US1579781A - Variable-capacity compressor - Google Patents

Description

Apfil 6, 1926. 1,579,781

M. RIESNER VARIABLE CAPACITY COMPRESSOR Filed Sept. 19. 1923 4 Sheets-Sheet 1 Svwwwboz @513 Gwen W1 0 April 6 ,1926. 1,579,781

M. RIESNER VARIABLE CAPACITY COMPRESSOR Filed Sept. 19, 1923 4 Sheets-Sheet 2 April 6-,1926. v A 1,579,781

M. RIESNER VARIABLE CAPACITY COMPRESSOR Filed Sept. 19 1925 4 Sheets-Shefc 5 7 w I Q n (nil/IllIIII/IIII/IIIIIIIIIIIIlI/IIIIIIII/Ill! II/I/IIl/l/flg :1 E

2] vcnfoi; kfizaMM Api'il 6, 1926. 1,579,731

M. RIESNER VARIABLE CAPACITY COMPRESSOR Filed Sept. 19-, 1923 4 Sheets-Sheet 4 IZyamoemtoz kwzk Patented Apr. 6, 1926.

UNITED'N'STATES- PATENT oFFIcEI' MICHAEL RIESNER, OF CINCINNATI, OHIO, ASSIGNOR TO WORTHING'ION PUMP AND MACHINERY CORPORATION, OF NEW YORK, N, Y., A CORPORATION OF VIRGINIA.

VARIABLE-CAPACITY COMPRESSOR.

Application filed. September 19, 1923. Serial No. 663,539.

To (/22 whom it may concern:

Be it known that I, hITCIIAEL RInsNnn, a citizen of the United States, residing at Cincinnati, county of H-amilton, and State of Ohio, have inventedccrtain new and useful Improvements in Variable-Capacity Compressors, fully described and represented in the following specification and the accompanying drawings, forn'iing a part of the same.

This invention relates to a novel apparatus for unloading and loading fluid compressors gradually, the especial object of the invention being to provide an apparatus of this type which shall be more economical in action and secure a higher compressor etiiciency, and further to provide a simpler and cheaper coi'istruction than those hereto fore used.

[In accordance with the present invention, I combine a plurality of unloading devices, each of which acts to partially unload and load the cylinder, in such a Way as to secure a larger number of unloading steps than the number of unloading devices used, thus reducing the number of unloading devices on the cylinder and making the com pressor itself more compact and less complicated in construction. I preferably employ a single clearance chamber and combine this with unloading devices acting on the suction, and preferably by unseating the suction valves, thus securing important advantages in the construction and operation of the compressor as explained hereafter. The invention includes, also, certain other features of construction and combinations of parts in a variable capacity fluid compressor apparatus, as described hereafter.

For a full understanding of the invention, a detailed description of constructions embodying the same in preferred forms will now be given in connection with the accompanying drawings forming apart of this specification, and the features forming the invention then specifically pointed out-in the claims.

on the line 2 of Fig. 1:

elevation Figure 3 is an enlarged longitudinal section of the cylinder on the line 3 of Fig. 2;

Figure 4 IS an enlarged view of the. control apparatus for the unloading devices, I

similar to. Fig. 1, but partly broken away to show the construction;

Figure 5 is a vertical section of the control apparatus;

Figure 6 is .a horizontal section on the line i inlet valves and its unloading device;

Figure 9 is a vertical section of ,a portion of the control apparatus, showing a modihcation, and

Figure 10 is a diagramn'iatic view of a duplex compound compressor embodying the invention, with a special arrangement of the unloading devices securing important advantages in multiple cylinder compressors. I "Referring now to the drawings, and especially to Figs. 1 to 8, A is the compressor cylinder, B the piston, O the piston. rod driven in any suitable manner, D, D and E, E inlet and discharge valves at,respectively, the crank and head ends of the cylinder; F a clearance pocket for the crank end of the cylinder, automatically controlled by the unloading apparatus. Twohand--, controlled clearance pockets G, at the head end of the cylinder are shown, for controlling the maximum loading, but it will be understood that these may be omitted or a different number of hand controlled unloading devices be used. v

