US1347136A - Terminal for pneumatic-despatch-tube systems - Google Patents

Description

A. WATSON.

TERMINAL FOR PNEUMATIC DESPATCH TUBE SYS TEMS.

APPLICATION FILED NOV. Y, I9I9.

Patented July 20, 1920.

f f l ALEXANDER WATSON, or ATLANTIC, MASSACHUSETTS,

Assierroa er ONE-HALF yro WILLIAM MITCHELL, oF MALDEN, MASSACHUSETTS.

TERMINAL FOR PNUMATIC-DESPATCH-TUBE SYSTEMS.

To all whom t may concern.' u

Be it known that I, ALEXANDER WATSON, citizen of the United States of America, and resident of Atlantic, in the county ot Norfolk and State of Massachusetts, have invented new and useful Improvements in Terminals for VPneumatic-Despatch-Tube Systems, of which the following is a specific at ion-.

This invention relates xto pneumatic despatch tube systems ofthe type having a despatch tube normally at atmospheric pressure only, and in which the transmission of the carrier is effected by pressure behind the carrier.

As shewn, described and claimed in my Letters APatent of tl1e United States No. 1,159,627, dated November 9, 1915, have heretofore provided Vmeans for the introduction ot a charge of compressed air at the rear end feta despatch tube behind a carrier inserted therein, including a valve or cover for closing the despatching entrance to the tube, and an air introduction valve opened by the motions of the mounting for the despatch tube closing valve or cover. This prier system provides an air admission valve of the balanced type in which the pressure tending to hold the valve upon its seat is released uponV the finalr part of the motion of thelvmounting for the despatch tubecover, and also provides for the closure of the air admission valve upon the resumption of balanced pressures after this event, and independentlyfor' opening the closure or cover tor the despatch tube automatically upon cessation. of carrier despatching pressure at a point near the despatching terminal.

In the practical operation of devices according to said patent some situations are encountered in which the automatic closure of the admission valve and opening of the despatch terminal is delayed too long by reason et pressure or air-currents continuing in thedespat'ch tube near the despatch end. his is particularly the case when the system includes transmission lines of Ygreatlyv different lengths or when itis desired to operate it under very high initial pressures; 1n some cases the pressures at the despatch terminal are such as not only to delay the closure 'of the admission valve and opening et the despatch terminal closure butentirely to prevent closure ofthe aipecilcatleh 'of Letters Patent.

Patented July 2o, 1920'.

Application filed Nbvembr 7, 1919. Serial No. 336,255.

admission valve, or. to delay opening of the terminal closure unduly, or both, and in either' case uselessly to cause a flow of air.

The present invention has for its principal objects to prevent the waste of energy in such` systems, and to improve the device of said Letters Patent by causing automatic cessation of air flow in an improved manner promptly upon delivery of the carrier at a distant station, no matter what may be the length or condition of the despatch tube to which it may be applied; to insure the automatic opening oi' the despatch terminal closure in response to the delivery of the carrier at the far end ot the system whether or not the air-admission valve has meanwhile closed; and thus to insure the prompt automatic closure of the air admission valve as a consequence of the opening of the terminal cover or valve.

Further objects are to improve the mechanical constructions of the patented device to secure increased durability, rigidity, strength and simplicity, and to render the devices employed less wasteful in the hands of ignorant users; to avoid wasteful flow of air when no carrier is to `be despatched, and to provide convenient adjustments by which the automatic admission of air for operating a particular despatch tube line may b e certainly secured and delicately regulated.

I shall describe the invention, which is independent ot' any particular mechanism, in connection with a specific preferredrinstance or' a construction selected to illustrate the genus. In the accompanying drawings,-

Figure, 1 is a vertical sectional view partly in elevation of an air admission valve and terminal closure corresponding to the present invention;

Fig. 2 is a section on line 2-2 and Y Fig. 8 is a detail section on line 3-3 'of Fig. 1. Y

Referring now to big. 1 the terminal comprises as a whole a hollow, preferably of Fig. 1;

cast-metal, casing A including a portion 1 fitting over the end of the despatch tube 2, and including the cylindrical easing A of my said prior Letters Patent No; 1,159,627, having therein a cylindrical valve chamber A? termed in a partition A4 separating the pressure compartment Y from the pressure delivery compartment Y,- andhaving therein a seat A5 for a valve C controlling com-l munication between a port a leading from the compartment Y7 and a port a leading into jthe compartment Y and to the despatchtube 2. Y

