AIR COMPRESSOR WITH OPPOSED COMPRESSION CHAMBERS

Abstract: An air compessor includes: an engine provided with a shaft (71); a case (1) for the said engine; a basement (15) provided with two opposite cylinders (37a, 37b), to which two heads (38a, 38b) are made integral; a piston (7) moving inside said cylinders under the effect of a connecting rod (6) and a crank (7), driven by the said shaft (71); a suction chamber(47a, 47b), for intaking air into each head (38a, 38b); a path for intaken air, connecting each chamber (47a, 47b), to a cavity (16), where an air filter (22) is accomodated, and opening into atmosphere through silencers; an element (21) connecting the said basement (15) to the said cavity (16); a compression chamber (47a, 47b) for air, located inside each head (38a, 38b); a path for air compressed by the said compession chambers (47a, 47b) to one user; a fan (80) for delivering cooling air to the compressor through two pipes (81a, 81b); supporting elements (88a, 88b) for the said compressor and the said engine.

Description: AIR COMPRESSOR WITH OPPOSITE COMPRESSION CHAMBERS The present invention refers to an air compressor with oppo= site compression chambers, having two pistons machined from one single structure, that is made reciprocate by a connect= ing rod, which is in turn connected with a crank assembled excentrically on the rotating shaft of engine. Compressors of the above type are already known from prior art, wherein air is sucked through a set of filters and si= lencer meanders,where its is compressed and then delivered toward user or storage tanks, in view of a successive use. Disadvantages occurring on compressors of known type are essentially as follows to attain a suction system,provided with an air filter, for cleaning air and then feeding it into the compression chambers, meanwhile eliminating the noise due to the same suction; to afford a structure comprising the compressor,with a base= ment, two heads containing the compression chambers,said structure being easy of assembly, cost saving and reliable to attain a structure for the equipment making up the com= pressor with an engine, which makes the pistons reciprocate, the said structure being cost saving, reliable and easy of assembly to the said monobloc and to the said heads; to obtain a structure, wherein air flow delivered by the compression chambers is conveyed into an unique delivering pipe, connected to an user or to a tank for compressed air; to provide an equipment with a system suited to cool heads and basement, effective, space saving and easy of operation at the same time; to provide an equipment with a structure equipped with rests for the same equipment, easy adaptable to its outer case. At present no equipment is provided, which might solve the above tasks alone. Object of the present invention is to overcome the inconve= niences of prior art. The present invention, as it is characterized by the attach= ed claims, solves the problem of affording a compressor of the above described type, through which all functions invol= 'ved in the above mentioned tasks are carried out. The advantages achieved by means of an equipment according to the present invention are essentially the following: a better total efficiency due to the reduced passive volumes in comparison with prior art and owing- to the fact that air included into the volume kept within the piston sliding for intaking further air and the delivery valve, is instrumental in shifting the same piston: an even lubrication, owing to the fact that the same lubrication is accomplished by means of oil steams, developping from heating of oil contained in= side the basement, thus preventing the movable parts from striking with liquid oil,said strike causing a slowdown of motion between the various parts; the said oil steams,more= over, when flowing out of monobloc as a result of the ther= mal expansion, impregnate the air filter, thus increasing the filtering effect thereof; or by making use of a lubri= cating method known from prior art, that, although it ex= ploits oil steams as described above, provides the movable parts of compressor with liquid oil,by means of a structure capable of minimizing the striking effect; an appropriate ventilating system, suited to keep the equipment at the best operating temperature; said ventilation is obtained by mak= ing air flow through two tubular