Torque measuring system for motor operated valve operators

• US 4,759,224 A
• Filed: 09/11/1987
• Issued: 07/26/1988
• Est. Priority Date: 04/11/1986
• Status: Expired due to Fees

• Current Assignee: Crane Company
• Original Assignee: Movats Incorporated
• Inventors: Nafziger, Steven, Charbonneau, Arthur G., McMennamy, John A.
• Primary Examiner(s): Noland, Tom
• Application Number:
  US07/096,338
• Time in Patent Office: 319 Days
• Field of Search: 73/168, 73/862.19, 73/862.27, 73/862.31, 73/862.32, 73/862.29, 137/552, 137/551, 251/129.03
• US Class Current: 73/862.31
• CPC Class Codes: F16K 31/045 with torque limiters
• CPC Class Codes: F16K 37/0083 by measuring valve parameters
• CPC Class Codes: Y10T 137/8175 Plural

Abstract

An apparatus and method for isolating certain rotating components within the operator and valve systems and artificially loading those rotating shafts to create and measure torque developed within the valve operator system; and for using the torque measurements to correlate and analyze torque in relation to other valve systems parameters.

Claims

1. Method of testing and analyzing proper switch settings for torque triggered safety switches in valve operators and other load driving systems including a load driving shaft which rotates to drive a load, thus developing a torque, and including a torque triggered safety switch for the purpose of shutting down the motor when torque has reached a predetermined point, said method comprising the steps of:

connecting a load displacing arm, at least temporarily, to the load driving shaft for rotation with the shaft;

rotating the shaft and load displacing arm by operation of a shaft driving means;

stopping rotation of the shaft by blocking rotation of the load displacing arm with a blocking means while the shaft driving means continues to seek rotation of the shaft;

measuring by force measuring means the force exerted over a period of time by the load displacing arm upon the blocking means;

generating a force/time curve;

converting by calculating means the force/time curve to a torque/time curve;

detecting the point in time at which the torque triggered safety switch shuts down the motor;

tracking the open and close position of the safety switch to generate a switch position/time curve; and

correlating the torque/time and switch position/time curves to provide an interrelated time relationship between the system torque and safety switch operation.

2. Method of testing and analyzing safety switch performance for torque triggered safety switches in valve operators and other motor driven systems having a load driving shaft which is rotated to drive a load, thus developing a torque, and having a torque triggered safety switch for the purpose of shutting down the motor when torque has reached a predetermined point, said method comprising the steps of:

replacing the load with means for selectively creating a counter rotation force on the load driving shaft;

rotating the load driving shaft by operation of the motor;

creating the counter-rotation force on the load driving shaft, thus developing a torque in the system;

measuring the torque so developed in the system over a period of time;

detecting the point in timat at which the torque triggered safety switch shuts down the motor; and

providing a correlated, interrelated time relationship between the system torque and safety switch operation.

3. Method of claim 2, further comprising the steps of:

generating a torque/time curve;

generating a switch position/time curve; and

recording the respective curves.

4. Method of determining and evaluating the general material and operational condition of a valve operator, having a driven worm shaft, which drives a worm which in turn drives a worm gear for driving a valve stem to open and close a valve attached to the valve stem, having a motor for effecting driving of the worm shaft, and having a torque triggered switch for the purpose of shutting down the motor when torque developed within the operator has reached a predetermined point, said method comprising the steps of:

operating the valve operator over a period of time;

creating a counter-rotation force to counter the rotation of the worm gear, thus developing a torque in the system;

monitoring the torque so developed in the system over the period of time;

providing a torque/time curve;

monitoring the torque switch position over the same period of time;

providing a switch position/time curve; and

correlating the torque/time and switch position/time curves to provide an interrelated time relationship between the system torque and switch operation.

5. Method of claim 4, further comprising the steps of:

recording the respective curves; and

diagnosing the correlated curves to evaluate the condition of the valve operator.

6. Method of determining and evaluating the general material and operational condition of a valve operator, having a driven worm shaft, which drives a worm which in turn drives a worm gear for driving a valve stem to open and close a valve attached to the valve stem, having a motor for effecting driving of the worm shaft, and having a torque triggered switch for the purpose of shutting down the motor when torque developed within the operator has reached a predetermined point, said method comprising the steps of:

operating the valve operator over a period of time;

creating a counter-rotation force to counter the rotation of the worm gear, thus developing a torque in the systems;

measuring the counter rotation force over the period of time;

providing a force/time curve;

monitoring the torque switch position over the same period of time;

providing a switch position/time curve; and

correlating the force/time and switch position/time curves to provide an interrelated time relationship between the counter rotation force and the switch position.

7. Method of claim 6, further comprising the steps of:

converting by calculating means the force/time curve to a torque/time curve; and

correlating the torque/time and switch position/time curves to diagnose and evaluate the operation of the valve operator.

