US 3444692 A
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v May 20, 1969 M. c. HUFFMAN 3,444,692
EXE'IAUST PIPE ASSEMBLY FOR PNEUMATIC TOOLS Filed Aug. 31. 1967 INVENTOR. I l E. 3 MERV/N C HUFFMAN ATTORNEY United States Patent 3,444,692 EXHAUST PIPE ASSEMBLY FOR PNEUMATIC TOOLS Mervin C. Hufiman, Denver, Colo., assignor to Gardner- Denver Company, a corporation of Delaware Filed Aug. 31, 1967, Ser. No. 664,864 Int. Cl. F01b 31/02, 31/16 US. C]. 6064 2 Claims ABSTRACT OF THE DISCLOSURE An exhaust pipe assembly for pneumatic tools, particularly applicable to percsussion type tools, consisting of a swivelly mounted curved tubular conduit in combination with a flexible inner sleeve fixed at one end relative to the outer surrounding conduit. The inner sleeve is of a flexible material such as neoprene and is subject to flexing and vibrating movement in response to the kinetic energy transmitted to it from the exhaust fluid pulsations emitting from the tool working chamber. The flexing inner sleeve serves to break up and prevent the lodging of ice in the tool exhaust system and also serves as a simple yet effective mufller of the exhaust noise generated by the tool working fluid.
Background of the invention The application of pneumatic rock drills and similar pneumatic expansion devices in underground operations such as tunneling and mining work usually produces a considerable amount of fog in the vicinity of the work area due to rapid expansion and cooling of the compressed air used to power the tools. The climatic conditions usually present in mines and tunnels are quite conducive to this fog formation and in addition the exhausting of the compressed air from the tools produces a noise level in the area often uncomfortable if not intolerable to personnel. As a result it is common practice to conduct the exhaust from pneumatic rock drills and associated equipment to locations remote from the immediate Work area by means of flexible hoses or the like attached directly to the exhaust ports of the tools. In this way fog, objectional fumes, and high noise levels near the tools are avoided. However, a condition which is often unavoidable near the exhaust ports of rock drills and the like, particularly when the exhaust is conducted through a closed conduit, is the formation and accumulation of ice immediately downstream of the exhaust port and in the exhaust pipe or hose, again, due to a well understood cooling phenomena which also produces the aforementioned fog. This ice accumulation is often substantial to the extent that the tool becomes inoperative after a short period of time due to blockage of the exhaust system. This ice accumulation usually occurs where directional change of some magnitude is given to the exhaust flow so that the small ice particles present in the fluid stream impinge and accumulate over a relatively small area.
The invention disclosed herein is somewhat analogous in purpose to the known prior art in the patents to Fuehrer 2,128,742, Morrison 2,166,218, and Jordan 3,164,962 each of which has a vibrating element fixed to a casing surrounding the tool proper and constituting an integral part of the tool body. It is, however, apparent that the prior art fails to disclose an external tool attachiment that may be positioned within the exhaust flow path 3,444,692 Patented May 20, 1969 'ice of a conventional tool and provided with vibrating means agitated by tool exhaust for the purpose of preventing accumulation of ice crystals in the exhaust flow path.
Summary of the invention.
The invention disclosed brings solutions to the problems of prohibiting ice formation and accumulation as .well as contributing to the attenuation of noise in the exhaust system of pneumatic power tools by providing an exhaust control means having a flexible sleeve of a suitable material held in spaced relation to an outer conduit and fixed atone end relative thereto. The conduit means is curved to assure impinging flow of the exhaust fluid on the flexible sleeve which results in the flexing and vibrating of the sleeve to prevent the accumulation of ice and to absorb a substantial amount of the pressure wave energy usually manifested as audible sound.
An object of the invention is the provision of a smooth surfaced, surroundingly disposed, flexible conducting means for the exhaust flow, wherein possible locations for the lodging of ice particles are eliminated by a simple yet effective structure of great reliability.
It is also an object of the invention to provide an exhaust control apparatus that can have secured to its free end a flexible hose of any desired length through which the final exhaust composed of broken ice particles or water and objectionable fumes may be conducted to a point remote from the operator. To facilitate handling of the tool with the exhaust hose attached, the manifold is swivelly mounted on the tool for ease in handling and positioning.
