Patent Application
20230071190
The present application claims the benefit of Japanese Patent Application No. 2021-144116 filed on Sep. 3, 2021 with the Japan Patent Office and Japanese Patent Application No. 2022-132826 filed on Aug. 23, 2022 with the Japan Patent Office, the entire disclosure of Japanese Patent Application No. 2021-144116 and the entire disclosure of Japanese Patent Application No. 2022-132826 are incorporated herein by reference.
The present disclosure relates to a blower.
Japanese Unexamined Patent Application Publication No. 2021-076098 discloses a blower that blows out dust and the like with a compressed air.
The blower as described above can draw an air from a pneumatically inflated structure, such as a floating tube, to thereby deflate the pneumatically inflated structure, if an air needle is connected to an air suction port of the blower and is inserted into the pneumatically inflated structure.
In a case in which the blower is used as a deflator, when the air is completely evacuated from the pneumatically inflated structure, there is no longer airflow flowing into the blower. Consequently, a load applied to the motor decreases, and a rotational frequency of the motor abruptly increases. In addition to that, heat generated in the motor is not released from the blower. If the motor is kept operating in such a circumstance, a failure may be generated in the motor.
In one aspect of the present disclosure, it is desirable to suppress a motor failure generated in a blower due to the blower being used to draw an air from a pneumatically inflated structure.
One aspect of the present disclosure provides a blower including a housing, a motor in the housing, a fan in the housing, a motor drive circuit, and a control circuit. The housing includes a suction port and a discharge port. The suction port and the discharge port communicate an inside of the housing with an outside of the housing. The fan is rotationally driven by the motor to thereby generate an airflow from the suction port to the discharge port. The motor drive circuit receives an electric power and drives the motor based on the electric power received. The control circuit detects an insufficient airflow (or an insufficient air) from the suction port to the discharge port based on an operation parameter. The operation parameter is associated with an operation of the motor.
The blower as described above can detect the insufficient airflow. This allows a user of the blower to take a preventive measure for suppressing a motor failure due to the insufficient airflow.
Another aspect of the present disclosure provides a method including: driving a motor of a blower; and detecting an insufficient airflow in a housing of the blower based on an operation parameter, the operation parameter being associated with an operation of the motor.
The method as described above makes it possible to detect the insufficient airflow. This allows the user of the blower to take the preventive measure for suppressing the motor failure due to the insufficient airflow.
An example embodiment of the present disclosure will be described hereinafter by way of example with reference to the accompanying drawings, in which:
One embodiment may provide a blower (or an inflator) including at least any one of the following features 1 through 6:
The blower including at least the features 1 through 6 can detect the insufficient airflow. This allows a user of the blower to take a preventive measure for suppressing a motor failure due to the insufficient airflow.
The operation parameter may be any parameter that is associated with the operation of the motor.
One embodiment may include, in addition to or in place of at least any one of the features 1 through 6, at least any one of the following features 7 through 10:
The blower including at least the features 1 through 10 can detect the insufficient airflow based on the actual rotational frequency of the motor.
One embodiment may include, in addition to or in place of at least any one of the features 1 through 10, the following feature 11:
One embodiment may include, in addition to or in place of at least any one of the features 1 through 11, at least any one of the following features 12 through 15:
The blower including at least the features 1 through 6, and 12 through 15 can detect the insufficient airflow based on the magnitude of the drive current.
One embodiment may include, in addition to or in place of at least any one of the features 1 through 15, at least any one of the following features 16 through 18:
The blower including at least the features 1 through 6, and 16 through 18 can drive the motor in accordance with the designated power. The designated power may be fixed or may be variable.
One embodiment may include, in addition to or in place of at least any one of the features 1 through 18, at least any one of the following features 19 through 21:
The blower including at least the features 1 through 6, and 16 through 21 can drive the motor based on the output duty ratio.
One embodiment may include, in addition to or in place of at least any one of the features 1 through 21, the following feature 22 and/or feature 23:
In the blower including at least the features 1 through 6, 16 through 18, 22, and 23, when the insufficient airflow occurs and a load applied to the fan, and consequently to the motor decreases, the actual rotational frequency of the motor increases due to the magnitude of the delivered power being maintained at the magnitude of the designated power. Such a blower can certainly detect the insufficient airflow.