As explained in said patent the valve C is held upon its seat by an attached piston C2 of greater area than the valve and having a suitablepacking,` working in the cylindrical chamber A3, and subject to the pressure in the part of the chamber A3 above the piston (.52. Normally pressure in the chambers Y, A3 is the same as pressure 1n the air-supply pipe B with which the chamber Y communicates.` Pressure in the upper part of the chamber A3 above the piston C2 is slowly equalized with the pressure bcneath the piston C2 through a port C adjusted by plate C3, as explained in said patent. Fressure above the piston C2 is released to operate the valve C by motion `of a hollow rod E carrying a valve E controlling the central opening in the rod leading into a bore in valve C in which rod slides. By this arrangement pressure downward upon the head G ol rod` E against a spring F Vreleases the pressure in the upper part of the chamber A3 and permits valve C to be opened by the unbalanced pressure from chamber Y on the lower side of the piston C2, which is larger in area than the valve C. lVhen pressure on Vthe rodvE and head Gr is released, pressures on" the upper and lower sides of the piston C2 become balanced after a time determined by the working pressure and the width of the port C', and at some time prior to balance of these forces, the valve C seats on the seat A5 by reason of lesser pressure in the chamber Yv, than in the chamber Y.' Of course this docs not occur until the valve E is' closed or partially closed, nor until the pressure in thechamber Y and tube 2`supplied by the' air admission valve C has dropped below the pressure in the supply pipe B to a marked extent.

As also explained in said patent, effective opening of the air admision valve- C is arranged not to occur until after the manual closing ot a cover `or despatch tube closure valve (l arranged to seat on a boss a5 of the part ot the casing in which the despatch tube 2 terminates. The valve O comprises a suitable metal casing having a locking lug O2, and an elastic and compressible Vpacking U3 for the seating disk O47 and having a central stem P surrounded by a spring s.

The casing O is integral with and attached to arms Opivoted concentrically with a shaft N extending between integralv brackets M projecting from the casing A. Instead of mounting the valve U as shown in said patent, I prefer to provide the arms O with comparatively large bearing rings O5 free to turn upon a tubular shaft 10 having a bearingat one end onv the 'shaft N and at the other end on the plug 11 seated Vinone of the brackets'M and'preferably held in predetermined rotary adjustment by a setV screwi12rfl The plug11 isbored to receive one end of the sha-ft N which extends through a bore in the other bracket M and is held against endwise movement'by a screw plugV 11a. Within the tubular shaft 10 a strong spring 13 for opening cover O reacts between a bore 14 in the end of the tubular sha-ft 10 anda bore 11" in'fthe plug 11, and said spring may lbe adjusted by rotating plug 11 and setting'the adjustment by set screw 12.

Tubular shaft 10 is attached tovor integral with an operatin-ghandle 15 provided with a central recess 16 to vtake over the spring S andV further provided with internally hollow lateral bosses 17 into which pins 18 on the arms O take for a slight freedom of independent movement between the arms O and the operating handle 15, as will be permitted when the disk 'O4 seats on the seat a5 and the spring S is further compresed by Jfurther motion of the handle 15. This 'further motion of the handle 15 is relied upon tofully depress the operating stem E of the compressed air admission valve C. A bell crank lever 2O is pivoted on a transverse pin- 21 between lugs 19 on the casing'` in such a' position thatv its arm22 is struck by a lug 23 on the handle 15 after the disk O4 is seated at a5 and asv a consequence of a further movement of' the handle 15. Y Y

The normal open position of the handle 15 under impulsion of the spring 13 is limited by a lug V25 takingagainst one of the lugs 19. l

In my said patent provision was made to latchY the cover or valve 0 in place until release ot the pressure in the entrance end of the despatch vtube was eiecte'd.

On a very long transmission line or with a sticking carrier it sometimes happened that pressure continued tobe lmaintained in the entrance end, and the valve O remained locked; and in an aggravated casel this back pressure in the despatch tube 2 was sufficient to prevent seating of the air admission valve C. 1n order to operate the latch to release the valve O of said patent, a spring pressed plunger was arranged to be moved against the pressure within the despatch tube to release the cover latch; but this-was not effective in all cases, because the plunger was acted upon directly by a blast of air from the air 'admission connections. When the difference of compression pressure in the despatch tube due to the emergence of the distant carrier is sligat7 this blast pressure tends to maintain the latch closed. The present invention provides an unlatching device responsive to compression pressure in pressure due to a current Vof air-blown against the pressure-sensitive element.'

