US2694519A

US2694519A - Pump speed controlling and unloading means

Info

Publication number: US2694519A
Application number: US147354A
Authority: US
Inventors: Win W Paget
Original assignee: Joy Manufacturing Co
Current assignee: Joy Manufacturing Co
Priority date: 1950-03-03
Filing date: 1950-03-03
Publication date: 1954-11-16
Anticipated expiration: 1971-11-16

Description

Nov. 16, 1954 w. w. PAGET 2,694,519

PUMP SPEED CONTROLLING AND UNLOADING MEANS Filed March 3. 19 50 3 SheetQ-Sheet l :1 I o i R W272 WPa get 14 ziorney Nov. 16, 1954 w. w. PAGET PUMP SPEED CONTROLLING AND UNLOADING MEANS Filed Malrch 3, 1950 3 Sheets-Sheet 3 i fizvenzor: 327 4 VVUZ 57 5 'W' V Hzfomey United States Patent'Ofiice 2,694,519 Patented Nov. 16, 1954 PUMP SPEED CONTROLLING AND UNLOADING MEANS Win W. Paget, Michigan City, Ind., assignor to Joy Manufacturing Company, Pittsburgh, Pa., a corporation of Pennsylvania Application March 3, 1950, Serial No. 147,354

20 Claims. (Cl. 230-4) My invention relates to controlling apparatus, and more particularly to apparatus for automatically controlling the speed and the loading and unloading of pumps-particularly air cmpressors-in accordance with pump discharge pressure variations.

In the operation of internal combustion engine driven compressors it is desirable: first, that while the compressor discharge pressure is in the desired range-for example, 88 to 93 p. s. i. gauge-the speed of the compressor be controlled generally inversely to the pressure, so that as far as possible the compressor may be operated continuously and in such a way as to maintainthe discharge pressure within the chosen limits mentioned merely by variation of its speed; second, that, if the demand for air be so low that even at the lowest normal operating speed the discharge pressure cannot be kept from rising above the chosen upper limit, then, after operation at such lowest normal operating speed until the discharge pressure exceeds the chosen upper limit by a predetermined substantial amountfor example, seven pounds-the compressor be unloaded and be slowed down to a substantially lower idling speed; third, that the compressor then be operated unloaded at such lower idling speed until the discharge pressure falls back at least substantially said predetermined amount-in the example, 7 p. s. i.and back to the upper limit of the chosen pressure range and then be brought back up to the lowest normal loaded operating speed and reloaded; and fourth, that there then be either (a) a gradual speeding up of the compressor if the compressor discharge pressure continues to fall, or, (b) operation at said lowest normal operating speed if compressor discharge pressure remains constant or (c) a return to unloaded condition and a renewed slowing down to an idling speed if the compressor discharge pressure again builds up the predetermined amount above mentioned. In such a system it is desirable that the controlling devices be as simple as possible, that they be adjustable to all the critical pressures in a simple manner, that, as fully as possible, the controls be under the regulation of a minimum number of compressor discharge pressure responsive devices and use a minimum number of pilot mechanisms, and that the control mechanism be so arranged that adjustments of certain of the critical pressures need not affect others of such pressures.

To meet the objective set forth, I prefer to employ according to a preferred embodiment of the present invention, a primary control mechanism which includes a pressure responsive element of relatively substantial area, subjected on one side to the pressure which is to be controlled (compressor discharge pressure) and on its other side to a pressure which is automatically prevented from exceeding a value which is a predetermined amount less than the lower limit of the desired loaded working range of the compressor. Desirably, means is provided whereby the pressure may be maintained on the last mentioned side of said pressure responsive element and may be increased or diminished through a single adjustment whereby the working pressure range of the compressor may be readily adiusted. Desirably, moreover, means is provided whereby the pressure on the last mentioned side of the pressure responsive element may be bled off at will. Desirably, the pressure responsive element acts on another element which is movable to effect a reduction in the operating speed of the compressor as compressor discharge pressure increases and which,

uponthe attainment thereof .to .a predetermined position of said pressure responsive element, can be moved no further by the latter, such position corresponding to the desired minimum loaded operating speed of the compressor.

Desirably, the structure of the device includes another pressure responsive element subjected to compression discharge pressure and cooperating with the first pressure responsive element in the formation of an expansible chamber communicating with the compressor discharge, said second pressure responsive element movable to effect both unloading of the compressor and further movement of the element which is movable to effect a reduction in the operating speed of the compressor, so as to bring the compressor down to an idling speed, said second pressure responsive element being subjected on its side opposite the one subjected to compressor discharge pressure to a pressure which is automatically prevented from exceeding a value which is a predetermined amount less than the value at which unloading of the compressor and operation of the latter at an idling speed are desired to be effected. Desirably, the second pressure responsive element operates on a pilot valve mechanism which controls both unloading apparatus for the compressor and a device for acting on the element movable to effect a reduction in the operating speed of the compressor. Desirably too the structure of the pilot valve mechanism is such that a reduction in compressor discharge pressure substantially equal in amount to the predetermined increase between the start and finish of movement of the second pressure responsive element in the pilot valve moving direction will occur before the pilot valve will operate to effect speeding up and reloading of the compressor. Desirably, the connection between the element movable to effect a reduction in the operating speed of the compressor and the control mechanism of the compressor will include a mechanically adjustable mechanism enabling manual control of compressor speed without alteration of what may be called the fixed adjustment of the apparatus.