One embodiment may include, in addition to or in place of at least any one of the features 1 through 23, at least any one of the following features 24 through 27:
The blower including at least the features 1 through 6, 16 through 18, and 22 through 27 can certainly detect the insufficient airflow based on the drive duty ratio.
One embodiment may include, in addition to or in place of at least any one of the features 1 through 27, the following feature 28 and/or feature 29:
In the blower including at least the features 1 through 6, 16 through 18, 28, and 29, the user can vary the power designating signal with the manual switch to thereby vary the magnitude of the electric power to be delivered to the motor.
One embodiment may include, in addition to or in place of at least any one of the features 1 through 29, at least any one of the following features 30 through 32:
The blower including at least the features 1 through 6, and 30 through 32 allows the user to insert the air needle into a pneumatically inflated structure to draw an air from the pneumatically inflated structure.
One embodiment may include, in addition to or in place of at least any one of the features 1 through 32, at least any one of the following features 33 to 35:
The blower including at least the features 1 through 6, and 30 through 35 allows the user to insert the air needle into the pneumatically inflated structure distant from the blower, and to draw the air from the pneumatically inflated structure.
One embodiment may include, in addition to or in place of at least any one of the features 1 through 35, the following Feature 36:
The blower including at least the features 1 through 6 and 36 can reduce the actual rotational frequency or stop the motor, when the insufficient airflow occurs, to thereby suppress the motor failure.
One embodiment may include, in addition to or in place of at least any one of the features 1 through 36, the following feature 37:
One embodiment may include, in addition to or in place of at least any one of the features 1 through 37, the following feature 38:
In one embodiment, the control circuit may be integrated into a single electronic unit, a single electronic device, or a single circuit board.
In one embodiment, the control circuit may be a combination of two or more electronic circuits, of two or more electronic units, or of two or more electronic devices, each of which is individually disposed on the blower or in the blower.
In one embodiment, the control circuit may include a microcomputer.
In one embodiment, the control circuit may include, in place of or in addition to the microcomputer, a combination of electronic components, such as discrete devices, an application specific integrated circuit (ASIC), an application specific standard product (ASSP), a programmable logic device, such as a field programmable gate array (FPGA), or any combination thereof.
Examples of the motor include a brushed DC motor, a brushless DC motor, and an AC motor.
Examples of the motor drive circuit include any forms of bridge circuits including a half-bridge circuit and a full-bridge circuit, and any forms of semiconductor switches.
One embodiment may provide a method including at least any one of the following features 39 through 41:
The method including at least the features 39 through 41 makes it possible to suppress a motor failure generated in the blower when an air is completely evacuated from a pneumatically inflated structure with the blower.
One embodiment may include, in addition to or in place of at least any one of the features 39 through 41, the following feature 42 and/or feature 43:
The method including at least the features 39 through 43 makes it possible to detect the insufficient airflow based on the actual rotational frequency, the magnitude of the drive current, and/or the drive duty ratio.
One embodiment may include, in addition to or in place of at least any one of the features 39 through 43, the following feature 44:
The method including at least the features 39 through 41, and 44 makes it possible to suppress the motor failure due to the insufficient airflow.
In one embodiment, the features 1 through 44 may be in any combination.
In one embodiment, any of the features 1 through 44 may be omitted. Examples of the pneumatically inflated structure include, but are not limited to, a floating tube, an inflatable ball, an inflatable pool, an inflatable boat, a balloon, an inflatable toy, a pneumatic tire, an air-supported structure, an air mattress, and a vacuum bag.
A description will be given below of a specific exemplary embodiment.
This specific exemplary embodiment is merely an example, and the present disclosure is not limited to this embodiment and may be implemented in any forms.
2-1. Schematic Structure
As shown in
The blower 1 includes a main body 2. The main body 2 includes a housing 4.
The housing 4 includes a storage 11. In the present embodiment, the storage 11 has a cylindrical shape extending along an axis AR.
