Patent Publication Number: US-2023158523-A1

Title: Mist blower

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of Japanese Patent Application No. 2021-190297 filed on Nov. 24, 2021 with the Japan Patent Office and Japanese Patent Application No. 2022-108451 filed on Jul. 5, 2022 with the Japan Patent Office, the entire disclosures of which are incorporated herein by reference. 
     BACKGROUND 
     The present disclosure relates to a mist blower. 
     Japanese Unexamined Patent Application Publication No. 2016-182090 discloses a backpack-type mist blower including a blower unit, a tank, an air feed pipe, a liquid feed pipe, and a manual valve. The blower unit is drived by an engine and generates an airflow into the air feed pipe. The tank contains liquid to be sprayed. The tank communicates with the air feed pipe via the liquid feed pipe. The manual valve is operated manually by a user of the mist blower to open and close the liquid feed pipe. In such a mist blower, when the user opens the manual valve and starts the engine, the liquid inside the tank is sucked towards a head aperture of the air feed pipe via the liquid feed pipe by the atmospheric pressure inside the tank and the negative pressure generated inside the air feed pipe, and the liquid is sprayed from the head aperture in atomized form. 
     SUMMARY 
     In the aforementioned mist blower, if the user fails to close the manual valve when the engine is stopped, the liquid may leak from the liquid feed pipe into the air feed pipe. In a case of a mist blower that carries an electric motor instead of an engine, if the user fails to close the manual valve when the electric motor is stopped, the liquid may leak from the liquid feed pipe into the air feed pipe. 
     Desirably, one aspect of the present disclosure is to provide a technique that can inhibit a leakage of a liquid from a liquid feed pipe into an air feed pipe of a mist blower at an inappropriate timing. 
     One aspect of the present disclosure provides a mist blower including an air blower, an air feed pipe, a tank, a liquid feed pipe, a nozzle, a first electromagnetic valve, a controller, and a first manual switch. The air blower (i) generates or increases an airflow in response to the air blower being activated and (ii) stops or decreases the airflow in response to the air blower being deactivated. The air feed pipe (i) has a first discharge port and (ii) guides the airflow from the air blower to the first discharge port. The tank holds a liquid therein. The liquid feed pipe (i) has an inflow port and an outflow port and (ii) guides the liquid from the inflow port to the outflow port. The inflow port is connected to the tank. The nozzle (i) has a second discharge port and (ii) is connected to the outflow port. The second discharge port is arranged in the air feed pipe so as to discharge the liquid in the liquid feed pipe into the air feed pipe by a negative pressure generated by the airflow flowing through the air feed pipe. The first electromagnetic valve opens the liquid feed pipe in response to the first electromagnetic valve being activated. The first electromagnetic valve closes the liquid feed pipe in response to the first electromagnetic valve being deactivated. The controller activates or deactivates the air blower and the first electromagnetic valve. The first manual switch is manually moved by a user of the mist blower. The first manual switch commands the controller to activate or deactivate the air blower based on a movement of the first manual switch. 
     In such a mist blower, the first electromagnetic valve is activated or deactivated by the controller, and accordingly, the liquid feed pipe is opened or closed by the controller. Therefore, this mist blower can inhibit, by the controller, a leakage of the liquid from the liquid feed pipe into the air feed pipe at an inappropriate timing. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Example embodiments of the present disclosure will be described hereinafter with reference to the accompanying drawings, in which: 
         FIG.  1    is a perspective view schematically showing an outer view of a mist blower in a first embodiment; 
         FIG.  2    is a front view schematically showing the outer view of the mist blower in the first embodiment; 
         FIG.  3    is a schematic drawing showing an air passage and a liquid passage of the mist blower in the first embodiment; 
         FIG.  4    is a block diagram showing an electrical configuration of the mist blower in the first embodiment; 
         FIG.  5    is a flow chart showing a first control process in the first embodiment; 
         FIG.  6    is a flow chart showing a faulty temperature detection process in the first embodiment; 
         FIG.  7    is a flow chart showing a faulty electric current detection process in the first embodiment; 
         FIG.  8    is a flow chart showing a second control process in a second embodiment; 
         FIG.  9    is a flow chart showing a third control process in the second embodiment; 
         FIG.  10    is a schematic drawing showing an air passage and a liquid passage of a mist blower in a third embodiment; 
         FIG.  11    is a schematic drawing showing an air passage and a liquid passage of a mist blower in a fourth embodiment; 
         FIG.  12    is a block diagram showing an electrical configuration of the mist blower in the fourth embodiment; 
         FIG.  13    is a table with liquid volume levels in association with respective opening levels of a first electromagnetic valve; 
         FIG.  14    is a flow chart showing a fourth control process in the fourth embodiment; 
         FIG.  15    is a flow chart showing a faulty flow rate detection process in the fourth embodiment; 
         FIG.  16    is a schematic drawing showing an air passage and a liquid passage of a mist blower in a fifth embodiment; 
         FIG.  17    is a block diagram showing an electrical configuration of the mist blower in the fifth embodiment; 
         FIG.  18    is a flow chart showing a fifth control process in the fifth embodiment; 
         FIG.  19    is a flow chart showing a sixth control process in a sixth embodiment; 
         FIG.  20    is a schematic drawing showing a partial configuration of a mist blower in a seventh embodiment; 
         FIG.  21    is a flow chart showing a seventh control process in the seventh embodiment; 
         FIG.  22    is a flow chart showing an eighth control process in the seventh embodiment; and 
         FIG.  23    is a flow chart showing a ninth control process in an eighth embodiment. 
     
    
    
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     1. Overview of Embodiments 
     One embodiment may provide a mist blower (or a spray or a sprayer or an atomizer) including at least any one of:
         Feature 1: an air blower configured (i) to generate or increase an airflow in response to the air blower being activated and (ii) to stop or decrease the airflow in response to the air blower being deactivated;   Feature 2: an air feed pipe (i) having a first discharge port and (ii) configured to guide the airflow from the air blower to the first discharge port;   Feature 3: a tank configured to hold a liquid therein;   Feature 4: a liquid feed pipe (i) having an inflow port and an outflow port and (ii) configured to guide the liquid from the inflow port to the outflow port, the inflow port being connected to (or being in communication with) the tank;   Feature 5: a nozzle (i) having a second discharge port and (ii) connected to the outflow port, the second discharge port being arranged in the air feed pipe so as to discharge the liquid in the liquid feed pipe into the air feed pipe by a negative pressure (or a low pressure or a decreased pressure) generated by the airflow flowing through the air feed pipe;   Feature 6: a first electromagnetic valve configured (i) to open the liquid feed pipe in response to the first electromagnetic valve being activated and (ii) to close the liquid feed pipe in response to the first electromagnetic valve being deactivated;   Feature 7: a controller configured to activate or deactivate the air blower and the first electromagnetic valve; and   Feature 8: a first manual switch configured to be manually moved by a user of the mist blower, the first manual switch being configured to command the controller (or transmit a command to the controller) to activate or deactivate the air blower based on a movement of the first manual switch.       

     The mist blower including at least the features 1 through 8 can inhibit, by the controller, a leakage of the liquid from the liquid feed pipe into the air feed pipe at an inappropriate timing. 
     One embodiment may include, in addition to or in place of at least any one of the aforementioned features 1 through 8,
         Feature 9: the controller is configured (i) to activate the first electromagnetic valve in association with an activation of the air blower and (ii) to deactivate the first electromagnetic valve in association with a deactivation of the air blower.       

     In the mist blower including at least the features 1 through 9, the liquid feed pipe can be opened in association with the activation of the air blower and can be closed in association with the deactivation of the air blower. 
     One embodiment may include, in addition to or in place of at least any one of the aforementioned features 1 through 9, at least any one of:
         Feature 10: the first manual switch is configured to be manually moved between a first position and a second position by the user, the second position being distinct from the first position;   Feature 11: the controller is configured to activate the air blower and the first electromagnetic valve based on the first manual switch being in the first position; and   Feature 12: the controller is configured to deactivate the air blower and the first electromagnetic valve based on the first manual switch being in the second position.       

     In the mist blower including at least the features 1 through 12, the user can activate the air blower and the first electromagnetic valve by moving the first manual switch to the first position. The user can also deactivate the air blower and the first electromagnetic valve by moving the first manual switch to the second position. 
     One embodiment may include, in addition to or in place of at least any one of the aforementioned features 1 through 12, at least any one of:
         Feature 13: a flow speed sensor configured to measure a speed of the airflow flowing through the air feed pipe; and   Feature 14: the controller is configured to activate the first electromagnetic valve based on (i) the air blower being activated and (ii) the speed of the airflow measured having reached a preset flow speed threshold.       

     In the mist blower including at least the features 1 through 8, 13, and 14, the liquid feed pipe is kept closed until the speed of the airflow flowing through the air feed pipe reaches the preset flow speed threshold. If the preset flow speed threshold is set to a speed at which the liquid can be sufficiently atomized (or turned into mist), it can be inhibited for the liquid to be leaked from the liquid feed pipe into the air feed pipe at an inappropriate timing when the liquid cannot be sufficiently atomized. 
     One embodiment may include, in addition to or in place of at least any one of the aforementioned features 1 through 14, at least any one of:
         Feature 15: the controller is configured to activate the first electromagnetic valve based on (i) the air blower being activated and (ii) an elapsed time having been advanced to a preset time threshold;   Feature 16: the elapsed time is advanced based on the first manual switch commanding the controller to activate the air blower; and   Feature 17: the elapsed time is initialized based on the first manual switch commanding the controller to deactivate the air blower.       

     In the mist blower including at least the features 1 through 8, and 15 through 17, the liquid feed pipe is kept closed until the elapsed time is advanced to the preset time threshold. If the preset time threshold is set to a time required for the airflow to reach the speed to sufficiently atomize the liquid since the initiation of the activation of the air blower, it is possible to inhibit the leakage of the liquid from the liquid feed pipe into the air feed pipe at an inappropriate timing when the liquid cannot be sufficiently atomized. 
     One embodiment may include, in addition to or in place of at least any one of the aforementioned features 1 through 17, at least any one of:
         Feature 18: the controller is configured to activate the air blower based on the first manual switch being in the first position;   Feature 19: the elapsed time is advanced based on the first manual switch being in the first position; and   Feature 20: the elapsed time is initialized based on the first manual switch being in the second position.       

     In the mist blower including at least the features 1 through 8, 10, and 15 through 20, the liquid feed pipe can be automatically opened in response to (i) the user having manually activated the air blower via the first manual switch and (ii) the elapsed time having been advanced to the preset time threshold. 
     One embodiment may include, in addition to or in place of at least any one of the aforementioned features 1 through 20, at least any one of:
         Feature 21: the controller is configured to detect that the controller is in a fault condition; and   Feature 22: the controller is configured to deactivate the first electromagnetic valve based on the controller detecting that the controller is in the fault condition.       

     In the mist blower including at least the features 1 through 8, 21, and 22, the liquid feed pipe can be automatically closed when the controller is in the fault condition. Accordingly, it is possible to inhibit the leakage of the liquid from the liquid feed pipe into the air feed pipe at an inappropriate timing when the controller is in the fault condition. 
     One embodiment may include, in addition to or in place of at least any one of the aforementioned features 1 through 22,
         Feature 23: the controller is configured to, in response to the controller detecting that the controller is in the fault condition, keep deactivating the first electromagnetic valve until the first manual switch is moved from the first position to the second position and to the first position again.       

     In the mist blower including at least the features 1 through 8, 10 through 12, and 21 through 23, the liquid feed pipe can be kept closed when the controller is in the fault condition until the first manual switch is moved from the first position to the second position and to the first position again. 
     One embodiment may include, in addition to or in place of at least any one of the aforementioned features 1 through 23, at least any one of:
         Feature 24: a second manual switch (i) configured to be manually moved by the user and (ii) distinct from the first manual switch;   Feature 25: the second manual switch is configured to designate a volume of the liquid to be discharged from the second discharge port based on a movement of the second manual switch; and   Feature 26: the controller is configured to control an opening level of the first electromagnetic valve based on the volume of the liquid designated by the second manual switch.       

     In the mist blower including at least the features 1 through 8, and 24 through 26, the user can adjust the volume of the liquid to be sprayed via the second manual switch. 
     One embodiment may include, in addition to or in place of at least any one of the aforementioned features 1 through 26,
         Feature 27: a flow rate sensor configured to measure a flow rate of the liquid flowing through the liquid feed pipe.       

     The mist blower including at least the features 1 through 8, and 27 can measure the flow rate of the liquid flowing through the liquid feed pipe. 
     One embodiment may include, in addition to or in place of at least any one of the aforementioned features 1 through 27,
         Feature 28: a second electromagnetic valve configured (i) to open the liquid feed pipe in response to the second electromagnetic valve being activated and (ii) to close the liquid feed pipe in response to the second electromagnetic valve being deactivated.       

     The mist blower including at least the features 1 through 8, and 28 can close the liquid feed pipe by the second electromagnetic valve even when the first electromagnetic valve has a fault. 
     One embodiment may include, in addition to or in place of at least any one of the aforementioned features 1 through 28,
         Feature 29: the controller is configured to deactivate the second electromagnetic valve based on (i) the first manual switch being in the second position and (ii) the flow rate measured being greater than or equal to a first preset flow rate threshold.       

