US3007445A - Compressed gas operated power tool - Google Patents

Description

Nov. '1, 1961 J. W. OLAN DT COMPRESSED GAS OPERATED POWER TOOL Filed March l1, 1960 cn m N... Lmn\ Fig.2

INVENTOR JOHN \N. OLANDT United States 3,007,445 CQMPRESSED GAS OPERATED POWER T091. John W. Olandt, North Arlington, NJ., assignor to Specialties Development Corporation, Belleville, NJ., a corporation of New Jersey Filed Mar. 11, 1960, Ser. No. 14,293 Claims. (Cl. 121-21) The present invention relates to compressed gas operated power tools, and, more particularly to a valve for admitting the gas to the expansion chamber of the tool provided with means for controlling the amount of gas admitted to the chamber.

Heretofore, portable power tools have been used for performing shearing or crimping operations which generally comprise a source of compressed air stored in a cylindrical cartridge, a valve secured to the cartridge, an expansion chamber such as a cylinder secured to the valve, a piston in the cylinder for `operating linkage which in turn operates a shearing or crimping tool, and a return spring for the piston.

A very distinct disadvantage of such tools was that the amount of compressed air at 2000 p.s.i.g. which could be stored in a cartridge having a size and weight capable of being comfortably handled by a workman did not provide for very many operations. This is because, at a given temperature, the pressure of the gas is almost directly proportional to the mass of the stored gas. Thus, when half of the initial mass of gas has been used the initial pressure is reduced in half. Consequently, the tool must be designed to operate at the highest (e.g. 2000 psig.) gas pressure as well as at a lower gas pressure (eg. 300 p.s.i.g.). The gas therefore is consumed in amounts greater than required to perform the tool operation in the beginning because the gas pressures in the cartridge and the expansion chamber are permitted to equalize, and the pressure in the cartridge soon drops to a value below 300 p.s.i.g. at which it is insuicient t0 properly operate the tool.

Accordingly, an object of the present invention is to provide a portable power tool which is not subject t0 the foregoing difculties and disadvantages.

Another object is to provide such a power tool which is operated by compressed gas in a manner toy conserve the supply of gas.

Another object is to provide such a power tool having a valve which prevents the pressure in the expansion chamber to become equal to the pressure in the cartridge when the pressure in the cartridge is higher than the pressure required to operate the tool.

Another object is to provide such a power tool which can perform an -exceedingly large number of operations while using a relatively small and lightweight carbon dioxide storage cartridge.

A further object is to accomplish the foregoing in a simple, practical and economical manner.

Other and further objects of the invention will be obvious upon an understanding of the illustrative embodiment about to be described, or will be indicated in the appended claims, and various advantages not referred to herein will occur to one skilled in the art upon employment of the invention in practice.

A preferred embodiment of the invention has been chosen for purposes of illustration and description, and is shown in the accompanying drawing, forming a part of the speciiication7 wherein:

FIG. l is a fragmentary longitudinal sectional view illustrating the valving in accordance with the present invention, and a portion of the expansion chamber and the cartridge.

FIG. 2 is an enlarged fragmentary sectional view illustrating restricted flow by-passing means.

3,007,445 Patented Nov. 7, 1961 Referring to the drawing in detail, a power tool is partially shown, which generally comprises a cartridge 10, for storing compressed gas or liqueed and/or gaseous carbon dioxide, a coupling or body 11 secured to the cartridge, an expansion chamber or cylinder 12 Secured to the coupling, and a piston 13 in the cylinder having a piston for operating the working head of the tool (not shown).

The cartridge 10 preferably is cylindrical in shape `and may have a length of about ten inches and a diameter of about two inches to facilitate handling the same. Such a cartridge weighs about 2.2 pounds when lled and can store a 0.5 pound charge of carbon dioxide which has a pressure of about 980 p.s.i.g. at 82 F.