It is an object of the invention to provide an improved controlling mechanism for effecting variation in the speed of drive of a compressor and to control the loading and unloading of the latter. It is another object to provide an improved compressor controlling apparatus possessing the characteristics heretofore set forth. It is still a further object of the invention to provide an improved apparatus incorporating the features hereinbefore mentioned. It is still another object of the invention to provide control mechanism of the character mentioned having improved means for varying the several critical operating characteristics of the compressor which it controls. It is still another object to provide an improved compressor controlling apparatus incorporating a plurality of pressure responsive elements subjected on adjacent sides to full compressor discharge pressure, and with separately adjustable means for subjecting the sides thereof which are not subjected to full compressor discharge pressures to different, independently adjustable opposing pressures. Still another object of the invention is to provide an improved internal combustion engine driven pumping apparatus having improved speed controlling and regulating mechanism associated therewith. Other objects and advantages of the invention will hereinafter more fully appear.

In the accompanying drawings, in which for purposes of illustration one illustrative embodiment of my invention is shown,

Fig. 1 is a fragmentary view of a diesel engine with which the illustrative embodiment of a control mechanism according to one aspect of my invention is associated.

Fig. 2 is a left hand view of the specific pressure responsive controlling apparatus shown in Fig. 1.

Fig. 3 is a right hand view of the same apparatus.

Fig. 4 is a longitudinal vertical section through the apparatus, the section being taken on a plane of the line -'-l4 of Fig. 2.

Fig. 5 is a sectional view on the plane of the line 55 of Fig. 4.

Fig. 6 is an enlarged detailed fragmentary section on the plane of the line 6-6 of Fig. 4.

Fig. 7 is a detail section on an enlarged scale on the plane of line 77 of Fig. 4.

Fig. 8 is a detail fragmentary section on the plane of the line 88 of Fig. 4, on an enlarged scale.

Fig. 9 is an axial sectional view through a compressor cylinder head showing inlet and discharge valve mechanisms and unloading devices.

Fig. 10 is a detailed sectional view on an enlarged scale on the same plane as Fig. 4.

Fig. 11 is a diagrammatic view showing the controlling apparatus with a receiver and compressor unloading means.

Referring to the drawings:

It will be noted that my improved controlling mechanism is shown applied to a diesel engine drive compressor. In following the ensuing description, it should be borne in mind that diesel engines are provided with builtin mechanisms for controlling the injection of fueL. In one well-known form of such an invention, in conjunction with which I have chosen to illustrate my invention in its illustrative embodiment, the fuel injection pump plunger is turned by a pinion connected to it and by a rack to one end of which a speed governor controlling shaft is connected. The other end of the rack is linkconnected to a lever, herein indicated at 12, to which a spring 13 is connected and the tension of the spring is adjustable to eifect a change in the engine speed. The spring tension is adjusted by varying the position of a lever 14 to which the other end of the spring 13 is connected. When the rack is moved back and forth by the opposed actions of the governor (not shown) and of the spring 13, the fuel injection pump plunger is turned and the amount of fiuid injected is varied. This mechanism acts on all of the injection pumps simultaneously so that an equal and correct amount of fuel is delivered to each cylinder. It is unnecessary to illustrate this wellknown commercial mechanism other than to the extent of the foregoing description. Obviously, other fuel injection control mechanisms may be controlled by the basic control mechanism of this embodiment of my invention.

For controlling the adjustment of the lever 14, I have provided the improved control apparatus illustratively shown in side elevation in Fig. 1; in opposite end elevations in Figs. 2 and 3, in section in Figs. 4 and and in diagrammatic association with other elements of a gaseous fluid pumping system in Fig. 11, this control apparatus being generally designated 16.

The unit 16 is adapted to cause the engine to operate on the order of 1400 to 1450 R. P. M. at and below a compressor discharge pressure of 88 p. s. i. gauge. As compressor discharge pressure rises above 88 p. s. i. the compressor speed is reduced until at 93 pounds it is 1050 R. P. M. If the compressor discharge pressure rises to 100 pounds unloading is effected and the compressor speed is cut to an idling speed which may desirably be in the range of 550 R. P. M. to 700 R. P. M. When the compressor discharge pressure again falls to 93 pounds, reloading occurs, and the speed returns to 1050 R. P. M.

The control unit 16 is shown as made up of three casing sections or

elements

21, 22 and 23. The casing element 21 carries at its right hand side in Fig. 4 pivotally supported thereon for turning upon a pivotpin 25,.a lever 26. This lever has pivotally connected .to it at 27 another lever 28, whose position relative to the lever 26 is controllable by a mechanically adjustable screw, nut and slot connection 29. (See Fig. 8.) The'lever 28 has a projecting arm 30, which is pivotally connected as at 31 with a link 32 which is in turn pivotally connected as at 33 with an arm 34 rigidly connected with the lever arm 14 previously mentioned. It will be understood that swinging movements of the lever 26 upon the pivot mounting 25 will, if the screw, nut and slot connection 29 is tight, effect swinging movements of the bell crank lever 14, 34. Movement of the lever 26 clockwise about its pivot 25, reduces the tension of the spring 13, thus causing slowing down of the diesel engine. It will also be understood that by loosening the screw, nut and bolt connection 29, the lever 28 may be swung independently of the lever 26 and thus provide manual change in the speed of theengine when it is desired.

A relatively long, fiat-rate spring 40 is supported between a recessed bracket portion 41 on the casing element 21 and an adjustable screw 42 provided with a lock nut 43 and carried by the lower end of the lever 26 and adapted to engage at 44 a spring follower member 45. The force exerted by the spring 40 in any angular position of the lever 26 may evidently be varied by varying the adjustment of the screw 42 in the lower end of the lever 26.

The distance which the upper end of the lever 26 can move to the left in Fig. 4-and thus the maximum operating speed of the diesel engine which drives the compressor--is controllable by an adjustable screw 50 having a lock nut 51 and mounted in the upper end 52 of the lever 26 and adapted to engage an abutment surface 57, later again referred to. It will be noted that, in the absence of other forces, the spring 40 will maintain the lever 26 in such a position that the end of the screw 50 will engage the abutment surface 57.