The housing 4 includes a discharge portion 12. The discharge portion 12 extends along the axis AR at a position anterior to the storage 11. The discharge portion 12 has a diameter smaller than that of the storage 11. The discharge portion 12 includes a front end that has a first discharge port 12a through which an air is discharged. The axis AR runs through the first discharge port 12a.
The housing 4 includes a suction portion 13. The suction portion 13 covers an opening at a rear end of the storage 11. The suction portion 13 includes two or more first suction ports 13a that penetrate through the suction portion 13 to introduce an air outside the blower 1 into the storage 11.
The housing 4 includes a connector 14. The connector 14 is interposed between the storage 11 and the discharge portion 12, and connects the storage 11 to the discharge portion 12. The connector 14 has a shape of a funnel, and an outer diameter of the connector 14, which is perpendicular to the axis AR, gradually reduces as going from a rear end of the connector 14 toward a front end thereof.
The housing 4 includes an attachment fitting portion 15. The attachment fitting portion 15 surrounds an outer peripheral surface of the discharge portion 12.
As shown in
The main body 2 includes a handgrip 5. The handgrip 5 downwardly extends from the housing 4. The handgrip 5 is formed so as to be gripped by a user of the blower 1 in one hand.
The main body 2 includes a trigger 6. The trigger 6 is arranged at an upper frontward position with respect to the handgrip 5 and is manually operated by the user to drive the blower 1. The trigger 6 is arranged so as to be pulled by a finger of the user while the handgrip 5 is gripped by the user.
The main body 2 includes a battery attachment part 7. The battery attachment part 7 is arranged at a lower end of the handgrip 5. A battery pack 3 is detachably attached to the battery attachment part 7. The battery pack 3 supplies a DC power to the main body 2.
The main body 2 includes an operation panel 8. In the present embodiment, the operation panel 8 is arranged on the battery attachment part 7.
The operation panel 8 includes a mode changeover switch 9. The mode changeover switch 9 is manually operated by the user to select operation modes of the blower 1. In the present embodiment, the mode changeover switch 9 is configured to be pressed by the user. The mode changeover switch 9 may include a tactile switch and may be in an ON state only while the user presses and holds down the mode changeover switch 9. In other embodiments, the mode changeover switch 9 may be configured to be manually slid or manually rotated by the user to select the operation modes.
The operation panel 8 includes a mode indicator 10. The mode indicator 10 is configured to indicate an operation mode selected. In the present embodiment, the mode indicator 10 includes four LEDs and is configured to individually turn on or off these LEDs to thereby indicate the operation mode selected. In other embodiments, the mode indicator 10 may include an indicator in any other form, such as a liquid crystal display (LCD), and the operation panel 8 may be arranged at any other position in the main body 2, such as on the housing 4 or on the handgrip 5.
As shown in
The air needle 23 includes a fitting portion 23a. The fitting portion 23a has a cylindrical shape. The fitting portion 23a includes a front end that is connected to the rear end opening of the air suction hose 22.
The air needle 23 includes an insertion portion 23b. The insertion portion 23b includes a front end that is connected to a rear end of the fitting portion 23a. The insertion portion 23b has a shape of a funnel whose diameter gradually reduces as going from the front end of the insertion portion 23b toward a rear end thereof. The rear end of the insertion portion 23b includes a second suction port 23c for introducing an air. When an air is drawn from the pneumatically inflated structure, the rear end of the insertion portion 23b (in other words, a tip of the air needle 23) is inserted into the air introduction port of the pneumatically inflated structure.
As shown in
The blower 1 includes a control board 33 for controlling the motor unit 31. In the present embodiment, the control board 33 is accommodated in the battery attachment part 7. In other embodiments, the control board 33 may be arranged at any other position in the main body 2, such as inside the housing 4 or inside the handgrip 5.
2-2. Electrical Configuration
As shown in
The motor unit 31 includes a drive board 42. The drive board 42 includes a motor drive circuit 44. The motor drive circuit 44 receives the DC power from a battery 36 in the battery pack 3 via a power line 34 and a ground line 35, and delivers a DC current (hereinafter, to be referred to as a drive current) to three phase windings of the motor 41, which are not shown. The power line 34 is a current path from a positive electrode of the battery 36 to the motor drive circuit 44. The ground line 35 is a current path from a negative electrode of the battery 36 to the motor drive circuit 44.
