US3044681A - Control circuit - Google Patents

Description

July 17, 1962 E. A. WACHSMUTH CONTROL CIRCUIT Filed Aug. 27, 1959 FIG. 1.

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United States Patent Q 3,044,681 CONTROL ClRCUlT Erich A. Wachsmuth, Michigan City, 11111., assignor to Joy Manufacturing Company, Pittsburgh, Pin, .a corporation of Pennsylvania Filed Aug. 27, 1959, Ser. No. 836,499 13 Claims. (Cl. 2305) This invention relates to a control circuit and more particularly to a circuit for controlling the fuel consumption of and the quantity of compressed medium delivered by a counterstroke type of free piston engine compressor.

As more clearly described in Patents Nos. 2,755,988 and 2,841,322, issued July 24, 1956, and July 1, 1958, respectively, a counterstroke free piston engine compressor comprises two compressor units of the opposed piston type so arranged and connected that the work stroke of the pistons of one unit are attended by the compression strokes of the pistons of the other unit, there being mechanical connections by the corresponding piston pairs of the units and also mechanical connections between the mechanically connected pairs 'sothat compression strokes always attend working strokes and the elements of the complete compressor are properly synchronized. Since the one pair of pistons drives the other pair, it Will readily be appreciated the proper amount of fuel must be supplied to maintain the work output of the compressor at all times or otherwise the compressor will stall or overstroke. In the past it has been known to increase and decrease fuel injected to such a compressor unit with relation to the work output of the compressor by employing a pressure responsive control device which is utilized to reduce the amount of fuel only after a predetermined high receiver pressure has been achieved but which device has been subjected to the pressure of the receiver throughout its entire range of pressures. Such a device is not as sensitive as a device which is only actuated after the receiver has achieved such predetermined pressure.

Accordingly, one object of this invention is to provide a new and improved circuit for controlling the fuel consumed by a free piston counterstroke engine compressor throughout its entire operating range.

Another object of this invention is to provide a new and improved circuit for controlling the fuel consumed by a free piston counterstroke engine compressor which includes a device which is operative through a limited range of high receiver pressure to reduce the amount of fuel received by the engine compressor.

Still another object of this invention is to provide a ew and improved circuit for controlling the fuel consumed by a free piston counterstroke engine compressor which includes a device for effecting fuel discharge by the fuel pumps therefor at a variable rate.

A more specific object of this invention is to provide a new and improved circuit for controlling the fuel consumed by a free piston engine counterstroke compressor comprising a first pressure responsive device which effects a variable rate of fuel discharge by the fuel pump therefor up to an initial high receiver pressure and a second pressure responsive device which is effective only after such initial high receiver pressure has been achieved to reduce the fuel delivered by the fuel pump therefor.

Another specific object of this invention is to provide a new and improved circuit for controlling the fuel consumed by a free piston counterstroke engine compressor comprising a control valve which is effective after an initial high receiver pressure has been achieved to permit simultaneous operation of a device for unloading the compressor and for decreasing the fuel supplied thereto.

- when taken in conjunction with the following drawing, in

which:

FIG. 1 is a schematic diagram of a control circuit construtced in accordance with the principles of this invention as employed with a counterstroke type of free piston engine compressor.

FIG. 2 is a side elevational view of a control valve in its open position as employed in the circuit of FIG. 1.

As more fully described in the above identified patents a free piston coun-terstroke type of engine compressor 2 is provided with a pair of cylinders which are connected to fuel pumps 4, respectively, for supplying fuel for operating the engine compressor 2. The engine compressor 2 is also provided with four compressor cylinders which discharge through a line 6 to a suitable receiver 8 for the medium being compressed. Each cylinder of each pair of opposed compressor cylinders is provided with a suitable hydraulically actuated unloading means for varying the quantities of compressed medium delivered by each compressor cylinder. The pairs of unloading devices for opposed compressor cylinders are simultaneously actuated by means of suitable hydraulic impulse givers 10, respectively.