It has been noted that the control unit 16 is shown as made up of three

casing elements

21, 22 and 23. The casing element 22 is generally annular and has an inner periphery 64 and end surfaces 65 and 66.

Sections

21 and 23 are adapted 'to clamp between them and the surfaces 65 and 66 respectively, flexible

metallic diaphragm elements

67 and 68. The element- 21 has an annular surface 69 engageable with a plane peripheral portion 70 of the diaphragm 67 and pressing this portion against the surface 65. correspondingly, casing element 23 has anannular surface 71 engaging an annular plane portion 72 of the diaphragm 68 and pressing the latter, in the assembled relation of the parts, against the surface 66. As a result of this construction there is provided a chamber 75 between the

diaphragms

67 and 68, this chamber being bounded by the

adjacent surfaces

77 and 78 respectively of the

diaphragms

67 and 68 and by the surface 64. A passage 80, with which conduit 81, later further mentioned, communicates, opens radially through the section 22 and into the chamber 75. A radial passage 82 closed at its outer end by a plug 83, opens from the chamber 75 as shown in Fig. 5. A passage 84, formed in the casing section 21, connects the radial passage 82 in the section 22 with another and longer radially extending passage 85 in the casing section 21. The outer end of the radial passage 85 is closed by a plug 86. It may be noted that the portion of the passage 84 which extends through the diaphragm 67, is surrounded by a sleeve or bushing 87, seated in part in the recess 88 in the casing section 22, and in part in a bore 89 formed in the casing section 21. Similar arrangements are used wherever passages pass through openings in the diaphragms and this detail of construction will not be mentioned in connection with other such passages.

The casing section 21 is recessed at 90 at the side next to the diaphragm 67. This casing element also has a bore 92 coaxial with the recess 90, and with the bore 92 the radial passage 85 communicates. A smaller bore 93 is arranged coaxial with the bore 92, and against a shoulder 94 formed at the junction of said bores an appropriate packing ring 95 is arranged. The end of the bore 92 towards the chamber 90 is provided with a threaded plug 96 and a guide bushing 97 is arranged in the outer end of the bore 93. The plug 96 is traversed by an opening 99 and through this opening and through the bore 100 of the bushing 97, there extends an operating rod 102 which carries at its inner end a plate 103 which is engaged by a'flat external portion 104 of the diaphragm 67, and which is adapted upon predetermined movement to the right in Figs. 4 and 5, to engage the end of bushing 96. The outer end of the operating rod 102 is adapted to engage an adjustable screw element 105, provided with a lock nut 106 and extending through a threaded opening 107 in the lever 26. It will be evident that the diaphragm 67 is capable of exerting a limited control upon the angular position of the lever 26, through the operating rod 102a control which, so far as further movement of the lever is concerned, is terminated when the plate 103 engages the face of the plug 96. The control rod 102 is slightly smaller in diameter than the internal diameter of the opening 99, with the result that there is a constant restricted communication between the chamber 75 and the chamber 90, this communication being maintained even when the plate 103 engages the plug 96 by reason of the radial grooving of the end of the latter, as at 110. The chamber 90 is in constant communication through an opening 111 with a chamber 112, formed in the casing element 21. The chamber 112 has arranged radially outwardly of it an enlarged bore 114, in which there' is threadedly secured a ball valve seat and valve housing member115. The threaded con nection 116 enables the member 115 to be pressed tightly against a washer 117 supported on a shoulder 118 at the junction of the chamber 112 and the bore 114. The member 115 contains a chanber 120 in which there is a ball valve 121. The ball valve is engageable with a seat 122 surrounding a port 123 which, when the ball 121 is lifted from its seat, provides communication between the chamber 112 and the chamber 120. The chamber 120 communicates through radial passages 125 with an annular space 126, between the member 115 and the peripheral wall of the bore 114, and the annular space 126 is vented to atmosphere through an opening 127. Thus, the chamber 120 is constantly vented to atmosphere. The ball 121 is pressed to its seat by a follower 130 having a stem 131 and received in an adjustable follower chamber-providing member 133. The position of the follower chamber providing member is variable by reason of its threaded connection 134 with the member 115 and a lock nut 135 is adapted to hold the parts in adjusted position. A spring 136 is enclosed Within the follower chamber providing member 133 and engages the follower 138. The tension of the spring may be varied by changing the relation of the follower chamber providing member to the member 115. The loading of the ball valve 121 will be described more fully later.

A passage 138 opens out of the radial passage 80 and extends to the left in Fig. 4 and is connected to a passage 139, which communicates with a passage 140 extending radially of the casing section 23. The passage 140 terminates in a reduced portion 141 and opens into a chamber 142. The chamber 142 constitutes a portion of a stepped bore generally designated 143, which, though it is broken up by a plug, a packing, a bushing, and a valve seat member, and closed at its outer end by another plug, may be said to extend completely through the casing element 23 along the axes of the latter. Starting at the left hand end of the casing element 23, as viewed in Fig. 4, it will be observed that there is, forming a portion of the bore 143, an internally threaded, relatively large chamber 144 closed by a threaded plug 145 and communicating with a slightly smaller bore or chamber 146 forming another portion of the bore 143. There is a counterbore 147 between the chamber 144 and the chamber 146. Within the chamber 146 there is mounted a chambered valve seat element 148, and a valve, herein a ball valve 149, is adapted to seat on the valve seat 150, formed on the valve seat element 148, and this valve is normally pressed towards said seat -by a spring 151, housed within a recess 152 formed in the threaded plug 145. The valve seat element 148 is bored as at 155 so that the reduced portion 156 of a valve stem 157 can extend and move through it. The valve stem extends through a smaller chamber 158 adjacent the valve seat member 148 and the chamber 158 is vented to atmosphere through a passage 159. It may be noted that a conduit 160, of which more will be said shortly, communicates through a passage 161 with the chamber 146. The valve stem 157 extends through, and is guided by a bushing 162 mounted in the bore 143, and also extends through a packing 163 mounted in a slight enlargement 164 of the bore 143. To the right of the packing there is a larger bore 166 in which a threaded plug 167 is mounted. This plug is traversed by an axial bore 168 which also serves as a guide for the stem 157, but its guiding is a loose one since there is provided a small circumferential clearance 169 around the valve stem so that the chamber 142, communicates restrictedly with a large chamber 170 to the left of the diaphragm 68 in Figs. 4 and 5. The stem 157 carries an enlarged plate member 171 which is engageable with a large central portion 172 of the diaphragm 68, between which central portion and the plane portion 72 there is an annular flexible portion 173. It may be noted that the diaphragm 67 is of corresponding construction, having also a flexible portion 176 connecting its central portion and its peripheral portion 70. A spring 178 surrounds the stem 157 and acts between the threaded plug 167 and the plate 171, this spring compensating, at the pressure normally maintained at the opposite sides of the diaphragm 68, for the reduction in pressure area at the left side of the diaphragm occasioned by the valve stem 157. It may now be noted that there is communication between the chamber 75 and the chamber 170 through the opening 138, passage 139, passage 140, passage portion 141, chamber 142 and the annular clearance 169.

