System for evaluating the condition and performance of a valve and valve operator combination

• US 4,879,901 A
• Filed: 04/22/1988
• Issued: 11/14/1989
• Est. Priority Date: 08/20/1987
• Status: Expired due to Term

• Current Assignee: Crane Nuclear, Inc. (Crane Company)
• Original Assignee: Liberty Technology Company Limited
• Inventors: Leon, Robert L.
• Primary Examiner(s): Yasich, Daniel M.
• Application Number:
  US07/185,210
• Time in Patent Office: 571 Days
• Field of Search: 73/168, 73/862.31, 73/767, 364/508
• US Class Current: 73/168
• CPC Class Codes: F16K 37/0083 by measuring valve parameters
• CPC Class Codes: G01B 7/16 for measuring the deformation in a solid, e.g. by resistance strain gauge
• CPC Class Codes: G01L 5/0061 Force sensors associated with industrial machines or actuators for the specific machine or actuator involved see relevant class, e.g. F01, F04, F16, B66, E21
• CPC Class Codes: G07C 3/00 Registering or indicating the condition or the working of machines or other apparatus, other than vehicles

Abstract

A device for measuring and indicating the forces on a valve stem over at least a portion of the valve strokes is comprised of a strain sensor secured to the valve yoke for sensing strains experienced by the valve yoke. The sensed strains are proportional to the forces on the valve yoke and are equal but opposite to the forces on the valve stem. The strain sensor generates electrical signals proportional to the forces on the valve stem. In one embodiment, a second strain sensor is secured to the valve operator for sensing strains experiences by the valve operator and for generating proportional electrical signals. A display, electrically connected to the strain sensors, is provided for receiving the generated electrical signals and for indicating the forces on the valve stem and the forces on the valve operator. A system for evaluating the performance of a valve and valve operator also utilizes the yoke strain sensor in combination with the operator strain sensor and with other sensors, including a valve stem motion sensor, a spring pack motion sensor, a motor current sensor and, possibly, a stem strain sensor, as well as an indicator of the condition of torque and limit switches. In another embodiment, a vibration sensor is secured to the valve operator for sensing vibrations occurring within the valve and/or the valve operator and for generating proportional electrical signals which are displayed in conjunction with other signals for evaluation of valve and valve operator performance.

Claims

1. A device for measuring and indicating the forces on a valve stem of a valve having an operator within an operator housing, over at least a portion of the valve stroke, the device comprising:

first strain sensor means secured to a valve yoke and substantially parallel to the valve stem for sensing strains experienced by the valve yoke which are proportional to the forces on the valve yoke and are equal and opposite to the forces on the valve stem, the first strain sensor means for generating first electrical signals proportional to the forces on the valve stem;

second strain sensor means secured to the valve operator housing for sensing strains experienced by the operator housing, the second strain sensor means for generating second electrical signals proportional to forces on the operator housing; and

display means electrically connected to the first and second strain sensor means for receiving the first and second electrical signals and for indicating the forces on the valve stem and the operator housing.

2. The device as recited in claim 1 wherein the first and second strain sensor means are each comprised of:

a tensile strain member; and

a strain gage bridge circuit connected to the display means, and including at least one strain gage secured to the tensile strain member.

3. The device as recited in claim 2 wherein the first and second strain sensor means each further comprises four strain gages secured to the tensile strain member, two of the strain gages being longitudinally oriented with respect to the member to experience longitudinal strain and two of the strain gages being transversely oriented with respect to the member to experience Poisson strain, the four strain gages forming the strain gage bridge circuit.

4. The device as recited in claim 3 wherein each tensile strain member is a generally flat elongated beam having first and second opposite elongated surfaces, two of the strain gages being secured to the first surface and two of the strain gages being secured to the second surface.

5. The device as recited in claim 4 wherein one longitudinally oriented strain gage and one transversely oriented strain gage is secured to each of said first and second surfaces of each beam.

6. A system for evaluating the condition and performance of a valve and valve operator combination, including a valve, a valve operator, a valve stem extending between the valve operator and the valve, and a valve yoke surrounding the valve stem, the system comprising:

first strain sensor means secured to the valve yoke and substantially parallel to the valve stem for sensing strains experienced by the valve yoke which are proportional to the forces on the valve yoke and are equal and opposite to the forces on the valve stem, the first strain sensor means also for generating electrical signals proportional to the forces on the valve stem;

second strain sensor means secured to the valve operator for sensing strains experienced by the valve operator and for generating electrical signals proportional to the forces on the valve operator;

valve stem motion sensor means for detecting motion and direction of movement of the valve stem and for generating electrical signals proportional to the velocity of valve stem movement, the signals having a polarity indicative of the direction of valve stem movement; and

display means electrically connected to the first and second strain sensor means and to the valve stem motion sensor means for receiving the generated electrical signals and for indicating the forces on the valve stem, and on the valve operator and the corresponding valve stem velocity to permit identification of a disruption in normal valve and/or valve operator functioning.