The cartridge 10 has a threaded opening 14 into which a valve body 1S is secured to provide a cartridge assembly adapted for securement to the coupling 11. The valve body 15 is provided with a Valve chamber 16 having an inlet 17 in communication with the interior of the cartridge and having an outlet passageway 18 surrounded by a valve seat 19. A valve member 20 is slidably mounted in the valve chamber and is normally urged against the valve seat by a spring 21 and the pressure within the cartridge. The valve body further is provided With a stepped bore 22, 23 at the downstream end of the passageway 18 for receiving a valve operating assembly to be described hereinafter. The outer end 24 of the valve body 15 is externally threaded for removable securement to the coupling 11.

The coupling 11 is generally cylindrical in shape, and has a tubular extension 25 and an end wall 26 at `the left end (as viewed) which Serve `as a closure for the open end of the cylinder 12. At the other end, the coupling has a stepped bore 27, 28, 29, for respectively threadedly securing a valve operating assembly 30, threadedly securing the end portion 24 of the valve body 15, and shrouding the other portions of the valve body which are disposed outwardly of the cartridge.

The valve operating assembly 30 comprises a sleeve 31, a stem 32 for unseating the valve member.

The sleeve 31 has a portion threadedly secured into the bore portion 27, and carries gaskets 34 and 35 for respectively forming seals in the bore portions 23 and 27. The sleeve further has a stepped bore 36, 37, 38 for the purpose about to be described. The external sleeve portion in which the bore portion 37 is located is reduced in diameter to provide an annular passageway 39 Within the coupling, and radially extending apertures 40 pro vide communication between the bore portion 37 .and passageway 39.

The stem 32 has an enlarged portion 41 which is slidably disposed in the bore portion 36 of the sleeve, a left end portion 42 which extends outwardly of the bore portion 36 into a radially extending bore 44 formed in the coupling, and a right end portion 45 extending from the enlarged stem portion 41 through the bore portions 37 and 3S to the valve member 20, with suflicient clearance for gas to flow through these bore portions when the valve member is unseated. The left end portion 42 of the stem has a bore 46 extending just beyond the enlarged portion 41, and radially extending apertures 47 provide communication between the bore portions 36 and 37 and the bore 46.

The stem 32 is operated by a lever 4S pivotally mounted at 49 in the coupling bore 44. This lever comprises an exterior arm 50 for operating the same, andan arm 51 within the bore 44 having a pad 52 for sealing off the bore 46 of the stem when the stern is operated to unseat the valve member 20. A return spring 54 is provided for moving the arm 51 away from the stem so that the pad 52 unseals the bore 46 after the valve member 20 has reseated.

The apparatus as so far described is more or less conventional and operates as about to be described to deliver gas to a point where .it then flows to the means for controlling the amount of gas admitted into the expansion chamber.

Upon manually moving the arm 50 upwardly, the arm S1 moves towards the right as viewed, the pad 52 seals the bore 46, and the stem unseats the valve member 20, whereby gas is delivered to the passageway 39. When the arm 50 is released, the spring 54 moves the arm 51 to the left as viewed, the valve member 20 reseats and drives the stern 32 towards the left, the pad S2 unseals the bore, and gas within and downstream of the passageway 39 is vented to atmosphere by the apertures 47 and the bores 46 and 44.

In accordance with the present invention, the amount of gas delivered to the expansion chamber 12 is controlled by a delayed check or cut-off valve 55 located between the chamber 12 and the passageway 39. This is accomplished by providing an oi center longitudinally extending bore 56 in the coupling closed at one end and communicating with the chamber at the other end, and a radially extending passageway 57 adjacent, but spaced from, the closed end of the bore 56 for establishing ilow communication between the passageway 39 and the bore 56.

The valve 55 comprises a seat member 5S threadedly secured into the bore 56 at its open end which has a central bore 59 and a valve seat 60 facing the closed end of the bore, and a valve member 61 normally disposed to the right of the passageway S7 (as viewed) which has a stem 62 extending outwardly of the bore 59 to abut the wall 26 of the coupling 11 with clearance between the stem 62 and the bore 59 to permit gas to flow when the valve member 61 is unseated.

