Патент USA US2409398код для вставки
im i5, mß, E_F,SHEEHAN ETA; ‘ f 2,409,397 SAFETY CUTOFF FOR POWER OPERATED' HAND TOOLS Filed Oct. 13, 1943 . A .CSOURCE 2 Sheets-Sheet> l Oct. 15,- 1946. 2,409,397 v E. F; sHEr-:HAN ETAL SAFETY CUTOFF FOR POWER OPERATED HAND TOOLS ì Filed oci. 15, 1943 2 sheets-sheet 2 Patented Oct. 15, -1946 Í2,409,397 UNITED >s'rrxr-lïs PATENT _ ortica `Í - sAFE'rvoUfronF‘roR POWER-,onimusha ‘ Edward , HAND 'rooLs Lstechen and George-v. Hunt, n _rmladelpma;, ra. 4 _ Application iOotoÍbcr ‘13, 19313,;Scriall No. 5106398.43 3 .oni-ms; (ol. 121-35.) ' l „Objects :of `the :present ;-iny_ention .are first, '.to y-protect »workmen »and equipment-rand sub-surface structures when 'pow-er :driven 4manually guided tools are ~used for cutting, drilling, `:breaking or `working «on :relatively nonaelectrically icon-ducting stopping operation l„once ,theshutt-lng» downlactìon of the _supervisory circuit .is initiated -by .elven momentary occurrence of the `condition under which tit is «desir-_ed wto Ästop the --toolg and-eleventh, to prov-ide an :audi-ble signal ,to .indicate 1that l«the tool has been shut downley contact with mate. rial which is <relatively _a goed :electric .conducton Other` objects of the invention wil-l Yappear.from :the Y‘following description .et the rend of which-«the material in or under orin :contact -With‘whichirell yatively high electrically »conducting .material may ¿be embedded, for-'example when such tools 'work Aon asphalt or other like stnee'tinavement in‘which, .or .in the foundation of which, ¿or "under which high tension 4metal-lic sheath :cables :irl-.pipes car rying water; gas, steam Aor `other -fluids., :or tele invention will `-be claimed. Y ` i The invention also icomprises ,the improvements to loe ,presently described and ,finally clair-ned» „I-n »the ,following description ’reference will vbe phone and »other ’conduits are usually laid orlo cated; second, to automatically off .the power ,and >stop ‘the opera-tion «of :the tool as soon :aait 1 -has `penetrated the "layer `of :relatively mon-’elec made .to the accompanying draw-ings forming part trically >conducting `zanraterial ,and alternating Ycurrent loper-ated ,safety cut-,off em contacted an underlying Yor :adjoining layerv Vof :relatively hereof :andin which, „ l l ‘ Figure .l is v~a „diagrammatic :View .illustrating :all bodyinggfeatures .of vthe invention ,and ,showing or indicating the Lposition of the lparts of .the valye mechanism when îthe ,tool is cut oil -from the »high «conducting material; third, Ito automatically cutoff the power and 'therefore to stop .the :tool immediately it «contacts >with relatively high .elec trically :conducting material, for lexample l»the 4sour-ee of power. - » i . ‘ Figure vf2 is asimilar view yshowing ,the „position of the jpants when the tool -isiconnected with :the metal ,sheath of ,a :cable and before sit Acontacts source-of power; 1and with and insulated the high -from _tension ‘fthe conductors 'metallic sheath; ¿contained fourth, to provide simple, reliable and efficient ,apparatus ‘ , « ¿Figure 3 isa view similar `to Eigure >l .and ill-us Vtra'ting -the employment -of la fdirect- 1,cu-rnent .cir cuit ,and omitting certain rteatures ,shown inFigS. for :accomplishing ‘the -objects indicated :as well as the objects tanti :results :hereinafter rseît forth l iand‘2. . . or :appearing: ,ñfth :lto `loros/tide `for 'workingìa Referring to the drawings, ,I indicates a .han-di power driven Vhand :guided tool on' an intended Y guided Ypovwer- operated tool, >snecíiicalvly a nnen' material :in the way and for automatically mratic tool. `i'. indicates «,arsourcevof `power f_orßfop» erating the tool. .3 is :a vsalve housing in» cludes a valve mechanismhav-íng a `port-A. .tor stopping it as soon as ii-t‘contacts with and `befnre fit penetrates another material 'which it might damage :or which :might he highly :charged with ,admitting `air «under lprensure -to the »tool -by _way Aa :hazardous medium~and cause injury to tele.. phone, water, _electric :power or ¿other :systems ¿or of the hose â. - The valve .mechanismalso includes -a port r6 `for exhausting :air under Vpressure from the tool by of the pipe .5 ,to the :atmosphere at I. The valves of the -valve mechanism .are injury to `the operator :or `¿damage ‘to fthe ätool‘; sixth, to provide for automatically ,stopping :a pneumatic :hand ‘tool Working l»on n :street lpave operated ,by `the pivotal .arm ÍB which is shown ment, building floor, -or the like, ïin the event “f in FigureZ in .position for „operating the tool under power, .and .in Figure 1 ,it is `shown imposition .for that fand as «soon as it contacts lwith and -betore it ‘penetrates »an object such :as is :likely to loe cutting .oli the supply of .fluid under _pressure from the „source and „for exhausting :from the buried in or under .the pavement, V«floor or "the like, :and which might ,be damaged by the tool, .tool «and line 5 tothe atmosphere so ,that ,thetoo'l stops quickly. .The pi-votalhand-le 3 is connected or itself cause injury to the _tool `.orto the 'opera by >a link with‘the .arm S the spring I9 op»r tor; seventh, to _provide Àa supervisory vv.electric .crates to normally put .and ,hold the valves the circuit for shutting „dow-nthe ‘tool upon :occur position shown in Figure l in whichnosition ¿the rence of -the'conditions under <.which :it :desired tool l `is Vat rest. ll is a -,pivotal latch normallyT to Istop the tool; zeig-nth, kto ,provide 'for shut-down positioned by .the spring l2, as .shown ‘in Figure of the tool incase of .failure of «electric ,power to the supervisory electr-ic ¿circui-t; ninth, to provid-e 1„ `in Vwhich .position it _disengagesthe handle` 9 at >a visual Lsignal ‘to Aindicate :failure of electric VI3 .whenthe _power is out .off from the tool„ and. it engages the handle ..9 .at lI3 when »the ¿tool is operating .under power, ‘The 'latch ,l .l `is ìoon'tnol-lecl power to ëthe «supervisory electric circuit; tenth, to `provide `a :seal-in .provision in the Vsupervisory electric ïcircuit to cause completion of >-the tool 55 by .the solenoid ,L4 .which when energized causer» 2,409,397 3 4 the latch to hold the handle 9 in position, thereby permitting the tool to operate under power. The and permit the handle 9 to take up the tool stoppìng position shown in Fig. 1. The parts are so constructed that when the handle 9 has moved far enough to release engagement with the lead 26, the latch Il will not be able to reengage the handle 9 may be shifted to latched position man ually or otherwise. The solenoid I4 is shown as included across the leads I5 and I6 of the A. C. source. I'I is a sensitive fast-acting two pole double-throw relay which normally closes the line latch pin I3. There is also a lead 21 through the alarm 28 to the contact at the rother side of the handle 9 I6 so that the latch II is normally held against so that when the valve is in position for stopping the force of its spring I2 in position for en gaging the handle 9 and permitting the tool 10 the tool the circuit is closed through the signal 28 which indicates that the power is cut off from I to operate in the ordinary and usual manner. the tool. Obviously, if desired, the sealing-in cir If the position of the two pole double-throw relay cuit may be omitted and it is, therefore, not be changed toward the right in Figure 1, lthe shown in Figure 3. In the latter figure there is circuit through the solenoid will be broken, the a D. C. source but the circuits and translating spring I2 will release the latch and the tool will devices are, as has been described, in connection stop. The coil I9 serves to shift the position of with Figures 1 and 2. In this case, however, there the two pole double-throw relay I‘I appropriately is a lead 29 from one side of the circuit which for stopping the tool. There is a lead 20 from branches to and through the coil I9' Ito ground one side of the secondary of the transformer I8 through the coil I9 to a relatively low resistance 20 at 2 I, and through signal 28 and lead 29 through the two-pole double-throw relay Il back to the ground at 2I.v Two leads 22 and 23 extend from line. The operation of the apparatus shown in the secondary of the transformer -to the tool I Figure 3 is as above described in connection with where they may be regarded as connected to Figures 1 and 2 except as indicated above. In gether and to the tool I, and in the lead 23 there is a signal lamp 24. At this point'in the de 25 both Figures 1 and 3, 30 is a blocking switch which is, of course, normally closed. scription it may be said that the tool I is for the The operation of the apparatus of Figs. 1 and purposes of description, assumed to be a pneu matic tool and is intended to operate upon or work on material a, of relatively low electrical 2 may be summarized as follows: Under normal conditions the hand tool, driven pneumatically conductivity, for example the asphalt pavement 30 or by other power, with the valve mechanism in the Iposition illustrated in Fig. 2, is operated in of a street. In the pavement there is likely to be the usual manner to disintegrate pavement or embedded material of relatively high electrical other material of relatively high electric resist conductivity, such for example as a high tension ance a. If, however, the Pneumatic ltool in its lead covered cable b grounded for example at c. It must, of course, be understood that the fore 35 normal operation makes contact with under ground water pipes, conduits or the like, b, an going explanation is given by way of description electric circuit is completed from one terminal of and not by way of limitation, for example, lthe the secondary winding of transformer I8 by Way tool may be operated otherwise than by air, and of conductor 22 through the tool I, conducting -'che material b, so long as it is of relatively high electrical conductivity, may be a telephone cable, 40 medium b, grounds c and 2|, coil I9, and con pipe or the like. and the material a may be the earth beneath the pavement. Riesuming the de scription and assuming the tool to be working in or on the material a of relatively low electrical conductivity, any ground circuit that may exist ‘ is of too high resistance to permit the coil I9 to be energized sufficiently to throw the relay I1. However, if the tool contacts the material b of relatively high conductivity, the ground circuit between 2| and c is of relatively low resistance ‘ and is of good conductivity and permits of the energization of the coil I9 sufficiently to throw the relay I‘I and stop the tool. Because the contact of the tool I with the ma terial b, may be momentary or of chattering na- ' ture, a sealing-in circuit is provided to prevent the