VInthe preferred form shown an improved latch mechanism includes a latch 30 made as a bell lcrank lever pivoted at' 31 so as to take o'ver'tlie locking lug()2 Whengmoved against the "resistance of an adjustable spring 32 held in a bore 33 of the Ylug 34 forming part of the casing A, by internal pressure vinthe bore 33 acting upwardly against a piston 35, 38,Y seated in the lbore lfVhen in locked position, the latch 30 through the connection O, 18,

23, 22, 2O preferably holds down on the,

rod E sufficiently to cause leakage from chamber Aaabove piston C? by holding valve E very slightlyaway from its seat, as may be delicately adjusted by screw-cap "G on -rod E. Blow holes provide a free path to atmosphere for this leakage. A countervailing pressure acting to seat valve C except upon rapid reduction 1n chamber Y or` tight closure of valve E- is thus prevented.v Valve VC will remain open until latch 30 is released.

latch 30 is made adjustable in accordance with the needs ofthe particular line of despatch tube by varying the "distance between the plunger 35 and the llatch 30 by means of the nut 3G and the set collar 37 on the threaded stem 38 of the plunger piston 35. In order to prevent sensitiveness of the piston to blast pressures, admission of air pressure to bore 33 is arranged through a regulated and tortuous passage, including a port 39, a longitudinal port 40 in the cylindrical portion 1 of the casing A, and one opening 41 only of a series of relatively small air openings 47 formed in the despatch end of the despatch tube 2.-

lt will be observed that the passage 40, 39, is indirect, and that the port 40 is set off from communication with the chamber Y Within the casing A by partitions 48, which prevent access to the passage 40, 39, by direct flow from vthe air admission valve C and chamber Y. Y Y

The relative pressures within the tube 2 are further controlled by arranging an effective adjustment for the openings 47. VOne preferred arrangement for this is a sleeve 43 between the tube 2 and casing A having a hand-flange 45 and provided with a vnumber of entrance holes 46 adapted to be moved more or less into register with the holes 47 upon turning the adjusting sleeve 43. Preferably the sleeve 43 is arranged simultaneously toadjust the port 4l by movement into and out of register with it of a hole 42 in the sleeve. j

Referring particularly to Fig. 2 it will be noticed that an air blast flowing from a space Y in the casing A into the despatch tube 2 flows inwardly in the radial direction of the arrows b, and that there is no direct blast from any of these apertures in the direction of the arrow c which could produce a pressure in the port 40 differing from the 'true compression or barometric pressure, as

distinguished from blast pressure, in the despatch end of the tube 2.y

The importance of the last-mentioned provisions willbe evident from consideration of the operation of the device, as follows: v

A carrier is inserted in the tube 2 and the handle'vl is closed upon the tube. Then Vthe cover valve O, O4 seats upon the seat a5 and the handle is further moved, the valve C unseats promptly and a rush of air occurs through the holes 41. Pressure within the tube 2 behind the carrier builds up promptly, and is communicated through theV passage 41, 40, 39, to the plunger 35, and the latch 30 is actuated vthereby to hold the cover valve O on its seat and retain valve C olf' its seat. If no carrier is in the tube, the coinpression pressure is not enough to operate Y the latch 30, and accidental or mischievous Preferably the spring 33 tending to open operation of the handle 15 results in a momentary lifting of valve C only.

Uien the carrier gathers speed the pressure falls to a balance between the supply coming from the supply pipe as admitted by the regulated ports 47 and the rate of flight of the carrier, but when the carrier emerges at the far end of the despatch tube a sudden drop in the true compression or barometric pressure in the despatch end of the despatch tubev ensues. If the line is long and the carrier light, this is not a sufficient difference of pressure reliably to be transmitted through ports 47 and chamber Y in order to seat the valve C by the pressure of the air trapped in the upper part of the cylindrical space A3. An adjustment of the relativeareas of piston C2 and valve C for every different initial pressure and every different despatch tube 2 would thenbe required -for infallible operation.

In order to insure seating of the valve C under these circumstances, it is preferred to rely upon causing motion of the valve C, first as a consequence of detection of drop in pressure by the latch mechanism, and seeond, as a consequence of a sharp release of compression pressure in the tube 2, such as will be effected byopening the cover valve O.

rlhe plunger 35, being sensitive to changes in the pressure in the tube 2 and insensitive to the blast from valve C by reason of the arrangement of the passage 40, 39, and the regulated opening 41, is reliable to act upon the sharp but slight drop in pressure which follows emergence of the distant carrier. Its first effect is to release the valve E through the connection O, O', 18, 23, 22, 20,

and thereafter to cause the cover Ov to be.

pressure above piston C2 as to insure promptV seating of the valvesGby the unbalanced pressure upon it, if closure of valve E has operating 1n said hollow stem and carryingv notalready effected this. .Y A The ports 47 and 4l, can be adjusted for any duty of tube 2 Vand anyvinitial pressure in supply lineB with ease and without skill, since the conditions of 4the apparatus call for simultaneous increase and decrease in these openings. VVhen the ports 47. are set to admit enough air to move a carrier to the required height or distance, the pressure-` sensitive latch is then inadjustment tolopen the tube and cut off theair supply upon the exit ofthe carrier at its distant station.