The motor drive circuit 44 receives a power designating signal output from the control board 33.
The power designating signal in the present embodiment is in the form of a pulse width modulation (PWM) signal. The power designating signal has an output duty ratio (that is, an actual duty ratio) that varies based on a magnitude of a designated power. The motor drive circuit 44 delivers, to the motor 41, a DC power (hereinafter, to be referred to as a delivered power) in accordance with the above-described power designating signal to thereby rotate the motor 41. In addition, the motor drive circuit 44 performs a constant power control that regulates a magnitude of the delivered power to be achieved to and maintained at the magnitude of the designated power. In the present embodiment, the motor drive circuit 44 performs, as the constant power control, a closed loop control (or a feedback control) for the delivered power.
As shown in detail in
The motor drive circuit 44 includes a voltage measurement circuit 442.
The voltage measurement circuit 442 measures a value of the voltage of the power line 34.
The motor drive circuit 44 includes a current measurement circuit 443. The current measurement circuit 443 measures a value of the drive current flowing through the ground line 35. In other embodiments, the current measurement circuit 443 may measure a value of the drive current flowing through the power line 34.
The motor drive circuit 44 includes a multiplier 444. The multiplier 444 takes (i) the value of the voltage measured by the voltage measurement circuit 442 and (ii) the value of the drive current measured by the current measurement circuit 443, and produces their product (corresponding to the magnitude of the delivered power). The multiplier 444 may be in the form of an analog multiplier or may be in the form of a digital multiplier.
The motor drive circuit 44 includes a switching signal generator 445.
The switching signal generator 445 (i) receives the produced product and the power designating signal and (ii) generates first through sixth switching signals. The first through third switching signals correspond to the respective high-side switches, and turn on and off the corresponding high-side switches. The fourth through sixth switching signals correspond to the respective low-side switches, and turn on and off the corresponding low-side switches. The first through third switching signals and/or the fourth through sixth switching signals are in the form of PWM signals. The switching signal generator 445 determines a drive duty ratio in such a manner that an error between the produced product and the magnitude of the designated power indicated by the power designating signal is minimized (preferably to zero or near zero). The switching signal generator 445 generates the first through third switching signals and/or the fourth through sixth switching signals each having the drive duty ratio determined. Accordingly, the drive duty ratio affects an effective voltage applied to the motor 41. The switching signal generator 445 may be configured to output, to the control circuit 51, a feedback signal indicating the drive duty ratio, as indicated by the dashed line arrow. The switching signal generator 445 may include a microcomputer and/or a hardwired circuit. In other embodiments, the switching signal generator 445 may be integrated with the multiplier 444 and/or the three-phase full-bridge circuit 441.
The motor drive circuit 44 achieves the constant power control with the above-described circuit configuration. In other embodiments, the motor drive circuit 44 may perform the constant power control with a circuit configuration in any other form. In other embodiments, the power designating signal may be in the form of an analog signal having a variable voltage that varies based on the magnitude of the designated power. Alternatively, the power designating signal may be in the form of a serial communication signal indicating the magnitude of the designated power.
Referring back to
The drive board 42 includes a rotational frequency detection circuit 45.
The rotational frequency detection circuit 45 receives the first through third rotational position signals, and then generates and outputs a rotational frequency signal based on the rotational position signals to the control board 33. In the present embodiment, the rotational frequency signal is in the form of a pulse train. The number of pulses included in the pulse train varies in accordance with an actual rotational frequency of the motor 41. In other embodiments, the rotational frequency signal may be a signal in any other form, such as an analog signal having a variable voltage in accordance with the actual rotational frequency of the motor 41.
The control board 33 includes a control circuit 51. In the present embodiment, the control circuit 51 is in the form of a microcomputer or a micro control unit (MCU), each of which includes a CPU 61, a ROM 62, a RAM 63, and the like. Various functions of the control circuit 51 are achieved by the CPU 61 executing a program stored in the ROM 62. Due to the execution of this program, a method corresponding to the program is performed. The ROM 62 corresponds to one example of a non-transitory tangible storage medium storing the program. In other embodiments, a part of or entire functions executed by the CPU 61 may be achieved by one or more electronic components, such as a discrete device and an integrated circuit (IC), and the control circuit 51 may include one or more additional microcomputers or one or more additional MCUs, or the control circuit 51 may be in the form of a hardwired circuit.