     In the mist blower including at least the features 1 through 8, 10 through 12, and 27 through 29, the controller can close the liquid feed pipe by deactivating the second electromagnetic valve when the first electromagnetic valve has a fault and the controller therefore cannot deactivate the first electromagnetic valve, resulting in the liquid flowing through the liquid feed pipe at the flow rate greater than or equal to the first preset flow rate threshold. 
     One embodiment may include, in addition to or in place of at least any one of the aforementioned features 1 through 29,
         Feature 30: the controller is configured to deactivate the first electromagnetic valve and/or the second electromagnetic valve based on (i) the first manual switch being in the first position and (ii) the flow rate measured being less than a second preset flow rate threshold.       

     In the mist blower including at least the features 1 through 8, 10 through 12, 27, 28, and 30, the controller can close the liquid feed pipe by deactivating the first electromagnetic valve and/or the second electromagnetic valve when the first electromagnetic valve has a fault and the liquid feed pipe is therefore insufficiently opened, resulting in the liquid flowing through the liquid feed pipe at the flow rate less than the second preset flow rate threshold. 
     One embodiment may include, in addition to or in place of at least any one of the aforementioned features 1 through 30,
         Feature 31: a mechanical valve configured to be manually operated by the user to thereby open or close the liquid feed pipe.       

     In the mist blower including at least the features 1 through 8, and 31, the user can manually open or close the liquid feed pipe via the mechanical valve. The leakage of the liquid from the liquid feed pipe into the air feed pipe can be inhibited when the liquid feed pipe is closed by the mechanical valve even in a case where the mist blower is turned laterally or upside down. 
     One embodiment may include, in addition to or in place of at least any one of the aforementioned features 1 through 31, at least any one of:
         Feature 32: the liquid feed pipe is provided with the first electromagnetic valve and the mechanical valve; and   Feature 33: the mechanical valve is arranged so as to receive the liquid having passed the first electromagnetic valve.       

     In the mist blower including at least the features 1 through 8, and 31 through 33, the user can manually close the liquid feed pipe via the mechanical valve even when the first electromagnetic valve has a fault and is unable to close the liquid feed pipe. 
     One embodiment may include, in addition to or in place of at least any one of the aforementioned features 1 through 33,
         Feature 34: the first electromagnetic valve is arranged so as to receive the liquid having passed the mechanical valve.       

     In the mist blower including at least the features I through 8, 31, 32, and 34, the user can manually close the liquid feed pipe via the mechanical valve even when the first electromagnetic valve has a fault and is unable to close the liquid feed pipe. 
     One embodiment may include, in addition to or in place of at least any one of the aforementioned features 1 through 34, at least any one of:
         Feature 35: the air blower includes an impeller configured to be rotated to thereby generate the airflow;   Feature 36: the air blower includes an electric motor configured to rotate the impeller; and   Feature 37: the controller is configured to (i) activate the electric motor to thereby activate the air blower and (ii) to deactivate the electric motor to thereby deactivate the air blower.       

     In the mist blower including at least the features 1 through 8, and 35 through 37, the airflow can be generated by rotating the impeller by the electric motor. 
     In the mist blower including at least the features 1 through 9, and 35 through 37, the liquid feed pipe can (i) be opened in association with the activation of the electric motor and (ii) be closed in association with the deactivation of the electric motor. 
     One embodiment may include, in addition to or in place of at least any one of the aforementioned features 1 through 37, at least any one of:
         Feature 38: a connector configured to be connected to a battery;   Feature 39: the first electromagnetic valve includes a solenoid;   Feature 40: the controller is configured to receive an electric power from the battery connected to the connector;   Feature 41: the controller is configured to respectively deliver a first drive current and a second drive current to the electric motor and the solenoid to thereby respectively activate the electric motor and the first electromagnetic valve; and   Feature 42: the controller is configured to respectively interrupt the first drive current and the second drive current to thereby respectively deactivate the electric motor and the first electromagnetic valve.       

     In the mist blower including at least the features 1 through 8, and 35 through 42, the electric motor and the first electromagnetic valve can be activated or deactivated by respectively delivering the first drive current and the second drive current to the electric motor and the first electromagnetic valve or by respectively interrupting the first drive current and the second drive current. 
     One embodiment may include, in addition to or in place of at least any one of the aforementioned features 1 through 42,
         Feature 43: the controller is configured to activate the first electromagnetic valve based on an actual rotational frequency of the electric motor having reached a first preset rotational frequency threshold.       

     In the mist blower including at least the features 1 through 8, 35 through 37, and 43, the liquid feed pipe is kept closed until the actual rotational frequency of the electric motor reaches the first preset rotational frequency threshold. If the first preset rotational frequency threshold is set to a rotational frequency of the electric motor required to generate the airflow that sufficiently atomizes the liquid, it is possible to inhibit the leakage of the liquid from the liquid feed pipe into the air feed pipe at an inappropriate timing when the liquid cannot be sufficiently atomized. 
     One embodiment may include, in addition to or in place of at least any one of the aforementioned features 1 through 43, at least any one of:
         Feature 44: a rotational position sensor configured to detect a rotational position of the electric motor; and   Feature 45: the controller is configured to measure the actual rotational frequency of the electric motor based on the rotational position detected.       

     The mist blower including at least the features 1 through 8, 35 through 37, and 43 through 45 can measure the actual rotational frequency of the electric motor based on the rotational position of the electric motor. 
     One embodiment may include, in addition to or in place of at least any one of the aforementioned features 1 through 45, at least any one of:
         Feature 46: the air blower includes an internal combustion engine including a shaft, the internal combustion engine being configured to combust a fuel to thereby rotate the shaft, and the shaft being connected to the impeller;   Feature 47: the controller is configured to increase an actual rotational frequency of the internal combustion engine to thereby activate the air blower; and   Feature 48: the controller is configured to decrease the actual rotational frequency of the internal combustion engine to thereby deactivate the air blower.       

     In the mist blower including at least the features 1 through 8, 35, and 46 through 48, the airflow can be generated by rotating the impeller by the internal combustion engine. 
     In the mist blower including at least the features 1 through 9, 35, and 46 through 48, the liquid feed pipe can (i) be opened in association with the actual rotational frequency of the internal combustion engine increasing and (ii) be closed in association with the actual rotational frequency of the internal combustion engine decreasing. 
     One embodiment may include, in addition to or in place of at least any one of the aforementioned features 1 through 48,
         Feature 49: the controller is configured to activate the first electromagnetic valve based on the actual rotational frequency of the internal combustion engine having reached a second preset rotational frequency threshold.       

     In the mist blower including at least the features 1 through 8, 35, and 46 through 49, the liquid feed pipe is kept closed until the actual rotational frequency of the internal combustion engine reaches the second preset rotational frequency threshold. If the second preset rotational frequency threshold is set to a rotational frequency of the internal combustion engine required to generate the airflow that sufficiently atomizes the liquid, it is possible to inhibit the leakage of the liquid from the liquid feed pipe into the air feed pipe at an inappropriate timing when the liquid cannot be sufficiently atomized 
     One embodiment may include, in addition to or in place of at least any one of the aforementioned features 1 through 49, at least any one of:
         Feature 50: a first electric generator configured to generate a first electric power based on a rotation of the shaft; and   Feature 51: the controller is configured to measure the actual rotational frequency of the internal combustion engine based on the first electric power generated.       

     The mist blower including at least the features 1 through 8, 35, and 46 through 51 can measure the actual rotational frequency of the internal combustion engine based on the first electric power. 
     One embodiment may include, in addition to or in place of at least any one of the aforementioned features 1 through 51, at least any one of:
         Feature 52: a second electric generator configured to generate a second electric power based on a rotation of the shaft; and   Feature 53: the first electromagnetic valve is configured to receive the second electric power generated.       

     In the mist blower including at least the features 1 through 8, 35, 46 through 48, 52, and 53, the first electromagnetic valve can be activated by the second electric power generated based on the rotation of the shaft. 
     One embodiment may include, in addition to or in place of at least any one of the aforementioned features 1 through 53,
         Feature 54: the second discharge port is arranged inside the air feed pipe.       

     One embodiment may include, in addition to or in place of at least any one of the aforementioned features 1 through 54, at least any one of:
         Feature 55: the nozzle has an outer shape gradually narrower towards the second discharge port; and   Feature 56: the nozzle is arranged inside the air feed pipe so as to direct the second discharge port to a downstream of the airflow.       