The suction and discharge valves are shown as of a type of plate valve now well known and patented by United States Letters Patent to Meyer, No. Reissue 13,991and No. 1,341,413, so that no further description of these valves per se need be given. Each of the inlet valves, D, 1), however, is provided with pressure operated means for unseating and holding; open the inlet valves, this means consisting of a sliding member 10 carrying fingers 11 adapted to engage the plate" valves a, the member 10 being moved to openand hold open the valves by pressure-operated piston 12 and returned to release thevalves for normal operation by" spring 13. The port connecting the cylinder with the clearance chamber F is controlled b 'a valve 6 actuated by pressure-operated piston 14, which is moved by receiver pressure to open the valve for connecting the cylinder withthe clearance chamber and partial unloading and closed by. spring 15 which, in compound compressors, preferably is aided by lntercooler pressure transmitted to the outer sideof the piston throughpipe 16. The valves controlling the clearance chamber G are shown as plug valves 17 of common type operated by screw stems and hand wheels 18. I 7

Referring now to the apparatus for automatically controlling the pistons 12, 14, and valves a, b, pressure is applied to the inner side of piston 14 to open the clearance valve for the first unloading step, by receiver pressure transmitted through pipe 1. Pressure is applied'to the outer side of piston 12 to open inlet valvesD at the crank end of the cylinder for the second and fourth unloading steps by pressure transmitteed through pipe 2,- branched to each inlet valve. Pressure is applied to piston 12 for openin inlet valves D at the head end of theeylind er for the third unloading step by pressure transmitted through pipe 3 branched to each inlet valve. The pressure in these pipes 1, 2, 3 is controlled by valve 0 moving in valve chamber 19 supplied with pressure fluid from the receiver or other suitable source through pipe 20, this valve acting to, connect pipes 1, 2, 3 with valve chamber19, or with exhaust pipe 21, according to its position this valve 0 being formed, as shown clearly in Figs. 6 and 7, with a bottom groove or channel 6, adapted to connect each of the pipes 1, 2, 3 with the exhaust, and with port 7 through the valve for connecting pipe 3 with the valve chamber 19.

The valve 0 isactuated to control the pres- - sure pipes 1, 2, 3 for unloading and loading,

by apparatus controlled by the receiver pressure, as usual in such unloading devices, and this receiver pressure and operation of the valve 19 is preferably secured thron h a pressure-operated member controlled y a pilot valve, which pilot valve is controlled directly by the 'receiver pressure and the pressure fluid controlled by the pilot valve and actuating valve 0 being of any suitable --l -fcharacter and taken from any suitable source, thus enabling the apparatus to be controlled by slight. variations in the receiver pres sure, while employing pressure as heavy as desired for actuating the valve preferred, there is t c. As illustrated, and employed for actuating e valve ca governor or regulator of the well-known Mason regulator type, and, as shown, the valve 0 is connected by its stem 22 and arm 23 to the rod of piston 24 moving in cylinder 25 having fluid passages 26, 27 connecting with opposite ends of the cvlinder, these fluid pasi through a Wcent'ral passage 1n the valve, as

usual in such constructions. The pilot valve (Z is shifted by lever'31 connected by link 32 to Weighted lever 33 pivoted at 34 and bearing on diaphragm 35, which diaphragm is subjected to receiver pressure through pipe 36. The pilot valve isreturned to position after actuation for another unloading step on a further increase in receiver pres sure or for a loading step on decrease'in receiver presure, and for this purpose a compensatingdevlce of .the usual form is used, in which lever 31 is pivoted on one arm of bell crank lever 37 instead of at a fixed point, and the other arm of bell crank lever 37 is connected by a link 38 to one arm of bell crank lever 39, the other arm of which J- carries a roller engaging wedge 40 moving on slideway 41 and connected by link 42 and arm 43 to the rod of piston 24, so as to'move therewith. This regulator and compensating device is similar to the well-known Mason regulator with compensator, except for the following feature.

