US2361316A - Gas compressor - Google Patents

Description

J. w. NEWTON ETAI. v2,361,316

GAS COMPRESSOR Filed Aug. 18, 1942 4 Sheets-Sheet l Oct. 2 4, 1944.

Oct. 24, 1944. J, w, NEWTON ETAL GAS COMPRESSOR Filed Aug. .'18,- 1942 4 sheets-sheet 2 Oct 24, 1944 J. w. NEWTON ETAL GAS COMPRESSOR Filed Aug. 18, 1942 4 Sheets-Sheet 5 7M/ff Oct. 24, 1944. J. w. NEWTON ETAL 2,361,316

GAS COMPRESSOR '.Filed Aug. 18, 1942 I 4 Sheets-Sheet 4 MSW Patented Oct. 24, 1944/ UNITED STATES PATENroFFicE GAS COMPRESSOR- South Wales Application August 18, 1942, Serial No. 455,22@

' In Australia September 16, 1941 13 Claims.

'I'his invention relates to gas compressors and particularly to those moderate sized portable types used in industry; it has .been devised to Aprovide sucha gas compressor of improved con-- struction whereby the compressor unit and the ga's under compression can be efficiently maintained at such low temperatures and the Ine-- chanical eillciency of the construction is such as will enable a single stage compressor to Aachieve a compression index substantially equivalent to that of the average two-stage compressor when operating at similar speeds and under similar conditions. f

A further feature of the invention is the con'-` struction of a double-acting compressor which by reason of the facilities afforded by the construction to cool the working parts andthe mechanical eiiiciency thereof can be operated at speeds higher than the speeds which existing compressors of similar dimensions can attain the clearance between the end cover and the cylinder and this gas is compressed on the next stroke of the piston. l

Unloading means are provided to restrain the movement of the cylinder and to hold it centrally between the end covers when a predetermined compression pressure is reached so that during K the period of restraint the reciprocation of the discharges it again through the open ends.

Reciprocationofl the piston, is effected by a l' piston rod having the banjo frame of a harmonic link` motion thereon. A crank pin in such frame thereby increasing the output approximately proportionately to the speed increase.

A still further feature oi' the invention is the combination of parts wherebya compressor may` be assembled having twoopposed double-acting f compressor cylinders having all the characteristics before mentioned.

Basically the invention is a floating self-aligning compressor cylinder which is free to reciprocate between end covers and is so moved by a piston reciprocating therein.

This self-aligning cylinder takes the place of the conventional intake valve or valves and pro- I vides the utmost freedom for air intake. The air intake is controlled by movement of the cylinder such movement being obtained from power that would otherwise be lost in friction thaty is, the

, tension of the piston rings against the cylinder wall. This feature in addition to providing a distinctly improved means of taking in air permits the cooling of substantially the entire compressor heads or covers cylinder.

On each stroke of the piston the cylinder is as weil as the compressor moved by friction of the piston to seat against the end cover in the direction of movement of the ceeds that above the valves. 0n the return stroke the pressure in the said ports is gradually released and this permits of the valves seating gently. During this compression 'stroke gas is the reciprocating means described. Nevertheless is the actuating 'means A circulating pump actuated by the banjo frame provides a cooling liquid for the piston which liquid is passed through ducts in the banjo frame and the piston rod to. a cooling passage in the piston which traverses both faces thereof and the skirt.

The floating self-aligning cylinder permits the use oi.' comparatively thin metal or metal alloy which could not be used in cylinders forming an integral part, of a compressor casing as constructedfhitherto. This thin metal provides for the effective transfer of heat which` is taken away by gas circulating about the outer wall thereof. The end covers are cooled by water circulation.

The cooling of the cylinder and the end covers as aforesaid coupled with the cooling of the piston assists in the improvement of the compression index as previously stated and also makes possible the operationv of a double acting com` pressor, both single and twin opposed cylinders, atV high speeds not heretofore obtainable.

The use of the floating self-aligning cylinder of this invention is not of necessity confined to it will be appreciated that the utilisation of the harmonic link motion as the means to reciproadmittedtotheothersideofthepistonthrough I6 cate the piston makes a design of utmost simcompressor; Fig. 2 is a sectional elevationV on liner-tof Fig. 1: Fig. 3 is a. section plan on line 3 3 of Fig'. 2; Fig. 4 is a sectional elevation illustrating an unloading device and a modied air cushioning means of seating the cylinder against the end covers; Figs-5 and 6 are sectional plans on lines 5-I and l-l respectively of Fig. 4; Fig. '7 is an elevation (partly in section) of a compressor having two double-acting opposed cylinders; Fig. 8 is a sectional elevation approximately on line 8 8 of Fig. '1; Fig. 9 is a sectional plan on line 9 9 of Fig. 7.

