US2152540A

US2152540A - Rail flaw detector mechanism

Info

Publication number: US2152540A
Application number: US121571A
Authority: US
Inventors: Harcourt C Drake
Original assignee: Sperry Products Inc
Current assignee: Sperry Products Inc
Priority date: 1937-01-21
Filing date: 1937-01-21
Publication date: 1939-03-28
Anticipated expiration: 1956-03-28

Description

March 28,1939. H DRA@ 2,152,540

RAIL FLAW DETECTOR MECHANISM Filed Jan. 2l, 1937 IN VEN TOR Ha naar! C. Dra/re ATTORNEY Patented Mar. 28, 1939 UNITED STATES BAIL FLAW DETECTOR MECHANISM Harcourt C. Drake, Hempstead, N. Y., assignor to Sperry Products, Inc., Brooklyn, N. Y., a corporation of New York Application January 21,1937, Serial No. 121,571

- 9 Claims.

This invention relates to rail flaw detector mechanisms and particularly to the type oi mechanism employed in the Sperry rail iiaw detector car. The detection principle employed by said car is now well known and consists in establishing an electromagnetic eld surrounding the rail and then investigating the said iield by flux responsive means, such as induction means, for

irregularities in flux. One of the major probm lems of rail iiaw detection arises from the fact that surface defects in the rail distort the electromagnetic' field and are picked up by the flux responsive means to give an indication which is similar to the indication obtained from an inl5 ternal defect. These surface defects, however, are not the kind of defect which it is desired to detect since they do not impair the usefulness of the rail. Neverthelwn frequent instances, the surface of the rail has so many defects and so 20 many indications are obtained on the regular ilaw indicating mechanism that it is diiicult to distinguish actual internal defects from surface defets, and testing becomes ineiiicient and inaccura e.

25 It is the principal object of my invention,A

therefore, to provide means whereby, in the regular flaw detection process, indications due to surface defects are eliminated or substantially reduced 30 Further objects and advantages of this invention will become apparent in the following detailed description thereof.

In the accompanying drawing,- Fig. 1 is a. side elevation of a portion of a 35 Sperry rail ssure detector car to which my invention is adapted to be applied.

Fig. 2 is a wiring diagram illustrating the theory which makes my invention necessary.

Fig. 3 is a wiring diagram illustrating one form 40 of my invention.

Fig. 4 is a wiring diagram of. a modied form of my invention.

Fig. 5 is a diagram showing my invention applied to full wave rectication.

45 The Sperry rail fissure detector car to which my invention is adapted to be applied may comprise the car body II), only a portion of which is shown in Fig. 1, supported on trucks in the usual manner on the rails, and supporting the 50 iiaw detector mechanism. Said mechanism may consist of a main current brush carriage I I which is normally held in raised or ineffective position by means of retractile springs, not shown, and cables I2, but may be lowered into effective' posi- 55 tion in engagement with the rail R by permitting fluid pressure to enter cylinders ,I3 to depress piston rods I4, said piston rods being connected at their lower ends to said carriage. In the lowered position of carriage II it rests upon the rail by means of flanged wheels I5, and supports in 5 engagement with the rail two sets of spaced current brushes I6, II for leading current into and out of the rail, the said current being supplied from within the car-body by a generator G. An electro-magnetic iield is thus established surrounding the rail between sets of brushes I6 and II as the said oar moves along the rails, and said iield will be uniform except in the region of a flaw, where it will be distorted. Such distortion may be detected by ux responsive means, such as one or more pairsY of induction coils 20, which are maintained at a fixed distance above the rail surface by housing the same within a housing 2I supported on a detector carriage 22 which rides on the rail by means such as 20 wheels 23. Said carriage 22 is supported from carriage Ii for movement independent thereof by means of bolts 24 fitting loosely in the said carriage II and held in place by nuts 25 and springs 26. The coils are interconnected and 25 oppositely wound so that they are unaffected by changes in the supply of current from the generator G. Normally the coils cut the same number of lines of force in the electromagnetic iield surrounding the rail, but on entering a region oi naw, rst one and then the other of the coils will cut a different number of lines of force to generate a diierential EMF which after being suitably amplified may be caused to operate an indicator such as a recorder.