It is important that the piston 24 should move in exact steps and thus secure an exact movement of the valve 0 at each step, as an irregular movement of the piston 24 might not secure the desired accurate control of unloading through the pipes 1, 2,

3. For the purpose of securing this result,

1' have formed the wedge 40, not as a continuous incline, but in horizontal portions of different heights, with sharp inclined steps between them. Eachof these inclined steps, therefore, definitely fixes'the point in the movement of the piston 24 at which the pilot valve will be shifted to return it to its normal position and stop the piston 24, thus assuring the accurate positioning of the valve 0 to control the their unloading devices.

The operation of-the construction shown in Figs. 1 to 8 and above described, is as follows: Assuming that the compressor is operating at ,full capacity an increase in receiver pressure above that for which the apparatus is set raises lever 33 and pilot valve d so as to admit pressure fluid through passage 27 to the left end of cylinder 25 and connects the other end of the cylinder with passage 30 for exhaust, and thus moves the piston 24 tothefright in Fig. 5 until the cutoff edge of valve 0 passes the port of pipe 1, when'the pressurefluid in chamber 19 will pass through pipe l'to the inner side of 1251 piston 14 and open valve 1) to connect the compressor cylinder with clearance chamber F. This clearance chamber preferably will be madeof such capacity as 'to unload the crankend of-c'ylinden-A .one-half,that is,

pipes 1, 2, 3 and 1 through port 7' and unseat the inlet valves" II) at the crank ,end of the cylinder, thus full y unloading the crank end of the cylinder, so that the compressor operates at capacity.

On'a further increase of receiver pressure,

. the same operation is repeated withthe valve 0 moved another step, so as to connect pipe 2, with exhaust pipe21 and connect pipe 3 with the pressure chamberlt), so that'the unloading pressure is released on valves 1) and these valves re-seated for normal operation, and the valves 1) are nns'eated tor unloading the head endot, the cylinder. Thus thecrank end of the cylinder is un loaded one-half by the clearance chamber 1C and the head end of the cylinder is fully unloaded, the compressor thus operating at 25% capacity.

()n a further increase of pressure and movement of valve 0, pipe 2is opened toihe pressure chamber 19 by the cut-oil edge of valve c passing its port, so that the inlet valves 1) are z'igain' opened for unloading, completing thennloading oi the cylinder.

Decrease in receiver pressure permits the wei hted levei 33 to fall and reverses the t: i

above operation, the compressor being gradually loaded to full capacity by the movement of the valve 0 to the left in Fig. 5,

first by connecting pipe 2 to exhaust 21 for 25% capacity; then by connecting pipe 2 to pressure chamber 19 and pipe 3 to exhaust for 50% capacity then connecting pipe 2 to exhaust for capacity, and finally connecting pipe'l with exhaust for closing the clearance chamber and full capacity.

It is frequently desirable that the capacity of the cylinder ,shall be limited for a time to a maximum of less than'the cylinder capacity which maximum loading limit shall be maintained at all times independently of the a-uton'iatic unloading. This is provided for in the construction shown by the clearance chambers G andvalves 17, the opening of either or both of which valves increasing the cylinder clearance to the extent desired,

the clearance chambers G being made of any desired capacity, according to the maximum loading limit to be provided for. The ,use of a clearance chamber at only one end of the cylinder, and preferably the crank construction with hand-control of maximum load. 1

The construction shown in Fig. 9 is the same and the operation the sameas described above, in connection with Figures 1 to 8, except that the regulating valve system is modified and an intermediate valve used for securing the reversal of the operation of the pipe 2, for the third unloading step.

1 In the construction shown in this figure, the arm 23, operated by piston 24 of Figures 1-8, is connected to and operates piston valve 6 with pressure passage 8 for connecting pipes 1, 2 3, and 4 with receiver pipe 20, exhaust from piston valvechamber 43 being at the end through ports 44. ' Pipes 2, 3, and 4* are controlled by intermediate or reversing valve f moving in valve chamber 46, spring pressed in one. direction byspring 4:7, and provided with a head or piston end 48, by which the valve is moved by pressure transmitted through pipes 39, 4, spring 17 normally holding the valve in position to connect pipes 2 and 2 through the valve as shown in Fig. 9, andthe valve being providedwith a head 5 passing pipe 2. for connecting the latter with the exhaust 49, at the end 'of the valve chamber 4.6 and pipe 3, connects with pipe 3, as shown.