Referring to Fig. 1, the cylinder I has at each end an internal ange or lip Il which is conveniently made by screwing flanged rings I2 onto each end of the cylinder. The face I3 of these rings l2 constitutes a seating to seal the cylinder l0 against the end covers |4|5. On the outer wall of the cylinder I0 there is a collar 5 and there is a. spring I1 between this collar I6 and a cylinder supporting ring I8 which is adjustable by screwing on the inner (cavity) wall `|9 of cylinder casing 20, see Figs. 1 and 7. Where it is desired to construct a compressor with the wall I9 omitted the supporting ring I8 is mounted on the casing (see Fig. 4). This variation in the construction relates to different methods of cooling the cylinder I0 and will be described later. The cylinder III may be of centrifugally spun cast iron or other metal of thin section which will provide for the effective transfer of heat through the wall to be carried away by cooling means.

It will be seen that the weight of the cylinder I0 is taken by the spring I1 and that the cylinder is free to reciprocate-between the end covers |4|5. The amount of travelo! the cylinder I0 is very little; it can be easily calculated to provide an unrestricted air inlet to the cylinder on the respective suction strokes.

Cylinder Il) is the compression chamber and by its movement is also an air inlet controller. The amount of projection of the internal lip II is calculated to enable the pressure of air under compression to be utilised to assist the frictional effort of the piston in sealingthe cylinder against the end covers |4-I 5 on the respective compression strokes. This projection also provides a surface for that small portion of the compressed air remaining in the cylinder and outlet ports on completion of the compression stroke to act against and so prevent movement of the cylinder I0 until the piston has moved suinciently to release such pressure; consequently there will be no harmful back-flow of air through the inlet,

and the energy stored in the clearance volume of air is utilized in overcoming the inertia of the piston. This pressure of air also gives the discharge or outlet valve the necessary cushioning onto its seat thus preventing valve hammer.

End covers I4| 5 are mounted on the casing 20; as the joint between the end covers is not required to resist pressure it can be a face joint. This factor enables the clearance between the piston and the end covers to be reduced to a vpractical minimum which provides for the appropriate expansion of the metals of the respective parts thereby increasing the volumetric efliciency of the compressor.

In the end covers |4|5 there is a seating ring 2| juxtaposed the face I3 of the rings I2. This seating ring 2| may be of any resilient material and it is secured into the end covers I4 and I5 by means of an annular screw-threaded ring 23. Fig. 4 illustrates a metal ring piston 24 which may be substituted for the seating ring 2|; one such piston is slidably mounted in the annular chamber located in each of the end'covers I4 and I5. Each ring 24 is maintained in its annular chamber 25 by means of the annular screw threaded rings 26 and it is adapted to make contact with the ilanged ring I2. by means of air pressure as will be explained later.

Outlet ports 21 in said end covers |4-I5 are provided with annular disc valves 28 or other outlet valves of conventional construction. The valves illustrated are adapted to be controlled by the springs 29 located in the cup holders 30 which'are secured to the end covers |4-I 5.

The covers I 4-l5 are provided withjackets 32 and 33 respectively and each of which is furnished with a pair of compartments 34 and 35, the former are in communication with the air outlet ports 21 and the common outlet 36. Through the latter a cooling medium such as water circulates, an inlet 31 and outlet 38 being provided. Additionally the cover I5 has a stuffing box for the compressor piston rod 39. This stuiiing box consists of a neck ring 40, packing 4|, gland ring 42 and a gland cap 43 furnished with screw threaded rods 44 to press the gland ring 42 against the packing 4|; the gland cap 43 is held in place by studs 45.

Casing 20 has an air inlet 41 with ports 48 to each end of the cylinder I0. Air is drawn into the compressor by the action of the piston 49 therein and it may be assisted by a low pressure ian to act as a supercharger. is used it is designed to deliver more air than the cylinder can absorb the surplus passing through the ports 50 to cool the cylinder I0 and then discharging to atmosphere through port 5 I In an alternative construction where a supercharger fan is not desired the inner wall I9 of the casing 20 is eliminated (see Fig. 4) thus providing a free passage of air from the air inlet 41 around the cylinder I0 and thence to the compression chamber. This construction may be preferred in some cases although there is a tendency for the intake air to become somewhat heated prior to entering the compression `chamber due to contact with the cylinder I0. In this construction the cylinder supporting ring I8 is screwed onto the casing 20.

