Rotating blades 143 are fixed to the tip of the motor shaft 122. Electrodes 123 and 124 to which a voltage output from the storage battery 117 is applied are fixed to the outer surface of the motor case 121. The voltage applied to the electrodes 123 and 124 from the storage battery 117 is substantially constant.

[0032] As shown in Fig. 4, a rotor 125, permanent magnets 126 and 127, and brushes 128 and 129 are arranged inside the motor case 121. The permanent magnets 126 and 127 are fixed to the inner surface of the motor case 121 in positions facing each other. The permanent magnet 126 constitutes one of the south and north poles, and the permanent magnet 127 constitutes the other of the south and north poles.

[0033] The rotor 125 is fixed to the motor shaft 122, and when the rotor 125 rotates, the rotary vanes 143 attached to the tip of the motor shaft 122 can rotate together with the motor shaft 122. The rotor 125 has commutators 161 to 163 fixed to the motor shaft 122 at intervals in the circumferential direction of the motor shaft 122, and coils 164 to 166 connected to these commutators 161 to 163.

[0034] The brushes 128 and 129 are arranged so as to be in contact with at least two of the commutators 161 to 163 while the rotor 125 and the motor shaft 122 are rotating. The brushes 128 and 129 are electrically connected to the electrodes 123 and 124 shown in FIG. 3 . When a voltage is applied from the storage battery 117 to the electrodes 123 and 124, a direct current flows sequentially through the brushes 128 and 129, the commutators 161 to 163, and the coils 164 to 166. When the direct current flows through the coils 164 to 166, a magnetic field is generated from the coils 164 to 166. The rotor 125 and the motor shaft 122 rotate due to the magnetic force relationship between the magnetic fields generated from the coils 164 to 166 and the magnetic fields of the permanent magnets 126 and 127.

[0035] When a voltage is intermittently applied from the storage battery 117 to the electrodes 123 and 124, a direct current flows intermittently through the coils 164 to 166. In this case, a state in which a magnetic field is generated from the coils 164 to 166 and a state in which no magnetic field is generated from the coils 164 to 166 are alternately generated at a frequency corresponding to the frequency of the voltage applied to the electrodes 123 and 124. The direction and / or magnitude of the magnetic force received by the rotor 125 differs between the state in which a magnetic field is generated from the coils 164 to 166 and the state in which no magnetic field is generated from the coils 164 to 166. Therefore, when a direct current flows intermittently through the coils 164 to 166, the direction and / or magnitude of the magnetic force received by the rotor 125 changes periodically at a frequency corresponding to the frequency of the voltage applied to the electrodes 123 and 124. At this time, the periodic change in the magnetic force received by the rotor 125 causes the rotor 125 and the motor shaft 122 to vibrate. This vibration causes an operating noise to be generated from the motor 142. The frequency of this operating noise varies with the change in the frequency of the voltage applied to the electrodes 123 and 124.

[0036] Voltage is applied to the electrodes 123, 124, for example, according to the application pattern shown in Figure 5(a) or Figure 5(b). The magnitude of the voltage applied to the electrodes 123, 124 is the same between the application patterns shown in Figure 5(a) and Figure 5(b), but the application frequency of the voltage shown in Figure 5(a) is lower than the application frequency of the voltage shown in Figure 5(b). When voltage is applied to the electrodes 123, 124 according to the application pattern shown in Figure 5(a), the operating noise generated by the motor 142 is lower than when voltage is applied to the electrodes 123, 124 according to the application pattern shown in Figure 5(b).

[0037] The sum of the areas of the pulses shown in Figure 5(a) and the sum of the areas of the pulses shown in Figure 5(b) are equal. That is, the time-averaged value of the DC current (hereinafter referred to as "current value") flowing through the motor 142 while the voltage is being intermittently applied to the electrodes 123 and 124 is the same between the application patterns shown in Figure 5(a) and 5(b). Under these conditions, the motor 142 is configured so that the rotation speed of the rotor 125 and the motor shaft 122 does not fluctuate, regardless of whether the voltage application pattern to the electrodes 123 and 124 is switched. Note that if the current value of the DC current flowing through the motor 142 changes as the voltage is applied to the electrodes 123 and 124, the rotation speed of the rotor 125 and, ultimately, the rotating blades 143 also change, causing fluctuations in the suction performance of the vacuum cleaner 100. To suppress such fluctuations in suction performance, a voltage is applied intermittently to the electrodes 123 and 124 so as to suppress fluctuations in the current value. In order to apply the voltage in this manner, in this embodiment, the voltage application pattern is switched between the application pattern shown in FIG. 5( a ) and the application pattern shown in FIG. 5( b ).

[0038] The control circuit 170 is configured to change the voltage application pattern to the motor 142 from the application pattern shown in FIG. 5( a) to the application pattern shown in FIG. 5( b) when the remaining amount of power stored in the storage battery 117 falls below a predetermined power threshold. Specifically, as shown in FIG. 6, the control circuit 170 forms part of a power supply circuit 167 for supplying power from the storage battery 117 to the motor 142, and includes a voltage application unit 168 configured to open and close the power supply circuit 167. When the voltage application unit 168 closes the power supply circuit 167, a voltage is applied to the electrodes 123 and 124 of the motor 142. On the other hand, when the voltage application unit 168 opens the power supply circuit 167, no voltage is applied to the electrodes 123 and 124.

[0039] The control circuit 170 is further provided with an application control unit 169 that controls the voltage application unit 168, and a power detection unit 171 that detects the remaining amount of power stored in the storage battery 117. The application control unit 169 is electrically connected to the operation unit 141, and when a user operates the operation unit 141 to instruct operation of the motor 142, the application control unit 169 controls the voltage application unit 168 to repeatedly open and close the power supply circuit 167. The repeated opening and closing of the power supply circuit 167 by the voltage application unit 168 causes the magnetic field within the motor 142 to change periodically, causing the rotor 125 of the motor 142 to vibrate. At this time, if the remaining amount of power of the storage battery 117 detected by the power detection unit 171 exceeds the power threshold, the application control unit 169 controls the voltage application unit 168 to obtain the application pattern shown in FIG. 5( a). On the other hand, when the remaining power of the storage battery 117 detected by the power detection unit 171 is below the power threshold, the application control unit 169 controls the voltage application unit 168 so as to obtain the application pattern shown in Figure 5 (b).

[0040] (Operation of the Vacuum Cleaner) The operation of the vacuum cleaner 100 when the user starts cleaning work in a state where the storage battery 117 stores power exceeding the power threshold will be described below.

[0041] During cleaning work, the user holds the vacuum cleaner 100 with the vacuum cleaner body 110 and the grip 140 tilted backward relative to the suction nozzle 130. By tilting the vacuum cleaner body 110 and the grip 140 backward relative to the suction nozzle 130, it becomes easier to move the suction nozzle 130 forward while pushing it. In this state, the flow path of the suction tube 113 communicates with the suction space 131 of the suction nozzle 130.