     In the mist blower including at least the features 1 through 8, and 54 through 56, the aforementioned outer shape and arrangement of the nozzle causes the airflow around the second discharge port to accelerate, which causes an enhanced Bernoulli Effect at the second discharge port. As a consequence, the liquid in the liquid feed pipe can be effectively or efficiently discharged into the air feed pipe. 
     In one embodiment, the features 1 through 56 may be in any combination. 
     In one embodiment, any of the features 1 through 56 may be omitted. 
     In one embodiment, the controller may be integrated into a single electronic unit, a single electronic device, or a single circuit board. 
     In one embodiment, the controller may include a combination of two or more electronic circuits, two or more electronic units, or two or more electronic devices separately disposed on or in the mist blower. 
     In one embodiment, the controller may include a microcomputer, a microprocessor, a microcontroller unit, a wired logic, an application-specific integrated circuit (ASIC), an application-specific standard product (ASSP), a programmable logic device (such as a Field Programmable Gate Array (FPGA)), a discrete electronic component, and/or a combination of the above. 
     Examples of the first manual switch and the second manual switch include a trigger switch, a push-button switch, a dial switch, a slide switch, a tactile switch, a joystick, a touch panel, a touch screen, and a Graphical User Interface (GUI). With respect to the touch panel, the touch screen, and the GUI, the first position and the second position may indicate locations on the touch panel, the tough screen, and the GUI. 
     2. Specific Example Embodiments 
     Hereinafter, specific example embodiments will be explained. These specific example embodiments are merely examples, and the present disclosure can be implemented in any form without being limited to these embodiments. 
     2-1. First Embodiment 
     2-1-1. Mechanical Structure 
       FIGS.  1  and  2    show overall structures of a mist blower  100  in the present first embodiment. The mist blower  100  is a work machine configured to spray an atomized liquid. The liquid to be atomized and sprayed in the present first embodiment is a solution, such as a liquid chemical. Examples of the liquid chemical include an agricultural chemical. Examples of the agricultural chemical include a plant growth regulator, a herbicide, and a pesticide. The mist blower  100  may be used to spray the liquid chemical in an orchard. The liquid in other embodiments may be any other liquid, such as a liquid fertilizer and water. 
     The mist blower  100  includes a tank  10 . The tank  10  contains the liquid to be atomized and sprayed. The tank  10  in the present first embodiment is, but not limited to, approximately rectangular solid in shape. The tank  10  includes a not-shown opening on its upper surface for supplying the liquid. The tank  10  includes a detachable lid  11  that closes the opening. 
     The mist blower  100  includes a container  20  under the tank  10 . In the present first embodiment, the container  20  is, but is not limited to, approximately rectangular solid in shape. 
     The mist blower  100  includes an air blower  30  under the container  20 , The air blower  30  includes a housing  31 . In the present first embodiment, the housing  31  is, but is not limited to, approximately rectangular solid in shape. The housing  31  has a right-side surface having an air outlet  36 . The air outlet  36  discharges an airflow. 
     The mist blower  100  includes an air feed pipe (or an air feed conduit)  40  attached to the air outlet  36 . The air feed pipe  40  has a cylindrical shape that is bent forward and extended from the air outlet  36  towards the front of the mist blower  100 . The air feed pipe  40  includes a first end that has a first discharge port  45 . The air feed pipe  40  includes a second end that has a connection aperture  46 . The connection aperture  46  is coupled to the air outlet  36  to communicate with the air blower  30 . 
     The air feed pipe  40  includes a grip  41  that is slidably attached to an outer surface of the air feed pipe  40 . The grip  41  is formed to be gripped with one hand (right hand in the present first embodiment) of a user of the mist blower  100 . The grip  41  includes an airflow adjustment panel  48  on its rear side. The airflow adjustment panel  48  includes a not-shown adjustment switch, and a not-shown display. The adjustment switch is manually operated by the user to select a flow speed of an air discharged from the air feed pipe  40 . The adjustment switch in the present first embodiment is configured to be moved between two or more positions. These two or more positions are associated with different flow speeds. Examples of the adjustment switch include a push-button switch, a slide switch, and a dial switch. In the mist blower  100  in the present first embodiment, the flow speed of the air is increased or decreased in stages in response to the movement of the adjustment switch. The display is configured to indicate the flow speed selected. The display in the present first embodiment includes one or more light-emitting diodes (LED). In the present first embodiment, the user can set the flow speed of the air discharged from the air feed pipe  40  in three stages through the airflow adjustment panel  48 . In other embodiments, the flow speed of the air discharged from the air feed pipe  40  may be set in two stages or four or more stages. 
     A first manual switch  42  is disposed on a front side of the grip  41 . The first manual switch  42  in the present first embodiment is in the form of a trigger switch. In other embodiments, the first manual switch  42  may be in any form other than the trigger switch, such as a push-button switch, a dial switch, a slide switch, a joy stick, a touch panel, a touch screen, and a GUI. The first manual switch  42  is configured to be pulled (or moved) to an ON position by the user in order to discharge the atomized liquid from the air feed pipe  40 . The ON position corresponds to one example of the first position in the overview of embodiments. The ON position in the present first embodiment corresponds to a position where the first manual switch  42  is pulled to the maximum. The first manual switch  42  is configured to move back to an OFF position in response to having been released by the user in order to stop discharging the atomized liquid from the air feed pipe  40 . The OFF position corresponds to one example of the second position in the overview of embodiments. The OFF position in the present first embodiment corresponds to a position where the first manual switch  42  is not pulled by the user. 
     The mist blower  100  includes a liquid feed pipe (or a liquid feed conduit)  60  extending along the air feed pipe  40 . The liquid feed pipe  60  has a thin cylindrical shape. 
     The mist blower  100  includes a liquid volume adjuster  44  disposed on the liquid feed pipe  60 . 
     The liquid volume adjuster  44  is a mechanical valve. In other words, the liquid volume adjuster  44  is configured such that its opening level is manually operated by the user. The liquid volume adjuster  44  in the present first embodiment is configured to be turned by the user to vary its opening level. By adjusting the opening level of the liquid volume adjuster  44 , the user can adjust the volume of the liquid supplied to the air feed pipe  40 , and thus the volume of the liquid sprayed from the mist blower  100 . When the mist blower  100  is not used or is stored, the user closes the liquid volume adjuster  44  to block the liquid from entering the air feed pipe  40  from the liquid feed pipe  60 . 
     The mist blower  100  includes a first electromagnetic valve  66  provided with the liquid feed pipe  60 . The first electromagnetic valve  66  opens or closes the liquid feed pipe  60 . The first electromagnetic valve  66  opens the liquid feed pipe  60  when activated, and closes the liquid feed pipe  60  when deactivated. 
     The mist blower  100  includes a mechanical valve  65  provided with the liquid feed pipe  60 . The mechanical valve  65  is configured to be manually operated by the user to completely open or completely close the liquid feed pipe  60 . In the present first embodiment, the mechanical valve  65  is situated upstream of the liquid feed pipe  60  relative to the liquid volume adjuster  44  and downstream of the liquid feed pipe  60  relative to the first electromagnetic valve  66 . Accordingly, the mechanical valve  65  is arranged so as to receive the liquid having passed the first electromagnetic valve  66 . 
     By closing the mechanical valve  65 , a leakage of the liquid from the liquid feed pipe  60  into the air feed pipe  40  can be inhibited even in a case where the mist blower  100  is turned laterally or upside down. In addition, the user can manually close the liquid feed pipe  60  with the mechanical valve  65  even when the first electromagnetic valve  66  has a fault and is unable to close the liquid feed pipe  60 . 
     In other embodiments, the mechanical valve  65  may be excluded from the mist blower  100 . 
     In other embodiments, the liquid volume adjuster  44  may be excluded from the mist blower  100 . In addition, the mechanical valve  65  and/or the first electromagnetic valve  66  may be configured to enable fine adjustment of each opening level. In this case, the volume of the liquid to be fed to the air feed pipe  40  can still be adjusted while reducing the components of the mist blower  100  due to the exclusion of the liquid volume adjuster  44 . 
     On its front side, the mist blower  100  includes first and second shoulder straps  50 A and  50 B. Upper ends of the first and second shoulder straps  50 A and  50 B are attached to a front surface of the tank  10 . Lower ends of the first and second shoulder straps  50 A and  50 B are attached to a front surface of the housing  31 . The user can carry the mist blower  100  on his/her back by placing the first and second shoulder straps  50 A and  50 B on his/her shoulders. 
     As shown in  FIG.  3   , the air blower  30  includes an impeller  33  housed in the housing  31 . The impeller  33  is configured to rotate and generate the airflow directed to the air outlet  36 . Examples of the impeller  33  include an axial-flow fan, a centrifugal fan, a mixed flow fan, a closed fan, and a sirocco fan. 
     The tank  10  includes a discharge aperture  12  for discharging the liquid contained in the tank  10  at the bottom of the tank  10 . The liquid feed pipe  60  includes a first end having an inflow port  61  and coupled to the discharge aperture  12 . The liquid feed pipe  60  is inserted into the air feed pipe  40  and fixed to the air feed pipe  40  via the liquid volume adjuster  44  near a front end of the air feed pipe  40 . The liquid feed pipe  60  includes a second end having an outflow port  62  and disposed downstream of the impeller  33  inside the air feed pipe  40 . The outflow port  62  is coupled to a nozzle  63 . The nozzle  63  includes a second discharge port  63   a  at a front end of the nozzle  63 . The second discharge port  63   a  has a diameter that is sufficiently smaller than the diameter of the air feed pipe  40 . The nozzle  63  has an outer shape gradually narrower towards the second discharge port  63   a.  The nozzle  63  is arranged inside the air feed pipe  40  so as to direct the second discharge port  63   a  to a downstream of the airflow. In other embodiments, the nozzle  63  may be arranged at any part of the air feed pipe  40  other than the inside of the air feed pipe  40 , such as a wall of the air feed pipe  40  so as to direct the second discharge port  63   a  to the airflow. 
     The liquid contained in the tank  10  is under the atmospheric pressure. The atmospheric pressure acts on the liquid such that the liquid is fed from the discharge aperture  12  to the air feed pipe  40 . 
     Inside the air feed pipe  40 , the airflow generated by the impeller  33  causes a negative pressure at the second discharge port  63   a  of the nozzle  63 . This negative pressure acts on the liquid inside the liquid feed pipe  60  such that the liquid inside the liquid feed pipe  60  is drawn out from the second discharge port  63   a.  The negative pressure increases as the rotational frequency of the impeller  33  increases, which causes the liquid inside the liquid feed pipe  60  to be ejected out from the second discharge port  63   a . The ejected liquid is atomized by the airflow inside the air feed pipe  40  and sprayed from the first discharge port  45  of the air feed pipe  40 . 
     2-1-2. Electrical Configuration 
     An electrical configuration of the mist blower  100  will be explained with reference to  FIG.  4   . 
     The mist blower  100  includes an electric motor  35 . The electric motor  35  rotates the impeller  33 , In the present first embodiment, the electric motor  35  is housed inside the housing  31  of the air blower  30 . In the present first embodiment, the electric motor  35  is in the form of a three-phase brushless DC motor. In other embodiments, the electric motor  35  may be in any other form including a single-phase brushless DC motor, a two-phase brushless DC motor, a brushless DC motor with four or more phases, a brushed DC motor, and an AC motor. 
     The mist blower  100  includes a rotational position sensor  91 . In the present first embodiment, the rotational position sensor  91  is housed in the housing  31  of the air blower  30  with the electric motor  35  or attached to the electric motor  35 . The rotational position sensor  91  detects a rotational position of a not-shown rotor of the electric motor  35  and outputs one or more rotational position signals. The one or more rotational position signals vary depending on the detected rotational position of the rotor. Examples of the rotational position sensor  91  include a Hall sensor. 
     In the ON position, the first manual switch  42  disposed on the grip  41  outputs an activation command signal for commanding (i) an activation of the electric motor  35 , and (ii) an activation of the first electromagnetic valve  66 . In the OFF position, the first manual switch  42  outputs a deactivation command signal for commanding (i) a deactivation of the electric motor  35 , and (ii) a deactivation of the first electromagnetic valve  66 . The first manual switch  42  in the present first embodiment outputs a manual operation signal that serves as the activation command signal and the deactivation command signal. The manual operation signal is in the form of a binary logic signal. The manual operation signal having a logic HIGH corresponds to the activation command signal; the manual operation signal having a logic LOW corresponds to the deactivation command signal. In other embodiments, the manual operation signal having the logic HIGH may correspond to the deactivation command signal; the manual operation signal having the logic LOW may correspond to the activation command signal. Alternatively, in other embodiments, the mist blower  100  may include a path for transmitting the activation command signal and a path for transmitting the deactivation command signal in parallel, and the first manual switch  42  may output the activation command signal and the deactivation command signal separately via these paths. 
     The mist blower  100  includes a first battery  200 A and a second battery  200 B. In the present first embodiment, the first battery  200 A and the second battery  200 B have the same rated voltage. In other embodiments, the first battery  200 A may have a rated voltage different from that of the second battery  200 B. In the present first embodiment, each of the first battery  200 A and the second battery  200 B includes a lithium-ion battery. In other embodiments, the first battery  200 A and/or the second battery  200 B may include any other form of a primary battery (or a non-rechargeable battery) or a secondary battery (or a rechargeable battery) other than the lithium-ion battery. In the present first embodiment, the first battery  200 A and the second battery  200 B are housed in the container  20 . In other embodiments, the first battery  200 A and/or the second battery  200 B may be disposed at any part of the mist blower  100  other than in the container  20 . 
     In the present first embodiment, the first battery  200 A is configured to determine whether the first battery  200 A can discharge an electric power; and the second battery  200 B is configured to determine whether the second battery  200 E can discharge an electric power. The first battery  200 A and the second battery  200 B are configured to output a not-shown power discharge permission signal when they are able to discharge the respective electric powers. The first battery  200 A and the second battery  200 B are configured to output a not-shown power discharge prohibition signal when they are not able to discharge the respective electric powers. 
     The mist blower  100  includes a connector  220 . In the present first embodiment, the connector  220  is also housed in the container  20 . In other embodiments, the connector  220  may be disposed at any part of the mist blower  100  other than in the container  20 . The connector  220  includes one or more connection port. In the present first embodiment, the connector  220  includes a first connection port  220 A and a second connection port  220 B. The first connection port  220 A and the second connection port  220 B are respectively coupled to the first battery  200 A and the second battery  200 B, 
     The mist blower  100  includes a first controller  70 A. In the present first embodiment, the first controller  70 A is housed in the container  20 . In other embodiments, the first controller  70 A may be disposed at any part of the mist blower  100  other than in the container  20 . 
     The first controller  70 A includes a control circuit  71 . The control circuit  71  in the present first embodiment is in the form of a microcomputer (or a microprocessor, or a microcontroller unit) including a CPU  71   a,  a memory  71   b,  an analog-to-digital converter (ADC)  71   c,  an input/output (I/O) port  71   d,  and a clock generator  71   e.  The control circuit  71  in the present first embodiment achieves various functions of the control circuit  71  by the CPU  71   a  executing various programs stored in the memory  71   b.  The ADC  71   c  converts two or more analog signals received by the control circuit  71  into respective digital values. The clock generator  71   e  generates a clock signal oscillating at a constant frequency. 
     In other embodiments, the control circuit  71  may include, in place of or in addition to the microcomputer, a wired logic, an ASIC, an ASSP, a programmable logic device (such as an FPGA), a discrete electronic component, and/or a combination of these. 
     The first controller  70 A includes a latch circuit  88  including a wired logic. The latch circuit  88  is configured to enable or disable the control circuit  71  to activate the electric motor  35  and the first electromagnetic valve  66  based on the condition (or the state) of the first controller  70 A. 
     The first controller  70 A includes a first battery switch  210 A and a second battery switch  210 B. The first battery switch  210 A and the second battery switch  210 B are turned on or turned off by the control circuit  71 . Each of the first battery switch  210 A and the second battery switch  210 B includes a first terminal coupled to the first connection port  220 A or the second connection port  220 B. The first controller  70 A includes a power-supply line  250  that is to be electrically connected to a positive electrode of the first battery  200 A or to a positive electrode of the second battery  200 B. Each of the first battery switch  210 A and the second battery switch  210 B includes a second terminal coupled to the power-supply line  250 . In the present first embodiment, the first battery switch  210 A and the second battery switch  210 B are in the form of a semiconductor switch (such as a field effect transistor (FET)), a solid-state relay (SSR), or a mechanical relay. 
     The first controller  70 A includes a motor drive circuit  72 . The motor drive circuit  72  is coupled to the power-supply line  250  and to the electric motor  35 . The motor drive circuit  72  receives the electric power from the first battery  200 A or the second battery  200 B via the power-supply line  250  and delivers a first drive current to the electric motor  35 . The motor drive circuit  72  in the present first embodiment includes a not-shown three-phase full bridge circuit including three high-side switches and three low-side switches. These switches in the three-phase full bridge circuit is controlled by the control circuit  71 . In other embodiments, the motor drive circuit  72  may include, in place of the three-phase full bridge circuit, another bridge circuit in any form (such as a half-bridge circuit) other than the three-phase full bridge circuit. Alternatively, in other embodiments, the motor drive circuit  72  may include, in place of the three-phase full bridge circuit, an inverter circuit that converts a DC power into an AC power. Alternatively, in other embodiments, the motor drive circuit  72  may include, in place of the three-phase full bridge circuit, a semiconductor switch in any form including an FET, a bipolar transistor, an insulated-gate bipolar transistor (TGBT), and an SSR. 
     The first controller  70 A includes a first temperature measurement circuit  73  disposed in the vicinity of the motor drive circuit  72 . The first temperature measurement circuit  73  measures a temperature of the motor drive circuit  72  (hereinafter referred to as a first temperature T 1 ) and outputs a first temperature signal. In the present first embodiment, the first temperature measurement circuit  73  includes a not-shown thermistor. The first temperature signal has a voltage that varies in accordance with the measured first temperature T 1 . 
     The first controller  70 A includes a first current measurement circuit  74 . The first current measurement circuit  74  measures a value of the first drive current flowing through the electric motor  35  and the motor drive circuit  72  (hereinafter referred to as first current value I 1 ) and outputs a first current signal. In the present first embodiment, the first current measurement circuit  74  includes a not-shown shunt resistor. The first current signal has a voltage that varies in accordance with the measured first current value I 1 . 
     The first controller  70 A includes a first signal line  260  that electrically couples the control circuit  71  to the motor drive circuit  72 . The first controller  70 A includes a first enabling switch  78  on the first signal line  260 . The first enabling switch  78  is controlled by the control circuit  71  and the latch circuit  88 . In the present first embodiment, the first enabling switch  78  is in the form of a semiconductor switch (such as an PET), an SSR, or a mechanical relay. 
     The first controller  70 A includes a first solenoid drive circuit  75 . The first solenoid drive circuit  75  drives a first solenoid  66   a  disposed in the first electromagnetic valve  66 . The first solenoid  66   a  includes a first excitation coil  661 , and a not-shown first plunger (specifically, an iron piece). The first excitation coil  661  has a first end coupled to the power-supply line  250 . The first excitation coil  661  has a second end coupled to the first solenoid drive circuit  75 . The first solenoid drive circuit  75  conducts or interrupts a second drive current from the power-supply line  250  to the first excitation coil  661 . As the second drive current flows through the first excitation coil  661 , the first excitation coil  661  is magnetized (or excited) and attracts the first plunger, which consequently causes the first electromagnetic valve  66  to open. When the second drive current is interrupted, the first excitation coil  661  is demagnetized (or de-excited) and releases the first plunger, which consequently causes the first electromagnetic valve  66  to close. 
     The first controller  70 A includes a second temperature measurement circuit  76  disposed in the vicinity of the first solenoid drive circuit  75 . The second temperature measurement circuit  76  measures a temperature of the first solenoid drive circuit  75  (hereinafter referred to as a second temperature T 2 ) and outputs a second temperature signal. In the present first embodiment, the second temperature measurement circuit  76  includes a not-shown thermistor. The second temperature signal has a voltage that varies in accordance with the measured second temperature T 2 . 
     The first controller  70 A includes a second current measurement circuit  77 . The second current measurement circuit  77  measures a value of the second drive current flowing through the first solenoid drive circuit  75  (hereinafter referred to as a second current value I 2 ) and outputs a second current signal. In the present first embodiment, the second current measurement circuit  77  includes a not-shown shunt resistor. The second current signal has a voltage that varies in accordance with the measured second current value I 2 . 
     The first controller  70 A includes a second signal line  270  that electrically couples the control circuit  71  to the first solenoid drive circuit  75 . The first controller  70 A includes a second enabling switch  79  on the second signal line  270 . The second enabling switch  79  is controlled by the control circuit  71  and the latch circuit  88 . In the present first embodiment, the second enabling switch  79  is in the form of a semiconductor switch (such as an FET), an SSR, or a mechanical relay. 
     2-1-3. Operation of Control Circuit 
     The control circuit  71  receives the power discharge permission signal or the power discharge prohibition signal from each of the first battery  200 A and the second battery  200 B. Based on the received power discharge permission signal or the received power discharge prohibition signal, the control circuit  71  selects the first battery  200 A or the second battery  200 B. When the first battery  200 A is selected, the control circuit  71  turns the first battery switch  210 A on and turns the second battery switch  210 B off. When the second battery  200 B is selected, the control circuit  71  turns the second battery switch  210 B on and turns the first battery switch  210 A off. In other words, while the first battery switch  210 A and the second battery switch  210 B can be turned off at the same time, they are not turned on at the same time. Accordingly, the power-supply line  250  does not simultaneously receive the electric powers from both of the first battery  200 A and the second battery  200 B; the power-supply line  250  receives the electric power from either one of the first battery  200 A or the second battery  200 B that is selected. In other embodiments, the first battery switch  210 A and the second battery switch  210 B may be turned on at the same time; and the power-supply line  250  may receive the electric powers from the first battery  200 A and the second battery  200 B at the same time. 
     The control circuit  71  outputs, to the first solenoid drive circuit  75 , a first solenoid conduction signal that commands a magnetization of the first excitation coil  661 , and a first solenoid non-conduction signal that commands a demagnetization of the first excitation coil  661 . The control circuit  71  in the present first embodiment outputs a first solenoid control signal that serves as the first solenoid conduction signal and the first solenoid non-conduction signal. The first solenoid control signal is in the form of a binary logic signal. The first solenoid control signal having a logic HIGH corresponds to the first solenoid conduction signal; and the first solenoid control signal having a logic LOW corresponds to the first solenoid non-conduction signal. In other embodiments, the first solenoid control signal having the logic HIGH may correspond to the first solenoid non-conduction signal; and the first solenoid control signal having the logic LOW may correspond to the first solenoid conduction signal. Alternatively, in other embodiments, the mist blower  100  may include a path for transmitting the first solenoid conduction signal and a path for transmitting the first solenoid non-conduction signal in parallel, and the control circuit  71  may output the first solenoid conduction signal and the first solenoid non-conduction signal separately via these paths. 
     The control circuit  71  receives the activation command signal, the deactivation command signal, the rotational position signal, the power discharge permission signal, the power discharge prohibition signal, the first temperature signal, the second temperature signal, the first current signal, and the second current signal. Based on these received signals, the control circuit  71  outputs, to the motor drive circuit  72 , a motor drive signal for commanding a drive of the electric motor  35  or a motor stop signal for commanding a stop of the electric motor  35 . The control circuit  71  in the present first embodiment outputs a motor control signal that serves as the motor drive signal and the motor stop signal. The motor control signal is in the form of a binary logic signal. The motor control signal having a logic HIGH corresponds to the motor drive signal; and the motor control signal having a logic LOW corresponds to the motor stop signal. In other embodiments, the motor control signal having the logic HIGH may correspond to the motor stop signal; and the motor control signal having the logic LOW may correspond to the motor drive signal. Alternatively, in other embodiments, the mist blower  100  may include a path for transmitting the motor drive signal and a path for transmitting the motor stop signal in parallel, and the control circuit  71  may output the motor drive signal and the motor stop signal separately via these paths. 
     The control circuit  71  controls the first electromagnetic valve  66  based on a logic level of the motor control signal. In other words, the control circuit  71  outputs, to the first solenoid drive circuit  75 , the first solenoid control signal having the logic level in accordance with the logic level of the motor control signal. As a consequence, the first electromagnetic valve  66  is activated (and thus opened) in association with an activation of the electric motor  35 ; and the first electromagnetic valve  66  is deactivated (and thus closed) in association with a deactivation of the electric motor  35 . 
     2-1-4. Operation of Latch Circuit 
     The latch circuit  88  receives the first temperature signal, the second temperature signal, the first current signal, and the second current signal. The latch circuit  88  detects that the first controller  70 A is in a fault condition based on these received signals. In response to the detection of the fault condition of the first controller  70 A, the latch circuit  88  turns the first enabling switch  78  and the second enabling switch  79  off. 
     The latch circuit  88  receives the power discharge prohibition signal from each of the first battery  200 A and the second battery  200 B. In response to receiving the power discharge prohibition signal from each of the first battery  200 A and the second battery  200 B, the latch circuit  88  turns the first enabling switch  78  and the second enabling switch  79  off. Then, the latch circuit  88  keeps the first enabling switch  78  and the second enabling switch  79  turned off until a given condition is satisfied. Once the given condition is satisfied, the latch circuit  88  turns the first enabling switch  78  and the second enabling switch  79  on. 
     The latch circuit  88  receives the manual operation signal from the first manual switch  42 . In the present first embodiment, the given condition is satisfied in response to fulfillment of the following Requirements (i) and (ii).
         Requirement (i): the first controller  70 A has turned into a no-fault condition from the fault condition.   Requirement (ii): the manual operation signal has changed from the deactivation command signal to the activation command signal.       