Piston 49 in the cylinder I0 is stepped as indicated at 52 to clear the lip II of the rings I2. In its piston ring fitting the piston is of conventional construction. The tting of the piston is facilitated and the wear on the parts in frictional Contact is minimised by the floating and self aligning mounting of the cylinder l0. 'I'he piston 49 has a cavity 53 therein and an internal boss 54 to take a piston rod 39. There are ports 56 communicating through the boss 54 to the cavity 53. These ports are in register with an inlet duct 58 in the piston rod permitting the now of cooling liquid. An outlet duct 59 in the piston rod 39 permits the return of the cooling liquid after passing over the piston surfaces.l The cooling liquid returns to an oil sump or to an oil cooler.

On the end of the piston rod 39 is a banjo frame 60 of a harmonic link motion which is housed in the compressor base frame 6|. A' crank pin 62 in link block 63 in said banjo frame is mounted on shaft 64 in bearings 55 in the base frame 6|; said shaft 64 is rotated by an appropriate means.

In the single cylinder construction illustrated if; Fig- 1 the bottom $6r of the base. frame is an 011 Sump which may incorporate oil cooling means and in it is a pump barrel 61 having an inlet valve 68 while a hollow plunger 69 alxed to the banjo frame 60 in the same plane as the piston rod 33 has a delivery valve 1l therein.

Where a fan The outlet from this pump is in communication with the inlet duct B9 through port 1i. The outlet duct 59 in the piston rod 39 terminates in the outlet 12 which is directed onta the link block 69 and crank pin assembly. In this construction the plunger rod serves also as a. guide for the harmonic link assembly and for this purpose the upper part of the pump barrel l1 has a substantial bearing 19. i t

Fig. r(illustrates `a compressorwith opposed cylinders while Fig. 8 illustartes the piston cooling means. The compressor cylinderl and parts' 4in this construction are identical with that described with reference to Fig. l, the second lplston rod taking the place of the plunger 69. In

. is held in this position until the air pressure is` so reduced that the springs 93 overcome the pressure acting on the plunger 19 and withdraw saidA 'piungers from .engagement with the said stops 11. y The stops 11 are kept in alignment with the plungers 18 by slippers 81 on the,cylinder I9 which are mounted between guides 98 on the cas l inglll or I9 as the case may be. Such-an unloading mechanism as described above or other this construction the banjo frame 90 has tw`o inlet ports 1l in communication with the inlet ducts 59 in the respective piston rods I9 and two outlet ports in communication with the 'outlet ducts 59. There is a piston cooling pump such as that described with reference to Fig. l for-each compressor unit andthe plunger rods I9 are mounted in cross-heads 16 on the banjo frame 9|. The outlets from these pumps are in communication with the inlet 'ports 1I.

In operation, the piston 49 moving in one di-v rection will by means of the piston rings tension against .the cylinder il, mov'e said cylinder until the ring I Z-seats on the seating ring 1l of the end coversin the 4direction of movement of 'the rpiston. The piston thus causes the cylinder to make a totally enclosed area into which the piston` compresses the air-drawn in on the previous stroke of the piston-until the pressure is suilicient to lift the-outlet valves 29. The cylinder y I9 is kept well seated by the air pressure acting on the interna1 lip Il of the ring I2. The pressure o n the lip Il increases proportionally with the increase in air pressure so that such air pressure as well as the friction of the piston controls the effective sealing of the cylinder onto the end covers. -When ring piston seatings 2l are employed as' shown in Fig. 4 each' of such seatings' 24 when the piston 49. is on the compression stroke, is firmly pressed against the flanged rings I2 by the air pressure in compartment 94 passing into the ports 90 and leading into the annular chamber 25 and impingingupon the seatings 2l. seating ring 2! on the suction side of the piston contacts the projecting face 9| of the threaded ring 29 thus sealing the chamber 25 against leakage. v

Figs. 4, 5 and 6 illustrate one form of unloading device which may be incorporated in the compressor. In this lconstruction V nosed stops 11 are mounted on thecylinder I0 juxtaposed V notched plungers 18 in cylinder 19 mounted in the casing 20. These cylinders 19 are divided into plunger compartments 89 and spring compartments 8| and a plunger rod 82 passing through the plunger compartment 80 into the spring compartment 9i. has a helical spring '93 thereon held in place' by nuts 84. `Theplunger compartment has an air inlet 85 behind the plunger 19 and a pipe 96 therefrom is connected to the pressure side of the compressor through a conventional air governor. The springs' are loaded to hold the plungers'18 in the cylinders 19 until the air inthe pipe and behind the plungers reaches a predetermined pressure when the plungers are forced outwardly against the tenvsion of the springs until the V notches in the lplungers 18 engage the V nosed stops 11 and vso prevent movement of the cylinder I9. In this When the piston is on the suction stroke they suitable unloading mechanism will be incorp'orated in the compressors as illustrated in Figs.