structures, purposely and simply fitted to the same equipment, starting from a cham= ber, where a fan is assembled for delivering the said cool= ing air. Furthermore the equipment is distinguished among others known from prior art by the fact that it carries out its function better and has a longer working life. Now two preferred but not restrictive embodiments of the present invention are described by referring to the attach= ed diagrams, where: Fig.1 shows the equipment according to the present invention in "exploded" view; Fig.2 shows the ventilating system of an equipment according to the present invention Fig.3 shows a rest for an equipment of the above described type; Fig.4 shows a constructive detail of an equipment of the concerned type, according to a second embodiment, cutaway according to a vertical plane; Fig.5 shows the same detail, as shown in Fig.4, cutaway ac= cording to an horizontal plane. The equipment shown in Fig.1 is made-up of the assembly of the following structures: a case 1, made of non magnetical material, preferably of structural aluminium accomodates an electrical motor com= prising a stator 2 and a rotor 3 with a shaft 71, which enters a flange 4, in which the case 2 facing the compres= sor ends; a crank 5, made integral to the shaft 71 excentri= cally to the axis thereof, in order to drive a connecting rod 6, located between the said crank 5 and a piston 7,hav= ing two end parts, respectively 8a and 8b, so shaped that each accomodates three seal rings; the seal rings relevant to the end part 8a are marked 9a, 10a, 11 a; the seal rings relevant to the end part 8b are not represented, but they are identical to those just described. Furthermore,the pi= ston 7 is provided with a seat 12, where the said connect= ing rod 6 can move and a bore 13 is machined, suited to en= gage a pin 14 for the said connecting rod 6. A basement 15 includes a cavity 16, delimited by four fixed walls 17, 18a, 18b and 19, placed, respectively, at top, by the two sides and at bottom of the said cavity 16; the said basement 15 being suited to accept a given quantity of lu= bricating oil, that, when the machine is at standstill,reach es the level t'L" as shown in Fig.4 and 5. The wall 7 is provided with a threaded bore 20, where a tube 21 is screwed-in,which, through a radial bore 21, brings the the said cavity 16 in communication with the inner side 22a of an air filter 22, this latter being located inside a box 23, supported by the wall 17; the said bore 21b is suited to allow the steams developping from oil contained inside the basement 16 to expand toward the inside 22a of filter 22, as to increase the filtering effect thereof and to lubricate the movable parts contained inside the equipment. The said box 23 is closed at top by a first plate 24 and by a second plate 25; a gasket 26 is interposed between the ed= ges of the side walls of box 23 and the plate 24, to ensure tightness. The box 23 has a round relief 27, excentrical in comparison with the bore 20, suited to determine the posi= tion of filter 22 inside the box 23, so that the outer dia= meter of the said relief 27 is equal to the diameter of part part 22a of filter 22. The first plate 24 has a central opening 30, where a ring -shaped element 31 is found, supported by three ribs 32a, 32b and 32C, integral to the plate 24 and suited to keep the said element 31 horizontal. A nut 33 is screwed-in on the threaded section 21a of tube 21; in order to fix the filter 22 with respect to the ele= ment 31. Moreover, the first plate 24 has three concentric orders of ribs 28 degrading from outside toward inside and grooves 29, as well; the ribs of the first order face the grooves of the second order; the grooves of the first order face the ribs of the second order; the ribs of the second order face the grooves of the third order; the grooves of the second order face the ribs of the third order The second plate 25 has three concentric orders of ribs 3P, degrading from outside toward inside and grooves 35, arran= ged in the same way as the corresponding elements of plate 24; moreover, the said plate 25 is provided with spacers 36, arranged in such a way that air can flow between the said ribs and the said grooves of plates 24 and 25, radially to the said plates 24 and 25, that results in a reduction of noise generated by air sucked by the compressor; such air -streams