In my Patent No. 1,960,968 I have disclosed the idea of employing a plurality of pairs of coils spaced laterally across the rail whereby each pair of coils coacts with a definite portion of, the railhead. As shown in said patent the coils are interconnected and the total output from the plurality of pairs oi coils extends into the amplier (see Fig. 1 of said patent). The output from the ampliiier is adapted to energize a relay which controls a circuit through a pen magnet to cause a pen to be actuated with respect to a chart whenever suiiicient current passes through the relay to close the said circuit. If desired, the pen magnet circuit may normally be closed and adapted to be opened when suiiicient currentpasses through the said relay. The theoretical background of the present invention resides in the method at present employed which consists in leading the impulse from each pair of coils into a separate input channel of the amplifier, as shown in Fig. 2, and combining the outputs of the two channels before the last power tube is reached. The discharge from the single final power output tube 26 is caused to energize a relay 21 to close contacts 28 and energize pen magnet 30 to actuate the pen P relative to chart C. The input to said final tube is controlled by a resistance 32, and it has been found that if this resistance is made low, as, for instance, 100,000 ohms, a quick impulse would be impressed on the grid of said tube but not of sufiicient strengthn to vary the output appreciably. If the resistance is made of high value, as, for instance, 11/2 megohms, then variations of input on the grid result in a very powerful blow being delivered through the amplifier but theA duration of the impulse is prolonged so that it' can be added to by succeeding impulses. An intermediate value is therefore used of approximately 250,000 ohms, which means that an appreciable variation of output from the final power tube will be obtained in response to an input impulse with a medium prolongation of the impulse through the final power tube.

It is the above described prolongation of the impulse through the power tube which gives rise to the problem which this invention has solved, because this prolongation .is such that should the rail surface be corrugated, each successive impulse would be put into the final power tube before the preceding impulse has ceased. The circuit shown in Fig. 2 results in a predetermined small current normally flowing through thev output relay 21, this current being on the order oi' 3 millia'mperes. If, however, each successive impulse passes into the nal power tube before the preceding impulse has ceased, there would be superimposed on the normal 3 milliamperes an additional current which would be fairly conftinuous and which might be in the neighborhood of an additional 1 milliampere, to bring the output fairly steadily to about 4 milliamperes. The output relay is set to be operated at some definite increase from the normal 3 milliamperes output, as, for instance, at 4 milliamperes, so that should corrugated rail be encountered the additional amperage caused by the continuous impulses through the final power tube in response to said corrugations would be added to the normal amperage and might be sufficient to raise the continuous output to 4 milliamperes to cause the said relay to actuate the pen magnet circuit and op crate the same, as in the case of a fissure. The same is true in the ca se of a large burn sufficient to be picked up by several pairs of coils, in which case the impulse from o'ne pair would add on to the impulse from the other pair to give an increased output from the power tube.

It will be seen that the increase in current through the relay caused by such conditions as corrugations or burns, is the result of' the addition of impulses from the various pairs of coils, which gives an increased current output. I therefore solve the problem of this invention, namely, to eliminate or substantially reduce surface indications', by providing an arrangement for eliminating the additive effect of the plurality of pairs of coils. In the above described case, Whatever one pair of coils picks up when going over corrugated rail surface or a burn is superimposed on what the other pair picks up, so that a much greater output is obtained in response to the corrugations or fissure than would be the case if only one pair were employed. However, it is desirable to employ a multiple of pairs of' coils positioned laterally across the rail, for reasons well known in the testing art and stated in my said Patent No. 1,960,968, and therefore this invention provides means whereby the advantages of multiple pairs spaced laterally across the rail may be retained, While avoiding the disadvantage of having the continuous impulses of corrugated surface or the large impulse of a burn added together to increase the output of the amplier to a point where it will operate the pen relay.

'I'he above object is accomplished by providing a separate and independent amplifying system for each pair of coils so that addition of impulses is impossible, and providing means whereby the output from each amplifying system, independent of the output from the other amplifying systems, may actuate the pen magnet. For this purpose the output of each amplifier operates a separate relay 21', 21" controlling contacts 28', 28",which are connected in series with pen magnet 30 so that whichever relay is energized will open one set of contacts to operate the pen magnet P, as shown in Fig. 3. The essential difference of this system may be illustrated as follows: Assume that in going over corrugated rail one pair of coils is picking up a continuous `impulse which would tend to increase ythe plate current flowing out of the power tube from 3 milliamperes to 3.5 inilliamperes. The other pair of coils is generating asimilar series of impulses in response to the corrugations and also putting an additional .5 milliampere on the output of the power tube. This means that ln the arrangement shown in' Fig. 2 the output of the final power tube has been raised from a normal 3 milliamperes to a normal 4 milliamperes, and if the output relay 21 is set to operate at 4 milliamperes, indications will be obtained as for a flaw. With the above arrangement, however, each pair of coils adds .5 milll ampere to the plate circuit in the final power tube of the respective amplifier so that the output from each amplifier is 3.5 milliamperes, and if each of the output relays 21', 21" operated by the amplifier outputs is again designed tobe operated at 4 milliamperes it will be seen that these corrugations will not result in actuation of the pen magnet.

Instead of maintaining contacts 28' and 28" normally closed and arranged in series with pen magnet 30, the -same result may be obtained by maintaining

contacts

28 and 28 normally open and arranged in parallel with pen magnet 30, as shown in Fig. 4. It will be seen that closure of either set of

contacts

28 or 28 will result in L energizing the pen magnet.

