US2644307A - Pneumatic hoist - Google Patents

Description

-wQfBLAlR PNEUMATIC Hors'r Filed Jan. 1o, 195o July 7, 1953 '55' nnentor Patented July 7, `1953 UNifrsv @STA/reis ,PATENT j s 2,644,307- v f f .fPNEUMA'rIc HoisT A`Walter Blair, netrimvnch. .Application January 10, llllhfiseriallNo..137,785

n V* 1 claim. (Circo-5.7)

Y *l Y This Ainvention relates tohoists, .andin .particular, .to pneumatic hoists VOne Vobjectof this invention lis-to provide a pneumatic hoist having .a normal sustaining pressure .on one side of `a .piston capable -of raising a given load, :and means for: applying :an overbalancng pressure .on .theother -side of .the piston for .forcing kthge load .,dovmward, thereby requiringthe :application v.of only r4a slightpressure to overbalance the r.load .in .order lto-lower.vit, ,an;l economizing .on the amount of compressed gas required .to be produced .during operation.

lAnother object .is to provide a, pneumatic-hoist ofthe foregoing .character -wherein the sustaining pressure issupplied from-one .compressedgair tank having a .pressure.maintained` at .a .predetermined amount .sufiicientltoisustain .the .piston and its load in V.their raised positions, -the .overbalancing pressurefor.theopposite side of the piston being provided. by Aa `coinpressedair source at a different pressure, such as .a .second tank maintained at a different predetermined .pressure either with or without aregulating valve.

,Another object is to provide `a pneumatic -hoist of the foregoing character wherein the ,load is sustained in its raisedlspositionby .air pressure from .different sources at different pressures beneath different pistons in different cylinders connected to a common cross head v.or other structure to which the load is connected, the

pressure and piston area in one cylinder being such that it is slightly less than .that vnecessary to sustain the,L load, with the result that when pressure is released from the other cylinder, the remaining pressure in the first-mentioned cylinder is insufcient to sustain the lload, which make-up pressure being ordinarilyV the slight amount necessary to add to the pressure Vin the other cylinder in order to sustain -the load.

Another object is torprovidea pneumatic hoist of the foregoing character which isl especially Well adapted to the raising and lowering-oflcowling pin pickups .or Setters for bowling pin-setting machines, and which employs tanks for-.com-

pressed air or other gas which are `adequate to serve a number of such machines.

In the drawing:

I Figure `l is -a diagrammatic .side elevation,

l` partly in .central vertical section, showing a .pneumatic hoist, .according vto `one .formnf the invention; and

Figure vv2.is .a side elevation, partly inV central ...vertical section, 4of a r.modified pneumatic hoist, vaccording to another formof the invention.

#Referring to thedrawing in detail, Figure 1 -to a load sustaining .pressure tank .2l to which compressed .air or othersuitable compressed gas is supplied-through pipes.2-2.and 23Jfrom apresv.sure-supplytankZIl .by wayof a conventional pressure-.regulating valve "25. .It willlbe obvious rthat to avoid the setting up of an appreciable .back pressureas the ,piston .I4 vis .forceddown- `having aninlet vpipe v29.

Walid, thevolume of the .tank .2| must v.belarge .in proportion to. the .volume of vthe cylinder I6.

The 'pressure supply `tank 24 is supplied with .compressed air .or other .compressed gas through asupply pipe 26containinga check valve`21 open- .ing toward .the tank`24 .and Vconnectedtothe outlet .port .of an air or .other .gas .compressor 28 The compressor 28 is -driven by .a shaft 3|]- connected l.to .the .armature .,shaftl of an .electric motor 32., 'this assembly ,being bolted or otherwise secured to a base33.

' 'make-up pressure 'from a `separate cylinder, this s The motor 32 is vsupplied with velectric: current .from-.wires 34 and ..35 by Way of a pressure-re- .sponsive switch, vgenerally designated 36.