1 and 7; it has been omitted from the description of the mentioned figures in order'to clarify the same.

g .Although the drawings show compressors with the cylinders on a vertical axis it is to be understood that the 'compressor may be constructed to operate with the axis of the cylinders horizontal.

We claim:

1. A gas compressor comprising a casing having a gas inlet therein, end covers fixed to said casing, said end covers each having outlet ports therein and compartments leading from said outlet ports to a common outlet duct, valves on said outlet ports, means providing a water jacket in said end covers for cooling same, a cylinder in said casing spring balanced between said end covers and reciprocable between said end covers to'cause the admission of gas to said cylinder at each end alternately, means providing a seal between the cylinder and the end cover contacted thereby, a piston rod slidably mounted in one of said end covers and extending into said cylinder, a piston in lsaid cylinder and`connected to said piston rod, means for reciprocating said piston rod and piston, said piston having a cavity therein and communicating inlet and outlet ducts, means for supplying cooling liquid to said piston through said inlet/ duct, and means operable to unload the compressor when a predetermined pressure has been attained.

2. A gas compressor having a cylinder reciprocable between end covers operable to eilect the admission oi' gas to said cylinder alternately at each end thereof, means to elect a seal between the cylinder' and the end cover-contacted by said tion in said cylinder, means for reciprocating said piston. and means for holding the cylinder stationary for thepurpose of unloading the compressor when a'predetermined compression pressure has been attained.

3. A gas compressor as claimed in claim, 2 wherein the cylinder hasa stop on its outer wall,

-a notched plunger adjacent said stop, a cylinder for said plunger comprising a plunger compartment and a spring compartment, a rod on said plunger extending into the spring compartment of the plunger cylinder, a helical spring on said rod, a gas inlet to the plunger compartment'of said plunger cylinder, means connecting said gas inlet with the pressure outlet from the compressor, and guide means preventing rotation oi the compressor cylinder. t I

4. A gas compressor comprising a casing having end covers, a cylinder balanced in said casing between said end covers, a piston reciprocable in said cylinder, said cylinder being mounted in self-aligning relation in respect to the piston and arranged f or reciprocation between said Aend vcovers by the friction of the reciprocation of the when a predetermined compression' pressure hasv been attained.`

5. A gas compressor comprising a casing having end covers, a cylinder spring balanced in said casing between said end covers, a piston reciprocable in said cylinder, said cylinder being mounted in self-aligning relation in respect to the piston and arranged for reciprocation between said end covers by the friction of the reciprocation of the piston to effect the admission of gas to said cylinder alternately at opposite ends thereof, a flanged ring secured on each end of the cylinder with the flange thereof projecting inwardly and forming an internal lip, means to effect a seal between the lip and the end cover contacted by said cylinder, an outlet valve in each of said end covers, means for reciprocating said piston including means operable to maintain the same in axial alignment with said cylinder, and means for unloading the compressor when a predetermined compression pressure has been attained.

6. A gas compressor comprising a casing having end covers, a cylinder floating in said casing between said end covers, a piston reciprocable in said cylinder, said` cylinder being mounted for reciprocation between said end covers by the friction of the reciprocation of the piston to eiect the admission of gas to said cylinder alternately at opposite ends thereof, an inwardly projecting lip at each' end of said cylinder, an external collar on said cylinder, an adjustable supporting ring internally of the casing, a spring interposed b'etween said collar and supporting ring, means to eiect a seal between the lip and the end. cover contacted by said cylinder, an outlet valve in each of said end covers, means for reciprocating said piston including means operable to maintain the same in axial alignment with said cylinder, and means for unloading the compressor when a predetermined compression pressure has been attained.