The control board 33 includes a shunt resistor 52. The shunt resistor 52 is arranged on the ground line 35.
The control board 33 includes a current detection circuit 53. The current detection circuit 53 outputs, to the control circuit 51, a current detection signal based on a voltage across the shunt resistor 52. The current detection signal has a variable voltage that varies in accordance with the voltage across the shunt resistor 52, that is, a magnitude of the drive current flowing through the motor 41.
The control board 33 includes a switch device 54 on the power line 34.
The switch device 54 is switched between an ON state and an OFF state in accordance with a drive signal output from the control circuit 51. The switch device 54 in the ON state completes the power line 34. The switch device 54 in the OFF state interrupts the power line 34. In the present embodiment, the switch device 54 is an N-channel metal oxide semiconductor field-effect transistor (MOSFET). In other embodiments, the switch device 54 may be a semiconductor switch in any other form, such as a bipolar transistor, an IGBT, or an SSR, or may be a mechanical relay.
The blower 1 includes a trigger switch 37. The trigger switch 37 is turned on in response to the trigger 6 being pulled. The trigger switch 37 outputs a trigger-ON signal and a trigger level signal to the control circuit 51. The trigger-ON signal is a binary signal indicating whether the trigger switch 37 being turned on. The trigger level signal has a variable voltage that varies in accordance with a pulled distance of the trigger 6 (hereinafter, to be referred to as a trigger level).
In the operation panel 8, the mode changeover switch 9 outputs a mode changeover signal to the control circuit 51. The mode changeover signal is a binary signal indicating whether the mode changeover switch 9 being manually operated (in the present embodiment, whether the mode changeover switch 9 being pressed). The mode indicator 10 displays the selected operation mode on the mode indicator 10 in accordance with a display signal output from the control circuit 51. The display signal indicates the selected operation mode. In the present embodiment, the mode indicator 10 lights at least one LED that corresponds to the operation mode indicated by the display signal.
2-3. Details of Blower Control Process
Descriptions are given below of a blower control process executed by the CPU 61 of the control circuit 51. The blower control process is repeatedly executed every time a predetermined control period (for example, 1 ms) elapses.
As shown in
Subsequently, in S20, the CPU 61 executes an analog-to-digital (A-D) conversion process. In the A-D conversion process, the CPU 61 converts the variable voltage of the current detection signal from the current detection circuit 53 into a digital value and stores the digital value in the RAM 63. This digital value indicates the magnitude of the drive current flowing through the motor 41. The CPU 61 further converts the variable voltage of the trigger level signal from the trigger switch 37 into a digital value and stores the digital value in the RAM 63. This digital value indicates the trigger level.
Subsequently, in S30, the CPU 61 executes a fault detection process.
In the fault detection process, the CPU 61 detects a fault, such as an occurrence of an overcurrent, based on the magnitude of the drive current obtained through the A-D conversion process in S20.
Subsequently, in S40, the CPU 61 executes a motor control process, which will be described in detail later.
Subsequently, in S50, the CPU 61 executes a mode setting process. In the mode setting process, the CPU 61 switches the operation modes of the blower 1 based on the state of the mode changeover switch 9 detected through the switch operation detection process in S10.
Subsequently, in S60, the CPU 61 executes a display process. In the display process, the CPU 61 outputs the display signal to the mode indicator 10 and displays the selected operation mode on the mode indicator 10. Upon completion of the display process, the CPU 61 finishes the blower control process.
Detailed descriptions will be given below of the motor control process executed in S40.
As shown in
Subsequently, in S120, the CPU 61 determines whether the trigger switch 37 is in the ON state. If the trigger switch 37 is in the OFF state (S120: NO), the CPU 61, in S130, clears an insufficient airflow detection flag F1, which is stored in the RAM 63, and finishes the motor control process. The insufficient airflow detection flag F1 indicates whether an insufficient airflow from the two or more first suction ports 13a to the first discharge port 12a (or an insufficient air around the fan 32) is detected. In the present embodiment, a state in which the insufficient airflow detection flag F1 is cleared means that the insufficient airflow is not detected, whereas a state in which the insufficient airflow detection flag F 1 is set means that the insufficient airflow is detected.