The pressure-responsive .switch 36 is .conventional and v'its detai-lsare.beyondthescope of the. present invention. It is .suicient vfor purposes of :the `...present .invention -to state thatA theswitch v36 consists .of "a casing ,B'IYcOnneCted-by a lpipe 38 -to the Vpressuresupply tank 'Mand having a diaphragm v39 .connected to aspiring-pressed plunger, vthe lat-ter4 in -turn' being connected `to the switch .plungerd-I of the switch runit 42. When thefpres- Asure within the casing 31 rises v*beyond the point suflicient -toovercome Vthe counterbalancing .--fspring of the `.plunger 40,-the vlatter -rises.pushes unit 42, de-energizes the motor 32 and halts the compressor 28. No further pressure is delivered until the pressure falls within the tank 24 suiciently to permit the diaphragm 39 and plunger 4% to descend, closing the switch unit 42 and reenergizing the motor 32.

Compressed air or other gas from the pressure supply tank 24 passes through a pipe 43 and a conventional pressure-regulating valve 44 into a pipe 45, thence through an electro-magnetic valve 46 into the pipe I9 connected to the upper port I1 of the pneumatic cylinder I6. The pressureregulating valves 25 and 44 are similar to one another but are set to pass different pressures, as explained in connection with the operation of the invention. The electro-magnetic valve 46 has an air discharge or vent pipe 41 which is open to the atmosphere when the wires 48 and 49 are supplied with electric current to energize the solenoid 56 so as to shift the valve plunger (not shown) of the valve 46, and release air from the space above the piston head I3 through the pipe I9 and valve 46 into the discharge pipe 41, and thence to the atmosphere.

In the operationof the form of the invention shown in Figure 1, the pressure-regulatingvalve 25 is set at a pressure sufficient, when applied against the underside of the piston head i3, to

y raise the load I I andfsustain it in its raised position, for example at 75 pounds per square inch. The pressure-regulating valve 44, on the other hand, is set to pass gas at pressures below another predetermined pressure suicient to overbalance the pressure in the cylinder I6 beneath the piston head I3 and lower the load I I, for example, pounds per square inch. The pressure-responsive switch 36, on the other hand, is set at a sucient pressure to maintain an adequate pressure in theV pressure supply tank 24 lfor the foregoing purposes, for example, 90 pounds per square inch. Thus, the compressor 28 is `driven by the motor 32 to supply compressed air or other gas to the tank 24 so long as the pressure therein is insuflicient to raise the diaphragm 39 and plunger 46 vto open the switch unit 4I of the pressure-responsive switch 36 and halt the motor 32.

Thus, under normal Aconditions with the load lII raised, the pressure above the piston head I3 has been released by opening the valve 46 and discharging the compressed air therein through the vent pipe 41. When however, it is desired to lower the load II, the electro-magnetic Valve 46 is shifted so as to close off the vent pipe 41 and pass compressed air from the pipe 45 to the pipe I 9 and thence through the port I1 into the space above the piston head I3. This pressure, although at a much lower pressure in pounds per square inch than the pressure existing below the piston head I3Uis nevertheless suicient to overbalance the sustaining pressure and, aided by the weightror force of the load Il, to cause the load to descend In this manner, for example, the

` pins in the bowling pin setter may be lowered to the lalley and thereby set up on the alley.

Thus, even though only a slight overbalancing pressure isrequred to be exerted above the piston `head I3, only the air required for this overballbeneath the pistonhead I3 is forced out of the cylinder I6 through the port I8 and pipe 20 back 'f intothe load-sustaining pressure tank 2l when Y the-pistonfl4 and load II descend. The com- 4 pressed air in the load-sustaining pressure tank 2| is thus used over and over.