being conveyed toward the inner side of filter 22. The two walls 18a and 18b separate, respectively, the said cavity 16 from two cylinders 37a and 37b, externally finned, as to get cooled during their operation, and internally open toward the cavity 16, in order to accomodate the end parts 8a and 8b, respectively, of piston 7. The two cylinders 37a and 37b support, respectively, two heads 38a and 38b, identical and finned, too, for cooling during the equipment operation, made integral to the rele= vant cylinders through connecting screws; between each head 38 (a,b) and the relevant cylinder 37 (a,b) being interposed a valve plate 39 (a,b) and gaskets 40 (a,b) and 41 (a,b), ar ranged respectively between the said plate 39 (a,b) and the said cylinder 37 (a,b) and between the same plate and the head 38 (a,b). The plate 39 (a,b) is concerned by the copend ing Patent Application Nr. 3472 A/82, to the text thereof we are referring in view of a better understanding of'structure and operation of the said plate. From box 23, outside the filter 22, two identical paths for sucked air start, respectively, from cylinder 37a and 37b. Each path starts from an inlet orifice 42 (a,b) connecting the said box 23 to a pipe 43 (a,b), machined from the cy= linder 37 (a,b) and series-connected to: a first bore 44 (a,b),machined in the first gasket 40 (a,b); a second bore 45 (a,b) machined in the plate 39 (a,b); a third bore 46 (a,b) machined in the second gasket 41 (a,b). Each of the said pathes comprises a cavity 47 (a,b) machined in the head 38 (a,b); a wall 48 (a,b), that will bedescri= bed in details later, delimites the inner side of cavity 47 (a,b) with respects to the head 38 (a,b), thus enabling three slots 4-9(a,b), 50(a,b) and 51(a,b) to get in communi= cation with the said wall; the said slots being adjusted by a suction valve 52 (a,b) suited to open toward the inside of the cylinder under the effect of vacuum generated by the piston 7, moving from the top dead center toward the bottom dead center, thus intaking air to compress. Each path ends into the corresponding cylinder. A second path for compressed air starts from each cylinder. This second path starts from three slots 53 (a,b), 54(a,b) and 55(a,b) machined from plate 39(a,b) and adjusted by a delivery valve 56 (a,b) opening toward outside under the effect of pressure generated by the piston 7, moving from the bottom dead center to the top dead center, as to com= press air. The three slots face a cavity 57(a,) existing inside the head 38(a,b),separated by the said cavity 47(a, b) from wall 48(a,b), central to the said head 38(a,b). The said cavity 57 (a,b) communicates directly with a second cavity 58(a,b) machined from the same head 38 (a,b), where a pipe opens, that consists of two bores 59(a,b) and 60 (a, b) having the same diameter, and series connected one after another, which are machined, respectively, from gasket 41(a, b) and from plate 39 (a,b). The bore 60(a,b) engages a tubular element 62(a,b), suited to convey the compressed air toward a delivery manifold 63, entered by the two pathes for compressed air, coming ,respec tively, from cylinders 37a and 37b. The said tubular element 62(a,b) has an external profile 61(a,b), suited to enter a seat 70(a,b) foreseen inside the manifold 63,in order to fix both elements one to the other. The manifold 63 is integral to a structure 64, that is fitted onto the basement 15 and makes up the front wall thereof. Seal rings 66(a,b) and 67(a,b) are provided to the end part of the said tubular elements 62(a,b), which enter the bores 69(a,b) machined from manifold 63. This latter has a thread= ed bore 68, where a tubular element,not shown, will be enga= ged, in order to deliver the compressed air to an user or to a tank. The volume comprised between the end part 8(a,b) of piston 7 and the suction valve 52(a,b) and the delivery valve 57(a,b) is very small, so the volumetric efficiency of the equipment turns out to be higher than the one of known equipments;fur= thermore, the compressed air included in said volume is in= strumental, during the suction stroke relevant to each cylin der, in shifting the piston 7, thsu furtherly increasing the compressor efficiency according to the present invention. The case 1 is shut at top by a plate 63, provided with through hole for assembling the tie rods of the equipment; the said plate 63 has a