US1638674A - Compressor - Google Patents

Description

Aug. 9, 1927.

1 J. P. lWILDMAN COMPRESSOR l Filed March 26, 1925 2 Sheets-Sheet 1 31a/vanto@ Aug. 9, 1927. 1,638,674

' J. P. WILDMAN I COMPRESSOR Filed 'March 2e, 1925 2 sheets-sheet 2 Patented Aug, 9, 1927.

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COMPRESSOR.

Application filed March 26, 1925.

My invention relates to pumps and compressors, and is especially directed to compressors used in a refrigerating system for compressing the gaseous refrigerant.

ln a compressor of this character, and especially in those compressors in Which the refrigerant to be compressed is taken in through the crank case, an excess amount of oil is commonly forced Vup into the Working barrel of the cylinder by the pressure of the gas which has leaked past the piston into the crank case and the oil thus forced up is pumped out into the expansion coils. The oil forms a coating on the bore of the coils which serves as an insulating medium to prevent efficient radiation through the Walls of said coils. The particular object of my invention therefore is to arrange the parts in a compressor of this character so that its tendency to pump oil out of the crank case will be eliminated in a relatively simple manner.

Another feature to be contended with in compressors of this character is .that the gaseous refrigerant leaks past the piston and into the cank case and builds up relatively high pressure therein. The crank case must be made air-tight to prevent the gas from escaping to the room, and thus .when a relatively high pressure is set up in the crank case, it necessitates very tight packing and stuffing boxes.

The introduction of ammonia gas mto the crank case also causes the oil to foam and froth and the foaniy particles are easily forced into the cylinder by the pressure of the gas Within-.said crank case. A further object of my invention is to provide deyiees by which the refrigerant above tl e piston and the lubricant in the crank case can be kept' separate from each other so as not only to prevent pressure from being built up in the crank case, but alsoto eliminate the harmful effects caused by the refrigerant be ing` admitted into contact With the lubricant.

My invention may be said to consist in forming the piston element With tvvo heads and arranging intermediate the said heads, a circumferential chamber. Said chamber is vented, the contents preferably being With drawn through a branch of the intake pipe for the refrigerant, whereby the refrigerant Vwhich leaks past the piston and enters said chamber, is Withdrawn before it can escape into the crank case. `Excessive pressure,

therefore, is prevented from being set up in Serial No. 18,480.

the crank case Which Would tend to cause the lubricant contained therein to be pumped out due to a difference in pressure in said crank case, and in the space above the piston during its suction stroke.

To produce a machine, in which the parts are of suoli size as to withstand the constant usage, to which a refrigerant compressor is subjected, experience has proven that the cross-head should be of greater size than the piston so that sufficient bearing surface, and large enough pins can be provided to Withstand the pressures and Wear to which these parts are subjected. ln my invention I propose to form the intermediate chamber, herebefore referred to, by causing said spaced piston and said crossehead each to seal a portion of the bore of the cylinder. When said piston and said cross-head are of unequal size, a pumping action vvill be produced ivhich Would cause oil to be Withdrawn from the crank case and forced into the Working branch of the cylinder. The object ofmy invention, therefore, is to provide devices by which a piston, and a cross-head in the forni of a piston and of unequal size, can be used in the saine cylinder and by Which the resulting pumping action Will be eliminated.

attain' this object by proi'fiding tivo adj acent cylinders With'cylindrical pistons and crossheads each reciprocating snugly in the bore of each of said cylinders. The piston and crossshead in each cylinder is connected together by a portion which is smaller in diaineter thansaid bore so as to provide a chamber 4Within said bore circumferentially about said portionv The cross-head and piston in each cylinder are of unequal sizebut are exactly equal to the corresponding crossliead and piston in the adjacent cylinder. The connected piston and cross-head in one cylinder is arranged to be reciprocated oppositely to the corresponding piston and cross-head in the adjacent cylinder. By providing a passageway between said adjacent cylinders which connects he chamber in each, I cause the summation of the volume of said cliaiiioers and said passageway to remain constant. rl'his is for the reason that when one piston and cross-head moves downwardly to tend to produce a partial Vacuum inthe chamber vbetween the same, the piston and cross-head in the adjacent cylinder moves upwardly to compress the contents thereof. inasmuch as the diameter of said parts is relatively the same in the adjacent cylinders, the displacement ot each exactly corresponds to the displacement oit the other and there is no resultant change in the pressure ot the gases therein.

