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  Electric blowerUSPTO Application #: 20060099084Title: Electric blower Abstract: The present invention provides an electric blower that performs: measuring an amount of airflow against a fan rotation speed of the blower with a load magnitude detected previously; determining an empirical formula to calculate a fan rotation speed to discharge an amount of target airflow in response to the magnitude of a load of the blower according to the data obtained from the above measurement repeated a plurality of times varying the magnitude of the load on the blower; operating, firstly in practice, the blower to detect the magnitude of the load of the blower, then to calculate the fan rotation speed to discharge the amount of target airflow using the empirical formula; and then changing the blower operation to the fan rotation speed given by the calculation. (end of abstract) Agent: Mcdermott Will & Emery LLP - Washington, DC, US Inventors: Shizuo Otaki, Shinji Fujiwara, Kazuhiro Harada USPTO Applicaton #: 20060099084 - Class: 417042000 (USPTO) Related Patent Categories: Pumps, Condition Responsive Control Of Pump Drive Motor, In Response To Pump Speed The Patent Description & Claims data below is from USPTO Patent Application 20060099084. Brief Patent Description - Full Patent Description - Patent Application Claims
TECHNICAL FIELD [0001] The present invention relates to an electric blower for use in an air conditioner or the like coupled to a duct to supply an airflow necessary to a refrigerating cycle or the like in response to the duct condition. BACKGROUND ART [0002] There has been the kind of conventional electric blower that, observing always a fan rotation speed and the PWM (Pulse Width Modulation) signal for an electric motor to calculate the amount of airflow to compare the calculated amount of airflow with an amount of target airflow, corrects the control signal sent to the electric motor if there is a difference between the two, which is so-called a feedback control method. The technology is disclosed for instance in Japanese Patent Unexamined Publication No. H07-301450 (hereafter referred to as patent document 1). [0003] FIG. 3 shows a process flowchart of a conventional electric blower described in patent-document 1. As shown in FIG. 3, the control process of the conventional electric blower comprises; step 135 to recognize the amount of target airflow; step 140 to calculate the amount of airflow by using the PWM signal sent to the electric motor at present and the fan rotational speed; steps 145 and 150 to compare the calculated amount of airflow with the amount of target airflow; steps 155 and 165 to correct the PWM signal according to the comparison results; and step 160 to send the corrected PWM signal to the motor controller, repeating from step 135 to step 160 constantly. [0004] However, owing to pulsations occurring inevitably in the airflow of electric blowers, conventional electric blowers cannot continue to operate stably matching the amount of target airflow with the calculated amount of airflow, but is operated always fluctuated in the rotation speed. Moreover, elements having big inertia such as the electric motor and fan included in the feedback control system could cause overshooting or depending on conditions the pulsation could be amplified to cause an unstable rotation speed fluctuating largely SUMMARY OF THE INVENTION [0005] The present invention aims at providing an electric blower to solve the above-mentioned drawbacks, which can operate stably keeping an amount of target airflow in response to conditions of duct. [0006] To solve the above-mentioned drawbacks the electric blower of the present invention includes an electric motor, a blower with a fan driven to rotate by the electric motor, and a controller to control the electric motor. The controller comprises: a load-detector to detect output data on the magnitude of the load; a rotation-speed-calculator to calculate output data on the fan rotation speed required for the blower to discharge the amount of target airflow according to the magnitude of the load of the fan output from the load-detector and the given amount of target airflow; a rotation-speed-selector to switch over the rotation speed from the load-detection-rotation-speed determined previously to the rotation speed required for the blower to discharge the amount of target airflow according to the data output from the rotation speed calculator; and a timing-device to determine the operation timing for the load-detector, rotation-speed-calculator and rotation-speed-selector respectively. [0007] The configuration can perform a stable operation for the controlled airflow without amplifying the pulsation in the rotation speed, because the timing device is allowed to work according to need such as before the operation starts or when a load condition varies to detect the duct condition beforehand and can operate the blower at a rotation speed capable of discharging the amount of target airflow in response to the duct condition detected. BRIEF DESCRIPTION OF THE DRAWINGS [0008] FIG. 1 illustrates a block diagram of the electric blower used in exemplary embodiment 1 of the present invention. [0009] FIG. 2 illustrates a characteristic showing a relation between the amount of airflow and rotation speed of the electric blower used in exemplary embodiment 1 of the present invention. [0010] FIG. 3 illustrates a flowchart of a conventional electric blower. DETAILED DESCRIPTION OF THE INVENTION Exemplary Embodiment 1 [0011] Generally, an amount of airflow is proportional to a rotation speed of a fan included in a duct when the duct condition is determined and the duct condition affects relative gradients or the like. If, therefore, the duct condition is detected somehow the relation between the amount of airflow and rotation speed can be determined. The duct condition is detectable as a load of the blower and the load of the blower is detectable as an output force of an electric motor as well. Moreover, because the output force of the electric motor is proportional to the product of the rotation speed and torque of the fan, the duct condition can be detected from the torque of the electric motor when the rotation speed is kept constant. In case of a DC motor, whose torque is proportional to the input current, the torque can be detected by measuring the motor input current. Therefore, the duct conditions can be detected by measuring the motor input current. [0012] The present invention is to detect the duct condition according to a value showing the magnitude of the load of the blower (hereafter referred to as a blower-load-variable) obtained from the input current of the electric motor operating at a predetermined rotation speed. To measure the blower-load-variable, the blower must operate at a predetermined rotation speed. [0013] Namely, through the operation to detect the load by measuring the input current of the electric motor operating at a predetermined rotation speed, the duct condition is detected as a blower-load-variable. A fan rotation speed to discharge the amount of target airflow in response to the duct condition is calculated according to an empirical formula having been obtained from the characteristics of the blower. Subsequently, controlling the motor to rotate the fan at the given rotation speed can realize an operation for a stable airflow without doing any constant feedback control. [0014] Now, exemplary embodiment of the present invention is described with reference to the drawings. The present invention is not limited to the exemplary embodiment only. [0015] FIG. 1 is a block diagram of the electric blower used in exemplary embodiment 1 of the present invention. In FIG. 1, electric blower 1 of the present invention includes electric motor 25, blower 20 and controller 10. [0016] Electric motor 25 supplies a driving force necessary to rotate blower 20. A DC brush-less motor is employed in the exemplary embodiment. The driving shaft of electric motor 25 is coupled to blower 20 directly. [0017] Blower 20 flows air through duct system 15 forming an air-path. A sirocco fan is used in the blower of the exemplary embodiment. [0018] Controller 10 includes variable-motor-controller 30, airflow-controller 35 and system-controller 40. Continue reading... Full patent description for Electric blower Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Electric blower patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. Start now! - Receive info on patent apps like Electric blower or other areas of interest. ### Previous Patent Application: Dry pumps Next Patent Application: Plant for producing compressed gas and method for using said plant Industry Class: Pumps ### FreshPatents.com Support Thank you for viewing the Electric blower patent info. 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