With this arrangement, when the valve member 20`is unseated, gas delivered to the passageway 39 is conducted into the bore 56 and to the chamber 12 through the bore 59 whereby the piston 13 is operated. As gas tlows through the bore S6, the valve member 61 is entrained and moved towards the left as viewed onto its seat `60 to shut off the further flow of gas into the chamber. The speed at which this valve cuts-off decreases as the pressure in the cartridge decreases whereby sulcient gas is delivered to operate the tool as higher .and lower gas pressures but in no case does the pressure in the expansion chamber become equal to the pressure in the cartridge while the pressure in the cartridge is higher than the pressure required to operate the tool.

When the operating lever 48 is released, gas in the bore 56 is vented by the passageway 57 to the passageway 39 and then to atmosphere as already described, whereupon the valve member 61 moves towards the right (as viewed) and gas in the expansion chamber 12 is likewise vented to atmosphere. The return spring (not shown) is then effective to return the piston 13 which engages the free end of the stem 62 and assures that the valve member is returned to its normal position as shown.

The amount of gas delivered to the chamber 12 de'- pends upon the distance the valve member 61 must travel before it engages its seat 60 and the speed of travel. It has been found that sucient carbon dioxide gas at about 980 p.s.i.g. and about 82 F. can be delivered to operate a piston having an area of 1.92 square inches and a stroke of 1.35 inches in an expansion chamber having a volume of 2.59 cubic inches by providing a passageway between the bore 59 and the stem 62 having an effective area of about 0.01 square inch and requiring the valve member 61 to move about one inch before engaging its seat. Carbon dioxide flows for a brief time, about 0.05 second, and about 0.005 pound of carbon dioxide at about 30 p.s.i.g. are delivered which expands to about 250 p.s.i.g` upon operation of the piston.

It has been found that for heavy duty tools a small amount of additional gas is beneficial in moving the tool head operating members to their final position. This can be accomplished by providing a loose t between the threads of the bore 56 and lthe threads of the seat member 58 (FIG. 2) whereby the pressure in the ,expansion chamber can be maintained close to 300 p.s.1.g.

In practice, it `has been found that a power operated crimping head could exert a force of about 4000 pounds at least times with about 0.5 pound of carbon dioxide by utilizing a chamber and cut-oit check valve dimension as previously explained.

While the apparatus in accordance with the present invention can be operated with compressed air, the use of carbon dioxide is preferred for the considerations about to be explained.

The critical temperature of carbon dioxide is 87.8 F., whereby, below this temperature, some liquid carbon dioxide will be in the cartridge having a constant vapor pressure for any given temperature. Thus, when a portion of the vapor phase carbon dioxide is delivered to the expansion chamber, the pressure in the cartridge drops slightly but is restored almost immediately by the vaporization of liquid carbon dioxide as this drop in pressure occurs so that carbon dioxide at the same pressure will be delivered during the next operation of the tool.

When ambient temperature is above the critical temperature of carbon dioxide, the cartridge contains only gaseous carbon dioxide and the apparatus functions as if compressed gas were used. However, the gasified liquid carbon dioxide, which at 70 F. had a vapor pressure of about 830 p.s.i.g., now has a pressure of about 1200 p.s.i.g. at F. whereas compressed air having a pressure of about 830 p.s.i.g. at 70 F. would have a pressure of only about 860 p.s.i.g. at 90 F. This high pressure gaseous carbon dioxide is admitted into the expansion at about 300i p.s.i.g. by means of the cut-olif valve which at higher gas pressures admits less gas.

Because of the foregoing behavior of the cut-ott valve, compressed air at 1000 p.s.i.g. in the cartridge can be :used more economically by being admitted into the expansion chamber at about 300 p.s.i.g. rather than at the full cartridge pressure and an increased number of operations can be performed before the cartridge pressure is reduced to about 300 p.s.i.g.