fast-acting relay I'I being deenergized and restored to its normal position before the latch holding solenoid I4 can function to release the latch II and permit the valve to assume the cut-off position. This sealing-in circuit com prises the lead 25 from one side of the secondary circuit of the transformer to the handle 9 and thence through the lead 26, the armature of the relay I'I, the coil I 9, and the conductor 20, back to the other side of the secondary circuit of the transformer. With the valve mechanism in the tool-operative position illustrated in Fig. 2, the relay I‘I, when energized and thrown to the right, will remain in that position because the coil I9 u will remain energized through the sealing-in cir cuit regardless of any opening or chattering of the ground circuit through the tool I and mate rial b. This will allow any time lag which may be required for the solenoid I4 to release latch II ductor 20 to the other terminal of said winding. Flow of current in this circuit energizes coil I9, throwing relay I1 to the right and energizing the sealing-in circuit to hold Ithe relay in this posi tion despite any chattering of the tool. This energizing of the relay I‘I opens the .circuit from the electric source Ito the solenoid I4, thereby permitting the spring I2 to release the latch IIThe spring I0 is then free to move the arm 8 and handle 9 to the tool-stopping position shown in Fig. 1, moving the valve to cut off the air supply and permit the line 5 to exhaust to the atmos phere at 1. This movement of the handle 9 to the position shown in Fig. 1 connects the audible signal 28 to the secondary winding of transformer I8 to direct attention to the occurrence of valve operation. The visual signal 24 is connected to the transformer I8 and when energized indicates (1) that the supervisory electric circuit is ener gized, and (2) that the flexible electric conductor 22 to the tool is unbroken, it being readily under stood that this conductor is subjected to consid erable flexure and possible abuse and is therefore likely to break. The apparatus is reset for op eration of the tool by merely moving the handle 9 upwardly into the position shown in Fig. 2, the latch II automatically engaging with the pin I3. It is obvious, of course, that should failure of the electric source occur, solenoid I4 will be deener gized and the tool will shut down. The super visory electric circuit of the device shown in Fig. 3 operates in a similar manner from a direct cur rent source, but without the sealing-in feature. It may be remarked that as a matter of con venience certain of the described Working parts 2,409,397 Y may be assembled in a portable housing or case, for example, the valve mechanism, indicated at 3, may be arranged in the case with the handle 9 projecting to theoutside, and the blocking switch 3@ may be similarly arranged. The signal lamp 24 may be displayed at the outside of the case, and the relay Il may be arranged inside of the case, and, if desirable, there may be arranged 6 i from‘moving said cut-off means to the cut-o position'when said detent is energized by said electric current and to release said yieldahle means lpermitting said cut-oiî means to assume the cut-oil' position when the electric current .ta said detent is interrupted, a normally closed re lay having its contacts in said iirst circuit in series with said detent, a second electric circuit in the case as a D. C. source a storage battery, connected to said source and including the oper and the alarm 23 may also'be arranged in the 10 ating coil of said relay, and means in said second circuit for energizing said relay operating coil case and in that way the invention is applied to street paving and like Work in a convenient man responsive to the conditions under which it is de ner. sired tc stop the tool, whereby the .tool will be stoppedupon operation of the means for energiz It will be obvious to those skilled in the art ing said relay operating coil and also upon the that modifications may be made in details of construction and arrangement and application in occurrence of any other interruption of the cur respect to the apparatus chosen for illustration rent supply to said first circuit. and above described without departing from the 2. The invention set forth in claim 1 char acterized in that the relay energizing means is spirit of the invention, which is therefore not limited as to such matters or as to matters of 20 provided with a sealing-in circuit for holding said mere form or otherwise than .the appended claims relay in tool stopping position when once in that may require. position and until manually released. We claim: 3. The invention set forth in claim l char l. A safety cut-off apparatus comprising in acterized in that said apparatus includes an elec trically operated visual signal, said signal being combination a power driven hand tool, power cut off means having yieldable means normally urg connected in series with a part of said tool .to said ing said cut-off means to the cut-off position to electric source, whereby the operator may be ap prised that the circuit to the `tool is energized. stop the tool, a source of electric current, a ñrst electric circuit connected to said source and in EDWARD F. SHEEHAN. cluding an electro-mechanical detent constructed 30 and arranged to restrain said yieldable means GEORGE V. HUNT.