The construction of the fuel pumps 4 may be of any suitable conventional form, having provision for auto matic variation of the instant of fuel delivery and the duration of such delivery, the variation being effected in a generally well known manner, as by the reciprocation of a rack bar 5, which rotates elongated plungers in the pumps 4 on their axes in such a manner as to vary the fuel delivery of the pump between a maximum and zero.

r By the proper shaping of the usual slanting control edge of the pump plunger practically any rate of fuel delivery can be effected as a function of the angle of rotation of the pump plungers. As in the case of the fuel pump the control element of each impulse giver it) is a plunger with a sloping control edge reciprocated in synchronism with the compressor piston with which it is coordinated and moving in a bore in a cylinder which is provided for it. The impulse givers 10 also have provision for automatic variation of the duration of their impulses which are effected in a generally well known manner as by the reciprocation of a suitable rack bar 7.

As shown, the rack bar 5 is pivotably connected to one end of an elongated lever 12 to which the ou-ter'end of a piston rod 14 of a pressure responsive device 16 is also pivotably secured at an intermediate portion thereof and to which the outer end of a piston rod 18 of a pressure responsive device 20* is also pivotably secured at the other end thereof. As is well known, such counterstroke type of compressors are designed to provide compressed medium throughout a range of pressures which vary from practically compressor inlet pressure to a pressure substantially above the inlet pressure of the medium prior to its being compressed. For the purpose of more readily understanding this invention air will be employed as the compressed medium in the description hereof which has an inlet pressure at atmospheric pressure.

As shown the inner end of the piston rod 14 is rigidly secured to a piston 22 which is slidably received within the bore of a closed ended cylinder 24 of the pressure responsive device 16 Whi'ch'extends outwardly from the lever 12. The piston 22 is biased outwardly from the lever 12 by means of a multiple spring structure within the cylinder 24 which comprises three axially aligned closed end helical springs 26, 28 and 30 acting between the piston 22 and the end of the cylinder 24 adjacent the lever 12. The bore of the cylinder 24 is connected by means of a suitable line 32 to the receiver 8 so that as the pressure increases in the receiver 8 the piston 22 is moved outwardly of the cylinder 24 towards the lever 12. As will become more apparent hereinafter the pressure responsive device 20 is inoperative below the lower design pressure so that as the piston rod 14 moves outwardly of the cylinder 24 the lever 12 pivots about the pivotable connection between the lever 12 and the piston rod 18 to move the rack with reference to the fuel pumps 4 so as to increase the fuel delivered by the fuel pumps 4.

Inasmuch as the springs 26, 28 and 30 are axially aligned, the deflection per unit of applied load of the spring system is determined by the composite characteristic of the three springs. Since each spring 26, 28 and 3% is individually formed, each spring has its own spring characteristic which may be varied within design limitations, to provide an innumerable number of characteristics for the spring system. With such a three spring system the deflections per unit of applied load of the spring system is greater than the deflection per unit of applied load of any spring alone or in combination with either of the other springs. In such a system, if any one spring were eliminated the remaining two springs would have a greater deflection per unit of applied load than a single spring and would have a smaller deflection per unit of applied load than the three axially aligned springs. if two springs were eliminated the remaining spring would have a still smaller deflection per unit of applied load.

With the above principles in mind, this invention provides the three springs 26, 28 and 30 with different deflections per unit of applied load whereby one spring achieves its closed height before the other two so that the deflection per unit of applied load of the remaining springs is smaller than before. One of the remaining springs achieves its closed height before the other so that the deflection per unit of load of the remaining spring is still smaller. Thus, the three springs provide a variable deflection rate which is a non-linear rate through the operating range of the spring system 26, 28 and 30. If desired rather than employ the closed heights of the springs 26, 28 and 30 as the limiting factor, suitable cup-shaped retainers 34 can be placed over each end of each spring so that the engagement of the opposed free edges thereof will limit the deflection of the spring contained therebetweeen. As shown the retainers between the springs 26, 28 and 28, 36 may be formed as one-piece members 34 respectively.

