Metal working – Method of mechanical manufacture – Electrical device making
Reexamination Certificate
1998-01-23
2001-01-09
Hall, Carl E. (Department: 3729)
Metal working
Method of mechanical manufacture
Electrical device making
C073S660000, C264S272150, C324S207260
Reexamination Certificate
active
06170148
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to an encapsulated transducer with an alignment plug and, in particular, to an encapsulated transducer substantially impervious to any mechanical, physical or chemical aggressions from the surrounding environment and a method of manufacturing such transducer which is used to monitor vibration of rotating and recipocating machinery, temperature sensing and the monitoring and sensing of other physical phenomenon.
BACKGROUND OF THE INVENTION
Monitoring and diagnosing the status of rotating and reciprocating machinery start with accurate and dependable measurements from a transducer and its associated electronics and then precede to other sophisticated analyzing apparatus for reduction and display. One such transducer is a proximity transducer which may be utilized for, inter alia, monitoring the vibration characteristics of a rotating shaft of a machine. In this environment, the transducer must operate under very adverse physical, chemical and mechanical conditions and it is often very difficult to replace such transducers. Thus, there is an ongoing effort to make the proximity transducer one of the most reliable parts of the monitoring system.
Typically, the proximity transducer, in conjunction with associated electronics, outputs a signal correlative to the spacing between an object or “target” (the rotating shaft of the machine) and a sensing coil of the proximity transducer. It is critical that the length or spacing between the target and the sensing coil of the proximity transducer remains within the linear range of the transducer for providing accurate and reliable measurements when in operation. Thus, one hallmark for providing accurate and reliable measurements relies on providing a transducer which is impervious to the predations of the environment and which does not consume an inordinate amount of the linear range of the transducer.
The following prior art reflects the state of the art of which applicant is aware and is included herewith to discharge applicant's acknowledged duty to disclose relevant prior art It is stipulated, however, that none of these references teach singly nor render obvious when considered in any conceivable combination the nexus of the instant invention as disclosed in greater detail hereinafter and as particularly claimed.
U.S. PATENT DOCUMENTS
DOCUMENT NO.
DATE
NAME
2,361,348
October 24, 1944
Dickson et al.
2,890,505
June 16, 1959
Brand
3,932,828
January 13, 1976
Plunkett et al.
4,000,877
January 4, 1977
Shead et al.
4,162,138
July 24, 1979
Byrne
4,377,548
March 22, 1983
Pierpont
4,408,159
October 4, 1983
Prox
4,419,646
December 6, 1983
Hermle
4,470,786
September 11, 1984
Sano et al.
4,680,543
July 14, 1987
Kohen
4,829,245
May 9, 1989
Echasseriau et al.
4,954,307
September 4, 1990
Yokoyama
4,959,000
September 25, 1990
Giza
5,016,343
May 21, 1991
Schutts
5,018,049
May 21, 1991
Mehnert
5,021,737
June 4, 1991
Schutts
5,039,942
August 13, 1991
Buchschmid, et al.
5,049,055
September 17, 1991
Yokoyama
5,122,046
June 16, 1992
Lavallee et al.
5,133,921
July 28, 1992
Yokoyama
5,138,292
August 11, 1992
Forster
5,147,657
September 15, 1992
Giza
5,151,277
September 29, 1992
Bernardon, et al.
5,182,032
January 26, 1993
Dickie et al.
5,226,221
July 13, 1993
Kilgore
5,240,397
August 31, 1993
Fay et al.
5,252,051
October 12, 1993
Miyamoto et al.
5,351,388
October 4, 1994
Van Den Berg, et al.
5,376,325
December 27, 1994
Ormson
FOREIGN PATENT DOCUMENTS
DOCUMENT NO.