[0042] When the user subsequently operates the operation unit 141 to start the vacuum cleaner 100, the voltage application control unit 169 controls the voltage application unit 168 to obtain the voltage application pattern shown in Fig. 5(a). At this time, the motor 142 drives the rotary blades 143 at a rotation speed corresponding to the current value (the time average value of the DC current flowing through the motor 142) in the voltage application pattern shown in Fig. 5(a). In this case, the frequency of the voltage applied to the motor 142 is low, so the rotor 125 of the motor 142 vibrates at a low frequency. As a result, the motor 142 emits a low-frequency operating sound.

[0043] When a voltage is applied to the motor 142, the rotor 125 of the motor 142 rotates. The rotating blades 143 connected to the rotor 125 also rotate with the rotation of the rotor 125. The rotation of the rotating blades 143 generates an upward suction force. This suction force rotates the check valve 114 upward, opening the upper end of the suction pipe 113.

[0044] When the upper end of the suction pipe 113 is opened, an upward suction airflow is generated, and this suction airflow flows into the dust storage chamber 152 through the suction space 131 of the suction nozzle 130 and the flow path of the suction pipe 113. Dust on the floor surface is carried by this suction airflow and flows into the dust storage chamber 152. The filter unit 115 allows the suction airflow to flow into the drive chamber 153, while the dust contained in the suction airflow is captured by the filter unit 115. This dust may be adsorbed to the lower surface of the filter unit 115 while the rotary vane 143 is rotating.

[0045] As the motor 142 operates, the remaining amount of power stored in the storage battery 117 decreases. When the power detection unit 171 detects that this remaining amount has fallen below the power threshold, the application control unit 169 controls the voltage application unit 168 so that a voltage is applied to the motor 142 according to the application pattern shown in FIG. 5( b). The time average value of the DC current flowing through the motor 142 when a voltage is applied to the motor 142 according to the application pattern shown in FIG. 5( b) is the same as the time average value of the DC current flowing through the motor 142 when a voltage is applied to the motor 142 according to the application pattern shown in FIG. 5( a). Therefore, the rotation speed of the rotating blades 143, which are rotationally driven by the motor 142, hardly changes even when the voltage application pattern is switched from the application pattern shown in FIG. 5( a) to the application pattern shown in FIG. 5( b).

[0046] 5(b) , the frequency of the voltage applied to the motor 142 increases, causing the rotor 125 of the motor 142 to vibrate at a higher frequency. As a result, the operating sound of the motor 142 changes from a low-pitched sound to a high-pitched sound. This change in the operating sound of the motor 142 allows the user to recognize that the remaining power of the storage battery 117 is getting low.

[0047] In the vacuum cleaner 100 of the first embodiment, if a cleaning operation is started when the remaining power of the storage battery 117 is above the power threshold, the user can recognize that the remaining power of the storage battery 117 is low due to a change in the operating noise of the motor 142. If the user starts a cleaning operation when the remaining power of the storage battery 117 is below the power threshold, a high-frequency operating noise is emitted from the motor 142 at the start of the cleaning operation. This high-frequency operating noise allows the user to recognize that the remaining power of the storage battery 117 is low.

[0048] In the vacuum cleaner 100 of the first embodiment, even if the pattern of voltage application to the motor 142 is changed, there is almost no change in the current value of the DC current flowing through the motor 142 (i.e., the time average value of the DC current). Therefore, whether the pattern of voltage application to the motor 142 is the application pattern shown in Figure 5(a) or the application pattern shown in Figure 5(b), there is almost no change in the rotation speed of the rotor 125 of the motor 142, and therefore the rotating blades 143. Therefore, the operating noise of the motor 142 can be changed without causing almost any change in the suction force associated with the rotation of the rotating blades 143.

[0049] In the vacuum cleaner 100 of the first embodiment, the voltage application pattern to the motor 142 is changed from the application pattern shown in Fig. 5(a) to the application pattern shown in Fig. 5(b). Conversely, the application control unit 169 may control the voltage application unit 168 so that the voltage application pattern to the motor 142 is changed from the application pattern shown in Fig. 5(b) to the application pattern shown in Fig. 5(a). In this case, when the remaining power of the storage battery 117 falls below the power threshold, the operating sound of the motor 142 changes from a high-pitched to a low-pitched sound.

[0050] When motor 142 is fixed to housing 111 so that vibrations of rotor 125 of motor 142 are transmitted to motor housing 172, a state of resonance may be generated between motor housing 172 and rotor 125 of motor 142. In this case, in order to obtain this state of resonance, control may be performed to bring the frequency of voltage applied to motor 142 closer to the resonance frequency of motor housing 172 after the remaining amount of power in storage battery 117 falls below the power threshold.

[0051] That is, before the remaining power of the storage battery 117 falls below the power threshold, the application control unit 169 controls the voltage application unit 168 so that the power supply circuit 167 is opened and closed at a frequency that is away from the resonance frequency of the motor housing unit 172. In this case, a resonance state between the motor housing unit 172 and the motor 142 does not occur, and even if vibrations of the motor 142 are transmitted to the motor housing unit 172, the motor housing unit 172 vibrates with a small vibration amplitude.

[0052] Thereafter, when the remaining power of the storage battery 117 falls below the power threshold, the application control unit 169 controls the voltage application unit 168 to open and close the power supply circuit 167 at a frequency close to the resonance frequency of the motor housing 172. In this case, the motor housing 172 and the motor 142 resonate, increasing the vibration amplitude of the motor housing 172 and, in turn, the operating noise emitted from the motor housing 172. Therefore, the user can recognize from this increase in operating noise that the remaining power of the storage battery 117 is getting low. Furthermore, because an increase in the operating noise of the vacuum cleaner 100 can be unpleasant to the user, the increase in the operating noise of the vacuum cleaner 100 can prompt the user to stop the vacuum cleaner 100.

[0053] Second Embodiment The vacuum cleaner 100 of the first embodiment is configured so that the operating sound of the motor 142 changes when the power stored in the storage battery 117 becomes low. In contrast, the vacuum cleaner 100 of the second embodiment is configured so that the operating sound of the motor 142 changes when the amount of dust stored in the dust storage chamber 152 exceeds a predetermined dust storage threshold. In this case, the vacuum cleaner 100 may have a dust storage detection unit 173 that detects the amount of dust stored in the dust storage chamber 152, as shown in Fig. 7. The dust storage detection unit 173 may be configured as a transmission-type optical sensor provided at the bottom of the dust storage chamber 152.

[0054] When there is little dust in dust storage chamber 152, most of the dust is attracted to the underside of filter unit 115 by the suction force generated by the rotation of rotary blades 143 while motor 142 is operating. However, when the amount of dust in dust storage chamber 152 increases, some of the dust falls from the underside of filter unit 115 and may block the optical path of dust storage detection unit 173. At this time, dust storage detection unit 173 outputs a signal indicating that dust exceeding the dust storage threshold is present in dust storage chamber 152.