central hole 63a for supporting the shaft 71 of engine 3; a pulley 72 is splined on the said shaft 71 (Fig.2), that drives through a first belt 73 a pul= ley 74, splined in turn on a shaft 75 supported by the said plate 65; a third pulley 76 is splined on the said shaft 75, that is coupled, through a second belt 77, to a fourth pul= ley 78, that is assembled on a shaft 79, coaxial to the shaft 71; on the said shaft 79, a fan 80 is splined,that is made rotate at twice the rotating speed of shaft 71,as a re= sult of ratios between diameters-of said four pulleys, in or der to optimize the cooling effect of air on compressor.The case 1 has longitudinal outer ribs, that improve the heat ex change toward outside during engine's operation; four of the se ribs are suited to be engaged with clamping elements of two structures 81(a,b), in order to make them integral to the case 1, and to provide two collecting pipes for cooling air, that is delivered by the fan 80 to the compressor The bottom of case 1 supports a structure 83 for protection of belts, pulleys and fan; the said structure 83 is provi= ded with a grating 82, in order to let air flow into the space comprised within the same structure 83,and then to be conveyed toward the compressor through the two pipes placed inside the two structures 81 (a,b). The structure 83 is provided with a terminal strip 84,whe= re the power supply cables of engine contained inside the case 1 end. In order to sustain the compressor on the work= ing plane, two identical structures are foreseen, one of which is shown in Fig.3; the said structure comprises: two feet 85a and 85b, connected by two tie rods 86 and 87; two elements 88a and 88b suited to enter a space included be= tween the two fin rows of the said case 1. The two structu= res shown in Fig.3, purposely arranged, support the compres= sor and can be disassembled for an easier handling. By referring to Fig.4 and 5, the concerned equipment con= sists of the said basement 15, including the said cavity 16 delimited by the fixed walls 17, 18a, 18b and 19, that are arranged as previously explained with reference to Fig.1;the said basement 15, suited to contain a given oil quantity, in order to lubricate the movable parts of the equipment, said oil quantity being kept at a relatively steady level L. The said flange 4, diagramatically shown in Fig.4, has a first support 90 for the said shaft 71; a crank 91 is made inte= gral to the said shaft 71, as to rotate around the axis A of the same shaft. The said crank is made integral also to the following parts: a thin tapered needle 92, suited to en ter the oil bulk contained inside the basement 15 and to ge nerate, by quickly turning together with the said crank 91, an atmosphere of liquid-state oil dispersed in particles, that joins the atmosphere of oil steam existing inside the said basement 15 as a result of thermal effect; this allows the movable parts of the equipment to be provided with the lubricating oil quantity necessary for the correct operation of the same equipment; a pint 39, suited to transmit the mo= tion of shaft 71 to two opposite pistons 94a and 94b, which enter, respectively, the said two cylinders 37a and 37b, dia gramatically shown in Fig.4 and 5. The two pistons 94a and 94b are made mutually integral by means of a sliding structure 95 comprising, essentially, a central bushing 96, suited to support integrally two arms 97a and 97b, which bears respectively the two pistons 94a and 94b, fixed to the corresponding arms by means of fasten= ing screws. In Fig.4 the piston 94a, shown in partial cut= away view, is fixed to the supporting arm 97a by means of a screw 98a, the thread thereof is engaged in a threaded hole 99a, machined from the said piston 94a, coaxial to the said arm 97a,; in similar way the piston 94b is fixed to the corresponding supporting arm 97b; that enables both pistons 94a and 94b to be kept exactly coaxial. A seal ring 100a is foreseen on the said ar.l, 97 & ( nd,oL- viously, on arm 97b) in order to prevent air leakages from heads 38(a,b) toward the basement 15 during the compression phases of pistons 94(a,b). Both pistons are provided with compression rings; Fig.4 shows the rings 101 a, 102a and 103a only, relevant to the pi ston 94a, but it is understood, that as many compression rings, not shown, are provided to the piston 94b. The last compression ring 