US2892078A

US2892078A - Detecting apparatus

Info

Publication number: US2892078A
Application number: US646045A
Authority: US
Inventors: Richard K Orthuber
Original assignee: Deutsche ITT Industries GmbH
Current assignee: TDK Micronas GmbH; International Telephone and Telegraph Corp
Priority date: 1957-03-14
Filing date: 1957-03-14
Publication date: 1959-06-23
Anticipated expiration: 1976-06-23

Description

R. K. ORTHUBER 2,892,078

June 23, 1959 DETECTING APPARATUS 2 Sheets-Shet 2 Filed March 14, 1957 INVENTOR. RICHARD K. ORTHUBER QZPOMBHQ ATTORNEY United States Patent ()fiice 2,892,078 Patented June 23, 1959 2,892,078 DETECTING APPARATUS Richard K. Orthuber, Sepulveda, Calif., assignor to International Telephone and Telegraph Corporation Application March 14, 1957, Serial No. 646,045 7 Claims. (Cl. 246-249) The present invention relates to detecting apparatus and more particularly to a variable reluctance switching device for use in connection with operating hot journal box detectors for railroad equipment.

In Orthuber et a1. application Serial No. 405,944, filed January 25, 1954, and Orthuber et a1. application Serial No. 499,595, filed April 6, 1955, there are disclosed and.

claimed apparatuses and methods for detecting overheated journal boxes. Specific requirements as to the construction and design of such apparatuses were set forth in detail in said applications, which details, insofar as necessary, are made a part of this description.

These prior applications disclose the use of mechanical switches mounted on the rails of a railroad trackway, these switches being actuated by the wheels of the equipment as they pass thereover. Obviously, such a switch is subjected to an appreciable number of operations due to the large number of wheels in a normally sized train, whereupon the switch must be carefully designed for proper operation yet be extremely rugged and have a long wear-life. Since a faulty switch can result in improper operation of the hot box detecting apparatus and such faulty operation result in failing to discover a dangerously hot journal box, the chances of damage to rolling equipment or of the occurrence of a serious accident are correspondingly high whereby it is desirable to V eliminate such faulty operation insofar as possible.

In view of the foregoing, it is an object of this invention to provide a switching device for use in connection with hot box-detecting apparatus, which contains no moving parts.

It is another object of this invention to provide a switching device of the character described which embodies a variable reluctance pickup sensitive to the passage of a railroad wheel.

It is still another object of this invention to provide a variable reluctance switching device which may be utilized in such a manner as to produce a short pulse of voltage each time a wheel passes a given location, the duration of the pulse being independent of wheel speed.

The switching device of this invention may be mounted in or on a rail or between adjacent ends of two rail sectons, such device comprising a support disposed between the rail ends, two inductors of substantially the same inductance mounted on the support, one inductor being closer to the rail surface than is the other inductor, and a bridge circuit which incorporates said inductors in two arms thereof, respectively, which circuit generates a signal as a wheel passes over the inductors.

The above-mentioned and other features and objects of this invention and the manner of attaining them will become more apparent and the invention itself will be best understood by reference to the following description of an embodiment of the invention taken in conjunction with the accompanying drawings, wherein:

Fig. 1 is a cross-sectional illustration of one embodiment of this invention;

Fig. 2 is a partial side elevation thereof;

Fig. 3 is a block diagram illustrating the electrical circuitry; and

Fig. 4 is a schematic diagram of the circuit of Fig. 3.

Referring to the drawings, and more particularly'to Figs. 1 and 2, a rail is shown as comprising two rail sections 1 and 2 which are laid end to end and spaced apart a suitable distance to provide a joint 3. A variable reluctance device, indicated generally by the reference numeral 4, is disposed between the rail ends as shown in Figs. 1 and 2 and comprises two inductors or electromagnets L1 and L2 which have identical impedances but which are slightly different in size as seen in Fig. 1. Each of the inductors has an

iron core

5 and 6, respectively, these cores being identical with the exception that core 5 is shorter than core 6.

These two inductors are mounted on the cross-bar of a T-shaped support 7 made of iron or some similar magnetic material. As seen in Fig. 1, the top of the core 6 is substantially flush with the upper rail surface 8 whereas the top of the core 5 is spaced downwardly therefrom, and in one practical embodiment of this invention, the core 5 is depressed about one-eighth /s) of an inch.

The lower extremity 8 of the support 7 is threaded for receiving a washer 9 and nut 10. The washer 9 is also made of iron or some other suitable magnetic material and is large enough to bridge the gap between the two rails 1 and 2, as shown in Fig. 2. The cross-bar 11 of the support 7 rests on the top edges of two

clamping plates

12 and 13 which are secured to the opposite sides, respectively, of both rails 1 and 2. Suitable bolts 14 may be used for securing the two plates in place. By tightening the nut 10, the support 7 is securely clamped in position for mounting and positioning securely the two inductors L1 and L2.

The two inductors L1 and L2 are incorporated in a suitable circuit as seen in Figs. 3 and 4. Specifically, the

inductors L1 and L2 constitute the two arms 15 and 16 point.

A source 22 of alternating voltage is coupled to the

input circuits

23, 24 of the bridge. This source 22 may comprise an ordinary oscillator which generates a sinewave of voltage at a frequency of about five (5) kilocycles. As will appear from the description to follow, this frequency may vary over a considerable range Without departing from the spirit or scope ofthis invention.

