Electricity: motive power systems – Automatic and/or with time-delay means – Movement – position – or limit-of-travel
Reexamination Certificate
1999-02-23
2001-03-06
Nappi, Robert E. (Department: 2837)
Electricity: motive power systems
Automatic and/or with time-delay means
Movement, position, or limit-of-travel
C318S266000, C318S467000, C318S468000
Reexamination Certificate
active
06198243
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to electrical actuators for operating a mechanical device, such as valves and dampers; and more particularly to techniques for automatically determining the range of travel for the device.
Many types of mechanical devices are operated by an electrical actuator which moves components of the device between two extreme positions. For example, the damper in a heating, ventilation and air conditioning (HVAC) system may employ an electric motor to move the damper plate between fully opened and fully closed positions. In other mechanical systems, an electric motor opens and closes a valve to control the flow of a liquid. It may also be desirable in some applications to place the damper or the valve at various positions between fully open and fully closed to provide a variable flow of air or liquid.
The mechanical linkage of different types of valves and HVAC dampers require different amounts of rotation to move them between the fully opened and fully closed positions. For example, the mechanical configuration of some HVAC dampers require only 45° of movement to move the damper between those extreme positions, while other dampers require 60° or 90° of movement. Universal actuators are available which rotate their output coupling a maximum of 95°, thus being able to accommodate several types of dampers. Employing a universal actuator eliminates having to stock a variety of actuators specifically designed for each type of mechanical device being driven. However, in order to properly operate a particular damper, the HVAC controller must be configured with the amount of travel or movement that the actuator has to provide to move the mechanical device between its extreme positions. That configuration also enables the controller accurately to place the damper at various desired intermediate positions.
Previously the controller was configured manually with the appropriate amount of rotational movement required by the associated damper. Such manual configuration was time consuming and prone to human error. In addition, the controller had to be reconfigured periodically to compensate for wear of the mechanical device.
SUMMARY OF THE INVENTION
A general object of the present invention is to provide a method by which a controller for an electromechanical actuator can automatically determine the range of movement for a particular mechanical device to which the actuator is connected.
Another object is to provide such an auto ranging mechanism that is periodically recalibrated to compensate for the effects of wear on the mechanical device.
These and other objectives are satisfied by a method which commences by placing the mechanical device into the one of the extreme positions of its range of movement. Then the actuator is energized to move the mechanical device into the other extreme position.
While the device is moving, the amount of movement which occurs for the mechanical device to reach the second extreme position from the first extreme position is quantified. That amount of movement can be quantified by any of several measurement parameters. For example, the time of movement may be measured, or when a stepper motor is used, the number of steps can indicate the range of movement. The time of movement may be derived indirectly by the number of steps multiplied by the period of each one to derive the time of the movement between the extreme positions.
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Knutzen Douglas G.
Kuckuk William R.
Ritmanich David C.
Haas George E.
Johnson Controls Technology Co.
Leykin Ritor
Nappi Robert E.
Quarles & Brady
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