The pressure maintained within the chamber is determined by the seating of a relief valve mechanism 180. This mechanism includes a relief valve proper 181, herein shown as the ball type, received in a chamberforming bore 182 in the casing portion 23. Bore 182 is closed at its outer end by a threaded plug 183, housing within a chamber 184 thereof a spring 185 which presses the valve 181 towards a valve seat 186 formed on a hollow valve seat member 187 having a chamber 188 therein. The chamber 188 communicates through a passage 189 with the chamber 170. A passage 191 opens out of the bore or chamber 182 and is provided with a manually controllable valve 192 openable to vent to atmosphere the passage 191 and the chamber 182. The passage 191 is connected by another passage 193 formed in part in each of the

casing elements

23, 22 and 21 and by a further passage 194, with the chamber 90.

The interior of the chambered valveseat member 148 is connected by a passage 200 with a chamber 201 in the casing element 23. Chamber 201 is connected by a passage 202, made up of angularly related

portions

203, 204 and 205, in the casing element 23, a passage portion 206 in the casing element 22, and a passage portion 207 in the casing element 21, with a bore 209 formed in the casing element 21, and arranged parallel with the axis of the operating rod 102. A liner member 211 having a head portion 212 upon which the surface 57 is formed, is threaded into the bore 209 and has a bore 213 providing a cylinder C in which a suitably packed piston 214 is reciprocable. The stem or rod 215 of the piston 214 extends outwardly through a bushing 216 carried by the member 211 and is engageable with the end of a screw 218 having a lock nut 219 and threaded through the lever member 26 between the screw 105 and the screw 50. The chamber 201 is closed by a compound plug including an outer element 221 threaded into the casing member 23 and an inner member 222 threaded into the outer plug member. There is another opening 225 leading from the side of the chamber 201. This opening is connected by a conduit 226, as shown in Fig. 11, with the unloading devices for the compressor. When one unit is to be used to control several engine driven compressors, the inner elements 222 of the compound plugs of the units associated with the compressors to be controlled (the slave compressors) will be screwed down into threads 227 formed in the inner ends of the chambers 201, and thus in the slave units the respective chambers 201 will be cut off from communication with the interiors of the valve seat members 148, while the chambers 201 on the slave units will still continue to communicate with the unloading and idling devices. The removal of the element 222 from the master unit, and the connection of the bores of the several outer elements 221 by suitable conduit means will permit the master unit to control the unloading and idling of all of the units, while each will be controlled as to slow down individually.

The power shaft of the engine is operatively connected by means not shown to a compressor of which one piston is shown at 228 in Fig. 9; and the engine effects reciprocation of the piston 228 in a cylinder bore 229 formed in a cylinder block 230. It will be understood that other compressor cylinders containing pistons connected for reciprocation by the power shaft may be provided if desired, and that such will ordinarily be used. Fluid is admitted through an intake passage 231 and past an inlet valve 232 to the cylinder bore 229, where it is compressed and whence it is discharged past a discharge valve 23-4 to a passage 235 which is connected by suitable connections, not shown, to a receiver R. The cylinder 230 has a head 236 connected thereto by bolts 237, and attached to the head as by bolts 238 is a member 239 having a chamber 240 which receives a piston 241 having connected to it a plate 242. Rods or fingers 243 connected to the plate 242 extend through openings in the cylinder head to engage the inlet valve 232, for unseating the latter and effecting an unloading of the compressor cylinder When the piston 241 is subjected to pressure fluid. The piston 241 is normally held in its raised position by a spring 244 and is adapted to be forced to its lower position against the action of the spring 244 by pressure fluid supplied to the chamber 240 through a conduit 245. The conduit 245 is connected with the conduit 226.

The mode of operation of the invention will be readily understood. It has been noted that the arm 30 of the lever 28 is connected by a link 32 with an arm 34 which is rigidly connected with the arm 14. Accordingly, clockwise rotation of the lever 28, either about its pivot 27 on the lever 26, or with the lever 26 about the pivot 25 of the latter, reduces the resistance offered by the spring 13 in such a manner that the forces produced by the governor of the diesel engine at lower engine speeds will be able to overcome the spring 13 in such a manner as to effect slowing down of the diesel engine. When the wing nut 29 is loosened the lever 28 can be swung relative to the lever 26 and provide hand control of diesel engine speed. By tightening the nut 29 when the lever 28 is in proper relation to lever 26 automatic speed control will be elfected. When the lever 28 is swung as far counter-clockwise about its pivot 27 as is permitted by the length of the slot, and when the adjusting screw 50 is against abutment surface 57, an adjustment of the tension of the spring 13 corresponding to maximum operating speed will be provided.