7. A system for evaluating the condition and performance of a valve and valve operator combination, including a valve, a valve operator containing a motor, gearing, a spring pack and torque and limit switches, a valve stem extending between the valve operator and the valve, and a valve yoke surrounding the valve stem, the system comprising:

first strain sensor means secured to the valve yoke and substantially parallel to the valve stem for sensing strains experienced by the valve yoke which are proportional to the forces on the valve yoke and are equal and opposite to the forces on the valve stem, the first strain sensor means also for generating electrical signals proportional to the forces on the valve stem;

second strain sensor means secured to the valve operator for sensing strains experienced by the valve operator and for generating electrical signals proportional to forces on the valve operator;

spring pack motion sensor means for detecting motion and direction of movement of the spring pack and for generating electrical signals proportional to the velocity of spring pack movement, the signals having a polarity indicative of the direction of spring pack movement; and

display means electrically connected to the first and second strain sensor means and to the spring pack motion sensor means for receiving the generated electrical signals and for indicating the forces on the valve stem, and on the valve operator and the corresponding spring pack velocity to permit identification of a disruption in normal valve and/or valve operator functioning.

8. A system for evaluating the condition and performance of a valve and valve operator combination, including a valve, a valve operator containing a motor, gearing, a spring pack and torque and limit switches, a valve stem extending between the valve operator and the valve, and a valve yoke surrounding the valve stem, the system comprising:

first strain sensor means secured to the valve yoke and substantially parallel to the valve stem for ensing strains experienced by the valve yoke which are proportional to the forces on the valve yoke and are equal and opposite to the forces on the valve stem, the first strain sensor means also for generating electrical signals proportional to the forces on the valve stem;

second strain sensor means secured to the valve operator for sensing strains experienced by the valve operator and for generating electrical signals proportional to forces on the valve operator;

motor current sensor means for detecting the flow of current through the motor and for generating electrical signals proportional to the motor current; and

display means electrically connected to the first and second strain sensor means and to the motor current sensor means for receiving the generated electrical signals and for indicating the forces on the valve stem, and on the valve operator and the corresponding motor current to permit identification of a disruption in normal valve and/or valve operator functioning.

9. A system for evaluating the condition and performance of a valve and valve operator combination, including a valve, a valve operator containing a motor, gearing, a spring pack and torque and limit switches, a valve stem extending between the valve operator and the valve, and a valve yoke surrounding the valve stem, the system comprising:

first strain sensor means secured to the valve yoke and substantially parallel to the valve stem for sensing strains experienced by the valve yoke which are proportional to the forces on the valve yoke and are equal and opposite to the forces on the valve stem, the first strain sensor means also for generating electrical signals proportional to the forces on the valve stem;

second strain sensor means secured to the valve operator for sensing strains experienced by the valve operator and for generating electrical signals proportional to forces on the valve operator;

torque and limit switch indicating means for detecting the state of the torque and limit switches and for generating electrical signals; and

display means electrically connected to the first and second strain sensor means and to the torque and limit switch indicating means for receiving the generated electrical signals and for indicating the forces on the valve stem, the forces on the valve operator and the opening and closing of the torque and limit switches to permit identification of a disruption in normal valve and/or valve operator functioning.

10. A device for measuring and indicating the forces on a valve stem of a valve having an operator within an operator housing, over at least a portion of the valve stroke, the device comprising:

first strain sensor means secured to a valve yoke and substantially parallel to the valve stem for sensing strains experienced by the valve yoke, which are proportional to the forces on the valve yoke and are equal and opposite to the forces on the valve stem, the first strain sensor means for generating first electrical signals proportional to the forces on the valve stem;

vibration measuring means on a surface of the valve operator for sensing vibrations in the valve and/or valve operator and for generating second electrical signals proportional thereto; and

display means electrically connected to the first strain sensor means and to the vibration measuring means for receiving the first and second electrical signals and for indicating the forces on the valve stem and the vibrations occurring in the valve and/or valve operator.

11. A device for measuring and indicating the forces on a valve stem of a valve having an operator within an operator housing, over at least a portion of the valve stroke, the device comprising:

first strain sensor means secured to a valve yoke and substantially parallel to the valve stem for sensing strains experienced by the valve yoke which are proportional to the forces on the valve yoke and are equal and opposite to the forces on the valve stem, the first strain sensor means for generating first electrical signals proportional to the forces n the valve stem;

second strain sensor means secured to the valve operator housing for sensing strains experienced by the operator housing, the second strain sensor means for generating second electrical signals proportional to forces on the operator housing;

vibration measuring means on a surface of the valve operator for sensing vibrations in the valve and/or valve operator and for generating third electrical signals proportional thereto; and

display means electrically connected to the first and second strain sensor means and to the vibration measuring means for receiving the first, second and third electrical signals and for indicating the forces on the valve stem and on the operator housing and vibrations occurring in the valve and/or valve operator.