The operation 01 this valve mechanism is as .follows:

Valve e on its n'iovement to the right in Fig. 9 first connects pipe 20 to pipe- 1 through passage 8 for the first or clearance unloading step, and, on the next movement, with pipe 2 and through valve with pipe 2, for the second unloading step of opening the inlet valves at the crank end. On furi The next movement of valve 0 connects receiver pipe 20 to pipe 4 which, with the pressure of spring 34:7, returns valve 7 to the position shown in Fig. 9, again connecting pipes 2 and 2 and opening the inlet valves at the crank end of the ,cylinder for full unloading. i

In Fig. 9, also, is illustrated an improved means for limiting the maximum loading of the compressor through the automatic unloading devices, which may be used with or without clearance chambers and hand-operated valves for maximum load, as illustrated in Figs. -1 to 3. As shown, I have provided this maximum load control in connection with only two ofthe automatic unloading,

35 this clearance chambernee 55 ,ployed, formingadup inders, and I the intercooler.

devices, viz., the clearance chamber F'controlled by pipe 1, and the inlet valves D at the crank en of the cylinder controlled by pipe 2, but it will be understood that morehand valves p and hand-operated valves g are provided on each of pipes 1 and 2 between the connections of these pipes to the branch pipes and totheir control valve.

With this construction it is obvious that it will be possible to maintain clearance chamber F constantly open to the cylinder independently of the automatic control valve by opening pipe p to admit receiver pressure to pipe 1 and closing valve to cut 2 out the automatic control of this pipe, and,

in the same way, by opening and closlng "valves 9, 9 between pipe and the control valve connection to pipe 2, to cut out pipe 2 from automatic control and maintain the. inlet valves D constantly open for a further reduction of maximumloading.

It Wlll be seen that, with thisconstruction controlling two of the automatic unloading detices for maximum load, a wide range of maximum load control may be secured Witha single clearancechamber in the head end of. the cylinder, and that this clearance chamber may be so small as not to interfere practically with full jacketing. fact,

not occupy substantially more space than the piston rod and stuflin box at the crank end. "For instance, with a hand-controlled clearance cham'ber in, the head end, givinga reduction 40 of 12 in total capacity'fl obtain with the control of the two automatic unloading devices shown, a maximum loading control of 100%, 87 A;%, 75%, ee 50%, and 37 This control may be carriedlower, if desired, by putting the hand control onto other of the automatic control pipes, but this rarely, if'ever, will be necessary.

In some cases, and especially with large compressors operating at comparatively slow speed, it is im ortant that the compressor should be be anced throughout un loading, and for this purpose the arrangement shown in Fig. 10 is preferable. this construction four cylinders are emflex com ound compressor, and these cyhnderjan unloading evices are arranged so that .each of ,the cylinders of one side, consisting l of high and low pressure cylinders;

chamber at the-head-end of the cylinders.

In the drawings, A, A? are the high pressure cylinders, B, B the lowpressure cyl- The plstons have the clearance chamber at the crank endpffthe cylof the cylinders A, B are on one rod and the pistons of cylinders A B on another rod, so as to form two sets of compound cylinders, both connected to the same crank .of cylinders A, B, and the clearance chambers F and unloading devices are at the head end of cylinders A B With this arrangement, the unloading steps previously described are secured with complete balancing of the machine, as follows: L.

For load, the clearance chambers on all cylinders are opened simultaneously. The load on the engine or shaft, therefore,

is completely balanced, the rod of each set ofcylinders carrying the same load. For 50% load, the clearance chamber end of each cylinder is fully unloaded by holding the inlet valves open, so that the machine is still in perfect balance and in effect a duplex two-stage double-actin compressor is secured. For 25% load, the opening of the inlet valves is reversed on each cylinder, the inlet valves previousl opened for the 50% load being closed, an those at the opposite end opened,, which stillleaves the compressor in perfect balance.