The diesel engine will operate at maximum speed when the lever 26 is as far to the left at its upper end 52 in Fig. 4 as it can move, and accordingly the adjustment of the stop screw 50 will determine the maximum engine speed and, correspondingly, the maximum speed of the compressor which the engine drives. The adjusting screw 42 carried at the bottom of the lever 26 is adapted to vary the force opposed by the spring 40 to the clockwise movement of the lever 26 by the diaphragm. It has been noted that the diaphragm 67 is adapted to act through a control rod 102 upon adjustable screw 105, and it will be appreciated that the minimum speed at which the engine will drive the compressor while the latter is loaded, will be determined by the adjustment of the screw 105. The adjustment of the screw 218 determines the minimum speed of the engine when the compressor is unloaded.

Certain pressures, which will be understood to be exemplary, may now be reviewed in order that the mode of operation of the apparatus may be more fully understood. The pressure exerted by the spring 136 will be so predetermined by adjustment of the member 133 so that the maximum pressure maintainable within the chamber 112 will be 88 pounds. When compressor discharge pressure, and accordingly the pressure within the chamber 75, is less than 88 pounds, the pressure in the chamber 112 will of course be less than 88 pounds, but when the pressure within the chamber 75 attains to 88 pounds, pressure in the chamber 112 will also be 88 pounds. When the pressure in the chamber 75 goes above 88 pounds the pressure in the chamber 112 will be maintained at 88 pounds by bleeding of fluid from the chamber past the ball valve 121.

The spring 185 will be so precompressed by adjustment of the plug member 183 that the maximum pressure which can be maintained in the

chambers

188 and 170 will be 93 pounds. Accordingly, when the pressure within the chamber 75 is less than 93 pounds the pressure in the chamber 188 will be correspondingly less than 93 pounds. When the pressure in the chamber 75 equals 93 pounds the pressure in the chamber 188 will be 93 pounds. When the pressure in chamber 75 exceeds 93 pounds, the pressure in the chamber 188 will be held to 93 pounds by the bleeding of pressure fluid past the ball valve 181 and through the passages 191, 193, 194, chamber 90, passage 111, chamber 112, past the ball valve 121, through passages 125 and space 126 and out through the passage 127 to atmosphere. Since the setting of the ball valve 121 is lower than the setting of the ball valve 181, the pressure fluid from the chamber 188 will bleed freely to atmosphere when the valve 181 lifts from its seat. The valve 149, due to its loading by the spring 151, and the unbalanced pressure area thereon subjected to compressor discharge pressure will require the pressure in the chamber 75 to attain a value of 100 pounds before the force produced by the unbalanced pressure on the diaphragm 68 will unseat the valve 149 and admit pressure to the unloading devices of the compressor and to act on the piston 214. When the valve 149 is once unseated there will be so substantial an increase in area thereon subjected to compressor discharge pressure that the pressure in the chamber 75 will have to drop off again on the order of 7 pounds, that isback to 93 pounds-before the valve will close and vent the chamber to atmosphere through the interior of valve seat element 148, passage 155, chamber 158, and port 159.

Now let it be assumed that the compressor discharge pressure is 88 pounds and that this pressure subsists in the chamber 75 and in the chamber 112. The same pressure will subsist in chamber 188. Under these circumstances, the lever 26 will occupy the position shown in Figs. 1 and 4 and, the lever 28 being fixed in proper relative position to the lever 26, the compressor will be operating loaded and at its then maximum speed, say, on the order of 1400 to 1450 R. P. M. The smaller the angle between the

levers

26 and 28 the higher will be the top engine speed. If the load-the demand for airis insufficient to use up the compressed air as fast as it is delivered through the compressor discharge line, compressor discharge pressure will commence to build up, and so the pressure in the chamber 75 will commence to build up. There will be no corresponding increase in the pressure in the chamber 112, though there will be a corresponding increase in the chamber 188. Therefore, the diaphragm 67 will commence to move the control rod 102, and, through the abutment of the latter with the adjustable screw 105, the lever 26 will be moved clockwise and a slowing down of the compressor will be initiated. This slowing down will continue, if the receiver pressure continues to increase, until the plate 103 engages the plug 96, at which time the speed of the compressor may have been reduced to on the order of 1050 R. P. M. When the pressure in the chamber 75 reaches 93 pounds the pressure in the chamber 188 will also reach 93 pounds and any further increases of the pressure in the chamber 75, such as may occur if the air demand is still below the rate of compressed air delivery even at the reduced speed of operation of the compressor, will result in cracking from its seat of the ball valve 181 and the maintenance of pressure n the chamber 170 constant at 93 pounds. Subsequent increases in the pressure in chamber 75 will result in a differential in pressure between that chamber and the chamber 170 and the exertion of a force towards the left by the diaphragm 68, until, when the pressure differential becomes equal to 7 pounds, with the example given, the force will be suflicient to unseat the ball valve 149. With this ball valve unseated and with the vent passage 155 closed by the valve stem 157, fluid will be delivered to act on the piston 214 and also through the passage 225 to the unloading devices of the compressor and the compressor will not only be unloaded, but be slowed down an amount corresponding to the position of the lever 26 when the piston 214 reaches the right hand end of the bore 213. This will result in operation at an idling speed, and what this will be will be determined by the adjustment of the screw 218. Anywhere between, say 500 and 700 R. P. M. may be satisfactory.

If there is no demand for air the compressor may continue to operate for a substantial period at the reduced idling speed which corresponds to the position of the lever 26 attained as a result of the movement transmitted to the screw 218 by the piston rod 215. If leakage or air demand commences to reduce the receiver pressure-and the pressure in chamber 75below pounds, there will be a reduction of the force exerted in the left hand direction by the diaphragm 68, but this will be insufficient to permit reseating of the valve 149 and opening of the vent 159 to atmosphere until the pressure in the chamber 75 falls off approximately 7 pounds from the maximum value, that is, to 93 pounds, again. When this reduction in pressure has occurred the supply of fluid to the piston 214 and to the unloading device will be interrupted and these will be vented to atmosphere through the vent port 159. The compressor will then be operated loaded at its minimum loaded speed, for the lever 26 will move counter-clockwise until the screw enages the still projected stem 102.

