Patents by Inventor Robert D. McMillan

Robert D. McMillan has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Patent number: 6427517
    Abstract: A calibration system for a tube prover used in gas flow rate calibration equipment includes a low friction piston which provides an effective seal without the use of mercury. The low friction piston is easily movable in a prover tube of the calibration system in response to gas flow rates, even low flow rates. The piston is constructed of a light weight, low friction fluorinated hydrocarbon material. The piston has first and second seals which provide a positive seal with the inner surface of the prover tube and which maintain the alignment of the piston within the prover tube.
    Type: Grant
    Filed: December 4, 2000
    Date of Patent: August 6, 2002
    Assignee: McMillan Company
    Inventor: Robert D. McMillan
  • Publication number: 20020095972
    Abstract: A calibration system for a tube prover used in gas flow rate calibration equipment includes a low friction piston which provides an effective seal without the use of mercury. The low friction piston is easily movable in a prover tube of the calibration system in response to gas flow rates, even low flow rates. The piston is constructed of a light weight, low friction fluorinated hydrocarbon material. The piston has first and second seals which provide a positive seal with the inner surface of the prover tube and which maintain the alignment of the piston within the prover tube.
    Type: Application
    Filed: December 4, 2000
    Publication date: July 25, 2002
    Inventor: Robert D. McMillan
  • Patent number: 6240776
    Abstract: A sensing circuit of a thermal mass flow sensor provides enhanced precision control of heating and temperature sensing coils used for fast sensing responses. The sensing circuit includes a pair of coil servo loops achieving servo loop control of the sensing coils in each servo loop. The current paths in the servo loop include a main current path carrying low levels of current and minor current paths carrying very small levels of current. These small levels of current have insignificant current levels compared to the levels of current in the main current path. The single main current path in the servo loop allows nearly all of the current from the primary servo amplifier to be used for driving the coils, thereby improving the efficiency of the coil servo loop. The heating and sensing coil in each servo loop is coupled to an integration network for measuring power provided to the coil.
    Type: Grant
    Filed: January 7, 2000
    Date of Patent: June 5, 2001
    Assignee: McMillan Company
    Inventors: Robert D. McMillan, Robert M. McMillan
  • Patent number: 6119730
    Abstract: A laminar flow element for use in thermal mass flow sensors and flow controllers is designed to provide a high degree of precision. The precision laminar flow element includes a laminar flow element having a generally pointed entry end for maintaining a pure laminar flow path around the laminar flow element. The generally pointed entry end serves to direct an incoming gas flow stream equally about an outer surface of the laminar flow element. In this way, the laminar flow path is uniform so as to maintain a desired flow accuracy. The laminar flow element provides a plurality of standoff pins protruding from the outer surface of the laminar flow element to maintain a substantially equal radial clearance around the outer surface. By maintaining a substantially equal radial clearance from one laminar flow element to another, the laminar flow element is highly interchangeable.
    Type: Grant
    Filed: December 21, 1998
    Date of Patent: September 19, 2000
    Assignee: McMillan Company
    Inventor: Robert D. McMillan
  • Patent number: 6038921
    Abstract: A sensing circuit of a thermal mass flow sensor provides enhanced precision control of heating and temperature sensing coils used for fast sensing responses. The sensing circuit includes a pair of coil servo loops achieving servo loop control of the sensing coils in each servo loop. The current paths in the servo loop include a main current path carrying low levels of current and minor current paths carrying very small levels of current. These small levels of current have insignificant current levels compared to the levels of current in the main current path. The single main current path in the servo loop allows nearly all of the current from the primary servo amplifier to be used for driving the coils, thereby improving the efficiency of the coil servo loop. The heating and sensing coil in each servo loop is coupled to an integration network for measuring power provided to the coil.
    Type: Grant
    Filed: October 15, 1997
    Date of Patent: March 21, 2000
    Assignee: McMillan Company
    Inventors: Robert D. McMillan, Robert M. McMillan
  • Patent number: 5728949
    Abstract: A turbine wheel flow measuring transducer is provided for measuring low flow rates of corrosive fluids, whether fluids or gases. The transducer has a turbine wheel rotating in a housing fluid chamber at a rate set by the corrosive fluid flowing through the housing. Infrared light passing through the fluid is sensed and converted by an optical flow measurement circuit. The amount of light which passes through a rotating turbine wheel indicates flow rate. A processing circuit forms output signals indicative of fluid flow rate.
    Type: Grant
    Filed: April 12, 1996
    Date of Patent: March 17, 1998
    Assignee: McMillan Company
    Inventors: Robert D. McMillan, Robert M. McMillan
  • Patent number: 5542302
    Abstract: A turbine wheel flow measuring transducer is provided for measuring low flow rates of corrosive fluids, whether fluids or gases. The transducer has a turbine wheel rotating in a housing fluid chamber at a rate set by the corrosive fluid flowing through the housing. Infrared light from an optical flow measurement circuit passes through spaced holes in the rotating turbine wheel. The amount of light which passes through the wheel indicates flow rate. The housing is made from a corrosion resistant synthetic resin which is also translucent to infrared light from the light source. The light source thus need not be in the housing fluid chamber, materially simplifying the transducer. Further, the turbine wheel is provided with an improved bearing support so that problems of thermal expansion of the housing are overcome.
    Type: Grant
    Filed: January 24, 1995
    Date of Patent: August 6, 1996
    Assignee: McMillan Company
    Inventors: Robert D. McMillan, Robert M. McMillan
  • Patent number: 4467660
    Abstract: A turbine wheel flow measuring transducer having a reaction turbine wheel measures low flow rates of a gas. A disk (D) is rotatably mounted in a chamber (C) formed within a housing (H) through which the gas to be measured passes through a nozzle assembly (N). Plural teeth (T) are formed around the periphery of disk (D) for receiving the impact of the gas from nozzle assembly (N). A photoelectric circuit (P) directs light onto side portions of disk (D) to measure the relative movement of disk (D) in response to the impact of the gas against teeth (T).
    Type: Grant
    Filed: March 29, 1982
    Date of Patent: August 28, 1984
    Inventor: Robert D. McMillan, Jr.