The

output circuit

25 and 26 of the bridge is coupled g current amplifier 27 which supplies the output signal of the bridge in amplified form to a rectifying circuit 28. This rectifying circuit converts the alternating signal to a direct current signal or voltage which is next fed to a one-shot multivibrator 29, a spike generator or the like. This multivibrator is adjusted to respond to a unidirectional signal or voltage which exceeds a given threshhold value or amplitude and in so responding it generates a single pulse of voltage, as illustrated by the waveform 30. This pulse 30 is fed to the hot box-detecting apparatus 32, and in one form of the invention is directly utilized to operate an ordinary relay 31 as shown in Fig. 4, this relay being a part of the detecting apparatus 32. Orthuber et a1. application Serial No. 499,595 discloses the details of construction of the apparatus 32 including the relay 31.

All of the

circuit elements

22, 27, 28 and 29 are conventional and are shown in detail in Fig. 4. Suitable values for the individual components are noted in Fig. 4, these values being representative only of a working embe impressed on the multivibrator 29. Of course, this initial balancing adjustment should be effected with no wheel or metallic object near the rail joint 3.

With the circuit thus balanced, any noise produced by 'rail vibration or thelike and which might affect the inductance of either of the inductors L1 and L2 will be effectively cancelled inasmuch as both inductors will receive the sa "e vibration or noise and will generate like but opposing signals. Thus, ordinary disturbances in the rail will not effect spurious or accidental operation of the associated circuitry. However, upon the approach of a wheel 34 to the rail joint 3, the normal air gap between the inductor L2 and the rail structure will be substantially closed thereby producing an appreciable change in the reluctance of the magnetic circuit which has been indicated by the loop 35 in Fig. 2. It will be noted that this loop includes a path through the wheel and core 6 only.

While the reluctance of the inductor L2 is undergoing appreciable change, by reason of the depressed spacing of the inductor L1 it will not undergo such a reluctance change. Instead, this L1 air gap with the wheel will be substantial so that the reluctance thereof will change only negligibly.

The bridge 17 thereupon becomes unbalanced, and produces an alternating signal which is impressed on the amplifier 27. The amplified signal is rectified and fed to the multivibra'tor 29 which is triggered into operation for producing the pulse 30. This pulse 30 in turn operates the relay 31 and further effects operation of the detecting apparatus. Thus, as each wheel of the railroad equipment passes over the joint 3, a pulse 30 is produced.

As the wheel 34 leaves the joint 3 travelling in the direction of the arrow F, the wheel being shown by dashed lines 36, the bridge 17 is unbalanced in an opposite sense as compared to that of the approaching wheel, and tends to generate a negative signal in the system. However, a gain control 37 in the second stage of the amplifier 27 is so adjusted as to permit the amplifier to respond only to signals exceeding a given positive amplitude, This being true, the system will respond only to wheels approaching the joint3. While the principles of the invention have been described in connectionwith specific apparatus, it is to be clearly understood that this description is made only by way of example and not as a limitation to the scope of the invention.

What is claimed is:

V .1. Apparatus responsive to the passage of a railway wheel comprising two collinear rail sections having adjacent ends positioned to form a spaced joint, variable reluctance means having two different portions, said por- 4 tions situated in the space of said joint, each portion having the same reluctance and each spaced at different distances from the traction surfaces of said rail sections, means coupled to said variable reluctance means for producing a signal when the reluctance of one of said portions varies, the reluctance path of said one portion including one of said rail sections and a railway wheel when it passes over said joint.

2. Apparatus as claimed in claim 1, wherein said means for producing a signal comprises a balanced bridge having four arms, each portion of said variable reluctance means constituting a different arm of said bridge, a source of alternating current applied across first diagonal terminals of said bridge, and amplifying means coupled across second diagonal terminals of said bridge for amplifying signals from said current source upon unbalance of said bridge.

3. Apparatus as claimed in claim 2 wherein said means for producing a signal further comprises a two-condition static switch device coupled to said amplifying means, said switch device being responsive to an output of said amplifying means which exceeds a predetermined level.

4. Apparatus as claimed in claim 3, wherein said means for producing a signal further comprises detecting apparatus for detecting the change in condition of said Static switch device, said detecting apparatus comprising electromagnetic relay means operable when said static switch device is in one of its conditions.

5. Apparatus as claimed in claim 1, wherein said two different portions comprise a pair of parallel magnetic cores of different lengths, each having a winding therearound, the axes of said cores extending in a plane normal to the traction surfaces of said rail sections, the longest of said cores being substantially flush with the traction surface of said rail sections.

6. Apparatus asclaimed in claim 5, wherein each of said cores are disposed equidistantly from the ends of said rail sections.

7. Apparatus as claimed in claim 1, further comprising a pair of clamping plates disposed on opposite sides of said rail sections and clamped thereto underneath the traction surfaces thereof, a T-shaped support carrying said variable reluctance means the upper surface of the upper portion of said support extending flush with the traction surfaces of said rail sections the lower surface of the upper portion of said support resting across said clamping plates, the leg of the T extending downwardly in the space of said joint and means fastening the leg of said support to the lower portions of said rail sections.

References Cited in the file of this patent UNITED STATES PATENTS