12. A system for evaluating the condition and performance of a valve and valve operator combination, including a valve, a valve operator containing a motor, gearing, a spring pack and torque and limit switches, a valve stem extending between the valve operator and the valve, and a valve yoke surrounding the valve stem, the system comprising:

first strain sensor means secured to the valve yoke and substantially parallel to the valve stem for sensing strains experienced by the valve yoke which are proportional to the forces on the valve yoke and are equal and opposite to the forces on the valve stem, the first strain sensor means for generating first electrical signals proportional to the forces on the valve stem;

vibration measuring means on a surface of the valve operator for sensing vibrations in the valve and/or valve operator and for generating second electrical signals proportional thereto;

valve stem motion sensor means for detecting motion and direction of movement of the valve stem and for generating electrical signals proportional to the velocity of valve stem movement, the signals having a polarity indicative of the direction of valve stem movement; and

display means electrically connected to the first strain sensor means, the vibration measuring means and to the valve stem motion sensor means for receiving the first and second electrical signals and the valve stem movement signals and for indicating the forces on the valve stem, the vibrations occurring in the valve and/or valve operator and the corresponding valve stem velocity to permit identification of a disruption in normal valve and/or valve operator functioning.

13. A system for evaluating the condition and performance of a valve and valve operator combination, including a valve, a valve operator containing a motor, gearing, a spring pack and torque and limit switches, a valve stem extending between the valve operator and the valve, and a valve yoke surrounding the valve stem, the system, comprising:

first strain sensor means secured to the valve yoke and substantially parallel to the valve stem for sensing strains experienced by the valve yoke which are proportional to the forces on the valve yoke and are equal and opposite to the forces on the valve stem, the first strain sensor means for generating first electrical signals proportional to the forces on the valve stem;

vibration measuring means on a surface of the valve operator for sensing vibrations in the valve and/or valve operator and for generating second electrical signals proportional thereto;

spring pack motion sensor means for detecting motion and direction of movement of the spring pack and for generating electrical signals proportional to the velocity of spring pack movement, the signals having a polarity indicative of the direction of spring pack movement; and

display means electrically connected to the first strain sensor means and to the vibration measuring means for receiving the first and second electrical signals and connected to the spring pack motion sensor means for receiving the generated electrical signals, the display means for indicating the forces on the valve stem and the vibrations occurring in the valve and/or valve operator and the corresponding spring pack velocity to permit identification of a disruption in normal valve and/or valve operator function.

14. A system for evaluating the condition and performance of a valve and valve operator combination, including a valve, a valve operator containing a motor, gearing, a spring pack and torque and limit switches, a valve stem extending between the valve operator and the valve, and a valve yoke surrounding the valve stem, the system comprising:

first strain sensor means secured to the valve yoke and substantially parallel to the valve stem for sensing strains experienced by the valve yoke which are proportional to the forces on the valve yoke and are equal and opposite to the forces on the valve stem, the first strain sensor means for generating first electrical signals proportional to the forces on the valve stem;

vibration measuring means on a surface of the valve operator for sensing vibrations in the valve and/or valve operator and for generating second electrical signals proportional thereto;

motor current sensor means for detecting the flow of current through the motor and for generating electrical signals proportional to the motor current; and

display means electrically connected to the first strain sensor means, to the vibration measuring means and to the motor current sensor means for receiving the first and second electrical signals and the signals generated by the motor current sensor means and for indicating the forces on the valve stem, the vibrations occurring in the valve and/or valve operator and the corresponding motor current to permit identification of a disruption in normal valve and/or valve operator functioning.

15. A system for evaluating the condition and performance of a valve and valve operator combination, including a valve, a valve operator containing a motor, gearing, a spring pack and torque and limit switches, a valve stem extending between the valve operator and the valve, and a valve yoke surrounding the valve stem, the system comprising:

first strain sensor means secured to the valve yoke and substantially parallel to the valve stem for sensing strains experienced by the valve yoke which are proportional to the forces on the valve yoke and are equal and opposite to the forces on the valve stem, the first strain sensor means for generating first electrical signals proportional to the forces on the valve stem;

vibration measuring means on a surface of the valve operator for sensing vibrations in the valve and/or valve operator and for generating second electrical signals proportional thereto;

torque and limit switch indicating means for detecting the state of the torque and limit switches and for generating electrical signals; and

display means electrically connected to the first strain sensor means, to the vibration measuring means and to the torque and limit switch indicating means for receiving the first and second electrical signals and the electrical signals generated by the torque and limit switch indicating means and for indicating the forces on the valve stem, the vibrations occurring in the valve and/or the valve operator and the corresponding opening and closing of the torque and limit switches to permit identification of a disruption in normal valve and/or valve operator functioning.