Geometrical instruments – Distance measuring – Scale reading position sensor
Reexamination Certificate
1999-06-10
2001-07-03
Gibson, Randy W. (Department: 2859)
Geometrical instruments
Distance measuring
Scale reading position sensor
C033S708000, C033S710000, C033S707000, C324S207220, C324S207240
Reexamination Certificate
active
06253460
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention generally relates to a position measurement apparatus, system and method. More specifically, the present invention relates to a non-contact, no-wear monitor capable of measuring the position of translating, rotating and complex motion machine elements including, but not limited to, hydraulic cylinders, pistons and other like devices. In addition, the present invention provides a system and method for measuring machine elements using the non-contact, no-wear monitor.
It is, of course, generally known to monitor the displacement of machine elements. However, it is often difficult to determine the relative and absolute position of hydraulic cylinders, pistons and other like devices. Known monitoring systems of cylinders, pistons and other like devices utilize a sensor whereby contact is made between the monitor and the moving machine element. As a result, parts of the known monitoring systems tend to wear quickly and often require replacement. Further, as those parts wear, accuracy of measurements decreases.
In addition, displacement monitors that contact machine elements tend to interfere with the normal application of bearings and supporting machine elements. Also, typical contact measuring devices have difficulty operating in oil or oil-contaminated environments.
Furthermore, present contact and non-contact monitoring systems depend on an initial calibration in order to measure relative and absolute displacements. Also, present monitoring systems require activation with electrical power to maintain an absolute reference.
A need, therefore, exists for an improved displacement monitoring device, system and method for translating, rotating and complex motion generating elements that overcome the deficiencies of known devices, systems and methods.
SUMMARY OF THE INVENTION
The present invention provides a position measurement apparatus, system and method for measuring the position of translating, rotating and other complex motion generating machine elements including, but not limited to, hydraulic cylinders, pistons and other like devices. Applications of the present invention can be utilized in rugged defense industrial construction, truck, commercial, agricultural, automotive and other like applications.
To this end, in an embodiment of the present invention, an apparatus is provided for measuring displacement. The apparatus has a machine element and a shaft element that moves within the machine element. A core has a non-uniform surface inside the shaft element and a layer on the surface of the core provides a uniform surface of the shaft element. A sensor is provided for detecting the non-uniform surface of the core without contacting the shaft element.
In an embodiment, the sensor detects a distance between the sensor and the non-uniform surface of the core.
In an embodiment, a taper on an exterior of the core surface extends from a first end of the core to a second end of the core.
In an embodiment, repetitive exterior contour features are provided on the core that are capable of being sensed by the sensor. The repetitive exterior contours form a pattern on an exterior of the core running a length of the core.
In an embodiment, the repetitive exterior contour has an amplitude wherein the sensor detects a change in a distance between the sensor and the core surface.
In an embodiment, an eccentric surface on the core is capable of being detected by the sensor.
In an embodiment, the shaft element rotates within the shaft element.
In an embodiment, a base is provided on an end of the machine element through which the shaft element moves.
In an embodiment, the sensor is located within the base of the shaft element.
In an embodiment, a second sensor is provided for detecting the non-uniform surface of the core without contacting the shaft element.
In an embodiment, the core is made of a magnetic material producing a magnetic field.
In another embodiment of the present invention, a system is provided for measuring displacement. The system has a machine element and a shaft element that moves within the machine element. A sensor is capable of measuring displacement of the shaft element as the shaft element moves within the machine element. The sensor is capable of producing a signal representative of the displacement and does not contact the shaft element. A display means is provided to receive the signal and to provide an output of the displacement of the shaft element.
In an embodiment, a processing means receives the signal from the proximity sensor.
In an embodiment, the processing means may calculate a position, velocity and/or acceleration of the shaft element within the machine element.
In another embodiment of the present invention, a method is provided for measuring displacement. The method comprises the steps of: providing a machine element; providing a shaft element capable of moving within the machine element; providing a proximity sensor capable of measuring the displacement of the shaft element wherein the proximity sensor does not contact the shaft element; moving the shaft element; measuring the displacement of the shaft element with the proximity sensor; and producing an output signal as the shaft element moves within the shaft element.
In an embodiment, the output signal is fed into a processing unit that generates a second output signal and displays the second output signal.
In an embodiment, the output signal is fed into the processing unit to calculate shaft element position, velocity and/or acceleration.
It is, therefore, an advantage of the present invention to provide a measurement apparatus, system and method for translating, rotating and complex motion generating machine elements including hydraulic cylinders, pistons and other like devices known in the art.
Another advantage is to provide a measurement apparatus, system and method able to provide feedback to a central processing unit, stand-alone electronic control or provide a direct reference signal indicating absolute machine element position.
And, another advantage of the present invention is to provide a measurement apparatus, system and method that, with manipulation and the optional addition of a clock reference, permits measuring of element velocity and/or acceleration.
A further advantage of the present invention is to provide a measurement apparatus, system and method that may be installed in new machine elements or even retrofit to existing applications.
A still further advantage of the present invention is to provide a measurement apparatus, system and method whereby the surface of the sensed element includes a compound geometry such as an eccentric or tapered or faceted surface to permit measuring both linear displacement and/or rotary and/or angular displacement simultaneously.
And, another advantage of the present invention is to provide multiple sensors that may be distributed about the machine elements to provide means for correcting error.
And, another advantage of the present invention is to provide a measurement apparatus, system and method for measuring linear and/or rotary displacement that does not interfere with the normal application of bearings and supporting machine elements and permits normal assembly.
And, another advantage of the present invention is to provide a measurement apparatus, system and method for absolute linear and/or rotary displacement measurement not dependent on an initial calibration, but rather directly and absolutely fixed to the component geometry.
Moreover, an advantage of the present invention is to provide a “non-contact” measurement apparatus, system and method for linear and/or rotary displacement measurement with no wear possible between the sensor and the measured machine element.
A further advantage of the present invention is to provide a measurement apparatus, system and method for measuring linear and/or rotary displacement that uses the machine element as part of the measuring device.
A further advantage of the present invention is to provide a measurement apparatus, system and method for measuring
Gibson Randy W.
Patents+TMS
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