     In other embodiment, the given condition may be satisfied in response to fulfillment of any requirements other than Requirements (i) and (ii). 
     2-1-5. Processes Executed by Control Circuit 
     2-1-5-1. First Control Process 
     A first control process executed by the control circuit  71  (more specifically, by the CPU  71   a ) will be explained with reference to  FIG.  5   . The control circuit  71  initiates the first control process when activated. The user first opens the mechanical valve  65  when starting to use the mist blower  100 . Therefore, the mechanical valve  65  is open when the control circuit  71  initiates the first control process. 
     In S 10  (S represents a step), the control circuit  71  determines whether the first manual switch  42  is in the ON position. In other words, the control circuit  71  determines whether it is receiving the activation command signal from the first manual switch  42 . If the first manual switch  42  is in the ON position (S 10 : YES), the control circuit  71  proceeds to S 20 . If the first manual switch  42  is in the OFF position (S 10 : NO), the control circuit  71  repeats the process of S 10  until the first manual switch  42  is moved to the ON position. 
     In the subsequent S 20 , the control circuit  71  determines whether an error flag is set to OFF. The error flag indicates whether the first controller  70 A is in the fault condition. In other words, if the first controller  70 A is in the fault condition, the error flag is set to ON (or TRUE). If the first controller  70 A is in the no-fault condition, the error flag is set to OFF (or FALSE). 
     If the error flag is set to OFF (S 20 : YES), the control circuit  71  proceeds to S 30 . If the error flag is set to ON (S 20 : NO), the control circuit  71  returns to S 10 . 
     In S 30 , the control circuit  71  activates the electric motor  35  and the first electromagnetic valve  66 . More specifically, the control circuit  71  turns the first enabling switch  78  on and outputs the motor drive signal to the motor drive circuit  72 . In addition, the control circuit  71  turns the second enabling switch  79  on and outputs the first solenoid conduction signal to the first solenoid drive circuit  75 . 
     In the subsequent S 40 , the control circuit  71  determines whether the first manual switch  42  is in the ON position. If the first manual switch  42  is in the OFF position (S 40 : NO), the control circuit  71  proceeds to S 50 . If the first manual switch  42  is in the ON position (S 40 : YES), the control circuit  71  proceeds to S 60 . 
     In S 50 , the control circuit  71  deactivates the electric motor  35  and the first electromagnetic valve  66 . More specifically, the control circuit  71  turns the first enabling switch  78  and the second enabling switch  79  off. In addition/alternatively, the control circuit  71  outputs the motor stop signal to the motor drive circuit  72  and outputs the first solenoid non-conduction signal to the first solenoid drive circuit  75 . Upon completion of the process of S 50 , the control circuit  71  returns to S 10 . 
     In S 60 , the control circuit  71  determines whether the error flag is set to OFF. If the error flag is set to OFF (S 60 : YES), the control circuit  71  returns to S 40 . If the error flag is set to ON (S 60 : NO), the control circuit  71  proceeds to S 70 . 
     In S 70 , the control circuit  71  executes the process as in S 50 . Upon completion of the process of S 70 , the control circuit  71  proceeds to S 80  and determines whether the first manual switch  42  is in the OFF position. More specifically, the control circuit  71  determines whether it is receiving the deactivation command signal from the first manual switch  42 . If the first manual switch  42  is in the OFF position (S 80 : YES), the control circuit  71  returns to S 10 . If the first manual switch  42  is in the ON position (S 80 : NO), the control circuit  71  repeats the process of S 80  until the first manual switch  42  is moved to the OFF position. 
     In a case where the error flag is turned on due to the process of S 80 , the electric motor  35  and the first electromagnetic valve  66  are not reactivated unless the user intentionally moves the first manual switch  42  from the OFF position to the ON position. In other words, even if the error flag turns from. ON to OFF while the first manual switch  42  is in the ON position, the electric motor  35  and the first electromagnetic valve  66  are not suddenly reactivated. 
     2-1-5-2. Processes for Detecting Faults 
     Processes for detecting faults in the first controller  70 A will be explained. In the present first embodiment, the control circuit  71  executes, when activated, a faulty temperature detection process and a faulty electric current detection process along with the aforementioned first control process. 
     The faulty temperature detection process will be explained with reference to  FIG.  6   . 
     In S 100 , the control circuit  71  obtains the first temperature T 1  and the second temperature T 2 . More specifically, the control circuit  71  converts the first temperature signal and the second temperature signal into respective digital values via the ADC  71   c  and obtains the first temperature T 1  and the second temperature T 2 . 
     In the subsequent S 110 , the control circuit  71  determines whether the first temperature T 1  or the second temperature T 2  is higher than or equal to a preset temperature threshold. In the present first embodiment, the preset temperature threshold is 100° C. In other embodiments, the preset temperature threshold may be any temperature other than 100° C. 
     If the first temperature T 1  or the second temperature T 2  is higher than or equal to the preset temperature threshold (S 110 : YES), the control circuit  71  proceeds to S 120 . In S 120 , the control circuit  71  sets the error flag to ON and returns to S 100 . 
     In S 110 , if both of the first temperature T 1  and the second temperature T 2  are lower than the preset temperature threshold (S 110 : NO), the control circuit  71  proceeds to S 130 . In S 130 , the control circuit  71  sets the error flag to OFF and returns to S 100 . 
     The faulty electric current detection process will be explained with reference to  FIG.  7   . 
     In S 200 , the control circuit  71  obtains the first current value I 1  and the second current value I 2 . More specifically, the control circuit  71  converts the first current signal and the second current signal into respective digital values via the ADC  71   c  and obtains the first current value I 1  and the second current value I 2 . 
     In the subsequent S 210 , the control circuit  71  determines whether the first current value I 1  or the second current value I 2  is greater than or equal to a preset electric current threshold. In the present first embodiment, the preset electric current threshold is 100 amperes. In other embodiments, the preset electric current threshold may be any electric current values other than 100 amperes. 
     If the first current value I 1  or the second current value I 2  is greater than or equal to the preset electric current threshold (S 210 : YES), the control circuit  71  proceeds to S 220 . In S 220 , the control circuit  71  sets the error flag to ON and returns to S 200 . 
     In S 210 , if both of the first current value I 1  and the second current value I 2  are less than the preset electric current threshold (S 210 : NO), the control circuit  71  proceeds to S 230 . In S 230 , the control circuit  71  sets the error flag to OFF and returns to S 200 . 
     2-1-6. Effects in First Embodiment 
     The present first embodiment as described above in detail exerts the following first through seventh effects.
         First Effect: In the present first embodiment, closure of the first electromagnetic valve  66  and thus closure of the liquid feed pipe  60  are linked with the deactivation of the electric motor  35 . Accordingly, the mist blower  100  can inhibit the leakage of the liquid from the liquid feed pipe  60  into the air feed pipe  40  at an inappropriate timing when the electric motor  35  is deactivated.   Second Effect: In the present first embodiment, the first electromagnetic valve  66  is activated in response to the manual operation signal changing from the deactivation command signal to the activation command signal; and the first electromagnetic valve  66  is deactivated in response to the manual operation signal changing from the activation command signal to the deactivation command signal. Accordingly, the user can activate or deactivate not only the electric motor  35  but also the first electromagnetic valve  66  by manually moving the first manual switch  42 .   Third Effect: In the present first embodiment, the first electromagnetic valve  66  is closed in response to the detection that the first controller  70 A is in the fault condition. Accordingly, the mist blower  100  can inhibit the leakage of the liquid from the liquid feed pipe  60  into the air feed pipe  40  at an inappropriate timing when the first controller  70 A is in the fault condition.   Fourth Effect: In the present first embodiment, if it is detected that the first controller  70 A is in the fault condition, the first electromagnetic valve  66  is kept closed until the first manual switch  42  is moved to the ON position via the OFF position. Accordingly, the mist blower  100  can inhibit a spray of the liquid against the user&#39;s intention.   Fifth Effect: In the present first embodiment, the mechanical valve  65  is provided with the liquid feed pipe  60 . Accordingly, the mist blower  100  can inhibit the leakage of the liquid from the liquid feed pipe  60  into the air feed pipe  40  even in a case where the mist blower  100  is turned laterally or upside down.   Sixth Effect: In the present first embodiment, the first electromagnetic valve  66  is situated upstream of the liquid feed pipe  60  relative to the mechanical valve  65 , in other words, close to the first controller  70 A. Accordingly, wiring between the first solenoid  66   a  of the first electromagnetic valve  66  and the first controller  70 A can be shortened.   Seventh Effect: In the present first embodiment, the liquid volume adjuster  44  is provided with the liquid feed pipe  60 . Accordingly, the user can manually adjust the opening level of the liquid volume adjuster  44  to adjust the volume of the liquid to be sprayed from the air feed pipe  40 .       