[0055] The control circuit 170 can be configured as shown in Fig. 8 so that the voltage application pattern to the motor 142 changes in response to a signal from the dust accumulation detection unit 173. That is, the dust accumulation detection unit 173 is electrically connected to an application control unit 169 of the control circuit 170. The application control unit 169 is configured to change the voltage application pattern to the motor 142 from the application pattern shown in Fig. 5(a) to the application pattern shown in Fig. 5(b) in response to a signal from the dust accumulation detection unit 173.

[0056] When a user starts cleaning when there is not much dust accumulated in dust storage chamber 152, voltage application control unit 169 controls voltage application unit 168 to obtain the voltage application pattern shown in Fig. 5(a). In this state, motor 142 generates a relatively low operating noise. Thereafter, when the amount of dust in dust storage chamber 152 increases and the dust in dust storage chamber 152 blocks the optical path of dust accumulation detection unit 173, a signal is output from dust accumulation detection unit 173. In response to this signal, voltage application control unit 169 controls voltage application unit 168 to switch the voltage application pattern to motor 142 to the voltage application pattern shown in Fig. 5(b).

[0057] This change in application pattern changes the operating sound of motor 142 from a low tone to a high tone, and this change in sound allows the user to recognize that there is an increase in dust in dust chamber 152. On the other hand, this change in application pattern causes almost no change in the value of the DC current flowing through motor 142 (i.e., the time average value of the DC current), so there is almost no change in the rotation speed of rotor 125, and therefore of rotating blades 143. As a result, changes in suction force are suppressed.

[0058] In the vacuum cleaner 100 of the second embodiment, the voltage application pattern to the motor 142 is changed from the application pattern shown in Fig. 5(a) to the application pattern shown in Fig. 5(b). Conversely, the application control unit 169 may control the voltage application unit 168 so that the voltage application pattern to the motor 142 is changed from the application pattern shown in Fig. 5(b) to the application pattern shown in Fig. 5(a). In this case, when the dust accumulation detection unit 173 detects that the amount of dust accumulated in the dust storage chamber 152 has exceeded a predetermined dust accumulation threshold, the operating sound of the motor 142 changes from a high-pitched to a low-pitched sound.

[0059] If the motor 142 is fixed to the housing 111 so that vibrations of the rotor 125 of the motor 142 are transmitted to the motor housing 172, the vibrations of the motor housing 172 may also be used to notify the user that the dust detection unit 173 has detected an amount of dust exceeding the dust threshold. That is, the frequency of the voltage applied after the dust detection unit 173 detects an amount of dust exceeding the dust threshold may be set to be close to the resonant frequency of the motor housing 172. In this case, when the dust detection unit 173 has not detected that the amount of dust accumulated in the dust storage chamber 152 has exceeded the predetermined dust threshold, the vibration amplitude of the motor housing 172 associated with the transmission of vibrations from the motor 142 to the motor housing 172 is relatively small. On the other hand, when the dust detection unit 173 detects that the amount of dust accumulated in the dust storage chamber 152 has exceeded the predetermined dust threshold, the vibration amplitude of the motor housing 172 associated with the transmission of vibrations from the motor 142 to the motor housing 172 increases. This can increase the operating noise of the vacuum cleaner 100 due to vibration of the motor housing 172. Therefore, the user can perceive an increase in the operating noise of the vacuum cleaner 100 as an increase in the amount of dust in the dust storage chamber 152. Furthermore, since the increase in the operating noise of the vacuum cleaner 100 can be unpleasant for the user, the increase in the operating noise of the vacuum cleaner 100 can prompt the user to stop the vacuum cleaner 100.

[0060] (Third embodiment) The vacuum cleaner 100 of the second embodiment changes the operating sound of the motor 142 when the amount of dust in the dust storage chamber 152 exceeds the dust accumulation threshold. Alternatively, the vacuum cleaner 100 may be configured to change the operating sound of the motor 142 depending on whether the amount of dust flowing into the dust storage chamber 152 is large or small. In this case, the user can recognize whether they are cleaning an area with a lot of dust or an area with little dust, based on the operating sound of the motor 142.

[0061] To detect whether the amount of dust flowing into the dust storage chamber 152 is large or small, the vacuum cleaner 100 shown in FIG. 9 has a dust detection unit 181 that forms an optical path that crosses the flow path of the suction pipe 113. The dust detection unit 181 may be configured, for example, as a transmission-type optical sensor provided in the suction pipe 113. In this case, when there is a large amount of dust on the floor, the optical path of the dust detection unit 181 is blocked more frequently. Conversely, when there is little dust on the floor, the optical path of the dust detection unit 181 is blocked less frequently. The dust detection unit 181 may be configured to output a signal when the optical path is blocked.

[0062] 10 so that the pattern of voltage application to motor 142 changes depending on the frequency of signal input from dust detection unit 173. That is, dust detection unit 181 is electrically connected to application control unit 169 of control circuit 170, and application control unit 169 is configured to receive signals output from dust detection unit 181. In this case, by setting a predetermined threshold value for the frequency of signal input to dust detection unit 181, this threshold value can be used as a dust threshold value for determining whether there is a lot of dust on the floor surface.

[0063] When the frequency of signal input from the dust accumulation detection unit 173 is below the dust threshold, the voltage application control unit 169 controls the voltage application unit 168 to obtain the voltage application pattern shown in FIG. 5A. In this case, a low operating sound is emitted from the motor 142. Conversely, when the frequency of signal input from the dust accumulation detection unit 173 is above the dust threshold, the voltage application control unit 169 controls the voltage application unit 168 to obtain the voltage application pattern shown in FIG. 5B. In this case, a high operating sound is emitted from the motor 142. With this control, the user can determine whether the area they are cleaning is dusty or dusty based on the level of the operating sound from the motor 142. If the motor 142 is emitting a high operating sound, the user can stay in place and continue cleaning until the motor 142 emits a low operating sound.

[0064] Regardless of changes in the operating noise of the motor 142, the motor 142 can maintain a substantially constant rotation speed of the rotary vanes 143. Therefore, the suction force of the rotary vanes 143 is also maintained substantially constant.

[0065] In the vacuum cleaner 100 of the third embodiment, when a large amount of dust flows into the dust storage chamber 152, the operating noise of the motor 142 becomes louder, and when a small amount of dust flows into the dust storage chamber 152, the operating noise of the motor 142 becomes quieter. Conversely, the vacuum cleaner 100 may be configured so that when a large amount of dust flows into the dust storage chamber 152, the motor 142 generates a quiet operating noise, and when a small amount of dust flows into the dust storage chamber 152, the motor 142 generates a loud operating noise.

[0066] The vacuum cleaner 100 of the first to third embodiments changes the operating sound of the motor 142 to notify the user of the status of the vacuum cleaner 100 (i.e., the amount of stored power or the amount of dust) or whether the area being cleaned by the vacuum cleaner 100 is dusty or dusty. Alternatively, the vacuum cleaner 100 may be configured to play a melody with the operating sound of the motor 142. For example, the application control unit 169 of the vacuum cleaner 100 may control the voltage application unit 168 so that the frequency of the voltage applied to the motor 142 increases or decreases in accordance with the pitch of the notes on the musical score shown in FIG. 11 . In this case, the operating sound of the motor 142 plays a melody, so that the user can perform cleaning work while listening to the operating sound of the motor 142 as music.

