1. Field of the Invention
This invention relates to a flow switch responsive to a preselected flow rate of a fluid. More particularly, this invention relates to a combined positive displacement and variable area flow path flow switch or the like.
2. Information Disclosure Statement
Various flow switches have been developed to be responsive to the flow rate of a fluid within a flow line. Usually the flow switch is connected into the flow line so that the flow path of the fluid passes through the flow switch. With the in-line type of flow switch, a movable obstacle is disposed within the flow path so that as the rate of flow increases, the movement of the obstacle is responsive to the increase in the flow rate of the fluid. One type of flow switch includes a rotatable vane or sail disposed with the axis of the vane perpendicular to the flow path. The vane partially obstructs the flow of fluid so that as the flow rate increases, a switch is activated upon the flow rate obtaining some desired level.
Many processes require the accurate determination of the rate of flow of a fluid relative to a desired flow rate. Consequently, flow switches have been developed to indicate when the rate of flow in a pipe is above or below some desired rate of fluid flow. By this means, for example, the rate of flow within an oil line can be monitored by a flow switch.
However, it will be evident to those skilled in the art that in order to maintain a flow switch which is sensitive to a small fluctuation in flow rate, a large number of flow switches must be manufactured, each having a specific operating range, in order to meet requirements for a specific process requiring the metering of fluid flow at a specific rate.
The present invention provides a flow switch incorporating an electrical switching device and a combined positive displacement and variable area flow path. The variable area flow path of the present invention is provided so that the flow switch can be roughly set to permit a flow of fluid to the core tube such that a positive displacement piston can operate within a specific operating range which is preset during the manufacture of the flow switch. The variable area flow path of the present invention provides a partial bypass flow path which can be adjusted so that the flow of fluid not being bypassed falls within the range of the sensitivity of the positive displacement piston sliding within the core tube to expose the ports defined by the core tube. The provision of the variable area flow path avoids the necessity of manufacturing a wide range of flow switches to cover the specific requirements of various flow rates.
It is known to provide a flow switch having a magnetic piston with a spring biased against the direction of flow. One particular flow switch of this type includes a bypass orifice which can be positioned through the use of tools. However, this type of flow switch suffers from the problem of a high pressure drop, particularly due to the resistance to flow caused by the spring biased piston. Additionally, this magnetic piston-type flow switch includes a spring which is disposed in the fluid line. This presents a serious limiting factor when metering corrosive liquids. Furthermore, the use of spring biasing means introduces various problems due to the change in compression factors of the spring over a prolonged period which results in inadequate switching of the flow switch.
Therefore it is the primary object of this invention to provide a flow switch which overcomes the aforementioned inadequacies of the prior art and provides an improvement which significantly contributes to the ease with which the rate of flow of a fluid can be detected.
Another object of this invention is the provision of a flow switch having a variable area bypass flow path which is readily adjustable.
Another object of this invention is the provision of an inner and an outer core tube, each tube defining an aperture such that the apertures register with each other to define a variable area orifice therebetween.
Another object of this invention is the provision of an inner and an outer core tube, the core tubes being coaxial and with one of the core tubes being rotatable relative to the other of the core tubes to provide a varable area orifice defined by the apertures of the inner and the outer core tubes.
Another object of this invention is the provision of a top plug which is rotatably disposed relative to the body of the flow switch. The top plug being rigidly connected to the rotatable core tube such that rotation of the top plug relative to the body causes a variation of the area of the orifice.
Another object of the present invention is the provision of a scale indicia and indicator means disposed on the top plug and the flow switch body for inndicating the rotational position of the inner and the outer core tubes.
Another object of the present invention is the provision of a stud which protrudes inwardly from the body adjacent the inlet, the stud cooperating with an open-ended slot defined by the first end of the non-rotatable core tube to inhibit rotation thereof relative to the body.
Another object of the present invention is the provision of a cylindrical chamber defined by the second ends of the rotatable core tube. The chamber housing a composite piston which slides axially along the chamber in response to the increased rate of flow of fluid within the core tubes to progressively expose a larger area of a port defined by the second end of the rotatable core tube.
Another object of the present invention is the provision of a piston comprising a rod received thereto and a recess in the plug for slidably receiving the piston rod.
Another object of the present invention is the provision of a magnetic rod in combination with a magnetic switch for activating the magnetic switch upon movement of the magnetic rod and the piston due to the flow rate of the fluid through the fluid inlet.
Another object of this invention is the provision of a flow switch in which the outer core tube is integrally connected to the inlet and the inner core tube is rotatably disposed coaxially within the outer core tube.
Another object of this invention is the provision of a flow switch including an inductor means and a ferro magnetic rod connected to the first piston for activating the inductor.
Another object of this invention is the provision of a flow switch including a photoelectric sensor disposed adjacent the piston and a light emitting source for emitting a beam of light which is sensed by the sensor, the beam being interrupted by movement of the piston along the cylindrical chamber.
Another object of this invention is the provision of a flow switch in which the top plug includes a plurality of heat exchanger fins.
Another object of this invention is the provision of a flow switch including an observation window disposed within the plug, the window being disposed to permit observation of the movement of the piston within the chamber.
The foregoing has outlined some of the more pertinent objects of the invention. These objects should be construed to be merely illustrative of some of the more prominent features and applications of the present invention. Many other beneficial results can be attained by applying the disclosed invention in a different manner or modifying the invention within the scope of the disclosure. Particularly with regard of the use of the invention disclosed herein, this should not be construed as limited to any particular switching mechanism, but should include flow switches having a variable area bypass flow path and a positive displacement piston. Accordingly, other objects and a fuller understanding of the invention may be had by referring to the summary of the invention and the detailed description describing the preferred embodiment in addition to the scope of the invention defined by the claims taken in conjunction with the accompanying drawings.