     2-2. Second Embodiment 
     The present second embodiment corresponds to a partially modified first embodiment. Therefore, elements that are the same as those in the first embodiment will be given the same reference numerals and their explanations will be omitted. Differences from the first embodiment will be explained hereinafter. 
     2-2-1. Differences from First Embodiment 
     In the present second embodiment, the control circuit  71  executes, in place of the first control process described in  FIG.  5   , a second control process described in  FIG.  8    and a third control process described in  FIG.  9   . 
     2-2-1-1. Second Control Process 
     The second control process will be explained with reference to  FIG.  8   . 
     In S 600  and S 610 , the control circuit  71  executes the same processes as in S 10  and S 20 . 
     In the subsequent S 620 , the control circuit  71  activates the electric motor  35 . In other words, the control circuit  71  turns the first enabling switch  78  on and outputs the motor drive signal to the motor drive circuit  72 . In the present second embodiment, the control circuit  71  does not activate the first electromagnetic valve  66  in S 620 . 
     In the subsequent S 630 , the control circuit  71  executes the same process as in S 40 . If the first manual switch  42  is in the OFF position (S 630 : NO), the control circuit  71  proceeds to S 640 . If the first manual switch  42  is in the ON position (S 630 : YES), the control circuit  71  proceeds to S 650 . 
     In S 640 , the control circuit  71  deactivates the electric motor  35 . In other words, the control circuit  71  turns the first enabling switch  78  off. In addition to/alternatively, the control circuit  71  outputs the motor stop signal to the motor drive circuit  72 . 
     In S 650 , the control circuit  71  determines whether the error flag is set to OFF. If the error flag is set to OFF (S 650 : YES), the control circuit  71  returns to S 630 . If the error flag is set to ON (S 650 : NO), the control circuit  71  proceeds to S 660 . 
     In S 660 , the control circuit  71  executes the same process as in S 640 . Upon completion of the process in S 660 , the control circuit  71  proceeds to S 670 . 
     In S 670 , the control circuit  71  executes the same process as in S 80 . 
     2-2-1-2. Third Control Process 
     The third control process is explained with reference to  FIG.  9   . 
     In S 300 , the control circuit  71  determines whether the first manual switch  42  is in the ON position. If the first manual switch  42  is in the ON position (S 300 : YES), the control circuit  71  proceeds to S 305 . If the first manual switch  42  is in the OFF position (S 300 : NO), the control circuit  71  repeats the process of S 300  until the first manual switch  42  is moved to the ON position. 
     In S 305 , the control circuit  71  calculates an actual rotational frequency R of the electric motor  35  based on the rotational position signal received from the rotational position sensor  91 . 
     In the subsequent S 310 , the control circuit  71  determines whether the electric motor  35  is activated, in other words, whether the motor drive signal is being output to the motor drive circuit  72 . If the electric motor  35  is activated (S 310 : YES), the control circuit  71  proceeds to S 320 . If the electric motor  35  is deactivated (S 310 : NO), the control circuit  71  returns to S 300 . 
     In S 320 , the control circuit  71  determines whether the actual rotational frequency R calculated in S 305  is higher than or equal to a preset rotational frequency threshold. The preset rotational frequency threshold corresponds to one example of the first preset rotational frequency threshold in the overview of embodiments. In the present second embodiment, the preset rotational frequency threshold corresponds to 10,000 revolutions/minute (10,000 revolutions per one minute). In other embodiments, the preset rotational frequency threshold may corresponds to any revolutions/minute other than 10,000 revolutions/minute. 
     If the actual rotational frequency R is higher than or equal to the preset rotational frequency threshold (S 320 : YES), the control circuit  71  proceeds to S 330 . If the actual rotational frequency R is lower than the preset rotational frequency threshold (S 320 : NO), the control circuit  71  returns to S 300 . 
     In S 330 , the control circuit  71  activates the first electromagnetic valve  66 . In other words, the control circuit  71  turns the second enabling switch  79  on and outputs the first solenoid conduction signal to the first solenoid drive circuit  75 . In the present second embodiment, the control circuit  71  does not initiate the activation of the first electromagnetic valve  66  simultaneously with the activation of the electric motor  35 . If the actual rotational frequency R of the electric motor  35  is lower than the preset rotational frequency threshold, the flow speed of the airflow inside the air feed pipe  40  is relatively low. If the liquid is discharged from the nozzle  63  into the airflow having a low flow speed, the liquid may not be atomized. Accordingly, in the present second embodiment, the control circuit  71  activates the first electromagnetic valve  66  when the actual rotational frequency R of the electric motor  35  is higher than or equal to the preset rotational frequency threshold. 
     In the subsequent S 340 , the control circuit  71  recalculates the actual rotational frequency R of the electric motor  35  based on the rotational position signal received from the rotational position sensor  91 . 
     In the subsequent S 350 , the control circuit  71  determines whether the electric motor  35  is activated, in other words, whether the control circuit  71  is outputting the motor drive signal to the motor drive circuit  72 . If the electric motor  35  is deactivated (S 350 : NO), the control circuit  71  proceeds to S 360 . If the electric motor  35  is activated (S 350 : YES), the control circuit  71  proceeds to S 370 . 
     In S 360 , the control circuit  71  deactivates the first electromagnetic valve  66 . In other words, the control circuit  71  turns the second enabling switch  79  off. In addition to/alternatively, the control circuit  71  outputs the first solenoid non-conduction signal to the first solenoid drive circuit  75 . In a case where the electric motor  35  is deactivated, the control circuit  71  immediately deactivates the first electromagnetic valve  66  and stops discharging the liquid from the nozzle  63 . 
     In S 370 , the control circuit  71  determines whether the actual rotational frequency R recalculated in S 340  is higher than or equal to the preset rotational frequency threshold. If the actual rotational frequency R is higher than or equal to the preset rotational frequency threshold (S 370 : YES), the control circuit  71  returns to S 340 . If the actual rotational frequency R is lower than the preset rotational frequency threshold (S 370 : NO), the control circuit  71  proceeds to S 380 . 
     In S 380 , the control circuit  71  executes the same process as in S 360 . In the present second embodiment, if the actual rotational frequency R falls below the preset rotational frequency threshold while the electric motor  35  is activated, the control circuit  71  deactivates the first electromagnetic valve  66  and stops discharging the liquid from the nozzle  63 . Upon completion of the process of S 380 , the control circuit  71  proceeds to S 390  and executes the same process as in S 80 . 
     2-2-2. Effects in Second Embodiment 
     The present second embodiment exerts, in addition to the aforementioned first through seventh effects, the following eighth effect.
         Eighth Effect: In the present second embodiment, the first electromagnetic valve  66  is opened in response to the actual rotational frequency R of the electric motor  35  being higher than or equal to the preset rotational frequency threshold. Accordingly, the mist blower  100  in the present second embodiment can adequately atomize the liquid and spray the adequately atomized liquid.       

     2-3. Third Embodiment 
     The present third embodiment corresponds to a partially modified first embodiment. Therefore, elements that are the same as those in the first embodiment will be given the same reference numerals and their explanations will be omitted. Differences from the first embodiment will be explained hereinafter. 
     2-3-1. Differences from First Embodiment 
     In the aforementioned first embodiment, the first electromagnetic valve  66  is situated upstream of the liquid feed pipe  60  relative to the mechanical valve  65 . Meanwhile, the present third embodiment is different from the first embodiment in that, as shown in  FIG.  10   , the first electromagnetic valve  66  is situated downstream of the liquid feed pipe  60  relative to the mechanical valve  65 . In other words, the first electromagnetic valve  66  is arranged so as to receive the liquid having passed the mechanical valve  65 . 
     2-3-2. Effects in Third Embodiment 
     The present third embodiment exerts, in addition to the aforementioned first through fifth, and seventh effects, the following ninth effect.
         Ninth Effect: In the present third embodiment, the first electromagnetic valve  66 , which is situated downstream of the liquid feed pipe  60 , closes the liquid feed pipe  60  near the outflow port  62 . Accordingly, the liquid that remains between the first electromagnetic valve  66  and the outflow port  62  is reduced. As a consequence, the mist blower  100  in the present third embodiment can further reduce the liquid to leak when the user fails to close the mechanical valve  65 .       

