Communications: electrical – Condition responsive indicating system – Specific condition
Reexamination Certificate
1998-07-15
2001-08-07
Mullen, Thomas (Department: 2632)
Communications: electrical
Condition responsive indicating system
Specific condition
C184S108000, C340S683000
Reexamination Certificate
active
06271761
ABSTRACT:
TECHNICAL FIELD
This invention relates a device for the monitoring of bearing performance in apparatus having one or more apertures sized and configured for grease fittings. As used herein, the term bearings includes, but is not limited to, ball bearings, rotary bearings, and bushings.
BACKGROUND
Conventional bearing housings well known in the mechanical arts have grease ports through which grease or other lubricant may be injected into the housing for reducing friction between the bearing and the shaft rotating within the housing. Typically, these grease ports are threaded apertures designed to receive a threaded grease fitting. The grease fitting is removably insertable into the grease port, and includes an axial bore specially configured to permit grease or other lubricant to be injected through the fitting and into the bearing housing without leakage. Notwithstanding this feature, bearings within such housings are prone to fail over time from excessive wear and heat generated by friction between the bearing and the rotary shaft or other objects in contact with the bearing.
U.S. Pat. No. 3,603,280 to Zahuranec discloses a fitting which works in conjunction with a static pressure line, a temperature sensitive fusible plug, and a pressure sensitive alarm to warn of a component's increased temperature, increased temperature in the bearing housing signifying impending bearing failure. Bearing failure can cause equipment to become inoperable and may be hazardous, depending upon the particular function of the apparatus which includes the bearing. Because of the importance of maintaining functional equipment where ever bearings are employed, the ability to reliably and continuously monitor bearing performance during equipment operation and to forecast bearing failure would constitute a significant contribution to equipment maintenance and safety, especially if such a contribution could be made without otherwise affecting the functionality or design of the apparatus or housing containing the monitored bearing.
SUMMARY OF THE INVENTION
The invention described herein is deemed to constitute such a contribution by providing a device for monitoring bearing performance in apparatus having at least one threaded aperture sized and disposed to connectably receive a grease fitting for providing lubricant to the bearing. The device is configured so as to cooperate with bearing housings of widely divergent dimensions, and in each case to permit adjustment of the device, including the sensing components thereof, to place it in very close proximity to or in direct contact with the bearing. The device comprises a sensing fitting sized, threaded and configured to be threadably received in the aperture. In one embodiment of the invention, the sensing fitting includes both temperature sensing means and vibration sensing means to enable detection of impending bearing failure. Thus, in this embodiment impending bearing failure can be sensed by either or both of two indicators of impending bearing failure—an increase in temperature and an increase in vibration. In another embodiment, the sensing fitting includes temperature sensing means alone, while in yet another embodiment, the sensing fitting includes vibration sensing means alone. All such systems are effective for early detection of the inception of bearing failure. In each case, the sensing fitting is threadably and adjustably extendable into the apparatus housing the bearing to permit control of the proximity of the sensing fitting and the sensing means to the bearing.
In preferred embodiments having a sensing fitting with temperature sensing means, the temperature sensing means further comprises either (i) a thermistor temperature detector, which undergoes a change in resistance in response to a change in temperature within the apparatus, or (ii) a thermocouple sensing element, which undergoes a change in current in response to a change in temperature within the apparatus. Where a thermistor temperature detector is used, it is particularly preferred that the detector be adapted to send a signal to a receiver capable of converting the signal into an audible or visual record of the temperature within the apparatus and/or producing an audible or visual alarm if the temperature reaches a preselected level. When a thermocouple sensing element is used, it is particularly preferred that the element be adapted to send a signal to a receiver capable of converting the signal into an audible or visual record of the temperature within the apparatus and/or producing an audible or visual alarm if the temperature reaches a preselected level. It is also particularly preferred that the temperature sensing means be adapted to constantly send the aforesaid signal, and that the receiver be capable of trending the data produced by conversion of the aforesaid signal to provide trended data regarding temperature levels and impending bearing failure.
In preferred embodiments having a sensing fitting with vibration sensing means, the vibration sensing means further comprises a vibration sensor capable of detecting vibration within an x, y and/or z plane. It is particularly preferred that the sensor be adapted, upon detection of vibration within an x, y and/or z plane, to send a signal to a receiver capable of converting the signal into an audible or visual record of the vibration within the apparatus and/or producing an audible or visual alarm if the vibration reaches a preselected level. It is also particularly preferred that the vibration sensing means be adapted to constantly send the aforesaid signal, and that the receiver be capable of trending the data produced by conversion of the aforesaid signal to provide trended data regarding vibration levels and impending bearing failure.
Preferred embodiments also comprise a sensing fitting which is in addition a grease fitting for providing lubricant to said bearing, the sensing fitting including a grease inlet nipple, a grease path and a closure, which closure remains closed at all times when the internal pressure applied to the closure exceeds the external pressure applied to the closure, the closure thereby preventing lubricant from leaking out from the apparatus and through the nipple. Here, the sensing fitting has an axial bore throughout and is configured on one end opposite the inlet nipple to be threadably yet fixedly inserted into a threaded aperture which is sized and configured to receive a grease fitting. As used herein, “axial” is deemed to mean parallel to the axis of the device, but not necessarily coaxial therewith. The other end of the sensing fitting is configured to function as a grease fitting through which lubricant may be injected into the apparatus via the axial bore. Thus, in this embodiment, the grease fitting is integral to the sensing fitting, and the device may be substituted for a conventional grease fitting to permit monitoring of bearing performance and to enable detection of impending bearing failure, without sacrificing the utility of a conventional grease fitting.
In a particularly preferred embodiment, the sensing fitting is separate from, but employed in conjunction with, a grease fitting. There, the sensing fitting is configured on one end to be detachably yet fixedly inserted into an aperture of the apparatus containing the bearing which is sized and configured to receive a grease fitting. The sensing fitting has an axial bore throughout which is stepped so that the portion of the bore proximate to the other end of the fitting is sized and configured to provide an aperture for the detachable yet fixed attachment of a grease fitting. In this particularly preferred embodiment, the sensing fitting provides an intermediate connection between the grease fitting and the apparatus containing the bearing. The fitting thereby acts as a supplement to a grease fitting to permit monitoring of bearing performance and to enable detection of impending bearing failure, without sacrificing the utility of a grease fitting.
This invention also provides for an improvement in apparatus which comp
Bernard Thomas R.
Smith Charles C.
Mullen Thomas
Scientific Operating Systems, Inc.
Sieberth & Patty L.L.C.
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