If the trigger switch 37 is in the ON state in S120 (S120: YES), the CPU 61, in S140, determines whether the trigger switch 37 is switched from the OFF state to the ON state. If the trigger switch 37 is not switched from the OFF state to the ON state (S140: NO), the CPU 61 proceeds to a process of S160.
If the trigger switch 37 is switched from the OFF state to the ON state (S140: YES), the CPU 61, in S150, sets a variable duty ratio stored in the RAM 63 to an initial value and proceeds to the process of S160. The initial value is predetermined.
In S160, the CPU 61 executes a soft-start process shown in
As shown in
In the present embodiment, the trigger level is set at any one of twenty-one levels (namely, levels ranging from level 0 through level 20). Specifically, level 0 corresponds to a non-pulled distance in which the trigger 6 is not pulled at all or to a small pulled distance considered as equivalent to the non-pulled distance. Level 20 corresponds to the maximum pulled distance of the trigger 6. In other embodiments, the trigger level may be set at any one of twenty or less of the levels, or at any one of twenty-two or more of the levels.
In the present embodiment, the operation modes of the blower 1 includes first-through fourth-speed modes. Every time the mode changeover switch 9 is manually operated, the CPU 61 switches the operation modes in a cyclic manner in the order of the first-speed mode, the second-speed mode, the third-speed mode, the fourth-speed mode, and back to the first-speed mode. In the first-speed mode, the maximum rotational frequency of the motor 41 is set at the lowest among the first-through fourth-speed modes. In the fourth-speed mode, the maximum rotational frequency of the motor 41 is set at the highest among the first-through fourth-speed modes. In other embodiments, the operation modes may include three or less of the speed modes or five or more of the speed modes.
As shown in Graph G1 in
In each operation mode, the designated power is set so as to be increased as the trigger level goes higher. The designated power associated with each trigger level is the smallest in the first-speed mode and is the largest in the fourth-speed mode (specifically, the first-speed mode<the second-speed mode<the third-speed mode<the fourth-speed mode).
The desired duty ratio is associated with the magnitude of the designated power. As exemplified by Graph G1, in response to the fourth-speed mode being selected and the trigger level being set at level 8, the CPU 61 sets the desired duty ratio to a value associated with 100 watts of the designated power.
Referring back to
If the variable duty ratio is smaller than the desired duty ratio (S320: YES), the CPU 61, in S330, adds a first correction value, which is preset, to the variable duty ratio to thereby increase the variable duty ratio and finishes the soft-start process.
If the variable duty ratio, in S320, is equal to or greater than the desired duty ratio (S320: NO), the CPU 61, in S340, sets the desired duty ratio to the variable duty ratio and finishes the soft-start process.
Referring back to
As shown in
If the operation parameter indicates the occurrence of the overspeed (S410: YES), the CPU 61, in S420, adds an increment value, which is preset, to a second correction value stored in the RAM 63 to thereby increase the second correction value and then proceeds to a process of S440.
If the operation parameter does not indicate the occurrence of the overspeed (S410: NO), the CPU 61, in S430, subtracts a decrement value, which is preset, from the second correction value to thereby reduce the second correction value and then proceeds to the process of S440. In the present embodiment, the second correction value is equal to or greater than zero. Thus, in a case where a value obtained by subtracting the decrement value from the second correction value is smaller than zero (i.e. a negative value), the CPU 61 sets the second correction value to zero.
In S440, the CPU 61 subtracts the second correction value from the variable duty ratio to thereby reduce the variable duty ratio and then finishes the overspeed suppression process.
Referring back to
If the trigger level has varied (S190: YES), the CPU 61, in S200, sets the variable duty ratio to an output duty ratio of the power designating signal, outputs the power designating signal and then finishes the motor control process.