The same principle may be applied where full wave rectification is employed in connection with the amplication of the impulses transmitted by the pairs .of coils. Thus, as disclosed in my Patent No. 1,967,812, granted July 24, 1934, it will be seen that each pair of coils operates into a full ,wave rectifying tube and the outputs from said tubes are united at a point 5| in Yadvance of the final power relay which controls the pen magnet circuit. In this case there would be the addition of current impulses set up by each pair of coils when going over continuous surface defects, such as corrugations. My invention may be applied to full wave rectification in the same manner as described above by causing each pair of coils to operate into a separate and independent full wave -rectifying circuit, as shown in Fig. 5, the output of each circuit operating its respective relay, 40, 4|, 42, 43, controlling sets of contacts 40', 4|', 42',

tacts 40', 4I'," 42', 43 may be normally open andv 43' connected in series with the pen magnet 30 the responses from each of said devices actuates I so that if sufllcient current passes through any one of the relays to open the pen magnet circuit .the said pen magnet will be actuated. The setting of the relays is the same as in the Fig. 3 form of the invention. It is obvious that the Fig. 4 arrangement may be employed wherein the conconnected in parallel with the pen magnet xso that closure of any set of contacts will actuate the pen.

In accordance with the provisions ofthe patent statutes, I have herein described the .principle and operation of my invention, together with the apparatus which I now consider to represent the best embodiment thereof, but I desire to have it understood that the apparatus shown is only illustrative and that the invention can be carried out by other equivalent means. Also, while it is designed to use the various features and elements in the combination and relations described,- lsome of these may be altered and others omitted without interfering .with the more general results outlined, and the invention extends to such use.

Having described my invention, what I claim and desire to secure by Letters Patent is:

1. The method of detecting aws in rails which consists in passing current through the rail to establish an electromagnetic field surrounding the same, operating a plurality of independent fiux responsive devices through said field, said devices being arranged to cooperate withv predetermined portions of the rail head, independently amplifying the responses from each of said devices, and causing each of the amplified responses, independent of the other responses, to actuate indicating means when said indicating means is in -unactuated condition. l

2. The method of detecting flaws in rails Iwhich consists in passing current through the rail to establish an electromagnetic fleld surrounding the same, operating a plurality of independent flux responsive devices through s aid field in predetermined relation to the rail, independently amplitying the responses from each of said devices, and causing each of the amplified responses in excess of a predetermined magnitude, independent of the other responses, to actuate indicating means when said indicating means is in unactuated condition. n

3. The method ofdetecting flaws in railswhich consists in passing current through the rail to establish an electromagnetic eld surrounding the same, operating a plurality of independent flux responsive devices through said field, said devices being arranged to cooperate with predetermined portions of .the rail head, independently amplifying the responses from each of said devices, and causing each of the amplified responses in excess of a predetermined magnitude, independent of the other responses, to actuate indicating means when said indicating means is in unactuated condition.

4. In a rail flaw detector mechanism, means for passing current through the rail to establish -an electromagnetic field surrounding the same,

a plurality of independent flux responsive devices in predetermined relation to the rail head and each adapted to generate an impulse in the region of flaw, indicating means, and a plurality of means each independent of the others whereby said indicating means when said indicating means is in unactuated condition.

5. In a rail flaw detector mechanism, means for passing currentthrough the rail to establish an electromagnetic field surrounding the same, a plurality of independent flux responsive devices spaced laterally across the rail head and each adapted to generate an impulse in the region of flaw, indicating means, and a plurality of means each independent of the others whereby the responses from each of said devices actuates said indicating means when said indicating means is in unactuated condition.

V6. In a rail aw detector mechanism, means for passing current through the rail to establish an electromagnetic field surrounding the same, a plurality of independent iiux responsive devices in predetermined relation to the rail head, and each adapted to generate an impulse in the region of flaw, a plurality of independent amplifiers for amplifying the impulses from the respective responsive devices, indicating means, and means whereby the output of each of said ampliers, independent of the output of the other amplifiers, actuates said indicatingvmeans when said indicating vmeans is in unactuated condition.

7. In a rail flaw detector mechanism, means for passing current through the rail to establish an electromagnetic field surrounding the same, a plurality of independent iiux responsive devices spaced laterally across the railhead and each adapted to generate an impulse in the region of aw, a plurality of independent amplifiers for lin predetermined relation to the rail head, and each adapted to generate an impulse in theregion of flaw, a plurality of independent amplifiers for amplifying the impulses from the respective responsive devices, indicating means, and means whereby the output of each of said amplifiers in excess o f a predetermined magnitude, independent of the output of the other amplifiers, actuates said indicating means when said indicating means is in unactuated condition.

9. In a rail flaw detector mechanism, means for passing current through the rail to establish an electromagnetic field surrounding the same, a plurality of independent flux responsive devices spaced laterally across the rail head and `each adapted to generate an impuse inthe region of flaw, a plurality of independent amplifiers for amplifying the impulses from the respective responsive devices, indicating means, and means whereby the output of each of' said amplifiers in excess of a predetermined magnitude, independent of the output ofthe other amplifiers, actuates said indicating means when said indieating means is in unactuated condition.

HARCOURT d. BRAKE. ,o