DATE
COUNTRY
UK 1 313 748
April 18, 1973
Great Britain
UK 1 353 603
May 22, 1974
Great Britain
JA-139710
August 6, 1978
Japan
WO 84/03794
September 27, 1984
PCT
FR 2576-245-A
July 25, 1986
France
JA 6-37130-A
October 2, 1994
Japan
The two patents to Schutts and the patent to Van Den Berg, et al. reflect assignee's ongoing commitment to providing an accurate sensor which is impervious to predations of the environment.
The French patent to Jaeger teaches the use of a method and apparatus for injection molding of an elongated detector with a sensor at one end. One end of the detector is supported by the mold while the sensor end is engaged by a centering sleeve (
130
). The centering sleeve (
130
) terminates in a piston (
132
) which is mobile in a cylinder (
126
) and slides about a fixed rod (
138
). Thermoplastic is injected into the mold and the centering sleeve is removed from the sensor when the injection process is only partially complete.
The Japanese patent to Kawakami teaches the use of sealing a semiconductor chip by transfer molding. A semiconductor chip (
4
) is mounted on a carrier (
1
) and is held at a fixed position via mobile pins (
17
) and (
18
). The mobile pins (
17
) and (
18
) are movably fitted to a top force (
11
) and a bottom force (
12
) for freely advancing or retracting the pins into and out of the cavities (
15
) and (
16
). While the pins (
17
) and (
18
) are in contact with the carrier (
1
), a resin (
20
) is injected into the cavities (
15
) and (
16
) through gates (
13
) and (
14
) and the pins (
17
) and (
18
) are gradually retracted in accordance with the injecting state of resin (
20
).
The patent to Yokoyama teaches the use of an apparatus for manufacturing plastic encapsulated electronic semiconductor devices. A support pad (
11
) is firmly fixed by first and second sliders (
24
A) and (
24
B) and also by mold halves (
19
) and (
20
). The first and second sliders (
24
A) and (
24
B) are moved outwardly of a cavity (
25
) when the cavity is half filled with the plastic encapsulating material. Spaces, which are formed after movement of the sliders, are filled with the plastic encapsulating material directly poured through a gate (
23
). It should be noted that the sliders (
24
A), (
24
B) perform two functions in the cavity (
25
). The first function is to firmly grasp a thin end portion of the support pad (
11
) thereby fixing same in position and the second function is to narrow a passage through the gate (
23
).
The patent to Pierpont teaches the use of a method for encapsulating an electrical component having radial leads. A large multi-cavity mold is loaded with a plurality of horizontal radially leaded capacitors. The closed mold grips the leads (
15
). A top pin (
25
) pushes each component body downward a predetermined degree so that each body is left in about the same position within the corresponding mold cavity. A bottom pin (
28
) then pushes each component body upwardly only slightly above a center of the mold cavity so that upon bottom pin withdrawal, stresses within the lead wires of the electrical component cause the component bodies to spring back just to the mold cavity center portion. Molding resin is then introduced.
The other prior art listed above, but not specifically discussed, teach other sensor devices and molding processes and further catalog the prior art of which the applicant is aware. These references diverge even more starkly from the references specifically distinguished above.
SUMMARY OF THE INVENTION
The present invention is distinguished over the known prior art in a multiplicity of ways. For one thing, the present invention provides a transducer including a protective seamless encapsulation ensconcing a sensing element at one end and a cable extending out of the other end. In addition, the sensing element is symmetrically disposed about a long axis of the transducer and the seamless encapsulation includes an integrally formed protective wall having an uniform thickness along a forwardmost portion of the sensing element. The sensing element is electrically coupled to the cable for transmitting signals from the sensing element to an electrical processing unit. The signals can be correlative of, for example, machine vibration.
Preferably, the sensing element is in the form of a sensing coil having a front face, a back face, and a body having an outer surface and a center void extending through the body. The body extending between the front face and the back face. The sensing coil further includes at least a first lead and a second lead extending from th
Bently Nevada Corporation
DeBoo Dennis
Hall Carl E.
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