If the trigger level has not varied (S190: NO), the CPU 61, in S210, determines whether an insufficient airflow condition, which is predetermined, is established. In the present embodiment, the insufficient airflow condition is established when a variation in the operation parameter at the current period of time relative to the operation parameter prior to a specified period of time is equal to or greater than a predetermined threshold. In the present embodiment, the insufficient airflow condition is established when an increase in the actual rotational frequency is equal to or greater than the threshold. In other embodiments, the insufficient airflow condition may be established when a decrease in the drive current and/or an increase in the drive duty ratio, in addition to or in place of the increase in the actual rotational frequency, are/is equal to or greater than the corresponding thresholds/threshold.
If the insufficient airflow condition is not established (S210: NO), the CPU 61 proceeds to the process of S200. If the insufficient airflow condition is established (S210: YES), the CPU 61, in S220, performs a preventive measure for suppressing a failure in the motor 41. In the present embodiment, the CPU 61, in S220, sets the output duty ratio to a fixed duty ratio, which is preset to protect the motor 41, and outputs the power designating signal having such an output duty ratio. In other embodiments, the CPU 61, in S220, may stop the motor 41, may notify the user via the mode indicator 10 that the insufficient airflow has been detected, or may set the blower 1 to an operation mode, such as the first-speed mode or the second-speed mode, in which the maximum rotational frequency of the motor 41 is low. Upon completion of the process of S220, the CPU 61, in S230, sets the insufficient airflow detection flag F1 and then finishes the motor control process.
If the insufficient airflow detection flag F1 is set in S180 (S180: YES), the CPU 61, in S240, determines whether the fixed duty ratio is greater than the variable duty ratio.
If the fixed duty ratio is equal to or less than the variable duty ratio (S240: NO), the CPU 61 proceeds to the process of S220.
If the fixed duty ratio is greater than the variable duty ratio (S240: YES), the CPU 61, in S250, sets the variable duty ratio to the output duty ratio of the power designating signal and outputs, to the motor drive circuit 44, the power designating signal having such an output duty ratio. Subsequently, in S260, the CPU 61 clears the insufficient airflow detection flag F1 and then finishes the motor control process.
2-4. Summary of Operation
Graph G2 in
As shown in Graph G2, in this example, in response to the trigger 6 started to be pulled at Time t20, the actual rotational frequency abruptly increases. The actual rotational frequency exceeds an upper-limit rotational frequency R21 at Time t21 and reaches a peak rotational frequency R22 at Time t22. The actual rotational frequency decreases thereafter and converges to the upper-limit rotational frequency R21 at and after Time t23. The reason the actual rotational frequency converges to the upper-limit rotational frequency R21 is that an overspeed suppression function equipped on the motor unit 31 is activated.
Graph G3 in
In the blower 1, in response to the trigger 6 started to be pulled while the motor 41 is stopped, the soft-start process is executed and the output duty ratio gradually increases. Solid line L31 in Graph G3 indicates a variation in the output duty ratio over time. Solid line L32 in Graph G3 indicates a variation in the actual rotational frequency over time.
As shown in Graph G3, in response to the trigger 6 started to be pulled at Time t30, the output duty ratio gradually increases toward a desired duty ratio D31. Subsequently, the actual rotational frequency exceeds an upper-limit rotational frequency R31 at Time t31. In response to the actual rotational frequency having exceeded the upper-limit rotational frequency R31, the output duty ratio turns from increasing to decreasing at Time t31 when the output duty ratio does not yet reach the desired duty ratio D31. Consequently, the actual rotational frequency reaches a peak rotational frequency R32 at Time t32 and decreases thereafter.
In response to the actual rotational frequency having fallen below the upper-limit rotational frequency R31 at Time t33, the output duty ratio turns from decreasing to increasing. In response to the actual rotational frequency having reached the upper-limit rotational frequency R31 at Time t34, the output duty ratio turns from increasing to decreasing. The output duty ratio repeats increasing and decreasing in this way, and the actual rotational frequency converges to the upper-limit rotational frequency R31.
The blower 1 of the present embodiment executes the soft-start process and the overspeed suppression process, as shown in Graph G3 in
In the present embodiment, the actual rotational frequency in the blower 1 needs to be high so that a sufficient airflow can be generated solely by the single fan 32. Accordingly, the actual rotational frequency is slightly lower than the reference value (for example, 80,000 rpm). In other words, the actual rotational frequency easily exceeds the reference value. Thus, the blower 1 can effectively suppress the failure in the motor 41 through the overspeed suppression process.