[0067] In the vacuum cleaner 100 of the first embodiment, when the remaining power of the storage battery 117 falls below a power threshold, the voltage application pattern to the motor 142 is switched from the application pattern shown in Fig. 5(a) to the application pattern shown in Fig. 5(b). In the vacuum cleaner 100 of the second embodiment, when the amount of dust in the dust storage chamber 152 exceeds a dust storage threshold, the voltage application pattern to the motor 142 is switched from the application pattern shown in Fig. 5(a) to the application pattern shown in Fig. 5(b). In the vacuum cleaner 100 of the third embodiment, when the amount of dust flowing into the dust storage chamber 152 exceeds the dust threshold, the voltage application pattern to the motor 142 is switched from the application pattern shown in Fig. 5(a) to the application pattern shown in Fig. 5(b). However, the conditions for changing the voltage application pattern to the motor 142 are not limited to these, and the voltage application pattern to the motor 142 may be changed when other conditions are satisfied.

[0068] In the vacuum cleaner 100 of the first to third embodiments, a brushed motor is used as the motor 142. Alternatively, other types of motors may be used as the motor 142 as long as the rotation speed of the rotor is maintained regardless of changes in the applied frequency of the voltage, and the vibration frequency of the rotor, and therefore the operating noise from the rotor, changes with changes in the applied frequency of the voltage.

[0069] (Fourth embodiment) The driving device 101 of the vacuum cleaner 100 of the first to third embodiments changes the operating noise of the motor 142 that rotates the rotary blades 143. Alternatively, the driving device 101 may be configured to change the operating noise of another motor included in the vacuum cleaner 100.

[0070] For example, as shown in Fig. 12, the driving device 101 may be configured to rotate a first rotating brush 135 and a second rotating brush 136 provided in the suction space 131 of the suction nozzle 130. In this case, the driving device 101 may be configured using a first motor 137 and a second motor 138 provided at the rear of the nozzle case 132. The structures of the first motor 137 and the second motor 138 are the same as those of the motor 142 shown in Figs. 3 and 4.

[0071] A portion of the first rotating brush 135 and the second rotating brush 136 protrudes downward through the opening of the suction space 131 so as to come into contact with the floor surface. When the first rotating brush 135 and the second rotating brush 136 are rotated by the first motor 137 and the second motor 138, they can scrape off dust from the floor surface.

[0072] In a plan view, the nozzle case 132 has a generally C-shape that opens forward. Specifically, the nozzle case 132 has a motor housing 139 that houses a first motor 137 and a second motor 138, and a first protrusion 154 and a second protrusion 155 that protrude forward from the left and right ends of the motor housing 139, respectively. The motor housing 139 defines the rear end of the suction space 131. The first protrusion 154 defines the left end of the suction space 131, and the second protrusion 155 defines the right end of the suction space 131.

[0073] The first protruding portion 154 rotatably supports the first rotating brush 135 in a cantilevered manner. The second protruding portion 155 rotatably supports the second rotating brush 136 in a cantilevered manner. As shown in Figure 13, a nozzle cover 156 is placed over the first rotating brush 135 and the second rotating brush 136. The nozzle cover 156 is configured to define the upper and front ends of the suction space 131.

[0074] The first motor 137 is connected to the first rotating brush 135 via a drive belt 201 that extends between the first protrusion 154 and the left end portion of the motor housing 139. Rotation of a first rotor (same as rotor 125 shown in FIG. 4 ) of the first motor 137 is transmitted to the first rotating brush 135 via the drive belt 201. The second motor 138 is connected to the second rotating brush 136 via a drive belt 202 that extends between the second protrusion 155 and the right end portion of the motor housing 139. Rotation of a second rotor (same as rotor 125 shown in FIG. 4 ) of the second motor 138 is transmitted to the second rotating brush 136 via the drive belt 202.

[0075] The control circuit 210 that controls the first motor 137 and the second motor 138 may be configured as shown in Fig. 14. The control circuit 210 may be disposed inside the nozzle case 132 or inside the housing 111.

[0076] 14 , the control circuit 210 forms part of a first supply circuit 211 for supplying power from the storage battery 117 to the first motor 137, and part of a second supply circuit 212 for supplying power from the storage battery 117 to the second motor 138. A first voltage application unit 213 for opening and closing the first supply circuit 211 is provided on the first supply circuit 211, and a second voltage application unit 214 for opening and closing the second supply circuit 212 is provided on the second supply circuit 212.

[0077] 6 , the control circuit 210 also includes an application control unit 169 and a power detection unit 171. While the remaining power of the storage battery 117 is above the power threshold, the application control unit 169 controls the first voltage application unit 213 and the second voltage application unit 214 so that the operating sounds of the first motor 137 and the second motor 138 produce a consonant sound. For example, the application control unit 169 may control the first voltage application unit 213 and the second voltage application unit 214 so that one of the first motor 137 and the second motor 138 produces the sound of "do" and the other produces the sound of "mi." Alternatively, the application control unit 169 may control the first voltage application unit 213 and the second voltage application unit 214 so that one of the first motor 137 and the second motor 138 produces the sound of "mi" and the other produces the sound of "so."

[0078] Conversely, while the remaining power of the storage battery 117 is below the power threshold, the application control unit 169 controls the first voltage application unit 213 and the second voltage application unit 214 so that the operating sounds of the first motor 137 and the second motor 138 create a dissonant sound. For example, the application control unit 169 may control the first voltage application unit 213 and the second voltage application unit 214 so that one of the first motor 137 and the second motor 138 produces the sound of "do" and the other produces the sound of "re." Alternatively, the application control unit 169 may control the first voltage application unit 213 and the second voltage application unit 214 so that one of the first motor 137 and the second motor 138 produces the sound of "si" and the other produces the sound of "do."

[0079] When the first voltage application unit 213 and the second voltage application unit 214 are controlled in this manner, if the remaining power of the storage battery 117 is above the power threshold, the operating sounds of the first motor 137 and the second motor 138 become consonant, and the user is unlikely to find these operating sounds unpleasant. On the other hand, if the remaining power of the storage battery 117 falls below the power threshold, the operating sounds of the first motor 137 and the second motor 138 become discordant, and the user may find these operating sounds unpleasant. Furthermore, the operating sounds of the first motor 137 and the second motor 138 unpleasant to the user may prompt the user to stop cleaning.

[0080] When the vacuum cleaner 100 has the dust accumulation detection unit 173 as shown in Fig. 7, the control circuit 210 may be configured as shown in Fig. 15. In this case, while the dust accumulation detection unit 173 detects an amount of dust below the dust accumulation threshold, the application control unit 169 controls the first voltage application unit 213 and the second voltage application unit 214 so that the operating sounds of the first motor 137 and the second motor 138 produce a consonant sound. When this control is executed, the user can continue cleaning without feeling uncomfortable by the operating sounds of the first motor 137 and the second motor 138 as long as the amount of dust in the dust storage chamber 152 is below the dust accumulation threshold.

