REMOTE SPEED CONTROLLER FOR A MOTOR

Abstract: This invention relates to a remote speed controller for an electric motor. The controller comprises a switching unit having three switches (SW1, SW2, SW3). A capacitor pack (2) incorporating two capacitors (C1, C2) is connected to the switching unit such that different combinations of the capacitors can be selected by the switch (SW3). The controller is connected in circuit between an AC voltage supply and windings of a motor so that selective actuation of the switch (SW3) changes the speed of the motor in accordance with the values of the capacitors selected. The further switches (SW1, SW2) are incorporated to provide reverse motor capability and remote sensor capability.

Description: This invention relates to a remote speed controller for an electric motor employing capacitors and particularly, but not exclusively relates to such a controller for controlling the speed of a fan motor. JP-A-58029393 describes a main winding and an auxilary winding at an angle of 90 degrees to each other on a stator core. A series of three capacitors for high speed is connected serially to the auxilary winding by switching relay and is further connected in parallel to the main winding. The relay selects individual ones of the three capacitors to produce speed of operation. JP-A-5879496 also describes main and auxilary coils disposed at 90 degrees on a stator core. A capacitor is connected permanently in parallel with the main winding and in series with the auxilary winding. Two further capacitors and a switching relay are connected in parallel with the first capacitor whereby operation of the relay can select either of the capacitors for altering the operation speed. A similar circuit is disclosed in GB-A-2105931. The present invention is closely associated with the motor speed control circuit forming the subject of co-pending Patent Application EP-A-0181072 filed on the same day as the present Application. In the said co-pending Patent Application, there is described a permanent capacitor reversible motor speed control circuit wherein a plurality of capacitors are connected across the windings of the motor via means which when selectively switched or physically actuated cause different combinations of said capacitors to be connected in series or in parallel across the windings such as to select a particular motor speed and change the performance characteristics of the motor in accordance with the particular combination of capacitors selected. Preferably, the capacitors are located in and form a capacitor pack and connected by means of a plug or switched plug to a socket assembly which may be located within or on the motor casing or within or on an appliance casing in which the motor is installed. An object of the present invention is to provide such a speed controlling circuit operable by remote control. According to the present invention, there is provided a remote speed controller for an electric fan motor and wherein the controller, in use, is remotely located from the fan; the controller comprising:-a switching unit connectable in circuit with an AC voltage source and windings of said fan motor; and capacitor means consisting of a plurality of capacitors connectable to the switching unit to vary thereby the speed of the motor; characterised in that said capacitor means comprises, in use, a capacitor pack containing said plurality of capacitors and which is removably mountable in the electric fan; and in that the controller includes means for receiving said capacitor pack containing the plurality of capacitors; said switching unit comprising a single switch whereby operation of said single switch can selectively connect individual capacitors of the received pack to said motor windings. Further switches and features can be included in the switching unit such as indicator lamps, reverse motor rotation, remote sensors etc. Thus, the variety of selective speeds can be obtained from components already embodied within the main applicance having the motor, thus saving costs. A feature of the controller of the present invention is the inherent ability of the controller to automatically 'adopt' the voltage/frequency of the motor or appliance. Thus the controller is truly 'universal' in concept since the speed controller does not have to be manufactured in a variety of different voltage and frequency ranges, thereby achieving rationalised and low cost production. A further feature of the present invention is the provision of a switch for connection to a remote sensor which allows the appliance to be switched on or controlled automatically at whatever speed or functional mode the controller has been set to, such sensor or automatic switching device being by way of example a timer, thermostat, humidistat or secondary ON/OFF switch, smoke sensor or any other form of remote switching device. A further switch can also be provided to reverse the motor rotation or leave the motor static whilst activating a further device. The invention will now be described by way of example only with particular reference to the accompanying drawings wherein; Figure 1 is a perspective view of the switching unit and associated capacitor pack of the speed controller; Figure 2 is a perspetive view of the switching unit capacitor pack of the controller showing the plug and socket connection; and Figure 3 is a circuit diagram of the speed controller and associated capacitor pack. As shown in Figure 1, the speed controller comprises a switching unit 1 and capacitor pack 2 located within a casing 3, the switching unit and capacitor pack being mounted on the lid 4 of the casing 3 and the capacitor pack 2 having three pins 5 engageable in the corresponding holes 6 of the socket of the switching unit 1. Leads 7 connect the controller to the appliance. The lid 4 of the casing is provided with three switches SW1; SW2; SW3 (See Figure 3). As shown in Figure 3, the switching unit 1 includes the primary three switches SW1, SW2, SW3, having the contacts connected across an AC voltage source and between the source and the windings L1, L2 of the fan motor. The capacitor pack 2 comprises capacitors C1, C2 connected in a manner to permit connection in parallel by suitable actuation of switch SW3. By selective actuation of the switch SW3, the capacitors are connected in any required combination across the windings of the fan motor to alter thereby the motor speed. It will be apparent combinations of capacitors other than those illustrated may be employed. A remote switch or sensor may be connected across the terminals A3, A4, the former of which is connected to one of the fixed contacts of switch SW1 and terminal A4 is connected to another fixed contact of switch SW1 and to a fixed terminal of switch SW2 via a further switch SW4 which is ganged to switch SW3. The switch SW2 acts to reverse the motor direction or to leave the motor switched off but the shutter actuated. It should be noted that switch SW4 is ganged to switch SW3 in a manner to temporarily disconnect the mains supply during selection of motor speed by switch SW3, thus reducing switch contact arcing. The sensor or remote switch SW1 allows the controller to be switched on or controlled automatically at whatever speed or functional mode the controller is set to. It will be appreciated that the invention is not deemed limited to the particular features described and shown in the drawings. For instance, the capacitor pack may be mounted elsewhere on the controller and not necessarily on the lid of the casing as described.

Claims: A remote speed controller for an electric fan motor and wherein the controller, in use, is remotely located from the fan; the controller comprising:- a switching unit (1) connectable in circuit with an AC voltage source and windings (L1,L2) of said fan motor; and capacitor means consisting of a plurality of capacitors (C1,C2) connectable to the switching unit to vary thereby the speed of the motor; characterised in that said capacitor means comprises, in use, a capacitor pack (2) containing said plurality of capacitors and which is removably mountable in the electric fan; and in that the controller includes means (6) for receiving said capacitor pack containing the plurality of capacitors; said switching unit comprising a single switch (SW3) whereby operation of said single switch can selectively connect individual capacitors of the received pack to said motor windings. A controller as claimed in claim 1 wherein the switching unit includes switching means (SW2) actuable to alter connection of the windings to said AC voltage source so that the motor rotation can be reversed. A controller as claimed in claim 2 wherein said switch (SW2) has a position wherein the windings of said motor are not connected to the AC voltage source. A controller as claimed in any preceding claim including a further switch (SW1) in circuit between the switching unit and the AC voltage source and actuable to a position connecting the switching unit to said AC voltage source or to a position connecting said AC voltage source to a remote sensor connected in circuit with said switching unit. A controller as claimed in any preceding claim having a further switch (SW4) ganged with the switching unit (SW3) to disconnect said AC voltage source from said capacitor pack during said selective actuation.

Inventors: VINCENT, DAVID
Applicants: APV VENT-AXIA LIMITED
Application year: 1985
Main classification: H02P7
IPC codes: H02P23, H02P25