Graph G4 shown in
Solid line L41 in Graph G4 indicates a variation in the output duty ratio over time, in a case where the insufficient airflow condition is established and the protection of the motor 41 is performed. Dotted line L42 indicates a variation in the trigger level over time. Dotted line L43 indicates a variation in the actual rotational frequency over time, in a case where the insufficient airflow condition is not established. Dotted line L44 indicates a variation in the actual rotational frequency over time, in a case where the insufficient airflow condition is established. Solid line L45 indicates a variation in the actual rotational frequency over time, in a case where the insufficient airflow condition is established and the protection of the motor 41 is performed.
As shown in Graph G4, the trigger 6 starts to be pulled at Time t40, and the trigger level gradually increases until Time t41. The trigger level is maintained thereafter.
With the variation in the trigger level as described above, the output duty ratio starts to gradually increase, at Time t40, in accordance with the trigger level, and reaches a duty ratio D41 at Time t41. The output duty ratio is maintained at the duty ratio D41 thereafter.
The actual rotational frequency starts to gradually increase at Time t40, and reaches a rotational frequency R41 at Time t42. The actual rotational frequency is maintained at the rotational frequency R41 thereafter.
In response to the insufficient airflow having occurred at Time t43, the actual rotational frequency increases despite that the trigger level and the output duty ratio are not varying.
Subsequently, in response to the insufficient airflow having been detected at Time t44 when the actual rotational frequency reaches a rotational frequency R42, the output duty ratio rapidly decreases from the duty ratio D41 to a duty ratio D42, as indicated by Solid line L41. Consequently, as indicated by Solid line L45, the actual rotational frequency rapidly decreases and the failure in the motor 41 can be suppressed.
The blower 1 configured as described above can perform a preventive measure for suppressing a failure in the motor 41 when the insufficient airflow is detected, and can suppress the failure in the motor 41.
In the blower 1, in response to no air flowing in the housing 4 and a load applied to the motor 41 decreasing, the actual rotational frequency increases due to the magnitude of the delivered power maintained at the magnitude of the designated power. The blower 1 can detect the insufficient airflow based on the increase in the actual rotational frequency.
In the motor control process, in response to the detection of the insufficient airflow, the actual rotational frequency is reduced. The blower 1 can therefore suppress the failure in the motor 41 due to the insufficient airflow.
2-5. Correspondence between Terms
In the present embodiment, at least one of the two or more first suction ports 13a corresponds to one example of the suction port in the overview of embodiments. A combination of the trigger 6 with the trigger switch 37 corresponds to one example of the manual switch in the overview of embodiments. A combination of the air needle 23 with the air suction hose 22 corresponds to one example of the attachment in the overview of embodiments.
2-6. Variations
In the above embodiment, the motor drive circuit 44 may be configured not to perform the constant power control. In such a case, in response to the occurrence of the overspeed of the motor 41, the magnitude of the drive current can decrease to the reference value or less. Accordingly, the control circuit 51 may determine, in S410 shown in
In the above embodiment, the magnitude of the designated power may be fixed.
In the above embodiment, the blower 1 may be a non-handheld blower.
2-7. Complementary Description
Two or more functions of a single element in the above embodiments may be achieved by two or more elements, or a single function of a single element may be achieved by two or more elements. Two or more functions of two or more elements in the above embodiments may be achieved by a single element, or a single function achieved by two or more elements may be achieved by a single element. A part of the configurations of the above embodiments may be omitted. At least a part of the configuration(s) of one embodiment described above may be added to or replaced with the configuration(s) of another embodiment described above.
Besides the blower 1 as described above, the present disclosure can be implemented in various forms including a system that includes the blower 1, a program for functioning a computer as a part of the blower 1, a non-transitory tangible storage medium, such as a semiconductor memory, storing such a program, and a controlling method.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2021-144116 | Sep 2021 | JP | national |
| 2022-132826 | Aug 2022 | JP | national |