[0081] On the other hand, when dust accumulation detection unit 173 detects an amount of dust exceeding the dust accumulation threshold, application control unit 169 controls first voltage application unit 213 and second voltage application unit 214 so that the operating sounds of first motor 137 and second motor 138 create a discordant sound. In this case, if the amount of dust in dust storage chamber 152 exceeds the dust accumulation threshold, the user may find the operating sounds of first motor 137 and second motor 138 unpleasant. This can encourage the user to stop cleaning when the amount of dust in dust storage chamber 152 becomes too high.

[0082] If the vacuum cleaner 100 has the dust detection unit 181 as shown in Fig. 9, the control circuit 210 may be configured as shown in Fig. 16. In this case, while the dust detection unit 181 detects an amount of dust exceeding the dust threshold, the application control unit 169 controls the first voltage application unit 213 and the second voltage application unit 214 so that the operating sounds of the first motor 137 and the second motor 138 produce a consonant sound. When this control is executed, the user can continue cleaning without feeling uncomfortable by the operating sounds of the first motor 137 and the second motor 138 while the dust detection unit 181 detects that the amount of dust passing through the suction tube 113 exceeds the dust threshold.

[0083] On the other hand, when the dust detection unit 181 detects an amount of dust below the dust threshold, the voltage application control unit 169 controls the first voltage application unit 213 and the second voltage application unit 214 so that the operating sounds of the first motor 137 and the second motor 138 create a discordant sound. In this case, when the amount of dust passing through the suction tube 113 falls below the dust threshold, the user finds the operating sounds of the first motor 137 and the second motor 138 unpleasant. This may encourage the user to clean another area. If there is a lot of dust in this area, the operating sounds of the first motor 137 and the second motor 138 create a consonant sound. In this state, the user can continue cleaning the area without finding the operating sounds of the first motor 137 and the second motor 138 unpleasant.

[0084] In the vacuum cleaner 100 of the fourth embodiment, the operating sounds of the first motor 137 and the second motor 138 can be changed to notify the user of the state of the vacuum cleaner 100 (the amount of stored power or the amount of dust) or whether there is a lot of dust in the area being cleaned by the vacuum cleaner 100. Furthermore, while the operating sounds of the first motor 137 and the second motor 138 change, changes in the rotation speeds of the first rotating brush 135 and the second rotating brush 136, which are rotated by the first motor 137 and the second motor 138, are suppressed. Therefore, changes in the scraping ability to scrape dust off the floor surface are suppressed.

[0085] 14 to 16 changes the operating sounds of the first motor 137 and the second motor 138 to notify the user of the status of the vacuum cleaner 100 (the amount of stored power or the amount of dust) or whether the area being cleaned by the vacuum cleaner 100 is dusty or dusty. Alternatively, the control circuit 210 may control the first motor 137 and the second motor 138 so that the operating sound of one of the first motor 137 and the second motor 138 plays the main melody of a predetermined musical score, and the operating sound of the other motor plays the secondary melody. In this case, the user can perform cleaning work while listening to the operating sounds of the first motor 137 and the second motor 138 as music.

[0086] The control circuit 210 in FIGS. 14 to 16 is configured to change the operating sounds of both the first motor 137 and the second motor 138. Alternatively, the control circuit 210 may be configured to change the operating sounds of only one of the first motor 137 and the second motor 138. In this case, the control of this motor may be applied to the control of the first to third embodiments. When the first embodiment (control based on the remaining power of the storage battery 117) or the second embodiment (control based on the amount of dust stored in the dust chamber 152) is applied, the resonance between the first motor 137 or the second motor 138 and the motor housing 139 may be used to notify the user. That is, when the remaining power of the storage battery 117 falls below a power threshold, control may be performed to bring the frequency of the first rotor of the first motor 137 or the second rotor of the second motor 138 closer to the resonant frequency of the motor housing 139. Alternatively, when the amount of dust in the dust storage chamber 152 exceeds the dust storage threshold, control may be performed to bring the vibration frequency of the rotor 125 of the first motor 137 or the second motor 138 closer to the resonance frequency of the motor housing 139. In these cases, the operating noise emitted from the suction nozzle 130 becomes louder, which may prompt the user to suspend cleaning work when the amount of stored power in the storage battery 117 is low or when there is a lot of dust in the dust storage chamber 152.

[0087] In the vacuum cleaner 100 of the fourth embodiment, when any of the following conditions 1 to 3 is satisfied, the pattern of voltage application to the motor 142 is changed. However, the conditions for changing the pattern of voltage application to the motor 142 are not limited to these, and the pattern of voltage application to the motor 142 may be changed when other conditions are satisfied.

[0088] (Condition 1) The remaining amount of power in the storage battery 117 is below the power threshold.

[0089] (Condition 2) The amount of dust in the dust storage chamber 152 exceeds the dust storage threshold.

[0090] (Condition 3) The amount of dust flowing into the dust storage chamber 152 exceeds the dust threshold.

[0091] In the vacuum cleaner 100 of the fourth embodiment, brushed motors are used as the first motor 137 and the second motor 138. Alternatively, other types of motors may be used as long as the rotation speed of the rotor is maintained regardless of changes in the applied frequency of the voltage, and the vibration frequency of the rotor, and therefore the operating noise from the rotor, changes with changes in the applied frequency of the voltage.

[0092] In the first to fourth embodiments, the vacuum cleaner 100 is a stick type. Alternatively, the control techniques of the first to fourth embodiments may be applied to a canister type vacuum cleaner or a handheld type vacuum cleaner.

[0093] (Effects, etc.) The technology according to the above-described embodiment has the following features and provides the following effects.

[0094] (Technology 1) A drive device according to one aspect of the above-described embodiment is configured to drive a rotating brush that rolls on a floor surface to scrape dust off the floor surface, or a rotating blade that generates a suction force to attract dust as it rotates. The drive device includes a motor having a rotor that rotates the rotating brush or the rotating blade, and a voltage application unit that applies a voltage of a predetermined magnitude to the motor intermittently, thereby causing a periodic change in the magnetic field within the motor at a frequency corresponding to the frequency of the voltage applied to the motor. The motor is configured so that the rotor rotates at a rotation speed corresponding to a current value that is a time average value of a direct current flowing through the motor as a result of the intermittent application of the voltage to the motor, and vibrates in response to the periodic change in the magnetic field at a frequency corresponding to the applied frequency, thereby emitting an operating sound. The drive device further includes an application control unit that controls the voltage application unit to change the applied frequency while suppressing fluctuations in the current value, provided that a predetermined change condition is satisfied.