     2-4. Fourth Embodiment 
     The present fourth embodiment corresponds to a partially modified first embodiment. Therefore, elements that are the same as those in the first embodiment will be given the same reference numerals and their explanations will be omitted. Differences from the first embodiment will be explained hereinafter. 
     2-4-1. Differences from First Embodiment 
     2-4-1-1. Mechanical Structure 
     As shown in  FIG.  11   , the mist blower  100  in the present fourth embodiment additionally includes a second electromagnetic valve  67  between the mechanical valve  65  and the first electromagnetic valve  66  with the liquid feed pipe  60  (in other words, upstream of the mechanical valve  65  and downstream of the first electromagnetic valve  66 ). The second electromagnetic valve  67  have the same configuration as that of the first electromagnetic valve  66 . 
     Furthermore, the mist blower  100  in the present fourth embodiment additionally includes a flow rate sensor  68  downstream of the mechanical valve  65  in the liquid feed pipe  60 . The flow rate sensor  68  measures a flow rate Q of the liquid flowing inside the liquid feed pipe  60  and outputs a flow rate signal to the control circuit  71 . The flow rate signal has a voltage that varies in accordance with the measured flow rate Q. 
     The liquid volume adjuster  44  is excluded in the mist blower  100  in the present fourth embodiment. 
     2-4-1-2. Electrical Configuration 
     As shown in  FIG.  12   , the mist blower  100  in the present fourth embodiment additionally includes a second manual switch  49 . The second manual switch  49  in the present fourth embodiment is in the form of a dial switch. In other embodiments, the second manual switch  49  may be in any form other than the dial switch, such as a push-button switch, a slide switch, a touch panel, a touch screen, and a GUI. 
     In the present fourth embodiment, the second manual switch  49  is disposed on the grip  41 . In other embodiments, the second manual switch  49  may be disposed on any part of the mist blower  100  other than the grip  41 . 
     The second manual switch  49  is manually rotated by the user to set a liquid volume level to be sprayed. The second manual switch  49  is configured to be selectively rotated to any one of two or more rotational positions. Those two or more rotational positions are associated with respective two or more liquid volume levels. In the present fourth embodiment, the liquid volume level is increased or decreased in stages in accordance with the rotation of the second manual switch  49 . In the present fourth embodiment, the second manual switch  49  is configured to selectively set any one of six liquid volume levels. In other embodiments, the second manual switch  49  may be configured to selectively set any one of two or more and five or less liquid volume levels or seven or more liquid volume levels. 
     The second manual switch  49  outputs a liquid volume designating signal. The liquid volume designating signal has a voltage that varies in accordance with the rotational position of the second manual switch  49 . 
     The mist blower  100  in the present fourth embodiment includes, in place of the first controller  70 A, a second controller  70 B. 
     The second controller  70 B corresponds to the first controller  70 A that is modified as explained below. 
     The second controller  70 B additionally includes a second solenoid drive circuit  81 . The second electromagnetic valve  67  includes a second solenoid  67   a.  The second solenoid  67   a  includes a second excitation coil  671  and a not-shown second plunger (specifically, an iron piece). The second excitation coil  671  has a first end coupled to the power-supply line  250 . The second excitation coil  671  has a second end coupled to the second solenoid drive circuit  81 . The second solenoid drive circuit  81  conducts or interrupts a third drive current from the power-supply line  250  to the second excitation coil  671 . In response to the third drive current flowing through the second excitation coil  671 , the second excitation coil  671  is magnetized and attracts the second plunger, which consequently causes the second electromagnetic valve  67  to open. In response to the third drive current being interrupted, the second excitation coil  671  is demagnetized and releases the second plunger, which consequently causes the second electromagnetic valve  67  to close. 
     The second controller  70 B additionally includes a third temperature measurement circuit  82  disposed in the vicinity of the second solenoid drive circuit  81 . The third temperature measurement circuit  82  measures a temperature of the second solenoid drive circuit  81  (hereinafter referred to as a third temperature T 3 ) and outputs a third temperature signal to the control circuit  71  and to the latch circuit  88 . In the present fourth embodiment, the third temperature measurement circuit  82  includes a not-shown thermistor. The third temperature signal has a voltage that varies in accordance with the measured third temperature T 3 . 
     The second controller  70 B additionally includes a third current measurement circuit  83 . The third current measurement circuit  83  measures a value of the third drive current flowing through the second solenoid drive circuit  81  (hereinafter referred to as a third current value I 3 ) and outputs a third current signal to the control circuit  71  and to the latch circuit  88 . In the present fourth embodiment, the third current measurement circuit  83  includes a not-shown shunt resistor. The third current signal has a voltage that varies in accordance with the measured third current value I 3 . 
     The second controller  70 B additionally includes a third signal line  280  that electrically couples the control circuit  71  to the second solenoid drive circuit  81 . The second controller  70 B additionally includes a third enabling switch  84  on the third signal line  280 . The third enabling switch  84  is controlled by the control circuit  71  and the latch circuit  88 . In the present fourth embodiment, the third enabling switch  84  is in the form of a semiconductor switch (such as an FET), an SSR, or a mechanical relay. 
     2-4-1-3. Operation of Control Circuit 
     The operation of the control circuit  71  in the present fourth embodiment is modified from the operation of the control circuit  71  of the first embodiment as explained below. 
     The control circuit  71  in the present fourth embodiment outputs, to the second solenoid drive circuit  81 , a second solenoid conduction signal that commands a magnetization of the second excitation coil  671 , and a second solenoid non-conduction signal that commands a demagnetization of the second excitation coil  671 . The control circuit  71  in the present fourth embodiment outputs a second solenoid control signal that serves as the second solenoid conduction signal and the second solenoid non-conduction signal. The second solenoid control signal is in the form of a binary logic signal. The second solenoid control signal having a logic HIGH corresponds to the second solenoid conduction signal; and the second solenoid control signal having a logic LOW corresponds to the second solenoid non-conduction signal. In other embodiments, the second solenoid control signal having the logic HIGH may correspond to the second solenoid non-conduction signal; and the second solenoid control signal having the logic LOW may correspond to the second solenoid conduction signal. Alternatively, in other embodiments, the mist blower  100  may include a path for transmitting the second solenoid conduction signal and a path for transmitting the second solenoid non-conduction signal in parallel, and the control circuit  71  may output the second solenoid conduction signal and the second solenoid non-conduction signal separately via these paths. 
     The control circuit  71  in the present fourth embodiment receives the third temperature signal and the third current signal in addition to the activation command signal, the deactivation command signal, the rotational position signal, the power discharge permission signal, the power discharge prohibition signal, the first temperature signal, the second temperature signal, the first current signal, and the second current signal. Based on these received signals, the control circuit  71  outputs the motor drive signal or the motor stop signal to the motor drive circuit  72 . 
     The control circuit  71  in the present fourth embodiment receives the liquid volume designating signal from the second manual switch  49 , and based on the received liquid volume designating signal, controls the opening level of the first electromagnetic valve  66 . 
     As shown in  FIG.  13   , two or more liquid volume levels (six liquid volume levels in the present fourth embodiment) are associated with respective two or more opening levels (six opening levels in the present fourth embodiment) of the first electromagnetic valve  66 . The first solenoid control signal generated by the control circuit  71  in the present fourth embodiment not only opens or closes the first electromagnetic valve  66  but also controls the opening level of the first electromagnetic valve  66  in accordance with the liquid volume designating signal. More specifically, the first solenoid control signal in the present fourth embodiment is in the form of a multi-level logic signal having a voltage that varies in association with each of the two or more opening levels. The control circuit  71  outputs such a first solenoid control signal to the first solenoid drive circuit  75 . 
     2-4-1-4. Operation of Latch Circuit 
     The latch circuit  88  in the present fourth embodiment receives the third temperature signal and the third current signal in addition to the first temperature signal, the second temperature signal, the first current signal, and the second current signal. Based on these received signals, the latch circuit  88  detects that the second controller  70 B is in the fault condition. In response to the detection of the fault condition of the second controller  70 B, the latch circuit  88  turns the first enabling switch  78 , the second enabling switch  79 , and the third enabling switch  84  off. 
     2-4-1-5. Fourth Control Process 
     A fourth control process executed by the control circuit  71  in the present fourth embodiment will be explained with reference to  FIG.  14   . The mechanical valve  65  is open when the control circuit  71  initiates the fourth control process. 
     In S 400  and S 410 , the control circuit  71  executes the same processes as in S 10  and S 20 . 
     In the subsequent S 420 , the control circuit  71  activates the electric motor  35 , the first electromagnetic valve  66 , and the second electromagnetic valve  67 . More specifically, the control circuit  71  turns the first enabling switch  78  on and outputs the motor drive signal to the motor drive circuit  72 . In addition, the control circuit  71  turns the second enabling switch  79  on and outputs the first solenoid conduction signal to the first solenoid drive circuit  75 . Furthermore, the control circuit  71  turns the third enabling switch  84  on and outputs the second solenoid conduction signal to the second solenoid drive circuit  81 . 
     In the subsequent S 430 , the control circuit  71  determines whether the first manual switch  42  is in the ON position. If the first manual switch  42  is in the ON position (S 430 : YES), the control circuit  71  proceeds to S 450 . If the first manual switch  42  is in the OFF position (S 430 : NO), the control circuit  71  proceeds to S 440 . 
     In S 440 , the control circuit  71  deactivates the electric motor  35  and the first electromagnetic valve  66  and keeps activating the second electromagnetic valve  67 . In other words, the second electromagnetic valve  67  is kept opened while the first electromagnetic valve  66  is closed. If the first electromagnetic valve  66  is closed properly, the liquid does not flow into the air feed pipe  40  even when the second electromagnetic valve  67  is opened. Upon completion of the process of S 440 , the control circuit  71  returns to S 400 . 
     In S 450 , the control circuit  71  determines whether the error flag is set to OFF. If the error flag is set to OFF (S 450 : YES), the control circuit  71  returns to S 430 . If the error flag is set to ON (S 450 : NO), the control circuit  71  proceeds to S 460 . 
     In S 460 , the control circuit  71  deactivates the electric motor  35 , the first electromagnetic valve  66 , and the second electromagnetic valve  67 . In other words, both of the first electromagnetic valve  66  and the second electromagnetic valve  67  are closed, This means that, if the second controller  70 B is in the fault condition, the control circuit  71  closes the first electromagnetic valve  66  and the second electromagnetic valve  67  and stops discharging the liquid from the nozzle  63 . Upon completion of the process of S 460 , the control circuit  71  proceeds to S 470 . 
     In S 470 , the control circuit  71  determines whether the first manual switch  42  is in the OFF position. If the first manual switch  42  is in the OFF position (S 470 : YES), the control circuit  71  returns to S 400 . If the first manual switch  42  is in the ON position (S 470 : NO), the control circuit  71  repeats the process of S 470  until the first manual switch  42  is moved to the OFF position. 
     2-4-1-6. Processes for Detecting Faults 
     In the faulty temperature detection process (see  FIG.  6   ) in the present fourth embodiment, the control circuit  71  obtains in S 100  the third temperature T 3  in addition to the first temperature T 1  and the second temperature T 2 . More specifically, the control circuit  71  converts the first through third temperature signals into respective digital values via the ADC  71   c  and obtains the first through third temperatures T 1  through T 3 . In the subsequent S 110 , the control circuit  71  determines whether any one of the first through third temperatures T 1  through T 3  is higher than or equal to the preset temperature threshold. 
     In the faulty electric current detection process (see FIG,  7 ) in the present fourth embodiment, the control circuit  71  obtains in S 200  the third current value I 3  in addition to the first current value I 1  and the second current value I 2 . More specifically, the control circuit  71  converts the first through third current signals into respective digital values via the ADC  71   c  and obtains the first through third current values I 1  through I 3 . In the subsequent S 210 , the control circuit  71  determines whether any one of the first through third current values I 1  through I 3  is greater than or equal to the preset electric current threshold. 
     In the present fourth embodiment, the control circuit  71  executes a faulty flow rate detection process in addition to the faulty temperature detection process and the faulty electric current detection process. 
     The faulty flow rate detection process will be explained with reference to  FIG.  15   . 
     In S 500 , the control circuit  71  obtains a flow rate Q. More specifically, the control circuit  71  converts the flow rate signal into a digital value via the ADC  71   c  and obtains the flow rate Q. 
     In the subsequent S 510 , the control circuit  71  determines whether the obtained flow rate Q is greater than or equal to a preset flow rate threshold. The preset flow rate threshold corresponds to one example of the first preset flow rate threshold and also to one example of the second preset flow rate threshold in the overview of embodiments. The preset flow rate threshold is a threshold for determining whether the liquid is flowing through the liquid feed pipe  60 . If the flow rate Q is greater than or equal to the preset flow rate threshold (S 510 : YES), the control circuit  71  proceeds to S 520 . If the flow rate Q is less than the preset flow rate threshold (S 510 : NO), the control circuit  71  proceeds to S 550 . 
     In S 520 , the control circuit  71  determines whether the first manual switch  42  is in the OFF position. In other words, the control circuit  71  determines whether it is receiving the deactivation command signal from the first manual switch  42 . If the first manual switch  42  is in the OFF position (S 520 : YES), the control circuit  71  proceeds to S 530 . If the first manual switch  42  is in the ON position (S 520 : NO), the control circuit  71  proceeds to S 540 . 
     In S 530 , the control circuit  71  sets the error flag to ON and returns to S 500 . If the first manual switch  42  is in the OFF position, the first electromagnetic valve  66  is closed and therefore the liquid should not be flowing through the liquid feed pipe  60 . If the flow rate Q is greater than or equal to the preset flow rate threshold albeit that the first electromagnetic valve  66  is closed, the first electromagnetic valve  66  may have a fault. Therefore, in S 530 , the error flag is set to ON. In association with S 530 , the second electromagnetic valve  67  is closed in the aforementioned fourth control process. 
     In S 540 , the control circuit  71  sets the error flag to OFF and returns to S 500 . 
     In S 550 , the control circuit  71  determines whether the first manual switch  42  is in the ON position. In other words, the control circuit  71  determines whether it is receiving the activation command signal from the first manual switch  42 . If the first manual switch  42  is in the ON position (S 550 : YES), the control circuit  71  proceeds to S 560 . If the first manual switch  42  is in the OFF position (S 550 : NO), the control circuit  71  proceeds to S 570 . 
     In S 560 , the control circuit  71  sets the error flag to ON and returns to S 500 . If the first manual switch  42  is in the ON position, the first electromagnetic valve  66  is opened and therefore the liquid should be flowing through the liquid feed pipe  60 . If the flow rate Q is less than the preset flow rate threshold albeit that the first electromagnetic valve  66  is opened, the first electromagnetic valve  66  may have a fault. Therefore, in S 560 , the error flag is set to ON. In association with S 560 , the first electromagnetic valve  66  and the second electromagnetic valve  67  are closed in the aforementioned fourth control process. 
     In S 570 , the control circuit  71  sets the error flag to OFF and returns to S 500 . 
     2-4-2. Effects in Fourth Embodiment 
     The mist blower  100  of the present fourth embodiment exerts, in addition to the aforementioned first through seventh effects, the following tenth through fourteenth effects.
         Tenth Effect: In the mist blower  100  of the present fourth embodiment, the opening level of the first electromagnetic valve  66  is controlled in accordance with the liquid volume level designated via the second manual switch  49 . Accordingly, the mist blower  100  of the present fourth embodiment can adjust the volume of the liquid to be sprayed to the liquid volume level set by the user.   Eleventh Effect: The mist blower  100  of the present fourth embodiment can measure the flow rate Q of the liquid flowing through the liquid feed pipe  60  by the flow rate sensor  68  disposed downstream of the first electromagnetic valve  66 , and in addition, based on the measured flow rate Q, can detect that the first electromagnetic valve  66  has a fault.   Twelfth Effect: With the second electromagnetic valve  67  provided with the liquid feed pipe  60  in addition to the first electromagnetic valve  66 , the mist blower  100  of the present fourth embodiment can inhibit the leakage of the liquid from the liquid feed pipe  60  into the air feed pipe  40  while the electric motor  35  is deactivated with the first electromagnetic valve  66  having a fault.   Thirteenth Effect: In the mist blower  100  in the present fourth embodiment, in a case where (i) the first manual switch  42  is in the OFF position and (ii) the flow rate Q is greater than or equal to the preset flow rate threshold, the second electromagnetic valve  67  is closed. Accordingly, the mist blower  100  in the present fourth embodiment can inhibit the leakage of the liquid from the liquid feed pipe  60  into the air feed pipe  40  while the electric motor  35  is deactivated with the first electromagnetic valve  66  having a fault and not closed.   Fourteenth Effect: In the mist blower  100  in the present fourth embodiment, in a case where (i) the first manual switch  42  is in the ON position and (ii) the flow rate Q is less than the preset flow rate threshold, the first electromagnetic valve  66  and the second electromagnetic valve  67  are closed. Accordingly, the mist blower  100  in the present fourth embodiment can inhibit the leakage of the liquid from the liquid feed pipe  60  into the air feed pipe  40  when the electric motor  35  is activated with the first electromagnetic valve  66  having a fault and insufficiently opened.       