If the demand for air is less than its rate of delivery at the relatively low speed of operation of the compressor under these conditions, the pressure in the chamber 75 will build up again and there may occur a re-unloading and a re-slowing down to idling speed. On the other hand, if at the slow speed of operation the compressor does not deliver enough air to meet the demand the pressure in the chamber 75 will continue to fall off and as it falls oil. from 93 p. s. i. to 88 the diaphragm 67 will progressively be moved to the left as counter-clockwise movement of the lever 26 is effected by the spring 40 and the compressor speed will build up until the quantity of air delivered equals the air demand and the pressure in the chamber 75 ceases to fall. Of course, if the demand is largeso large that even in the retracted position of the control rod 102, the compressor cannot supply all the air needed, the pressure in the chamber 75 may continue to fall but the engine speed will not be increased above that which prevails when the end of the screw 50 contacts the abutment surface 57--in the case now assumed, 1450 R. P. M.

From the foregoing description, it will be appreciated that I have provided an improved, pressure responsive control mechanism for an engine driven compressor, one particularly adapted for control of a diesel engine driven compressor. The mechanism is a unitary one, it includes a single chamber supplied with compressor discharge pressure and having a plurality of movable bounding walls one by its movements governing speed variation of the compressor while it operates loaded and the other controlling both unloading and idling of the compressor. The movable bounding walls are of relatively large area, but, having their sides opposed to those on which full compressor discharge pressure acts subjected to relatively high pressures, there is no danger of their rupture, and yet there are ample operating forces. A device capable of the control of a plurality of compressors is provided. The construction is simple, rugged and efiicacious.

A very great advantage of the control lies in its capacity for completely independent.adjustability of the full operating speeds, the minimum normal operating speed, the idling speed and the point of unloading and reloading.

While there is in this application specifically described one form both as to apparatus and as to method which the invention may assume in practice, it will be understood that this form of the same is shown for purposes of illustration and that the invention may be modified and embodied in various other forms without departing from its spirit or the scope of the appended claims.

What I claim is:

1. A controlling device for an engine driven compressor unit comprising, in combination, an element movable to control engine speed, means for resiliently pressing said member in one direction, and a plurality of means for moving said element in the opposite direction including an element continuously subjected to compressor discharge pressure and having means associated with it for transmitting its motion to said first mentioned element, another element movable by compressor discharge pressure and having means for transmitting its motion to said first mentioned element, a fourth element subjected to compressor discharge pressure, and a pilot valve controlled by said fourth element and controlling the action of compressor discharge pressure on said third element, said second and fourth elements each having a surface facing the other subjected to compressor discharge pressure.

2. A controlling device for an engine driven compressor unit comprising, in combination, an element movable to control engine speed, means for resiliently pressing said member in one direction, and a plurality of means for moving said element .in the opposite direction including an element continuously subjected to compressor discharge pressure and having means associated with it for transmitting its motion to said first mentioned element, another element movable by compressor discharge pressure and having means for transmitting its motion to said first mentioned element, a fourth element subjected to compressor discharge pressure and a pilot valve controlled by said fourth element and controlling the action of compressor discharge pressure on said third element, said second and fourth elements constituting walls of a common compressor discharge pressure supplied chamber.

3. A controlling device for an engine driven compressor unit comprising, in combination, an element movable to control engine speed, means for resiliently pressing said member in one direction. and a plurality of means for moving said element in the opposite direction including an element continuously subjected to compressor discharge pressure and having means associated with it for transmitting its motion to said first mentioned element, another element movable by compressor discharge pressure and having means for transmitting its motion to said first mentioned element, a fourth element subjected to compressor discharge pressure and a pilot valve controlled by said fourth element and controlling the action of compressor discharge pressure on said third element, said second and fourth elements constituting oppositely facing walls of a common compressor discharge pressure supplied chamber.

-4. A controlling device for an engine driven compressor unit comprising, in combination, an element movable to control engine speed, means for resiliently pressing said member in one direction, and a plurality of means for moving said element in the opposite direction including an element continuously subjected to compressor discharge pressure and having means associated with it for transmitting its motion to said first mentioned element, another element movable by compressor discharge pressure and having means for transmitting its motion to said first mentioned element, a fourth element subjected to compressor discharge pressure and a pilot valve controlled by said fourth element and controlling the action of compressor discharge pressure on said third element, said fourth element also subjected to a superatmospheric fluid pressure less than and independent of variations in compressor discharge pressure during the normal working operating cycle of said device.

5. A controlling device for an engine driven compressor unit comprising, in combination, an element movable to control engine speed, means for resiliently pressing said member in one direction, and a plurality of means for moving said element in the opposite direction including an element subjected to compressor discharge pressure and having means associated with it for transmitting its motion to said first mentioned element, another element movable by compressor discharge pressure and having means for transmitting its motion to said first mentioned element, a fourth element subjected to compressor discharge pressure and a pilot valve controlled by said fourth element and controlling the action of compressor discharge pressure on said third element, said second and fourth elements each being subjected to a superatmospheric fluid pressure acting oppositely to compressor discharge pressure and less than and independent of variations in compressor discharge pressure during the normal working operating cycle of said device.