'7. A gas compressor comprising a casing having end covers, a laterally and longitudinally free floating cylinder in said casing between said end covers, a piston reciprocable in said cylinder, said cylinder being mounted for self-aligning concurrent and relative axial reciprocation with and with respect to said piston between said end covers by the friction of the reciprocation of the' piston within the cylinder to effect the admission of gas to said cylinder alternately at opposite ends thereof, an inwardly projecting lip at each end of said cylinder, a resilient seat'in each of said end covers adjacent' the ends of said cylinder, a valve controlled outlet port in each end cover, means for reciprocating said pistonincluding means operable to maintain the same in axial alignment with said cylinder, and means for unloading the compressor when a predetermined compression pressurehas been attained.

8. A gas compressor comprising a casing having end covers, a laterally and longitudinally free floating cylinder in said casing between said end covers, a piston reciprocable in said cylinder, said cylinder being mounted for self-aligning concurrent and relative axial reciprocation with and with respect to said piston between said end covers by the friction of reciprocation of the piston within the cylinder to eiect the admission of gas to` said cylinder alternately at opposite ends thereof, an inwardly projecting lip at each end of said cylinder, a ring piston seat slidably mounted in an annular chamber in each end cover adjacent said cylinder, means for admitting air under pressure to the back of said piston seat, a valve controlled outlet port in each end cover, means for reciprocating said piston including means operable to maintain the same in axial alignment with said cylinder, and means for unloading the compressor when a predetermined compression pressure has been attained.

9. A gas compressor comprising a casing having a gas inlet therein, end covers fixed to said casing, said end covers each having outlet ports therein, valves on saitl outlet ports, means providing a jacket for cooling fluid in said end covers for cooling same, a 'laterally and longitudinally free floating cylinder in said casing spring balanced between said end covers and reciprocable therebetween to effect the admission of gas to said cylinder at each end alternately, means providing a seal between the cylinder and the end cover contacted by said cylinder, a piston rod slidably mounted in one of said end covers and extending into said, cylinder, a piston in said cylinder and connected to said piston rod, a banjo frame of a harmonic link motion connected to' said rod, a link block in said frame, crank means in said block, means for rotating said crank means, and means to unload the compressor when a predetermined compression has been attained.

10. A gas compressor as claimed in claim 9 wherein the piston has a cavity therein and an internal boss in which the piston rod is secured, said boss having an inlet and an outlet port to said cavity and said piston rod having inlet and outlet ducts therein in register with the inlet and outlet ports of said boss, and the banjo frame of me harmonic link motion of said piston'rod having an inlet duct in register with said piston rod inlet duct and with a hollow pump plunger reciprocable in a pump casing, and means for delivering liquid through said hollow pump plunger and the inlet duct and port to the cavity in said piston upon reciprocation of said hollow pump plunger.

11. A gas compressor comprising a pair of axially aligned casings each having a gas inlet therein, end covers ilxed to each of said casings, said end covers each having outlet ports therein and compartments leading from said outlet ports to a common outlet duct for the covers of each casing, valves on said outlet ports, means providing a water jacket in each oi.'A said end covers for cooling same, a laterally and longitudinally free oating cylinder in each casing spring balanced between the end covers thereof and reciprocable between said end covers to effect the admission of gas to each cylinder alternately at opposite ends thereof, means providing a seal becylinder connected jto said piston rod, means for .reciprocating said piston rods and pistons conjointly, and means operable to unload the compressor when a predetermined pressure has been attained.

azionario I r 5 for cooling same, a laterally and longitudinally free floating cylinder in each casing spring balanced between'the end covers thereof and recprocable between said end covers'to eifect the admission of gaslto'each cylinder alternately at opposite ends thereof, means providing a seal Vbetween each cylinder and the casing emi cover contacted thereby, apiston rod slidably mounted in each of the inner end covers and extending into each of said cylinders, a piston in each cylinderconnected to Said piston rod, a banjo frame of a harmonic link motion intermediate n said piston rods and connected thereto, a link block in said frame, crank means in said block, means for rotating said crank means, and means to Vunload the compressor when a predetermined I compression preure has been attained. e

13. A gas compressor as claimedY in claim 12 wherein each piston has a cavity' therein and an internal boss in which the piston rod is secured, said boss having therein registering outlet and llinlet ports and ducts to said cavity, crossheads on opposite sides of the banjo frame,a hollow pump plunger aiiixed to each of said cross-heads, said frame having ducts therein in register with the ducts in said piston rods and the hollow pump Il Dllmgers, pump casings for said plungers, and

means for delivering liquid through said'plungers, ducts and ports to the piston cavities upon reciprocation of said piungers.

JOHN NEWTON.

M. J. DUFF-FYFE.

Images