It will be seen that my invention provides a very simple and efiicient variable capacity compressor and a control apparatus by which many important advantages are secured. Some of the important results secured I for the variation in capacity re-,

quired, is important, as it greatly simplifies the form of the cylinder casting, especially in connection; with the operation of the regular inlet valves for other capacity variation, the operation of these inlet valves requiring practically no change in the form of the'cylinder casting. Not only is the form of the cylinder casting simplified, but .the necessary size of the cylinder casting is reduced and the jacket area available increased,it being not only diflicult and ex-- pensive, but also requiring considerable ipace, to prov de \the necessary area through eclearance valves when more than one clearance 'chamber is used. "With the final unloading step secured by by-pas'sing the fluid through the inlet valves, moreover, the air passes into and out of the cylinder with- .out substantial change in pressure during the unloaded period, and, therefore, there is no temperature change in the fluid handled, while the air entering the suction serves .to cool off the compressor ports and thus avoids lubrication troubles and. other diiliculties attributable to high temperatures. l\'Ioreo.ver, the friction load on the compressor is less with by-passing steps, because no pressure is developed Within the cylinder by the by-passing, while inthe case of complete unloading by clearance chambers the pressure range in theeylinder is the same as under full load conditions, and the friction load 011 the compressor nearly the same. Under the noload condition, moreover, the work in the cylinder is less with by-passing than with clearance, and particularly so if the jackets are efficient. In. clearance unloading the greater the amount of heat carried away by the jackets, the greater will be the area of the indicator card showing the work in the cylinder. Many of the above advantages may be obtained with the later steps of unloading secured by total closure of the inlet at one or both ends of the compressor so that no air is taken in on the suction stroke, but the by-passing of the air through the inlet valves is preferred for simplicity, compactness, convenience, and the cooling of the valve ports and cylinder by the air passing through the suction ports.

I secure important results, also, by the use of the control valve and pilot valve apparatus shown, among which may be mentioned that the action is positive and certain, since the governor can not assume a balanced condition; the force required to operate the governor isvery small, as the variation in receiver pressure is required only to operate the small balanced pilot valve, so that a high degree of governor sensitiveness is secured and the capacity may be controlled within a very narrow range; this type of governor can be readily kept tight and free from leakage, so as to assure certainty of operation; and it is possible to tell by inspection which unloading devices are in operation or otherwise, by merely observing the position of the control valve or the compensating wedge.

It will be understood that the invention .is not limited to the specific form or arrangement of parts illustrated, but that many modifications may be made therein While retaining the invention defined by the claims. I

What I claim is: 1. In a variable capacity compressor, the

combination with a cylinder and a plurality of unloading devices each acting to partially unload the cylinder, of pressure controlled governor mechanism means for successively bringing one of said devices into action a plurality of times dur-.,

ing each of the cylinder unloading and loading operations.

2. In a variable capacity compressor, the combination with a cylinder, of pressure controlled means for unloading each end of including the cylinder, including a plurality of un loading devices at one end of the cylinder, and means for controlling said devices to unload said end by a plurality of steps and to load said end for an intermediate unloading step.

3. In a variable capacity compressor, the combination with a cylinder, of pressure controlled means for unloading the cylinder in successive steps, including a plurality of unloading devices at each end of the cylinder, and means for controlling said devices to unload the eylindcr'by partially unloading one end of the cylinder, then wholly unloading said end, then partially loading said end and wholly unloading the other end of the cylinder, and then wholly unloading both ends.