A turther and more specificl objectotmy' invention is to provide a novel valve arrangement in said compressor, in which the valves are arranged Ywholly within the cylinder head and are removable therewith. The intake and discharge valves are thus independent'oft hepistons and are preferably arranged concentric one within the` other,with the intake-v valve encompassed bythe discharge valve. The'out'er or encompassing` valve is provided with a plurality ot closure elements held, in place by a single spring` controlled element which is arranged to'act uniformly upon all or closure elements.

The details ot construction and mode oi? operation are hereinafter described with rc'terenceto the accompanying drawings, in which: i

F l is a longitudinal section through a compressor having two cylinders arranged side by side;

Fig. 2 Ais a plan section taken on the line 2-Q ot Fig. l;

Fig. 3 is a plan section taken on the line fl-3 ot lligj. l; and

Fig. /l is a vertical section taken on the line et+-lofllig. l

My compressor" comprises two cylinders a. which are jmounted upon a crank Acase a5 which Vacts/as 'a support therefor. lAs is common in lcranl; casesoi this character, the cranlrcase ior both cylinders is not divided by a partition and ythus the portion under each cylinder communicates freely with the other. Said cylinders are preferably cast in a single unit and are water aclreted as a. The compressor shown in the accompanying drawings has two cylind rs in which the piston elements l; and c reciprocate. Each piston element has two heads and Z22, and c and c2. The heads and c constitute the piston heads which operate in the working barrels d and e, and the heads 62 and 02 constitrte cross-heads which reciprocate in the cy A`dricalguides f and g. As can be noted in F l., the working barrels are substantially smaller' in diameter than the cylindrical guides. The working barrels are separated by a water jacket space a?, while the cylindrical guides f and g are separated merely by a partition t3 which terminates in a plane substantially in alinement with the bottom of the skirts,'which constitute the working` barrels d and c. The partition a3 is arranged equidistant,between the bottom portions of said skirts, and thus a communicating passageway 7ir is provided which connects the cylindrical guide f; with the cylindrical guideg, The piston elements and c are driven in time oppositely with. each other by the connecting rods el and y, respectivelv.

4 Y K s Y l, t

4, hat is, as shown in l, when the piston leirent 7J is at upper dead center, the piston element c is at lower dead center, and thus when the position ot one is reversed the other one changed similarly. ForY this re son the spaces above the cross-heads h2 and '02, and below the pistons and c', and the passageway /L 'through the transverse wall portion at ot the cylinder, remain constant even though the pistons o and c are smaller than the' cross-heads o2 and 02.

Vihen theypiston element c moves'downwardly, as shown in Fig. l, and the piston element Z) rmoves upwardly, the contents ot each of said spaces is permitted to pass through the passages/'ay /l so as to be equal.- ize'din pressure. `When the position of said piston elements change oppositcly the contents are permitted to pass through said passageway it into the opp siteside. The pistonsb and c are provided with a plurality oit sealingA rings 7' and j to prevent the gas in the working barrel from escaping` past` said piston. Experience has proved thatl sealing rings'maintain an etlicient seal but permit slight lealrao'e of gas to ecaperto the crank case it means are not provided tor catching and returning the same to the circulatory system. l thus. connect abranch It of the intake pipe 7c in the communicating .passageway L above the partition a3. ln saidbranch la, l place a check valve 7c3 which permits said gases to be withdrawn 4from said space but prevents the return :How therethrough past said check valve'. l/Vhenever the pressure in the suction pipe 7c becomes lowerV than that in the spaces between pistons ot cross-heads, the check valve A7c3 opens, allowing the passage of gas from said spaces into the intake pipe is.

rlhe cross-heads 722 and cl are each provided with singley lsealing` Z and m, which permit a gra-dial passage ot a slight amount of oil to escape, to serve to lubricate all portions above the ring.