[0095] In the above-described configuration, the voltage application unit intermittently applies a voltage of a predetermined magnitude to the motor, periodically alternating between a state in which a direct current is flowing through the motor and a state in which no direct current is flowing through the motor. The state of the magnetic field within the motor differs between a state in which a direct current is flowing through the motor and a state in which no direct current is flowing through the motor. Therefore, when the voltage application unit intermittently applies a voltage to the motor, the magnitude and / or direction of the magnetic force received by the rotor periodically changes at a frequency corresponding to the applied frequency of the intermittent voltage application. The periodic change in the magnetic force received by the rotor causes the rotor of the motor to vibrate, and the motor generates an operating sound corresponding to the rotor's vibration frequency. Therefore, when the frequency of the voltage applied to the motor changes, the frequency of the operating sound of the motor also changes. When the frequency of the voltage applied to the motor is changed under the condition that a predetermined change condition is satisfied, the user can recognize that the change condition has been satisfied by the change in the operating sound of the motor.

[0096] When the applied frequency is changed, fluctuations in the current value, which is the time average value of the DC current flowing through the motor, are suppressed. Therefore, even when the applied frequency is changed, fluctuations in the rotation speed of the rotor are suppressed. As a result, fluctuations in the rotation speed of the rotating brush or rotating blades, which are rotated by the rotation of the rotor, are also suppressed. Therefore, changes in the dust scraping performance of the rotating brush or the suction force of the rotating blades are unlikely to occur.

[0097] (Technology 2) A drive device according to another aspect of the above-described embodiments is configured to drive a first rotating brush and a second rotating brush that roll on a floor surface to scrape off dust from the floor surface. The drive device includes a first motor having a first rotor that rotatably drives the first rotating brush, a second motor having a second rotor that rotatably drives the second rotating brush, a first voltage application unit that intermittently applies a voltage of a predetermined magnitude to the first motor to cause a periodic change in a magnetic field within the first motor at a frequency corresponding to the frequency of application of the voltage to the first motor, and a second voltage application unit that intermittently applies a voltage of a predetermined magnitude to the second motor to cause a periodic change in the magnetic field within the second motor at a frequency corresponding to the frequency of application of the voltage to the second motor. The first motor is configured such that a first rotor rotates at a rotation speed corresponding to a current value that is a time average value of a direct current flowing through the first motor in response to intermittent application of a voltage to the first motor, and the first rotor vibrates in response to a periodic change in a magnetic field at a frequency corresponding to an application frequency to the first motor, thereby emitting an operating sound. The second motor is configured such that a second rotor rotates at a rotation speed corresponding to a current value that is a time average value of a direct current flowing through the second motor in response to intermittent application of a voltage to the second motor, and the second rotor vibrates in response to a periodic change in a magnetic field at a frequency corresponding to the application frequency to the second motor, thereby emitting an operating sound. The drive device further includes an application control unit that controls the first voltage application unit and the second voltage application unit. The application control unit controls the first voltage application unit to change the application frequency to the first motor while suppressing fluctuations in the current value to the first motor, provided that specified change conditions are satisfied, and controls the second voltage application unit to change the application frequency to the second motor while suppressing fluctuations in the current value to the second motor so that the application frequency to the second motor is different from the application frequency of the voltage to the first motor, thereby generating a dissonant or consonant sound from the operating sounds of the first motor and the second motor.

[0098] In the above-described configuration, a voltage of a predetermined magnitude is applied intermittently to each of the first motor and the second motor. While this intermittent voltage application is being performed, the magnitude and / or direction of the magnetic force received by the first rotor of the first motor periodically changes at a frequency corresponding to the application frequency of this intermittent voltage application. The magnitude and / or direction of the magnetic force received by the second rotor of the second motor also periodically changes. The periodic changes in the magnetic force received by the first rotor and the second rotor cause these rotors to vibrate. An operating sound corresponding to the vibration frequency of the first rotor is then emitted from the first motor, and an operating sound corresponding to the vibration frequency of the second rotor is emitted from the second motor.

[0099] By making the applied frequency to the first motor and the applied frequency to the second motor different from each other, it is possible to generate a discordant or consonant sound using the operating sounds from the first motor and the second motor. If a discordant sound is generated, the user may find the discordant sound unpleasant and stop cleaning work. If a consonant sound is generated, the user may find the consonant sound pleasant and be encouraged to continue cleaning work. By generating a discordant or consonant sound on the condition that a predetermined change condition is met, it is possible to encourage the user to stop or continue cleaning work when the change condition is met.

[0100] When the frequency of the voltage applied to the first motor and the second motor is changed, fluctuations in the current value, which is the time average value of the DC current flowing through the motor, are suppressed. Therefore, even if the applied frequency is changed, fluctuations in the rotation speed of the first rotor and the second rotor are suppressed. As a result, fluctuations in the rotation speed of the first rotating brush and the second rotating brush, which are rotated by these rotors, are also suppressed. Therefore, changes in the dust scraping performance of these rotating brushes are unlikely to occur.

[0101] (Technology 3) A drive device according to yet another aspect of the above-described embodiments is configured to drive a rotating brush that rolls on a floor surface to scrape dust off the floor surface, or a rotating blade that generates a suction force to suck in dust as it rotates. The drive device includes a motor having a rotor that rotates the rotating brush or the rotating blade, and a voltage application unit that applies a voltage of a predetermined magnitude to the motor intermittently, thereby causing a periodic change in the magnetic field within the motor at a frequency corresponding to the frequency of the voltage applied to the motor. The motor is configured so that the rotor rotates at a speed corresponding to a current value that is a time average value of a direct current flowing through the motor as the voltage is applied intermittently to the motor, and vibrates in response to the periodic change in the magnetic field at a frequency corresponding to the applied frequency, thereby emitting an operating sound. The drive device further includes an application control unit that controls the voltage application unit so that the applied frequency increases or decreases in accordance with the pitch of the notes on a predetermined musical score, while suppressing fluctuations in the current value.

[0102] In the above-described configuration, the voltage application unit applies a voltage to the motor intermittently, causing the magnitude and / or direction of the magnetic force received by the rotor to change periodically at a frequency corresponding to the applied frequency of the intermittent voltage application. The periodic change in the magnetic force received by the rotor causes the rotor of the motor to vibrate, and the motor emits an operating sound corresponding to the rotor's vibration frequency. Therefore, when the frequency of the voltage applied to the motor changes, the frequency of the operating sound of the motor also changes. If this applied frequency increases or decreases in accordance with the pitch of the notes on a predetermined musical score, the operating sound of the motor can produce a melody represented by the notes on the musical score. Therefore, a user can perceive the operating sound of the motor as music.

[0103] While the frequency of the voltage applied to the motor is increased or decreased in accordance with the pitch of the musical note, fluctuations in the current value, which is the time average value of the DC current flowing through the motor, are suppressed. Therefore, even if the applied frequency is changed, fluctuations in the rotation speed of the rotor are suppressed. As a result, fluctuations in the rotation speed of the rotating brush or rotating blades, which are driven to rotate by the rotation of the rotor, are also suppressed. Therefore, changes in the dust scraping performance of the rotating brush or the suction force of the rotating blades are unlikely to occur.