The modified pneumatic hoist, generally designated 60 shown in Figure 2 is for the same purpose as that shown in Figure 1, except that two single acting cylinders are employed rather than a single double-acting cylinder. The pressure supply tank 6I, like the pressure supply tank 24 of Figure 1, is similarly supplied with compressed air or other gas by a similar compressor 28 driven by a similar motor 32 and regulated by a similar pressure-responsive switch 36 in the manner described in connection with Figure l, similar parts bearing the same reference numeral. Pipes 62 and 63 containing a, pressure-regulating valve 64 supply compressed air to a primary pressure tank 65 from which compressed air or other gas is supplied through the pipe 66 to the port 61 at the lower end of a primary cylinder 68 containing a piston head 69 reciprocable therein and having a piston rod 10 connected at its upper end to a cross head 1I. This in turn is connected through a rod 12 to the load 13 to be raised and lowered. The pressure in the primary pressure tank 65 as supplied to the cylinder 68 is at a degree which is barely insuiiicient to sustain the load 13 and its connected parts. This deficiency in load-sustaining force is made up by the pressure in the secondary cylinder 14 containing a piston head 15 connected by a piston rod 16 to the cross head 1I. Pressure analogous to the overbalancing pressure supplied to the upper side of the piston head I3 in Figure 1 is supplied beneath the piston 15 of the secondary cylinder 14 through a similar arrangement bearing the same reference numerals, namely the pressure-regulating valve 44 and electromagnetic valve 46 located in the pipes 43, 45, I9 leading to the port I1 in the secondary cylinder 14 corresponding to the upper end of the cylinder I6 in Figure 1.

In the operation of the modied pneumatic hoist shown in Figure 2, the pressure-regulating valve 64 is set for a pressure which is not quite suflicient, when admitted beneath the piston head 69 in the primary cylinder y68, to sustain the weight of the load 13 and its connected parts. As a consequence, the load 13 descends to the desired location when no pressure is standing in the secondary cylinder 14,

To raise the load 13, the operator shifts the electromagnetic valve 46 to admit pressure through the port I1li'nto the secondary cylinder 14 beneath the secondary piston head 15. This pressure needs to be only the amount sufcient to make up the deficiency of pressure supplied to the primary cylinder 66 from the tank 65. As a consequence, the combined pressures in the primary and secondary cylinders 63 and 14 exerted against the piston vheads 63 and 15 are sufcient to overbalance the weightor force of the load 'i3 and its connected moving parts, so that these are raised to the desired height. `W hen the operator desires to lowerv the load, he operates the electro-magnetic valve 46 soras to vent the air from beneath the secondary piston head 15 to the atmosphere through the pipes I9 land 41. The pressure in the primary cylinder 68 is therefore no longer sufficient to sustain the load, and the latter therefore descends. The air within the primary cylinder 68, however', is forced downward through the port 61 and pipe 66 back into the primary tank `65 and is consequently not lost but can be used over and over again.

While the words pneumatic and air have been used throughout the present specification 5 and claim, it Will be obvious that any suitable compressed gas may be used in place of air, hence the specication and claim are to be construed as covering any suitable compressed gas.

What I claim is:

A pneumatic hoist for selectively raising and lowering a predeterminedl load, said hoist comprising a cylinder structure having load-raising and load-lowering spaces therein, a piston structure having load-raising and load-lowering piston areas reciprocable in said load-raising and load-lowering cylinder spaces respectively, a piston rod structure connecting said piston areas to said load, a compressed gas supply tank, a first conduit connecting said supply tank to said loadlowering cylinder space, a'compressed gas loadsustaining tank, a second conduit connecting said load-sustaining tank to said load-raising cylinder space, means pneumatically connected to said supply tank for maintaining the gas therein compressed to a predetermined high pressure, a third conduit interconnecting said tanks, a rst pressure reducing valve in said third conduit operative to conduct gas therethrough at a predetermined medium pressure from said supply tank to said load-sustaining tank, a second pressurereducing valve inr said rst conduit operative to conduct gas at a predetermined low pressure from said supply tank to said load-lowering cylinder space, and a control valve disposed in said rst conduit between said second reducing valve and said load-lowering cylinder space, said control valve being operable selectively to conduct gas through said first conduit and to discharge gas from said load-lowering cylinder space.

WALTER BLAIR.

References Cited in the file of this patent UNITED STATES PATENTS n Date Great Britain May 16, 1938

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