The cylinder hea-drU serves as the head Jtor both cylinders and is cast in a singleA unit, and is held down to the cylinder casting by studs n. I mount valve cages 0 and p in said head, as shown in Fig. l.

ing?, tubular extensions o2 and 292 extended upwardly therefrom. Saidpdisc portions o and p are recessed in the cylinder block directly-above the .working barrels d and eV and are arranged so'that their upper surfaces lie `substantially flat with the upper surface of said cylinders. By arranging said valve cages in this manner,v l amable, by providing` single gaskets g between the cylinder heada andcylinder a, not only to provide a sealing' medium between thev cylinder and said head, but also to provide a seal for the valve cag'eaas well. AThis is for the reason that said A, qg'aslrets extend about theV re-k and l n Said valve f cages comprise disc portions 0 and 2),liav-v cess in the cylinder in which said disc portion or the Valve cages are seated. The intake valves r and s are mounted centrally within said tubular extensions 02 and p2 and are preferably of the mushroom type, as shown in Fig. l. Valve springs r and s tend to hold said valves upon their seats on the undersurface of the disc portions 0 and p, respectively. The intake pipe c connects into a header or gland t which lits upon the top of said cylinder head and distributes the refrigerant to both cylinders. The gaskets or packing material u and u about the tubular portions o2 and p2 are held in place by a header or gland t. Said packing material or gaskets provide an air-tight passageway between the intake pipe and the working barrels.

The discharge pipes 7a2 are connected to the working chamber through three ball controlled ports 'v and w on the working chambers l and e, respectively. Said ports are spaced equidistant about the intake port directly above said working chambers and the balls o and w are held tightly against the seats by springs m and y which bear against holding rings and y, respectively, in the working' barrels d and e.

A cored out aperture m2 or y2 is arranged about each respective tubular extension o" and p2, respectively, to provide a passageway for the discharged refrigerant. Sand discharged refrigerant passes from said cored out portion through the pipe 7a2. The valves and the valve cages are removable from the cylinder, with the cylinder head, to expedite the grinding of said valves or replacement of the parts therein.

The operation of my compressor is as follows:

The gaseous refrigerant to become compressed, `is drawn into the compressor through the intake pipe 7c and is emitted therefrom through the discharge pipes L2. The branch intake pipe 7c communicates with the main intake pipe and thus is subjected to suction by the compressor each time the piston therein produces a region of reduced pressure and thus the same condit-ions of pressure are maintained in the space between the heads of the piston elements, and is maintained in the intake pipes.

Starting with the piston element at upper dead center as in the left hand cylinder in Fig. l, 'the movement of the piston head b downwardly will cause relatively reduced pressure in the Working barrel CZ will tend `to unseat the intake valve r and permit the gas to be introduced into said barrel from t-he intake pipe 7c. Vhen said piston head approaches vlower dead center, and the reduced pressure is compensated by gas flowing from said intake, the valve spring r will move the valve back upon its seat to prevent further gas from being admitted.

The movement of said piston head upwardly causes the gas to be compressed and when saidcompression is built up to such a degree as to overcome the springs m which hold the ball checks in place, said balls are lifted from their seat by said pressure and the gas is permitted to flow outwardly into the discharge line k2.

Said piston elements b and 0 move oppositely and thus, While one piston is compressing the gas and displacing it from a cylinder, the other is drawing in a charge of gas from the intake line. Such pistons moving in time oppositely to each other, thus causes the volume of the space between the heads of the piston elements to remain constant, as has been heretofore brought out, because' of the connecting passageway It.

I claim:

n a compressor: two pairs of alined and connected pistons and crossheads, the pistons of each pair being smaller than the crosshead of the same pair; parallel pairs of cylinders for each of said pistons and crossheads; a wall common to both of the larger cylinders and extending upwards to termi nate in a space between the smaller cylinders, said space being an equalizing passageway between the housings of said pistons; a crank shaft operating said crssheads oppositely; and means upon said crossheads to seal the crank case from the space thereabove.

JOHN P. WILDMAN.

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