I claim :---V

l. Pneumatic despatch tube apparatus having therein a despatch tube, a cover for the terminal of the tube, means to hold the cover closed, a valve for admitting Vair to the tube to propel a carrier, meansztor opening the valve active upon closure oit' the cover, and pneumatic means operating as a` consequence of releasing the cover for closing the valve. Y

2. Pneumatic despatch tube Vapparatus v. having therein a despatch tube, a cover for the terminal of the tube, means to hold the cover closed, a valve for admitting air to the tube to propel a carrier, a mounting for the cover and means acted on by the mounting for opening the valve upon closure of the cover, operating by release of pneumatic pressure tending to seat the valve, and pneumatic means operating as a consequence of releasing the cover for closing the valve by restoring the seating pressure.

3. Pneumatic despatch tube apparatus having therein a despatch tube, a cover "for the terminal of the tube, means to hold the coverv closed, a pneumatically operated valve for admitting air to the tube toV propel a carrier, means for opening the valveactive Vupon closure of the cover and means. operat-` ing as a consequence of releasing thevcove'r for closing the valve comprising a mounting for said cover and a valve :tor controlling pneumatic means for seating said air admission valve. Y

4. Pneumatic despatch tube apparatus having; therein a despatch tube, a main valve for admitting air to the tube to propel a carrier, a piston having a port, a connec-v tion between said piston and said main valve, and means comprising a push rod.

carrying an auxiliary valve, said auxiliary valve opening to the atmospherea port of greaterarea than said piston port, for releasing the air pressure on one side of said piston to enable the compressed air on the other side thereof to operate said piston and thereby unseat said main valve. f

for admitting air toV the tubeto propel a carrier, piston .having port, a hollow stem-connecting said piston and saidmain valve, and means comprising alpush rod anauXiliary valve, said 'auxiliary ,valveV openingto the atmosphere a portV of greater area than saidrpiston port, 'forreleasin'g the air pressure'on one side ofsaid piston to enable the compressed air on the other side thereof to operate said piston and thereby unseat saidimain valve,v Y

6. Pneumaticdespatch `tube' apparatus having therein a despatch tube, a cover forthe terminal of the tube, :a pneumatically operated latch `for retaining theV cover inV closed position, and means .oradjusting the transmission of the pneumaticpressure:

from the despatch tube tothe latch operating device. y

-7. Pneumatic despatch tube apparatus having'therein a despatch tube, a coverk for the terminal. of the tube, a lpneumatically operated latch for retaining the cover iIl Vclosed position, and means for Yadjusting the-transmission of the air under pressure from the despatch tube to the latchoperating device, said means comprising a sleeve movable upon the vdespatchtube to vary the area available for the passage of air from the despatch tube to the pneumatically operated latch. f

8.,-Pneumatic despatch tube apparatus having therein a despatch tube, a cover for the terminal of said tube, a latch, Jfor Vretaining the cover in closed position, pneumatically operated control means for* saidlatch, said control means being operated by pneumatic pressure transmitted rfrom said despatch tube through an orice therein, and means adapted tovary the eective size of said orifice, said means comprising'a col` Y lar having an opening therein and movable upon the Vdespatch tube to-vary the registrationbetween theoriice in the despatch tube and the opening in the collar.

9. Pneumatic despatch 4tube apparatus having thereina despatch tube, ports in said tube for supplying compressed air thereto, a cover for the terminal 'of the tube, a latch for retaining the cover in closed position, pneumatically operated control means for said latch, a passage between the vdespatch tube and the latch control means, and means for simultaneously adjusting the ports for supply of compressed airto the despatch tube and the passage for transmitting the pneumatic pressure from the despatch tube to the latch operating deiao matically controlled latch for said cover, a plurality of orifices around the circumference of the despatch tube, certain of said orifices being afforded communication between the despatch tube and a source of supply of compressed air, other of said oriyfices affording communication between the despatch tube and the pneumatic control of the cover latch, and means for simultaneously varying the size of all of said orifices, said means comprising a sleeve rotatable about the despatch tube, and openings in the sleeve brought into varying registration with the orifices in the despatch tube rotation of the sleeve.

by the 11. A terminal for pneumatic despatch tube apparatus having therein a despatch tube, a valve controlling a source of pressure fluid for propelling a carrier in said tube, a cover for closing the terminal of the tube, means for controlling the flow of pressure fluid into the tube when the cover is closed, pressure sensitive means for opening the'cover adapted to be actuated by pressure in the tube and means for protecting the said pressure sensitive means from the pressure of blast currents in the tube.

Signed by me at Boston, Massachusetts, this 30th day of October, 1919.

ALEXANDER VATSON.

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