[0104] (Technology 4) The vacuum cleaner according to the above-described embodiment includes a rotating brush that rolls on a floor surface to scrape off dust on the floor surface or a rotating blade configured to generate suction force for sucking in dust while rotating, the drive device described in Technology 1, a storage battery that stores power for the motor, and a power detection unit that detects the remaining amount of power stored in the storage battery. The application control unit controls the voltage application unit to change the application frequency while suppressing fluctuations in the current value, on the condition that the power detection unit detects that the remaining amount of power stored in the storage battery has fallen below a predetermined power threshold.

[0105] In the above configuration, when the remaining power stored in the storage battery falls below a predetermined power threshold, the operating sound of the motor changes. Therefore, the change in the operating sound of the motor can notify the user of the decrease in the power stored in the storage battery and encourage them to charge the storage battery.

[0106] (Technology 5) Another vacuum cleaner according to the above-described embodiment includes a first rotating brush and a second rotating brush that roll on a floor surface to scrape off dust on the floor surface, the drive device described in Technology 2, a storage battery that stores power for the first motor and the second motor, and a power detection unit that detects the remaining amount of power stored in the storage battery. On the condition that the power detection unit detects that the remaining amount of power stored in the storage battery has fallen below a predetermined power threshold, the application control unit controls the first voltage application unit and the second voltage application unit so as to suppress fluctuations in the current values ​​to the first motor and the second motor and to generate a discordant sound by the operating sounds of the first motor and the second motor.

[0107] In the above configuration, when the remaining power stored in the storage battery falls below a predetermined power threshold, a discordant sound is generated between the operating sounds of the first motor and the second motor. If the user finds this discordant sound unpleasant, the user may stop cleaning work. In other words, the user can be prompted to stop cleaning work when the remaining power stored in the storage battery is low.

[0108] (Technology 6) Yet another vacuum cleaner according to the above-described embodiments includes a rotating brush that rolls on a floor surface to scrape off dust on the floor surface or a rotating blade configured to generate a suction force for sucking in dust as it rotates, the drive device described in Technology 1, a dust storage unit that stores the dust scraped off by the rotating brush or the dust sucked in by the suction force generated by the rotation of the rotating blade, and a dust storage detection unit that detects the amount of dust in the dust storage unit. The application control unit controls the voltage application unit to change the application frequency while suppressing fluctuations in the current value, on the condition that it has detected that the amount of dust in the dust storage unit has exceeded a predetermined dust storage threshold.

[0109] In the above configuration, when the amount of dust in the dust storage section exceeds a predetermined dust accumulation threshold, the operating sound of the motor changes. Therefore, the change in the operating sound of the motor notifies the user that a large amount of dust has accumulated in the dust storage section, and urges the user to dispose of the dust in the dust storage section.

[0110] (Technology 7) A still further vacuum cleaner according to the above-described embodiment includes a first rotating brush and a second rotating brush that roll on the floor surface to scrape off dust on the floor surface, the drive device described in Technology 2, a dust storage unit that stores the dust scraped off by the first rotating brush and the second rotating brush, and a dust storage detection unit that detects the amount of dust in the dust storage unit. The application control unit, on the condition that it has detected that the amount of dust in the dust storage unit has exceeded a predetermined dust storage threshold, controls the first voltage application unit and the second voltage application unit so as to suppress fluctuations in the current values ​​to the first motor and the second motor and to generate a discordant sound by the operating sounds of the first motor and the second motor.

[0111] In the above configuration, when the amount of dust in the dust storage compartment exceeds a predetermined dust threshold, a discordant sound is generated between the operating sounds of the first motor and the second motor. If the user finds this discordant sound unpleasant, the user may stop cleaning. In other words, the user can be prompted to stop cleaning when the dust storage compartment is full of dust.

[0112] (Technology 8) A still further vacuum cleaner according to the above-described embodiments includes a rotating brush that rolls on a floor surface to scrape off dust or a rotating blade configured to generate a suction force for sucking in dust as it rotates, the drive device described in Technology 1, and a dust detection unit that detects the amount of dust being scraped off by the rotating brush or the amount of dust being sucked in by the suction force generated by the rotation of the rotating blade. The application control unit controls the voltage application unit to change the application frequency while suppressing fluctuations in the current value, on the condition that the amount of dust detected by the dust detection unit exceeds a predetermined dust threshold.

[0113] In the above configuration, when the amount of dust detected by the dust detector exceeds a predetermined dust threshold, the operating sound of the motor changes. This change in the operating sound of the motor can notify the user that there is a lot of dust in the area they are cleaning, and can encourage the user to continue cleaning in that area.

[0114] (Technology 9) A still further vacuum cleaner according to the above-described embodiments includes a first rotating brush and a second rotating brush that roll on the floor surface to scrape off dust on the floor surface, the drive device described in Technology 2, a dust storage unit that stores the dust scraped off by the first rotating brush and the second rotating brush, and a dust detection unit that detects the amount of dust scraped off by the first rotating brush and the second rotating brush. The application control unit controls the first voltage application unit and the second voltage application unit so as to suppress fluctuations in the current values ​​to the first motor and the second motor and to produce a consonant sound from the operating sounds of the first motor and the second motor, on the condition that the amount of dust detected by the dust detection unit exceeds a predetermined dust threshold.

[0115] In the above configuration, when the amount of dust detected by the dust detector exceeds a predetermined dust threshold, the operating sounds of the first motor and the second motor produce a consonant sound, which makes the user feel comfortable during the cleaning operation and encourages them to continue the cleaning operation.

[0116] (Technology 10) A still further vacuum cleaner according to the above-described embodiment includes a rotating brush that rolls on a floor surface to scrape off dust or a rotating blade configured to generate suction force for sucking in dust as it rotates, the drive device described in Technology 1, and a motor housing that houses a motor. The motor is connected to the motor housing so that vibrations of the rotor are transmitted to the motor housing. The application control unit controls the voltage application unit so that the application frequency approaches the resonant frequency of the motor housing while suppressing fluctuations in the current value, provided that a change condition is satisfied.

[0117] In the above-described configuration, the vibration of the rotor is transmitted to the motor housing, causing the motor housing to vibrate at the rotor's vibration frequency. When a predetermined change condition is met, the rotor and motor housing vibrate at a frequency close to the resonant frequency of the motor housing, increasing the vibration amplitude of the motor housing. As a result, the operating noise caused by the vibration of the motor housing increases, and this increase in operating noise can notify the user that the change condition has been met.

[0118] The techniques of the above-described embodiments are suitably used in devices used for cleaning work.

Claims

1. A drive device for driving a rotating brush that rolls on a floor surface to scrape off dust on it, or a rotating blade that is configured to generate a suction force to suck in dust as it rotates, comprising: a motor having a rotor that rotates the rotating brush or the rotating blade; and a voltage application unit that applies a voltage of a predetermined magnitude to the motor intermittently, thereby causing a periodic change in the magnetic field within the motor at a frequency corresponding to the frequency of the voltage applied to the motor, wherein the motor is configured so that the rotor rotates at a number of revolutions corresponding to a current value that is the time average value of a direct current flowing through the motor as the voltage is intermittently applied to the motor, and the rotor vibrates in response to the periodic change in the magnetic field at a frequency corresponding to the applied frequency, thereby emitting an operating sound; and the drive device further comprises an application control unit that controls the voltage application unit so that the applied frequency is changed while suppressing fluctuations in the current value, provided that a predetermined change condition is met.

