The present invention relates to an electronic regulating device for an electric motor applied to a fuel burner ventilator.
As is known, a gas or vapourized liquid fuel burner is supplied with a mixture of fuel and combustion air; and the combustion air supply to the burner is regulated by a ventilator driven by an electric motor, the speed of which is controlled by a flame control device commonly used to control operation of the fuel burner.
The flame control device is normally equipped with an electric control card for processing physical flame combustion parameters to regulate the fuel and combustion air mixture according to the desired calories. The electronic control card therefore has one or more outputs for controlling the speed of the electric motor, so as to regulate combustion air supply by the ventilator on the basis of processing by the electronic control card.
Currently marketed fuel burners are substantially of two types used for two different types of application.
A first type comprises two-stage burners, commonly used in floor-mounted boilers, in which the flame control device directly controls electric power supply to the motor by a motor output (current phase).
A second type comprises modulating burners, commonly used in wall-mounted boilers, in which the flame control device modulates the speed of the ventilator by a PWM (Pulse Width Modulation) signal, i.e. by varying the duty cycle of a square-wave signal.
Currently marketed electric motors for fuel burner ventilators are simply equipped with an electronic switching device, and are designed for use with a specific type of burner.
More specifically, electric motors for two-stage burners simply have an input for receiving electric power supply directly from the motor output of the flame control device; and electric motors for modulating burners simply have a PWM input for connection to the corresponding PWM output of the flame control device.
As an example, the US patent application published with number
In other words, being designed for a given type of flame control logic, the same type of electric motor cannot be used with different types of known or newly designed flame control devices.
It is an object of the present invention to provide an electronic regulating device for an electric motor applied to a fuel burner ventilator, designed to eliminate the aforementioned drawback, and which, in particular, is cheap and easy to produce.
According to the present invention, there is provided an assembly of an electronic regulating device and of an electric motor applied to a fuel burner ventilator, as claimed in Claim 1 and, preferably, in any one of the following Claims depending directly or indirectly on Claim 1.
According to the present invention, there is also provided a method of regulating an electric motor applied to a fuel burner ventilator, as claimed in Claim 6 and, preferably, in any one of the following Claims depending directly or indirectly on Claim 6.
A non-limiting embodiment of the present invention will be described by way of example with reference to the accompanying drawings, in which:
Number 1 in
Regulating device 1 is controlled by a number of inputs, in particular an electric power supply input 7; a first-stage control input 8; a second-stage control input 9; a PWM (Pulse Width Modulation) input 10; and a three-point modulation input 11.
Electric power supply input 7 is connected to a rectifying block 12 to convert a 230 volt alternating voltage phase to a 230 volt direct voltage required to electrically power electric motor 2 by means of switching device 5; and a DC/DC converter 13 is cascade-connected to rectifying block 12 to convert the 230 volt direct voltage to a 5 volt direct voltage required to electrically power programmable device 3 and speed sensor 4.
First-stage control input 8, second-stage control input 9, PWM input 10, and three-point modulation input 11 supply respective signals directly to programmable device 3, which also receives a signal proportional to the speed of electric motor 2 from speed sensor 4, a feedback signal from switching device 5 and filtered by an integrating circuit 14, and three constant calibration signals from respective potentiometers (trimmers) 15, 16, 17.
Programmable device 3 processes the above signals to control switching device 5, which electrically powers electric motor 2, and to supply an output signal, proportional to the speed of electric motor 2, at an RPM output 18 of regulating device 1.
Electric power supply input 7, first-stage control input 8, second-stage control input 9, PWM input 10, three-point modulation input 11, and RPM output 18 are connected respectively to respective outputs and to a respective input of a generic external flame control device (not shown) for controlling overall operation of the fuel burner.
More specifically, first-stage control input 8 and second-stage control input 9 interpret two-state ("ON", "OFF") signals from a two-stage burner flame control device; three-point modulation input 11 interprets a three-state ("DOWN", "UP", "ZERO") signal from an external power regulator (not shown) controlled by the flame control device of a more sophisticated two-stage burner; and PWM input 10 interprets a PWM signal from a flame control device of a wall-mounted boiler burner.
RPM output 18 and PWM input 10 are preferably provided with respective optocouplers 20, 19 to protect programmable device 3 from voltage peaks and/or spurious input currents.
Programmable device 3 is programmed (firmware) to process the above signals and accordingly control switching device 5 to regulate the speed of electric motor 2 using a regulating method shown schematically in the
The following is a detailed description of the regulating method.
In actual use, programmable device 3 continuously monitors the state of selector 6, which selects the operating mode of regulating device 1 and, therefore, the way in which programmable device 3 processes the signals from inputs 8, 9, 10, 11 of regulating device 1.
In a first (two-stage) operating mode, programmable device 3 :
In a second (PWM) operating mode, programmable device 3 :
In a third (three-point modulation) operating mode, programmable device 3 :
The main advantage of the present invention is that of providing an electronic regulating device 1, for an electric motor 2 applied to a fuel burner ventilator, which can be integrated with the motor and interfaced with any known flame control device to obtain a more versatile motor assembly comprising electric motor 2 and regulating device 1.
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