103a is a scraper ring for scraping walls of cylinder 37a; it is understood, that an identical scraper ring, not shown, is provided to the piston 94b, for scraping walls of cylinder 37b. The bushing 96 has an inner bore 104, suited to accomodate a piston pin 105, coaxial to the said bore 104 and to allow it sliding up and downwards along the said bore 104. The said piston pin 105 has two countersinks 106 and 107, respectively below and above, and a horizontal bore 108, suited to accomodate a brass 109 of known type, in order to support the said pin 93. A bore 110 connects the said upper countersink 107 to a cir= cular groove 111 ,machined from the said brass 109, as to let oil flow from the said countersink 107 and the said round groove 111, in order to lubricate the coupling of brass 109 with pin 93. As to compressor's operation, we are referring only to the constructive embodiment shown in Fig.4 and 5, since we have already explained the functions of structures represented in Fig.1,2 and 3. Therefore, in view of a better understanding of the embodiment represented in Fig.4 and 5, we have to di= stinguish the cinematic effect,due to the transmission of movement from shaft 71 to pistons 94(a,b) from the other effect, consequent to said former cinematic effect, that al= lows the movable parts of equipment to be lubricated. The cinematic effect is due to the rotation of shaft 71 of engine 3, shown in Fig.1, which, as to the embodiment re= presented in Fig.4 and 5, makes the crank 91 rotate around its own axis A. The pin 93 describes a circular trajectory at steady speed rate with center placed on one point of axis A, and takes along the pin 105 in the same trajectory. With reference to the bushing 96, the pin 105 can only move up or downwards, thus at every point of the trajectory de= scribed by the pin 93, the vertical component of the same pin velocity 93 makes the pin 105 move up or downwards, ac= cording to the direction of the two arrows B1 and B2 shown in Fig.4. The horizontal component of velocity of pin 93 shifts the bushing 96 to the right or to the left, according to the arrows C1 and C2, respectively concordant with the arrows B1 and B2. The rotating motion of the shaft 71, indicated by the arrows Al and A2,is changed into the rectilinear recX procating motion, to the left or to the right bf pistons 94 (a,b) integral to the said bushing 96. Lubrication is accomplished, besides the oil steams develop= ping from oil bulk contained inside the said basement 15 for the thermal effect, also by the needle 92 beating against the same oil. The needle 92 brings oil particles in suspen= sion at top of basement 15; these oil particles, along with the oil steams, contribute in lubricating the movable parts of the equipment; the braking effect of the needle 92 beat= ing against the oil bulk is minimized by the shape of the sa me needle, Oil drops fallen, because of gravity, into the bushing 96 lu bricate the bore 103, along which the pin 105 slides; when entering the countersink 107, the said drops are made avail= able for the brass 109, through the bore 108. Oil drops fallen onto the inner surface of cylinders 37(a,b) lubricate them,as to facilitate the relevant motion of pi= stons 94a and 94b, respectively; oil is then conveyed again into the basement 15by the oil scrapers (103a) fitted onto the same pistons. The advantages afforded by the embodiment shown in Fig.4 and Fig.5 in comparison with those offered by the embodiment represented in Fig.1 are the following: although the advanta ges due to the oil steams in benefit of the filtering effect of filter 22 are kept, a more appropriate lubrication can be obtained in case of heavy-duty equipments; the deleterious effects due to out-of-centers or to angular errors of pin 93 with respects to the brass 109 can be removed,even if both pistons 94(a,b) have to be kept perfectly coaxial. Further= more, the deleterious effects due to angular errors of pi= stons 94(a,b) with reference to the axis A can be removed. The above described versions are only two possible embodi= ments of the present invention, constructive modifications thereof can be accomplished without affecting its substan= tiality. Forms, dimensions and materials do not restrict the applica tion range of the present invention, any element thereof can be replaced with another equivalent from a technical point of view.