Brief description of the drawing FIG. 1 is a front elevation, partly in section, of a conventional percussion tool having associated therewith the elements of the invention.
FIG. 2 is an enlarged sectional view showing a part of the tool cylinder and its exhaust passage having attached thereto the exhaust pipe assembly and the elements swivelly connecting the two.
FIG. 3 is an end view of the pipe assembly taken along the line 33 of FIG. 2 illustrating the locking means for preventing movement of the locking nut on the pipe assem bly when the latter is swung relative to the tool casing.
Description of the preferred embodiments Referring to the accompanying drawing in detail, particularly FIG. 1, a conventional pneumatic percussion tool, generally designated by the numeral 10, has an expansible chamber defined by a reciprocating piston 12 and a cylinder 14. An exhaust port 16 communicates the cylinder 14 with the partially threaded bore 18 of a boss 20 disposed on the side of the tool casing 22. Positioned within the bore 18 is one end of an exhaust pipe assembly 24 having therein an element vibrated by the exhaust fluid pulsations passing therethrough. The pipe assembly 24 comprises a bent or curved tubular member 25 having connected to its free end, by any suitable means, a flexible hose 26 through which the exhaust flow may be conducted to a suitable point usually remote from the tool and the operating personnel.
FIG. 2 illustrates in detail the elements comprising the exhaust pipe assembly 24 including those elements used for swivelly connecting the pipe assembly to the boss 20 on the tool casing 22. In the pipe assembly illustrated, the outer tubular member 25 is preferably constructed of a piece of steel tubing machined to provide the grooves, relieved section, and flanges to be explained later in detail. A preferred method of obtaining the desired bent shape of the tubular member 25 is to cut one or more V-shaped notches all in the same longitudinal plane after the machining process. The tubular member 25 is then heated and bent until the edges of the V-shaped notches abut each other wherein they are joined by welding or an equivalent process.
Near the upper end of the tubular member 25 is an internal annular groove 28 which interfittingly receives an external flange 32 formed as an integral part of a flexible curved inner sleeve 34. Adjacent to the flange 32 the flexible sleeve 34 fits snugly in the bore 36 of the tubular member 25. The remaining major portion 35 of the flexible sleeve 34 is thereby held in fixed spaced relation to the internally relieved major portion 30 of the tubular member 25. To assist in maintaining the flexible sleeve 34 in fixed relation with the tubular member 25 a short metal tube 38 is pressed into a reduced bore portion 40 at the extreme upper end of the tubular member 25, as viewed in FIG. 2; and, the tube 38 compressively engages the inner wall 42 of the flexible sleeve 34. The upper end of the metal tube 38 is flared to fit tightly within the beveled end 44 of the tubular member 25. Albeit many materials are well known that would be suitable for the construction of the flexible sleeve 34, a particularly suitable sleeve is obtained when molded of one of the chloroprene elastomers, such as neoprene, which has resiliency, can be molded with a high degree of surface smoothness, and is relatively impervious to chemical substances.
For swivelly mounting the exhaust pipe assembly 24 on the pneumatic tool 10 the tubular member 25 is journaled in an externally threaded collar 46.
The threaded collar 46 is secured to the boss 20 by being screwed into the partially threaded bore 18 until a flange 74 on the collar 46 is tight against the face 70 of the boss 20. A gasket 72 is interposed between the flange 74 and the face 70 to prevent leakage of exhaust fluid therearound. A seal is also affected around the bore of the collar 46 by an O-ring 50 in a groove 52 sealingly engaging the outer diameter of tubular member 25. Limited axial movement of the tubular member 25 in its journaled relationship with the collar 46 is maintained by a locking nut 54 threaded over a reduced diameter portion 56 at the upper end of the tubular member 25, and by an external annular flange 48 projecting from the outer diameter of the tubular member 25 below the flange 74 on the collar 46. With the locking nut 54 screwed tightly against the shoulder 58 on the tubular member 25 suflicient axial play of the tubular member 25 relative to the collar 46 is maintained to allow the tubular member 25 to swivel freely.