6. A controlling device for an engine driven compressor unit comprising, in combination, an element movable to control engine speed, means for resiliently pressing said member in one direction, and a plurality of means for moving said element in the opposite direction including an element continuously subjected to compressor discharge pressure and having means associated with it for transmitting its motion to said first mentioned element, another element movable by compressor discharge pressure and having means for transmitting its motion to said first mentioned element, a fourth element subjected to compressor discharge pressure and a pilot valve controlled by said fourth element and controlling the action of compressor discharge pressure on said third element, said second and fourth elements each being subjected to an oppositely acting superatmospheric fluid pressure less than and independent of variations in compressor discharge pressure during the normal worklng operating cycle of said device, said fourth mentioned element having the fluid pressure acting oppositely to compressor discharge pressure thereon greater than the corresponding fluid pressure on said first mentioned compressor discharge pressure subjected element.

7. A controlling device for an engine driven compres sor unit comprising, in combination, an element movable to control engine speed, means for resiliently pressing said member in one direction, and a plurality of means for moving said element in the opposite direction including an element freely subjected on one side to compressor discharge pressure and having means associated with it for transmitting its motion to said first mentioned element, another element movable by compressor discharge pressure and having means for transmitting its motion to said first mentioned element, a fourth element freely subjected on one side to compressor discharge pressure and a pilot valve controlled by said fourth element and controlling the action of compressor discharge pressure on said third element, said second and fourth elements having their sides not freely subjected to compressor discharge pressure restrictedly connected therewith, and relief valve means for bleeding oft pressure from said other sides, to preclude the subjection of said last mentioned sides to pressures as high as normal working compressor discharge pressure.

8. A controlling device for an engine driven compressor unit comprising in combination, an element movable to control engine speed, means for resiliently pressing said member in one direction, and a plurality of means for moving said element in the opposite direction including an element freely subjected on one side to compressor discharge pressure and having means associated with it for transmitting its motion to said first mentioned element, another element movable by compressor discharge pressure and having means for transmitting its motion to said first mentioned element, a fourth element freely subjected on one side to compressor discharge pressure and a pilot valve controlled by said fourth element and controlling the action of compressor discharge pressure on said third element, said second and fourth elements having their sides not freely subjected to compressor discharge pressure restrictedly connected therewith, and relief valve means for bleeding off pressure from said other sides, to preclude the subjection of said last mentioned sides to pressures as high as normal working compressor discharge pressure, the relief valve means associated with said fourth element having the higher settin 9. a controlling device for an engine driven compressor unit comprising, in combination, an element movable to control engine speed, means for resiliently pressing said member in one direction, and a plurality of means for moving said element in the opposite direction including an element freely subjected on one side to compressor discharge pressure and having means associated with it for transmitting its motion to said first mentioned element, another element movable by compressor discharge pressure and having means for transmitting its motion to said first mentioned element, a fourth element freely subjected on one side to compressor discharge pressure and a pilot valve controlled by said fourth element and controlling the action of compressor discharge pressure on said third element, said second and fourth elements having their sides not freely subjected to compressor discharge pressure restrictedly connected therewith, and relief valve means for bleeding off pressure from said other sides, to preclude the subjection of said last mentioned sides to pressures as high as normal working compressor discharge pressure, the relief valve means associated with said fourth element having the higher setting, and said last mentioned relief valve means connected to discharge to the other relief valve means.

10. A controlling device for an unloading means equipped engine driven compressor unit comprising, in combination, an element movable to control engine speed, means for resiliently pressing said member in one direction, and a plurality of means for moving said element in the opposite direction including an element subjected to compressor discharge pressure and having means associated with it for transmitting its motion to said first mentioned element, another element movable by compressor discharge pressure and having means for transmitting its motion to said first mentioned element, and means for controlling the supply and venting of compressor discharge pressure relative to said third element including a fourth element subjected to compressor discharge pressure and a pilot valve controlled by said fourth element, said pilot valve device also constituting a controlling device for the unloading means of said unit and said second and fourth elements constituting opposite walls of a compressor discharge pressure supplied chamber.

11. In a controlling device, in combination, a casing having an annular central portion and recessed head portions one at each side of said central portion, flexible diaphragms clamped one between each head portion and the side of said annular central portion which is nearer thereto, means for conducting a pressure to be controlled to the space between said diaphragms, means for conducting pressure to the spaces between said diaphragms and said recessed head portions, means for bleeding pressure from said last mentioned spaces automatically upon the attainment of the pressure within such spaces to different predetermined values, an operating rod operatively connected with one of said diaphragms, a fluid operated operating rod arranged to act in like direction with said operating rod first mentioned, a control member movable by said operating rods, a third operating rod operatively connected with the other of said diaphragms, and valve means controlled by said third operating rod 12 for controlling the supply and venting of fluid for the control of said fluid operated operating rod.

12. In a controlling device, in combination, a casing having an annular central portion and recessed head portions one at each side of said central portion, flexible diaphragms clamped one between each head portion and the side of said annular central portion which is nearer thereto, means for conducting a pressure to be controlled to the space between said diaphragms, means for conducting pressure to the spaces between said diaphragms and said recessed head portions, means for bleeding pressure from said last mentioned spaces automatically upon the attainment of the pressure within such spaces to different predetermined values, an operating rod operatively connected with one of said diaphragms, means for limiting the movement of said rod, a fluid operated operating rod arranged to act in like direction with, but with greater travel than, said operating rod first mentioned, a control member movable by said operating rods, a third operating rod operatively connected with the other of said diaphragms, and valve means controlled by said third operating rod for controlling the supply and venting of fluid for the control of said fluid operated operating rod.

13. In a controlling device for a motor driven compressor, in combination, a casing having an annular central portion and recessed head portions one at each end of said central portion, flexible diaphragms clamped one between each head portion and the adjacent side of said annular central portion, a connection on said casing with the space between said diaphragms for the introduction into said space of compressor discharge pressure, means for conducting pressure to the spaces between said diaphragms and said recessed head portions, means for bleeding pressure from said last mentioned spaces automatically upon the attainment of the pressures within such spaces to respectively different predetermined values, an operating rod operatively connected with one of said diaphragms, an operating rod operatively connected with the other of said diaphragms, valve means controlled by said second operating rod, a servo-motor controlled by said valve means and having an operating rod, and a member adapted to act as a motor speed control element, and with which said first and third operating rods coact to control its position.