     2-5. Fifth Embodiment 
     The present fifth embodiment corresponds to a partially modified second embodiment. Therefore, elements that are the same as those in the second embodiment will be given the same reference numerals and their explanations will be omitted. Differences from the second embodiment will be explained hereinafter. 
     2-5-1. Differences from Second Embodiment 
     2-5-1-1. Mechanical Structure 
     As shown in  FIG.  16   , the mist blower  100  in the present fifth embodiment additionally includes a flow speed sensor  95 . In the present fifth embodiment, the flow speed sensor  95  is situated downstream of the impeller  33  and upstream of the nozzle  63  in the air feed pipe  40  and close to the nozzle  63 . The flow speed sensor  95  measures a flow speed V of the airflow flowing towards the nozzle  63 . In other embodiments, the flow speed sensor  95  may be situated at any part in the air feed pipe  40  away from the nozzle  63 . 
     As shown in  FIG.  17   , the flow speed sensor  95  outputs a flow speed signal to the control circuit  71 . The flow speed signal has a voltage that varies in accordance with the measured flow speed V. 
     2-5-1-2. Fifth Control Process 
     The control circuit  71  in the present fifth embodiment executes, in place of the third control process shown in  FIG.  9   , a fifth control process shown in  FIG.  18   . 
     As shown in  FIG.  18   , in S 700 , the control circuit  71  determines whether the first manual switch  42  is in the ON position. If the first manual switch  42  is in the ON position (S 700 : YES), the control circuit  71  proceeds to S 710 . If the first manual switch  42  is in the OFF position (S 700 : NO), the control circuit  71  repeats the process of S 700  until the first manual switch  42  is moved to the ON position. 
     In S 710 , the control circuit  71  obtains the flow speed V. More specifically, the control circuit  71  converts the flow speed signal into a digital value via the ADC  71   c  and obtains the flow speed V. 
     In the subsequent S 720 , the control circuit  71  determines whether the electric motor  35  is activated. If the electric motor  35  is activated (S 720 : YES), the control circuit  71  proceeds to S 730 . If the electric motor  35  is deactivated (S 720 : NO), the control circuit  71  returns to S 700 . 
     In S 730 , the control circuit  71  determines whether the obtained flow speed V is higher than or equal to a preset flow speed threshold. The preset flow speed threshold is higher than or equal to a flow speed that generates the negative pressure at the second discharge port  63   a  of the nozzle  63 . In the present fifth embodiment, the preset flow speed threshold is 56 m/s. In other embodiments, the preset flow speed threshold may be lower than 56 m/s or higher than 56 m/s. 
     If the flow speed V is higher than or equal to the preset flow speed threshold (S 730 : YES), the control circuit  71  proceeds to S 740 . If the flow speed V is lower than the preset flow speed threshold (S 730 : NO), the control circuit  71  returns to S 700 . 
     In S 740 , the control circuit  71  activates the first electromagnetic valve  66  by turning the second enabling switch  79  on and outputs the first solenoid conduction signal to the first solenoid drive circuit  75 . In the present fifth embodiment, the control circuit  71  does not simultaneously initiate the activation of the first electromagnetic valve  66  with the activation of the electric motor  35 . The reason being that, in a case where the flow speed V is lower than the preset flow speed threshold, the liquid discharged from the second discharge port  63   a  may not be atomized. The control circuit  71  initiates the activation of the first electromagnetic valve  66  once the actual rotational frequency R of the electric motor  35  is increased and the flow speed V reaches the preset flow speed threshold or higher. 
     In the subsequent S 750 , the control circuit  71  obtains the flow speed V again. 
     In the subsequent S 760 , the control circuit  71  determines whether the electric motor  35  is activated. If the electric motor  35  is activated (S 760 : YES), the control circuit  71  proceeds to S 780 . If the electric motor  35  is deactivated (S 760 : NO), the control circuit  71  proceeds to S 770 . 
     In S 770 , the control circuit  71  deactivates the first electromagnetic valve  66 . In other words, the control circuit  71  turns the second enabling switch  79  off. In addition to/alternatively, the control circuit  71  outputs the first solenoid non-conduction signal to the first solenoid drive circuit  75 . In other words, the control circuit  71  immediately closes the first electromagnetic valve  66  and stops discharging the liquid from the second discharge port  63   a  when the electric motor  35  is deactivated. 
     In S 780 , the control circuit  71  determines whether the flow speed V, which was obtained again, is higher than or equal to the preset flow speed threshold. If the flow speed V is higher than or equal to the preset flow speed threshold (S 780 : YES), the control circuit  71  returns to S 750 . If the flow speed V is lower than the preset flow speed threshold (S 780 : NO), the control circuit  71  proceeds to S 790 . 
     In S 790 , the control circuit  71  executes the same process as in S 770 . In the present fifth embodiment, if the flow speed V is lower than the preset flow speed threshold when the electric motor  35  is activated, the control circuit  71  closes the first electromagnetic valve  66  and stops discharging the liquid from the second discharge port  63   a.  Upon completion of the process of S 790 , the control circuit  71  proceeds to S 800 . 
     In S 800 , the control circuit  71  determines whether the first manual switch  42  is in the OFF position. If the first manual switch  42  is in the OFF position (S 800 : YES), the control circuit  71  returns to S 700 . If the first manual switch  42  is in the ON position (S 800 : NO), the control circuit  71  repeats the process of S 800  until the first manual switch  42  is moved to the OFF position. 
     2-5-2. Effects in Fifth Embodiment 
     The mist blower  100  in the present fifth embodiment exerts, in addition to the aforementioned first through sixth effects, the following fifteenth effect.
         Fifteenth Effect: In the mist blower  100  in the present fifth embodiment, the first electromagnetic valve  66  is opened after the flow speed V in the air feed pipe  40  reaches the preset flow speed threshold or higher. Accordingly, the mist blower  100  in the present fifth embodiment can adequately atomize the liquid and discharge the adequately atomized liquid.       

     2-6. Sixth Embodiment 
     The present sixth embodiment corresponds to a partially modified second embodiment. Therefore, elements that are the same as those in the second embodiment will be given the same reference numerals and their explanations will be omitted. Differences from the second embodiment will be explained hereinafter. 
     2-6-1. Differences from Second Embodiment 
     2-6-1-1. Sixth Control Process 
     The control circuit  71  in the present sixth embodiment executes, in place of the fifth control process shown in  FIG.  18   , a sixth control process shown in  FIG.  19   . 
     As shown in  FIG.  19   , in S 900 , the control circuit  71  determines whether the first manual switch  42  is in the ON position. If the first manual switch  42  is in the ON position (S 900 : YES), the control circuit  71  proceeds to S 910 , If the first manual switch  42  is in the OFF position (S 900 : NO), the control circuit  71  repeats the process of S 900  until the first manual switch  42  is moved to the ON position. In a case where (i) it is determined in the previous S 900  that the first manual switch  42  is in the OFF position, and (ii) it is determined in the current S 900  that the first manual switch  42  is in the ON position, the control circuit  71  starts counting an elapsed time T. In other words, if the first manual switch  42  is moved from the OFF position to the ON position, the control circuit  71  starts counting the elapsed time T. In the present sixth embodiment, the control circuit  71  counts the elapsed time T based on the clock signal generated by the clock generator  71   e.  In other embodiments, the control circuit  71  may count the elapsed time T with any device (such as a timer) other than the clock generator  71   e.    
     In S 910 , the control circuit  71  obtains the elapsed time T. In other words, the control circuit  71  obtains a time until the current time since the first manual switch  42  is moved to the ON position. 
     In the subsequent S 920 , the control circuit  71  determines whether the electric motor  35  is activated. If the electric motor  35  is activated (S 920 : YES), the control circuit  71  proceeds to S 930 . If the electric motor  35  is deactivated (S 920 : NO), the control circuit  71  returns to S 900 . 
     In S 930 , the control circuit  71  determines whether the obtained elapsed time T is greater than or equal to a preset time threshold. The preset time threshold corresponds to a time required until the flow speed V in the air feed pipe  40  reaches the preset flow speed threshold or higher since the initiation of the activation of the electric motor  35 . If the elapsed time T is greater than or equal to the preset time threshold (S 930 : YES), the control circuit  71  proceeds to S 940 . If the elapsed time T is less than the preset time threshold (S 930 : NO), the control circuit  71  returns to S 900 . 
     In S 940 , the control circuit  71  activates the first electromagnetic valve  66  by turning the second enabling switch  79  on and outputting the first solenoid conduction signal to the first solenoid drive circuit  75 . In the present sixth embodiment, the control circuit  71  initiates the activation of the electric motor  35  when the first manual switch  42  is moved to the ON position; however, the control circuit  71  does not initiate the activation of the first electromagnetic valve  66 . The reason being that, if the elapsed time T is less than the preset time threshold, the actual rotational frequency R of the electric motor  35  is not adequately increased and the flow speed V is insufficient, and therefore the liquid discharged from the second discharge port  63   a  may not be atomized. 
     In the subsequent S 950 , the control circuit  71  resets the elapsed time T to zero. 
     In the subsequent S 960 , the control circuit  71  deactivates the first electromagnetic valve  66  based on any one of the position of the first manual switch  42 , the actual rotational frequency R, the flow speed V, or the error flag. More specifically, the control circuit  71  deactivates the first electromagnetic valve  66  by executing any of the processes from S 40  through  80 , the processes from S 340  through S 390 , or the processes from S 750  through S 800 . 
     2-6-2. Effects in Sixth Embodiment 
     The mist blower  100  of the present sixth embodiment exerts, in addition to the aforementioned first through sixth effects, the following sixteenth effect.
         Sixteenth Effect: In the mist blower  100  in the present sixth embodiment, the first electromagnetic valve  66  is opened after the flow speed V in the air feed pipe  40  is sufficiently increased in response to the increase in the actual rotational frequency R of the electric motor  35 . Accordingly, the mist blower  100  in the present sixth embodiment can adequately atomize the liquid discharged from the second discharge port  63   a.          