8. Method of determining and evaluating the general material and operational condition of a valve operator, having a driven worm shaft, which drives a worm which in turn drives a worm gear for driving a valve stem in a rotating fashion to open and close a valve attached to the valve stem, having a motor for effecting driving of the worm shaft, and having a torque triggered switch for the purpose of shutting down the motor when torque developed within the operator has reached a predetermined point, said method comprising the steps of:

connecting a load displacing arm, at least temporarily, to the valve stem for rotation with the stem;

operating the valve operator over a period of time to drive the valve stem in a rotating fashion, whereby the valve stem rotates about its longitudinal axis;

stopping rotation of the valve stem by blocking rotation of the load displacing arm with a blocking means while the worm gear continues to seek rotation of the valve stem, and

measuring by force measuring means the force exerted over the period of time by the load displacing arm upon the blocking means;

generating a force/time curve;

monitoring at least one other operator parameter over the same period of time, which other parameter is one of motor current, torque switch position, or limit switch position;

providing a time related curve of the other parameter; and

correlating the time curves to evaluate the operation of the valve operator.

9. Method of determining and evaluating the general material and operational condition of a valve operator, having a driven worm shaft, which drives a worm which in turn drives a worm gear for driving a valve stem to open and close a valve attached to the valve stem, having a motor for effecting driving of the worm shaft, and having a torque triggered switch for the purpose of shutting down the motor when torque developed within the operator has reached a predetermined point, said method comprising the steps of:

operating the valve operator over a period of time;

monitoring torque developed within the valve operator;

providing a time related trace of torque developed within the valve operator over the period of time;

monitoring at least one other operator parameter over the same period of time, which other parameter is one of motor current, torque switch position or limit switch position;

providing a time related trace of the other parameter; and

correlating the time related traces of the torque and other parameter to evaluate the operation of the valve operator.

10. Method of determing and evaluating the general material and operational condition of a valve operating system, which operating system includes a worm gear mounted for rotation about an axis of rotation, which worm gear is driven by rotational forces perpendicular to the axis of rotation and delivers rotational forces perpendicular to the axis of rotation to effect driving of a valve stem, and which operating system also includes a motor which includes a drive mechanism to provide the rotational forces for driving the worm gear, and further includes a torque triggered switch for the purpose of shutting down the motor when torque developed within the system has reached a predetermined point, and a limit switch, said method comprising the steps of:

operating the motor over a period of time to drive the worm gear;

loading the worm gear;

monitoring rotational force acting on the worm gear over the period of time;

providing a rotational force/time trace;

monitoring at least one other parameter over the same period of time in which the other parameter is one of motor current, torque switch position or limit switch position;

providing a parameter/time trace of the other parameter; and

correlating the rotational force/time trace and the other parameter/time trace to provide an interrelated time relationship between the rotational force and the other parameter.

11. Method of claim 10, further comprising the steps of:

converting the rotational force/time trace to a torque/time trace; and

correlating the torque/time and other parameter/time traces to evaluate the valve operating system.

12. Method of claim 11, further comprising the steps of recording the respective traces.

13. Method of determining and evaluating the general material and operational condition of a valve operator, having a driven worm shaft, which drives a worm which in turn drives a worm gear for driving a valve stem to open and close a valve attached to the valve stem, having a motor for effecting driving of the worm shaft, and having a torque triggered switch for the purpose of shutting down the motor when torque developed within the operator has reached a predetermined point, said method comprising the steps of:

operating the valve operator over a period of time;

creating a counter-rotation force to counter the rotation of the worm gear, thus developing a torque in the systems;

measuring the counter rotation force over the period of time;

deriving torque from the measured rotational force;

providing a torque/time curve;

monitoring the torque switch position over the same period of time;

providing a switch position/time curve; and

correlating the force/time and switch position/time curves to provide an interrelated time relationship between the counter rotation force and the switch position.

14. Method of determining and evaluating the general material and operational condition of a valve operating system, which operating system includes a worm gear mounted for rotation about an axis of rotation, which worm gear is driven by rotational forces perpendicular to the axis of rotation and delivers rotational forces perpendicular to the axis of rotation to effect driving of a valve stem, and which operating system also includes a motor which includes a drive mechanism to provide the rotational forces for driving the worm gear, and further includes a torque triggered switch for the purpose of shutting down the motor when torque developed within the system has reached a predetermined point, and a limit switch, said method comprising the steps of:

operating the motor over a period of time to drive the worm gear;

loading the worm gear;

monitoring rotational force acting on the worm gear over the period of time;

deriving the torque on the worm gear;

providing a torque/time trace;

monitoring at least one other parameter over the same period of time in which the other parameter is one of motor current, torque switch position or limit switch position;

providing a parameter/time trace of the other parameter; and

correlating the rotational force/time trace and the other parameter/time trace to provide an interrelated time relationship between the rotational force and the other parameter.