The locking nut 54 is secured to the tubular member 25, for the prevention of unscrewing of the nut from the tubular member 25, by a retaining ring 60 shaped to be biased to seat in a groove on the locking nut 54. Referring to FIG. 3, the retaining ring 60 has one end bent to form a tab 62 which projects through a slot 64 in the locking nut 54 and into a slot 66 in the reduced diameter portion 56 of the tubular member 25. Should the slot 64 in the locking nut 54 not be in radial registration with the slot 66 in the reduced diameter portion 56 when the locking nut 54 is threaded down tight against the shoulder 58, the nut may be unscrewed until said radial registration occurs with the resulting increased axial play allowed the tubular member 25 relative to the collar 46 not being detrimental to the performance of the swivel assembly since the amount of axial play will not exceed one pitch of the threads 68.
In operation it will be apparent that the flexible sleeve 34 is so disposed relative to the exhaust port 16, and is curved to such proportions as to be impinged by and to deflect the exhaust fluid stream substantially. This impinging action of the exhaust stream with its attendant pressure waves caused by incomplete expansion of the working fluid in the tool proper imparts sufiicient energy to the flexible sleeve 34 to cause it to flex and vibrate sufliciently that those ice particles present in the exhaust flow are prevented from accumulating in the exhaust pipe and thereby preventing unwanted restriction in the exhaust system of the tool. The smooth curved shape of the flexible sleeve 34 and the absence of any sharp corners or shapes that could permit the lodging of solid particles also contribute to the prevention of ice particle accumulation. Although a curved or bent configuration assures impinging flow of the exhaust stream and more eflicient operation of the exhaust pipe assembly, a straight sleeve would absorb exhaust flow pulsations to an extent that substantial flexing of the sleeve would still occur. In the illustrated embodiment it will be noted that the curved portion of the pipe assembly is not a circular arc. Experimentation has determined that a basically elliptical shaped curvature is more effective in preventing ice accumulation and it is believed that this curvature allows more direct impingement by a greater portion of the exhaust flow and thereby transfers more energy of impact to the flexible sleeve. Singularly significant is the use of the chloroprene elastomer material for the flexible sleeve 34 which has such smooth surface character that it also aids in the prevention of ice accumulation.
Of no less importance is the fact that the unsteady and variable amplitude vibration of the flexible sleeve 34 also serves to impart a degree of cancellation of the pressure waves present in the exhaust flow which manifest themselves in the form of audible sound. In addition sound attenuation capability of the manifold assembly is enhanced by the layer of air insulation formed between the major portion 35 of the fiexible sleeve 34 and the relieved portion 30 of the tubular member 25.
As previously mentioned, a section of flexible hose 26 (FIG. 1) may be attached to the downstream end of the tubular member 25 by being snugly positioned over the raised portions 76 and 78 and held suitably secure by the same in a manner well known. The exhaust flow can then be conducted any desired distance from the operator and given directional attitude suflicient to obviate any further need for treatment to reduce noise.
Having shown that the invention has particular novelty and utility, it will be appreciated that application to the tool 10 would not be a limitation in its use but that a number of expansible chamber devices utilizing compressed air and subject to the problems herein solved could enjoy the benefits of the invention.
What is claimed is:
1. (a) An expansible chamber tool operable by compressed air and having an exhaust port for conducting expanded exhaust air from said chamber, said expanded exhaust air containing ice particles formed therein as an incident to expansion;
(b) an exhaust pipe assembly having one end connectable with said exhaust port for receiving said exhaust air and ice particles therefrom; said exhaust pipe assembly comprising; i
(1) tubular conduit means in communication with said exhaust port;
(2) flexible tubular sleeve means having a major portion disposed within said conduit means for flexing in response to exhaust fluid flow therethrough whereby such flexing prevents the accumulation of said ice particles in said exhaust pipe assembly, said flexible sleeve is secured adjacent said end of said exhaust pipe assembly which is connectable with said exhaust port, and the remainder of said sleeve being generally of like configuration with respect to said conduit is disposed in spaced relation therein, and
(3) said exhaust pipe assembly is curved sufficiently for expanded exhaust air flowing therethrough to impinge on said sleeve to flex the same.
2. The invention set forth in claim 1 wherein: 5 said flexible sleeve comprises a smooth surfaced hollow body molded of a chloroprene elastomer.
References Cited UNITED STATES PATENTS MARTIN P.
FOREIGN PATENTS Great Britain.
SCHWADRON, Primary Examiner.
I. C. COHEN, Assistant Examiner.
U.S. Cl. X.R.