     2-7. Seventh Embodiment 
     The present seventh embodiment corresponds to a partially modified fifth embodiment. Therefore, elements that are the same as those in the fifth embodiment will be given the same reference numerals and their explanations will be omitted. Differences from the fifth embodiment will be explained hereinafter. 
     2-7-1. Differences from Fifth Embodiment 
     2-7-1-1. Mechanical Structure 
     Although it is not illustrated, in the mist blower  100  in the present seventh embodiment, the container  20  and all of the components housed in the container  20  (namely, the first controller  70 A, the first battery  200 A, the second battery  200 B, the connector  220 , and the rotational position sensor  91 ) are excluded, and the air blower  30  is situated below the tank  10 . 
     As shown in  FIG.  20   , the air blower  30  in the present seventh embodiment includes an internal combustion engine  6  in place of the electric motor  35 . The air blower  30  in the present seventh embodiment additionally includes a third controller  70 C. In other embodiments, the third controller  70 C may be disposed at any part of the mist blower  100  other than the air blower  30 . 
     In the present seventh embodiment, the internal combustion engine  6  is but not limited to be in the form of a two-stroke single-cylinder reciprocating engine or a four-stroke single-cylinder reciprocating engine. 
     The internal combustion engine  6  includes a shaft  16 , a crank chamber  6   a,  a piston  6   b,  and an ignition plug  6   c.    
     The air blower  30  in the present seventh embodiment additionally includes a recoil starter  118 . The recoil starter  118  includes a not-shown rope. When this rope is pulled by the user, the shaft  16  rotates and a high-voltage current is intermittently supplied to the ignition plug  6   c.  The ignition plug  6   c  ignites a fuel such as gasoline supplied to the internal combustion engine  6 . The piston  6   b  reciprocates in response to the combustion of the fuel, which causes the shaft  16  to rotate. The impeller  33  is physically coupled to the shaft  16  and rotates along with the rotation of the shaft  16 . The shaft  16  includes a flywheel  127  supported by the shaft  16 . The flywheel  127  includes a first permanent magnet  127   a  and a second permanent magnet  127   b  on its outer circumferential wall. The flywheel  127  rotates with the shaft  16 . 
     The air blower  30  in the present seventh embodiment additionally includes a first electric generator  122  and a second electric generator  123 . 
     The first electric generator  122  generates the aforementioned high-voltage current by the rotation of the shaft  16  and delivers the high-voltage current to the ignition plug  6   c,  The first electric generator  122  outputs, to the third controller  70 C, a shaft rotation signal having a voltage that varies in accordance with the rotation of the shaft  16 . 
     More specifically, the first electric generator  122  includes a first generating coil  122   a,  and a first power feeding device  122   b.  The first generating coil  122   a  is situated in the vicinity of the flywheel  127 . The first generating coil  122   a  generates an AC power by the first permanent magnet  127   a  and the second permanent magnet  127   b  moving close to or away from the first generating coil  122   a  by the rotation of the shaft  16 . The first power feeding device  122   b  intermittently generates the aforementioned high-voltage current, at an ignition timing designated by the third controller  70 C, based on the AC power generated by the first generating coil  122   a  and delivers this high-voltage current to the ignition plug  6   c.  The first power feeding device  122   b  also generates the aforementioned shaft rotation signal based on the AC power generated by the first generating coil  122   a  and outputs the generated shaft rotation signal to the third controller  70 C. 
     The second electric generator  123  generates a DC power for the third controller  70 C and the first solenoid  66   a  by the rotation of the shaft  16  and delivers the DC power to the third controller  70 C and to the first solenoid  66   a.    
     More specifically, the second electric generator  123  includes a second generating coil  123   a,  and a second power feeding device  123   b.  The second generating coil  123   a  is situated in the vicinity of the flywheel  127 . The second generating coil  123   a  generates an AC power by the first permanent magnet  127   a  and the second permanent magnet  127   b  moving close to or away from the second generating coil  123   a  by the rotation of the shaft  16 . The second power feeding device  123   b  generates the aforementioned DC power based on the AC power generated by the second generating coil  123   a  and delivers this DC power to the third controller  70 C and to the first solenoid  66   a.    
     The third controller  70 C includes the control circuit  71  and the first solenoid drive circuit  75  similarly to the first controller  70 A in the fifth embodiment. As similarly to the first controller  70 A in the fifth embodiment, the third controller  70 C may additionally include the second electric current measurement circuit  77 , the second enabling switch  79 , and the latch circuit  88 , which are not shown in  FIG.  20   . 
     In addition, the third controller  70 C includes a rotational frequency measurement circuit  124 . The rotational frequency measurement circuit  124  measures an actual rotational frequency N of the internal combustion engine  6  based on the shaft rotation signal received from the first electric generator  122 . 
     The third controller  70 C receives the flow speed signal from the flow speed sensor  95 . The third controller  70 C receives the manual operation signal from the first manual switch  42  through a not-shown path. 
     2-7-1-2. Seventh Control Process 
     A seventh control process executed by the control circuit  71  will be explained with reference to  FIG.  21   . In the present seventh embodiment, the control circuit  71  initiates the seventh control process in response to an activation of the internal combustion engine  6  by a recoil starter  118 . 
     As shown in  FIG.  21   , in S 605 , the control circuit  71  executes the same process as in S 600 . 
     In the subsequent S 625 , the control circuit  71  adjusts the supply of the fuel, the ignition timing of the ignition plug  6   c,  or the like to increase the actual rotational frequency N of the internal combustion engine  6 . In other words, when the first manual switch  42  is in the ON position, the control circuit  71  increases the actual rotational frequency N of the internal combustion engine  6 . The control circuit  71  is electrically coupled to a not-shown fuel supplying device through a not-shown path and indicates the fuel supplying device an amount of the fuel to be supplied to the internal combustion engine  6 . The control circuit  71  is electrically coupled to the first power feeding device  122   b  through a not-shown path and commands the first power feeding device  122   b  to deliver the high-voltage current to the ignition plug  6   c  every time the ignition timing arrives. 
     In the subsequent S 635 , the control circuit  71  executes the same process as in S 630 . 
     In the subsequent S 645 , the control circuit  71  adjusts the supply of the fuel, the ignition timing of the ignition plug  6   c,  or the like to decrease the actual rotational frequency N of the internal combustion engine  6 . In other words, when the first manual switch  42  is in the OFF position, the control circuit  71  decreases the actual rotational frequency N of the internal combustion engine  6 . 
     In response to the increase in the actual rotational frequency N of the internal combustion engine  6 , the rotational frequency of the impeller  33  increases, which increases a load of the impeller  33  on the shaft  16 . When the load of the impeller  33  is balanced with the output of the internal combustion engine  6 , the actual rotational frequency N of the internal combustion engine  6  stops increasing. 
     2-7-1-3. Eighth Control Process 
     When activated, the control circuit  71  executes an eighth control process shown in  FIG.  22    in addition to the seventh control process. 
     As shown in  FIG.  22   , in S 303 , the control circuit  71  executes the same process as in S 300 . 
     In the subsequent S 308 , the control circuit  71  obtains the actual rotational frequency N measured by the rotational frequency measurement circuit  124 . 
     In the subsequent S 325  and S 335 , the control circuit  71  executes the same processes as in S 320  and S 330 . 
     In the subsequent S 345 , the control circuit  71  obtains the actual rotational frequency N measured by the rotational frequency measurement circuit  124  again. 
     In the subsequent S 375  through S 395 , the control circuit  71  executes the same processes as in S 370  through S 390 . The preset rotational frequency threshold in S 325  and S 375  corresponds to one example of the second preset rotational frequency threshold in the overview of embodiments. 
     2-7-2. Effects in Seventh Embodiment 
     The mist blower  100  in the present seventh embodiment exerts the following seventeenth and eighteenth effects.
         Seventeenth Effect: In the mist blower  100  in the present seventh embodiment, when the first manual switch  42  is commanding the increase in the actual rotational frequency N of the internal combustion engine  6 , the first electromagnetic valve  66  is opened; when the first manual switch  42  is commanding the decrease in the actual rotational frequency N, the first electromagnetic valve  66  is closed. The user can increase or decrease the actual rotational frequency N of the internal combustion engine  6 , and at the same time, open or close the first electromagnetic valve  66  by moving the first manual switch  42 .   Eighteenth Effect: In the mist blower  100  in the present seventh embodiment, in response to the actual rotational frequency N of the internal combustion engine  6  being higher than or equal to the preset rotational frequency threshold, the first electromagnetic valve  66  is opened and the liquid can be adequately atomized in the air feed pipe  40  and sprayed from the air feed pipe  40 .       

     2-8. Eighth Embodiment 
     The present eighth embodiment corresponds to a partially modified seventh embodiment. Therefore, elements that are the same as those in the seventh embodiment will be given the same reference numerals and their explanations will be omitted. Differences from the seventh embodiment will be explained hereinafter. 
     2-8-1. Differences from Seventh Embodiment 
     2-8-1-1. Ninth Control Process 
     The control circuit  71  in the present eighth embodiment executes a ninth control process shown in  FIG.  23    in place of the eighth control process shown in  FIG.  22   . 
     As shown in  FIG.  23   , in S 705  and S 715 , the control circuit  71  executes the same processes as in S 700  and S 710 . 
     In the subsequent S 735  through S 755 , the control circuit  71  executes the same processes as in S 730  through S 750 . 
     In the subsequent S 785  through S 805 , the control circuit  71  executes the same processes as in S 780  through S 800 . 
     2-8-2. Effects in Eighth Embodiment 
     The mist blower  100  in the present eighth embodiment exerts the aforementioned fifteenth and seventeenth effects. 
     2-9. Further Embodiments 
     Although the embodiments of the present disclosure have been explained above, the present disclosure may be implemented in various forms without being limited to the aforementioned embodiments. 
     In a further embodiment, any one of the second embodiment, the fifth embodiment, or the sixth embodiment may be combined with the third embodiment or the fourth embodiment. In other words, in the third embodiment or the fourth embodiment, the first electromagnetic valve  66  may be opened if (i) the actual rotational frequency R of the electric motor  35  is higher than or equal to the preset rotational frequency threshold, or (ii) the flow speed V is higher than or equal to the preset flow speed threshold, or (iii) the elapsed time T is greater than or equal to the preset time threshold; and the first electromagnetic valve  66  may be closed if (i) the actual rotational frequency R is lower than the preset rotational frequency threshold, or (ii) the flow speed V is lower than the preset flow speed threshold, or (iii) the elapsed time T is less than the preset time threshold. 
     In a further embodiment, any one of the first embodiment, the third embodiment, the fourth embodiment, or the sixth embodiment may be combined with the seventh embodiment or the eighth embodiment. 
     In the second embodiment, the motor drive signal may be in the form of a pulse width modulation signal. In this case, the control circuit  71  does not have to calculate the actual rotational frequency R and may assume the actual rotational frequency R based on a duty ratio of the motor drive signal. In other words, in S 320  and S 360 , the control circuit  71  may determine whether the duty ratio of the motor drive signal is greater than or equal to a preset duty ratio threshold in place of determining whether the actual rotational frequency R is higher than or equal to the preset rotational frequency threshold. 
     In the third embodiment, in S 550 , when the first manual switch  42  is in the ON position, the control circuit  71  may set an additional flag, which is distinct from the error flag, to ON, When the additional flag is set to ON, the control circuit  71  may close one of the first electromagnetic valve  66  or the second electromagnetic valve  67  instead of closing both. In other words, when the opening level of the first electromagnetic valve  66  is insufficient, the control circuit  71  may close one of the first electromagnetic valve  66  or the second electromagnetic valve  67 . 
     The mist blower  100  in the second embodiment, the third embodiment, or the fourth embodiment does not have to include the mechanical valve  65 . Alternatively, the mist blower  100  in the second embodiment, the third embodiment, or the fourth embodiment does not have to include the liquid volume adjuster  44 . 
     When the mist blower  100  in the second embodiment, the third embodiment, or the fourth embodiment does not include the liquid volume adjuster  44  but includes the mechanical valve  65 , the mechanical valve  65  may be configured such that the opening level of the mechanical valve  65  is manually adjusted by the user, or the first electromagnetic valve  66  may be configured to be able to adjust its opening level. 
     When the mist blower  100  in the second embodiment, the third embodiment, or the fourth embodiment does not include the liquid volume adjuster  44  and the mechanical valve  65 , the first electromagnetic valve  66  may be configured to be able to adjust its opening level. 
     Two or more functions achieved by one element in the aforementioned embodiments may be achieved by two or more elements, and one function achieved by one element may be achieved by two or more elements. In addition, two or more functions achieved by two or more elements may be achieved by one element, and one function achieved by two or more elements may be achieved by one element. A part of the configurations in the aforementioned embodiments may be omitted. Furthermore, at least a part of the configurations of the aforementioned embodiments may be added to or replaced with another part of the configurations of the aforementioned embodiments.