Asymmetric drive motor for a barrier operator or the like
An asymmetrical drive motor and apparatus with the asymmetric drive motor driving a barrier. The asymmetric drive motor drives the barrier at different drive powers according to direction, time of travel, safety requirements of speed. The drive power is controlled by electrically changing the capacitance value for a permanent split capacitor motor.
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1. Field of the Invention
The present invention is related to a movable barrier and more particularly, to a motor for driving a movable barrier such as a garage door.
2. Background Description
Movable barrier operators and, more particularly, garage door operators are well known and have become very sophisticated to provide users with increased convenience and security. The amount of drive power for such a barrier operator is usually selected based on a trade off between the need for power to start and continue the door's motion and the noise and vibration generated by the motor, as well as the availability of electrical power. Generally, it is desirable to have a higher power to open the door due to ice and snow freezing the door down. Also, during safety initiated operations larger amounts of power may be desired to reverse or stop the barrier. A problem is. that a higher power motor usually create larger levels of noise and vibration and require more electrical power and thus, generate more heat to operate for the same level of mechanical power.
For example, in a situation where the door has become extremely heavy such as when the door's counter balance spring has broken and the door is required to reverse, a low power motor which is adequate to keep a door in motion may not have enough power to overcome both the inertia of motion and the extreme weight of the door. Typically, in selecting a drive motor for a barrier operator, safety. takes precedence over noise and vibration or operational electrical efficiency and, the motor is selected to open the garage door in all situations.
By contrast selecting a high power motor allows the operator to have S enough power to lift the door even when the door's spring has broken. In this situation the high power operator has the ability to open the door but is often more inefficient and has higher levels of, noise and vibration.
The typical motor used in such a garage door operators is a single phase motor. A single-phase motor may be classified as a split phase motor, a permanent split capacitor (PSC) motor, a capacitor start-induction run motor or a capacitor start-capacitor run motor. Further, most single-phase induction motors require a switching arrangement for starting the motor, e.g., switching start windings, a start capacitor, a run capacitor or a combination thereof, to assist the motor in reaching full speed. Capacitor start motors have a start capacitor that is only used to start the motor.
Thus, there is a need for a motor than can have higher power during intervals that require it, yet switch to a lower power, to reduce electrical power requirement and noise and vibration.
SUMMARY OF THE INVENTIONThe present invention is an asymmetric drive motor and apparatus with the asymmetric drive motor for opening and closing a moveable barrier. The asymmetric drive motor may drive for example, a garage door open at a first drive power and closed at a second drive power. The first drive power is greater than the second drive power. A motor control circuit receives control commands and controls the motor to provide the first drive power if barrier is being opened and at the second drive power if the barrier is being closed.
Accordingly, the asymmetric motor of the present invention has improved power control for selecting higher power or lower power. Further, momentary application of higher power is available if needed at the start of travel for example to overcome inertia or ice that may have frozen the barrier shut. In emergency situations such as when the barrier has encountered an object on closing higher power is available to quickly open the barrier. Further, a power can be adjusted in the motor depending on the load driven by the motor.
BRIEF DESCRIPTION OF THE DRAWINGSThe foregoing and other objects, aspects and advantages will be better understood from the following detailed preferred embodiment description with reference to the drawings, in which:
Referring now to the drawings, and more particularly,
When the garage door operator is activated to drive the door down, e.g., by pressing a button on a remote; the control circuit closes light relay 166; direction relay 168 remains in the position shown of
The control circuit may be programmed to keep the high power relay 164 closed for substantially the entire travel of the garage door, keep the high power relay 164 closed for a period of time or, as determined by the sensed speed of the motor 150. Thus, the high power relay 164 may be closed for a period of time to initially open the garage door. When the high power relay 164 opens, bleed resistor 162 discharges any charge remaining on second capacitor 160. Alternately, the control circuit 200 (
Accordingly, the asymmetric motor of the present invention has improved power control for selecting higher power or lower power depending on a direction of travel of the garage door. Further, momentary application of higher power is available if needed at the start of travel for example to overcome inertia or ice that may have frozen the garage door shut. Higher power is available in emergency situations such as when the door has encountered an object on closing, higher power is available to quickly open the door. Further, a power can be adjusted in the motor depending on the load driven by the motor and depending on the sensed speed of the motor. In the preceding embodiments the switches for controlling motor activation are shown as relays. Such relays may be replaced by other devices such as semiconductor triacs in other embodiments.
The embodiments described include a motor having a pair of windings with a neutral tap at a common winding terminal. The control principles discussed herein are not limited to such a winding configuration, but may apply to any motor configuration capable of producing two or more levels of power output. For example, but not by limitation, the motor could comprise multiple serially energized windings which can be individually removed from providing substantial motive force by switching arrangements such as by shorting across the terminals of individual windings. Further, the increase of power output as well as phase shifting could be performed by reactive components other than capacitors, such as inductors.
Having thus described preferred embodiments of the present invention, various modifications and changes will occur to a person skilled in the art without departing from the spirit and scope of the invention. It is intended that all such variations and modifications fall within the scope of the appended claims. Examples and drawings are, accordingly, to be regarded as illustrative rather than restrictive.
Claims
1. A barrier movement arrangement comprising:
- a motor having a first power output and a second power output, for moving a barrier between open and closed positions;
- first apparatus for enabling the first power output;
- second apparatus for enabling the second power output, the second power output being greater than the first; and
- a controller responsive to sensed barrier movement conditions for controlling the first apparatus to enable the motor at the first power output when predetermined conditions are sensed and for controlling the second apparatus to enable the motor at the second power output when predetermined other conditions are sensed.
2. A barrier movement arrangement in accordance with claim 1 comprising apparatus for sensing expected barrier movement direction and wherein the controller responds to the sensed condition that a barrier is to be moved toward the open position for controlling the second apparatus to enable the motor at the second power output.
3. A barrier movement arrangement according to claim 1 comprising apparatus for sensing an expected direction of barrier movement and wherein the controller responds to a sensed condition that the barrier is to be moved toward the closed position for controlling the first apparatus to enable the first power output to start and move the door.
4. A barrier movement arrangement according to claim 1 comprising the ability to sense obstructions to barrier movement wherein the controller responds to sensed obstructions by reversing a direction of travel of the barrier and by controlling the second apparatus to enable the motor at the second power output.
5. A barrier movement arrangement according to claim 1 comprising the ability to sense barrier movement speed after the motor has been started and the controller responds to barrier movement speed after the motor has been started to control the second apparatus to enable the motor at the second power when the sensed barrier movement speed is below a predetermined value.
Type: Application
Filed: Jul 19, 2004
Publication Date: Feb 10, 2005
Applicant:
Inventors: James Fitzgibbon (Batavia, IL), Edward Laird (Lombard, IL)
Application Number: 10/894,136