4. In a variable capacity compressor, the coi'nl'iination with a cylinder and its suction valves, of pressune lCOIlt-IOllfld means for unloading the cylinder in successive steps, including a plurality of unloading devices at each end of the cylinder, and means for controlling said devices to unload the cylinder by partially unloading one end of the cylinder by increasing the clearance, then wholly unloading said end by holding the inlet valves open, then partially loading said end by releasing the inlet valves, and wholly unloading the other end of the cylinder by holding the inlet valves open, and finally wholly unloading the cylinder by holding the inlet valves of the first men tioned end open. v

5. In a variable capacity compressor, the combination with a cylinder and its suction valves, of pressure controlled means for partially unloading said cylinder by increasing the clearance and unloading further and 105 finally by successive steps consisting of holding the suction valves open, and including the successive opening of the suction valves at one end of the cylinder for one step, releasing said valves for normal 110 operation during another step, and again holding said valves open for a later step.

6. In a variable capacity compressor, the

combination with a cylinder and its suction valves, of pressure controlled means for par tially unloading said cylinder by increasing the clearance at one end of the cylinder and unloading further and finally by successive steps consisting of holding the suction valves open, and including the successive opening of the suction valves at the clearance end of the cylinder for one step, releasing said valves for normal operation during another step, and again holding said valves open for alater step.

7. In a variable capacity compressor, the combination with a cylinder and its suction control means and a single clearance chamber, of pressure controlled means for first partially unloading said cylinder by said the suction control means to prevent stantial compression of fluid by the piston clearance chamber and then fully unloading the cylinder by unloading steps acting obn su in each unloading step.

8. In a variable capacity compressor, the combination with a cylinder and its suction valves and a single clearance chamber, of

' pressurecontrolled means for first partially valves of one or both ends of the cylinder.

10. In a variable capacity compressor, the combination with a cylinder and unloading devices acting to unload the cylinder gradually, of a governor having a pilot valve con trolled by receiver pressure, a sin le control member actuated by fluid controlled by said pilot valve, and means controlled by said member for actuating the respective unloading 'devices' to unload and load the cylinder, gradually in accordance with the position of said member.

.11. In a variable capacity compressor, the

combination with a cylinder and a plurality of unloading devices actingto unload the cylinder gradually, of a*governor having a p lot valve controlled by receiver pressure, a single control member for said unloading devices actuated by fluid controll'edbysaid pilot valve, said single control valve with the respective pilot valve, and means controlled said member for actuating the respective unloading devices to unload and load the cylinder gradually in accordance with the position .of said member and to successively actuate one of the unloading-devices to partially unload and later partia y load the cylinder during the unloading of the cylinder.

12. Ina variable capacity compressor, the combination with a cylinder and unloading devices acting to'unload the cylinder gradually, of a governor having a pilot valvecontrolled by receiver pressure, a single control valve actuated by fluid controlled by said and fluid passages connecting unloading devices for unloading and loading the'cylinder gradually in accordance with the position of the control valve.

13. In a variable capacity compressor, the combinationwith unloading devices acting to unload the cylinder gradually, of a governor-having a pilotrvalve controlled by receiverpr'essure, a single control valve actuated by fluid controlled by saidpilot valve, fluid passages controlled by said control valve and connecting it with the respective unloading devices, and a valve device between the unloading devices and control valve acting to reverse the operation of one of the unloading devices relatively to the control valve in one position of thecontrol valve to successively bring said unloading device into unloading and loading position during the unloading; of the cylinder.

14. In a variable capacity compressor, the combination with a cylinder and a plurality of unloading devices therefor, of pressure controlled governor mechanism for said unloading devices including connections for operating said unloading devices by fluid pressure and hand operated means for con-' trolling the pressure onone or more of said unloading devices. to maintain said device or devices in unloading action independently of the governor mechanism.

15. In a variable capacity compressor, the

combinationwith a cylinderv and a plurality of. unloading devices therefor, of pressure controlled governor mechanism for said unloadin devices including connections for operating said unloading devices by fluid pressure, and pressure connections and hand operated valves for one or more of the unloading devices acting to control the unloading devices independently of the governor mechanism.

16. In a variable volume compound compressor, the combination with four cylinders arranged in pairs on separate rods on the same crank shaft with high and lowpressure cylinders on each rod, of a plurality of unloading" devices for each end of each cylinder, and. governor mechanism for bringing said unloading devices into action successively and acting to unload each cylinder in equal proportions at each unloading step and In hand.

y MICHAEL RIESNER.

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