14. In a controlling device for a motor driven compressor, in combination, a casing having an annular central portion and recessed head portions one at each end of said central portion, flexible diaphragms clamped one between each head portion and the adjacent side of said annular central portion, a connection on said casing with the space between said diaphragms for the introduction into said space of compressor discharge pressure, means for conducting pressure to the spaces between said diaphragms and said recessed head portions, means for bleeding pressure from said last mentioned spaces automatically upon the attainment of the pressures within such spaces to respectively different predetermined values, an operating rod operatively connected with one of said diaphragms, an operating rod operatively connected with the other of said diaphragms, valve means controlled by said second operating rod, a connection on said casing, controlled by said valve means, for a conduit connected with compressor unloading means, a servo-motor controlled by said valve means and having an operating rod, and a member adapted to act as a motor speed control element, and with which said first and third operating rods coact to control its position.

15. A controlling device. for an engine driven compressor unit for effecting, through a variation in the tension of a governor spring, a control of engine speed, said controlling device comprising a lever swingable to vary the tension of a governor spring, and actuating means for said lever including spring means for swinging the same in one direction and fluid operated means for swinging said lever in the opposite direction, said fluid operated means including a cylinder and a piston therein, and fluid supply means for said cylinder including a valve and operating means therefor including an element having areas at its opposite sides for the action thereon of fluid pressure, means for delivering compressor discharge pressure freely to one side of said element, and means for continuously subjecting the area at the other side of said element to a fluid pressure less than and independent of variations in the compressor discharge pressure during the normal operation of the unit.

16. A controlling device for an engine driven compressor unit for effecting, through a variation in the tension of a governor spring, a control of engine speed, said controlling device comprising a lever swingable to vary the tension of a governor spring, and actuating means for said lever including spring means for swinging the same in one direction and fluid operated means for swinging said lever in the opposite direction, said fluid operated means including a cylinder and a piston therein and fluid supply means for said cylinder including a valve and operating means therefor including an element having areas at its opposite sides for the action thereon of fluid pressure, means for continuously delivering to the opposite sides of said element pressure fluid from a common source, and means for venting fluid from one side of said element automatically when the pressure from said source builds up above a predetermined value.

17. A controlling device for an engine driven compressor unit for effecting, through a variation in the tension of a governor spring, a control of engine speed, said controlling device comprising a lever swingable to vary the tension of a governor spring, and actuating means for said lever including spring means for swinging the same in one direction and fluid operated means for swinging said lever in the opposite direction, said fluid operated means including a cylinder and a piston therein and fluid supply means for said cylinder including a valve and operating means therefor including an element having areas at its opposite sides for the action thereon of fluid pressure, means for delivering to the opposite sides of said element continuously a pressure fluid from a common source, means for venting fluid from one side of said element automatically when the pressure from said source builds up above a predetermined value, and valve means for venting fluid from said one side of said element at will.

18. A controlling device for an engine driven compressor unit for effecting, through a variation in the tension of a governor spring, a control of engine speed, said controlling device comprising a lever swingable to vary the tension of a governor spring, and actuating means for said lever including spring means for swinging the same in one direction and fluid operated means for swinging said lever in the opposite direction, said fluid operated means including a cylinder and a piston in said cylinder and controlling means for supplying and venting fluid relative to said cylinder including a valve and operating means therefor including an element having areas at its opposite sides for the action thereon of fluid pressure, means for delivering compressor discharge pressure freely to one side of said element, means for delivering compressor discharge pressure in restricted volume to the other side of said element, and a spring loaded relief valve responsive to the pressure which acts thereon and having provision for the adjustment of the load thereon for precluding the building up of pressure in excess of a given value at said latter side.

19. A controlling device for an engine driven compressor unit for effecting, through a variation in the tension of a governor spring, a control of engine speed, said controlling device comprising a lever swingable to vary the tension of a governor spring, and actuating means for said lever including spring means for swinging the same in one direction and fluid operated means for swinging said lever in the opposite direction, said fluid operated means including a cylinder and a piston in said cylinder and controlling means for supply and venting fluid relative to said cylinder including a valve and operating means therefor including an element having areas at its opposite sides for the action thereon of fluid pressure, means for delivering compressor discharge pressure freely to one side of said element, means for delivering compressor discharge pressure in restricted volume to the other side of said element, a spring loaded relief valve having provision for the adjustment of the load thereon for precluding the building up of pressure in excess of a given value at said latter side, and means for venting pressure from said latter side at will having a flow capacity exceeding the flow capacity of said means for delivering compressor discharge pressure in restricted volume.

20. In combination, in a controlling device for the unloading means and the engine speed of an engine driven compressor having means for varying the engine speed and means for unloading the compressor, a casing providing a chamber having opposed flexible walls, means for supplying compressor discharge pressure to said chamber, plungers operable by said walls, means for subjecting the sides of said flexible walls remote from said chamber to compressor discharge pressure at a restricted rate, means for relieving said sides of pressures in excess of different predetermined values below compressor discharge pressure, an engine speed control element movable in a predetermined direction to reduce engine speed, one of said plungers operable by its coacting flexible wall to actuate said speed control element in said predetermined direction, a fluid operated servo mechanism for actuating said control element further in said direction, and a control valve operable to eflect compressor unloading and supply of fluid to said servo mechanism, said control valve engageable by the other of said plungers.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,096,265 Richards May 12, 1914 2,102,865 Vickers Dec. 21, 1937 2,294,410 Lamberton Sept. 1, 1942 2,454,363 Wineman Nov. 23, 1948