Compressed air having an initial pressure of 1000 p.s.i. at about 80 F. in a 21.7 cubic inch cartridge and admitted into a 2.6 cubic inch chamber can operate a power tool without a cut-off valve only about ten times before the pressure drops to 300 p.s.i.g., assuming that there is no leakage. Under similar conditions such a power tool equipped with a cut-oirr valve can be operated about nineteen times. With air at 2000 p.s.i.g., the tool can be operated only about sixteen without a cut-olf valve and about forty-seven times with a cut-off valve.

From ythe foregoing description, it will be seen that the present invention provides a simple, practical and economical carbon dioxide operated power tool which is not subjected to excessive forces and yet can exert the necessary forces :to do its intended work with a of carbon dioxide or compressed gas consumpftion.

As various changes may be made in the form, construction and arrangement of the parts herein, without departing from the spirit and scope of the invention and without sacrificing any of its advantages, it is to be understood that all matter herein is to be interpreted as illustrative and not in any limiting sense.

I claim:

l. In a compressed gas operated power tool including an expansion chamber, the combination of a valve having passageway means for conducting the gas from a source to the chamber, a valve member for controlling lvm.

u., the entry of gas into the passageway means, a cut-off valve in said passageway means for conltiiouing the amount lof gas delivered to the chamber, and restricted dio-w means bypassing said vcut-'off valve for delivering gas from said passageway means to the chamber.

2. In a compressed Igas operated power tool including an expansion chamber, Ithe combination of la valve having passageway means for conducting the gas from a source to the Kchamber including a cylinder portion adjacent the chamber; a member valve for controlling 'fthe entry of gas into the passageway means, and a cutoit valve in said passageway means for controlling che amount of gas delivered to the chamber including a valve seat in said cylinder portion formed an aperature alt the chamber, a valve stem slidably mounted in said aperture Aand having one end adapted to 'extend into the chamber, and la valve member mounted on the other end of said stem adapted to engage said seat when the desired amount of gas has been delivered to the chamber.

3. In Aa compressed gas operated power tool including Ian expansion chamber, the combination oi a valve having passageway means for conducting the gas from a source to the chamber including a bore portion adjacent the chamber; a valve member for controlling the entry of gas into the passageway means; and a cut-ofi valve in said passageway means for controlling the amount of gas delivered to the chamber including a valve seat in said core portion formed with an aperture at the chamber, a valve stern slidably mounted in said aperture and having one end adapted to extend into the chamber, and a valve member mounted on the other end of said stem adapted to engage said seat when the desired amount of gas has been delivered to the chamber, said valve seat being a member tted into said bore portion with which to provide restricted flow means lay-passing said cut-off valve for delivering gas at a low rate from said passageway means to the chamber when said valve member is on its seat.

4. A cut-ot valve for contro-lling the amount of gas delivered from a source to an expansion chamber where the gas is utilized to do Work, said valve comprising a body having a bore therein provided with a closed end and an open end at the chamber Iand having a side passage way entering said bore at a point spaced from its closed end, a valve seat member mounted in said bore at its open end having yan aperture 4therein and a seat facing said closed end of said boire, a valve stem slidably mounted in said aperture, and a valve member on the inner end of said valve stem for engaging said seat, said valve member being dimensioned to be positioned between said closed bore end and said side passageway to maintain the same open when so positioned and said stem being of a length to extend through said aperture `and outwardly thereofr1 when said valve member is in the aforementioned position, said valve member being adapted to be entrained by gas flow through said bore and be moved onto its seat to shut 01T gas iiow after the desired amount of gas has been delivered to the chamber.

5. A valve according to claim 4, wherein said valve seat member is fitted into said bore to provide restricted ilow means by-passing said cut-ott valve for delivering gas at a low rate when said valve member is on its seat.

References Cited in the file of this patent UNITED STATES PATENTS

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