Claims: CLAIMS 1. Air compressor with opposite compression chambers, com= prising at least an engine provided with a shaft and two compression chambers, from which compressed air is delivered to a manifold and then to an user or to a tank, c h a r a c t e r i z e d by the fact that it includes: a case for said engine, a first and a second plate arranged, respectively,on one first and one second opening of the said case, the said plates being provided each with a through hole, suited to ac comodate a support for the said shaft; a basement for the said compressor, provided with a first and a second cylinder mutually opposite, the said basement being suited to contain a predetermined quantity of lubricating oil; a first and a second head, made integral, respectively, to the said first and second cylinder by means of fastening elements; a piston capable of sliding inside the said first and second cylinder being driven by a connecting rod, that is articulated be= tween the said piston and a crank integral to the said shaft; a first and a second chamber for air suction, arran= ged, respectively, in the said first and second head; a first and a second path for intaken air, that connect, re= spectively, the said first and the said second suction cham ber to a cavity provided with air filter and with silencer elements; an element suited to bring the said basement in communication with the said cavity; a first and a second com pression chamber arranged, respectively, in the said first and second head; a third and a fourth path for compressed air, that connect, respectively, the said first and second compression chamber with the manifold; valves for cutting off the said first and second path, when the piston is mo= ved as to compress air contained in the said compression chambers; valves for cutting off the third Sindourth path, when the piston is moved as to intake air from the said suc tion chambers; ventilating elements, driven by the said shaft, as to deliver cooling air to the said compressor;con veying pipes of the said cooling air toward the compressor; supporting elements for the said compressor. 2. Compressor, as per Claim 1, c h a r a c t e r i z e d by the fact that the said piston has two end parts so shaped that each can accomodate a given number of seal rings and a seat suited to be fitted to the said connecting rod, while it moves around a pin machined from the said seat. 3. Compressor, as per Claim 1, c h a r a c t e r i z e d by the fact that the said first and second path for intaken air are machined respectively from the said first cylinder and from the said first head, and from the said second cylin der and from the said second head. 4. Compressor, as per Claim 1, c h a r a c t e r i z e d by the fact that the said third and fourth path for compressed air are machined, respectively, from the said first cylinder and from the said first head and from the said second cylin= der and from the said second head. 5. Compressor, as per Claim 1, c h a r a c t e r i z e d by the fact that the said case has external longitudinal ribs, suited to improve the thermal exchange between the said case and the atmosphere. 6. Compressor,as per Claim 1 and 5,c h a r a c t e r i z e d by the fact that the said supporting elements are made up of two identical structures at least, each comprising two sup= porting feet, connected by means of two tie rods, and by two elements suited to be introduced into spaces included betwe= en the two rows of fins of the said case. 7. Compressor, as per Claim 1, c h a r a c t e r i z e d by the fact that the said element, suited to bring the same basement in communication with the said cavity is made of a small tube inserted into a threaded bore, machined from a wall, this latter delimitating the top of the said basement; the said small tube being provided with a radial bore at least, in order to bring the inner side of said basement in communication with the inner side of said filter, in order to let the oil steams flow from the said basement to the said inner side of filter, as to increase the filtering ef= fect thereof, and to lubricate the movable parts of compres-sor, by impregnating the intaken air with oil steams. 8. Compressor, as per Claim 1, c h a r a c t e r i z e d by the fact that the said silencer elements comprise a first and a second plate; the said first plate being provided with a predetermined number of concentric orders of ribs and grooves degrading from outside toward the inside, the ribs of the first order facing the grooves of the second orders and so on; the said second plate having the said predetermi= ned number of orders of ribs and grooves concentric and de= grading from inside toward the outside; arranged in similar way as the corresponding elements of the said first plate; spacers being foreseen as to let air streams flow between the said ribs and grooves of the said plates; the said air streams being conveyed to the inner side of the air filter. 9. Compressor, as per Claim 1, c h a r a c t e r i z e d by the fact that the said piston is made of a bushing suited to sustain two opposite pistons, integrally by means of two sup porting arms integral to the same bushing and perfectly co= axial, and to internally accomodate a piston pin provided with a bore, in order to sustain a pin, that is connected through a crank to the said shaft of the said engine, having a brass arranged between the said pin and the said bore and provided with a circular groove; the said piston pin being provided with a countersink at least, connected through a pipe to the said groove, as to let oil flow from the said countersink to the said groove. 10. Compressor, as per Claim 1 and 9, c h a r a c t e r i = z e d by the fact that the said crank bears a thin needle suited to be plunged into the oil bulk contained inside the said basement, as to create, during the compressor's operat= ion, an atmosphere of liquid oil particles inside the said basement.

Inventors: GRILLINI, MARCO, DR. ING.
Applicants: AIREL ITALIANA S.R.L.
Application year: 1984
Main classification: F04B27
IPC codes: F04B39, F04B27