2. A drive device for driving a first rotating brush and a second rotating brush that roll on a floor surface to scrape off dust and dirt, comprising: a first motor having a first rotor that rotates and drives the first rotating brush; a second motor having a second rotor that rotates and drives the second rotating brush; a first voltage application unit that applies a voltage of a predetermined magnitude to the first motor intermittently, thereby causing periodic changes in the magnetic field within the first motor at a frequency corresponding to the frequency of voltage application to the first motor; and a second voltage application unit that applies a voltage of a predetermined magnitude to the second motor intermittently, thereby causing periodic changes in the magnetic field within the second motor at a frequency corresponding to the frequency of voltage application to the second motor; wherein the first motor is configured so that the first rotor rotates at a speed corresponding to the current value that is the time average value of the direct current flowing through the first motor as the voltage is intermittently applied to the first motor, and the first rotor vibrates in response to the periodic changes in the magnetic field at the frequency corresponding to the frequency of application to the first motor, thereby emitting operating noise; The second motor is configured such that the second rotor rotates at a rotation speed corresponding to a current value that is a time average value of a direct current flowing through the second motor in response to the intermittent application of a voltage to the second motor, and the second rotor vibrates in response to periodic changes in a magnetic field at a frequency that corresponds to the application frequency to the second motor, thereby emitting an operating sound; the drive device further includes an application control unit that controls the first voltage application unit and the second voltage application unit, and the application control unit controls the first voltage application unit so that the application frequency to the first motor changes while suppressing fluctuations in the current value to the first motor, and controls the second voltage application unit so that the application frequency to the second motor differs from the application frequency of the voltage to the first motor while suppressing fluctuations in the current value to the second motor, on the condition that a predetermined change condition is satisfied, thereby generating a discordant or consonant sound by the operating sounds of the first motor and the second motor.

3. A drive device for driving a rotating brush that rolls on a floor surface to scrape off dust on it, or a rotating blade that is configured to generate a suction force to suck in dust as it rotates, comprising: a motor having a rotor that rotates the rotating brush or the rotating blade; and a voltage application unit that applies a voltage of a predetermined magnitude to the motor intermittently, thereby causing periodic changes in the magnetic field within the motor at a frequency corresponding to the frequency of voltage application to the motor, wherein the rotor rotates at a number of revolutions corresponding to a current value that is the time average value of DC current flowing through the motor as the voltage is intermittently applied to the motor, and the rotor vibrates in response to the periodic changes in the magnetic field at a frequency corresponding to the applied frequency, thereby emitting an operating sound; and the drive device further comprises an application control unit that controls the voltage application unit so that the applied frequency increases or decreases in accordance with the pitch of the notes on a predetermined musical score, while suppressing fluctuations in the current value.

4. A vacuum cleaner comprising: a rotating brush that rolls on the floor surface to scrape off dust on the floor surface, or a rotating blade configured to generate suction force to suck in dust as it rotates; a drive unit as described in claim 1; a storage battery that stores power for the motor; and a power detection unit that detects the remaining amount of power stored in the storage battery, wherein the application control unit controls the voltage application unit to change the application frequency while suppressing fluctuations in the current value, on the condition that the power detection unit detects that the remaining amount of power stored in the storage battery has fallen below a predetermined power threshold.

5. A vacuum cleaner comprising: a first rotating brush and a second rotating brush that roll over the floor surface to scrape off dust and dirt; a drive device as described in claim 2; a storage battery that stores power for the first motor and the second motor; and a power detection unit that detects the remaining amount of power stored in the storage battery, wherein the application control unit controls the first voltage application unit and the second voltage application unit so as to suppress fluctuations in the current value for the first motor and the second motor and to create a discordant sound from the operating sounds of the first motor and the second motor, on condition that the power detection unit detects that the remaining amount of power stored in the storage battery has fallen below a predetermined power threshold.

6. A vacuum cleaner comprising: a rotating brush that rolls on the floor surface to scrape off dust or a rotating blade configured to generate suction force to suck in dust as it rotates; a drive unit as described in claim 1; a dust storage unit that stores dust scraped by the rotating brush or dust sucked in by the suction force generated by the rotation of the rotating blade; and a dust storage detection unit that detects the amount of dust in the dust storage unit, wherein the application control unit controls the voltage application unit to change the application frequency while suppressing fluctuations in the current value on the condition that it detects that the amount of dust in the dust storage unit has exceeded a predetermined dust storage threshold.

7. A vacuum cleaner comprising: a first rotating brush and a second rotating brush that roll over the floor surface to scrape off dust on the floor surface; a drive device as described in claim 2; a dust storage section that stores the dust scraped off by the first rotating brush and the second rotating brush; and a dust storage detection section that detects the amount of dust in the dust storage section, wherein the application control section controls the first voltage application section and the second voltage application section so as to generate a discordant sound from the operating sounds of the first motor and the second motor while suppressing fluctuations in the current value for the first motor and the second motor, on the condition that it detects that the amount of dust in the dust storage section has exceeded a predetermined dust storage threshold.

8. A vacuum cleaner comprising: a rotating brush that rolls on the floor surface to scrape off dust on the floor surface, or a rotating blade configured to generate suction force to suck in dust as it rotates; a drive device as described in claim 1; and a dust detection unit that detects the amount of dust being scraped off by the rotating brush or dust being sucked in by the suction force generated by the rotation of the rotating blade, wherein the application control unit controls the voltage application unit to change the application frequency while suppressing fluctuations in the current value, on the condition that the amount of dust detected by the dust detection unit exceeds a predetermined dust threshold.

9. A vacuum cleaner comprising: a first rotating brush and a second rotating brush that roll over the floor surface to scrape off dust on the floor surface; a drive device as described in claim 2; a dust storage unit that stores the dust scraped off by the first rotating brush and the second rotating brush; and a dust detection unit that detects the amount of dust scraped off by the first rotating brush and the second rotating brush, wherein the application control unit controls the first voltage application unit and the second voltage application unit so as to produce a consonant sound from the operating sounds of the first motor and the second motor while suppressing fluctuations in the current value for the first motor and the second motor, on the condition that the amount of dust detected by the dust detection unit exceeds a predetermined dust threshold.

10. A vacuum cleaner comprising: a rotating brush that rolls on the floor surface to scrape off dust on the floor surface, or a rotating blade configured to generate suction force to suck in dust as it rotates; a drive device as described in claim 1; and a motor housing that houses the motor, wherein the motor is connected to the motor housing so that vibrations of the rotor are transmitted to the motor housing, and the application control unit controls the voltage application unit so that the application frequency approaches the resonant frequency of the motor housing while suppressing fluctuations in the current value, on the condition that the change condition is satisfied.

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