The impulse givers It) are controlled by means of an other pressure responsive device 38 having a piston rod 44 rigidly secured to a piston 42 which is slidably received within the bore of a closed ended cylinder 40. The piston rod 44 extends outwardly from the cylinder it) and is pivotably connected to one end of an elongated lever 46. The other end of the lever 46 is pivotably connected to the rack 7 and the lever 46 is pivotably connected intermediate its ends to the frame of the compressor 2 so that movement of the piston rod 44 towards the lever 46 causes the rack 7 to be moved with relation to the impulse givers so that the duration of the impulses delivered thereby increases. The piston 42 is biased outwardly from the lever 46 by means of a suitable spring within the cylinder 46' so that the piston rod 44 normally causes the rack 7 to be located with respect to the impulse givers 10 so that the compressor delivers its full capacity.

The pressure responsive device has a cylinder 47 and a biased piston 48 secured to the piston rod 18 to provide a device similar in construction and operation as the pressure repsonsive device 38. As will become more apparent hereinafter movement of the piston 48 can only occur after the piston 22 of device 16 has completed its full travel towards the lever 12 so that the subsequent movement of the piston 48 causes the piston rod 18 to pivot the lever 12 about the pivotable connection between the piston rod 14 and the lever 12 whereby the rack 5 is moved in the reverse manner as heretofore described and the fuel delivered by the fuel pumps 4 is decreased. The cylinders 40 and 47 are connected by means of a suitable line 41 so that the pistons 42 and 48 thereof move concurrently upon increases of pressure in the line 41.

The line 41 is selectably connected to the receiver 8 by means of an amplifying device which is another pressure responsive device comprising an elongated housing 50 the upper portion of which has an elongated bore 51 in which an elongated spool 52 is reciprocably received. The lower portion of the housing 50 is enlarged with respect to the bore 51 to provide a chamber 54 for re-. ceiving a suitable means for biasing the spool 52 outwardly from the chamber 54. As shown, such biasing means comprises an elongated closed end helical spring 56 extending upwardly within the chamber 54 and having suitable spring retainers 58 and 59 inserted over the upper and lower ends of the spring 56, respectively. The upper spring retainer 58 engages an integral axial extension 60 on the spool 52 which extends inwardly of the chamber 54 and the lower spring retainer engages a stud 62 threadedly secured to the bottom of the housing 50 so as to be movable to vary the compression of the spring 56 between the spring retainers 58 and 59. The upper end of the bore 51 is provided with a chamber 64 which is connected to the line 32 by means of a suitable line 66 whereby the pressure of the receiver 8 is exerted over the area of the upper surface 68 of the spool 52 to exert a downwardly directed force on the spool 52 to overcome the upwardly directed force on the spool 52 by the spring 56. With such structure the spool 52 will only move after the bias of the spring 56 has been overcome, and as such bias is adjustable, movement of the spool 52 may be set to occur at a given receiver pressure.

As shown, the spool 52 is provided with an elongated portion 70 intermediate its ends of a reduced cross section which extends centrally of the bore 51 to provide an elongated annular chamber 72 within the bore 51 intermediate its ends. By such undercutting of the spool 52 an annular surface 74 is provided on the spool 52 at the upper end of the chamber 72. In order to insure that the devices 38 and 20 are ineffective to obtain any movement of the levers 46 and 12 below the low design pressure, that is, before any downward movement of the spool 52 occurs, the lower portion of the chamber 72 is suitably vented to atmosphere by a suitable line 76 extending therefrom. The chamber 72 is also suitably connected to the line 41 by a suitable line 78. With such connections the line 41 is connected to atmospheric pressure through the chamber 72 and the line 76 when the spool 52 is in its upper position in the bore 51.

It will be noted that the line 78 is also connected by a suitable line to the bore 51 immediately below the upper surface 68 of the spool 52 so that when the spool 52 is biased to its upper position in the bore 51 (FIG. I) the lien 80 is closed by the side of the spool 52 extending downwardly from the upper surface 68.- By so relating the openings 79 and 81 of the lines 78 and 80, respectively, to the bore 51 to the surfaces 74 and 68, respectively, downward movement of the spool 52 will immediately start to connect the chamber 64 to the line 30 and concurrently start to close the line 78 from the chamber 72 which, since the chamber 72 is formed by the spool 52, moves in the same manner as the spool 52. In addition the ports 79 and 81 are preferably identical so that the area of the opening of one line 78 or 80 equals the area of closing of the other line 78 or 80.

For the purpose of better understanding this invention the operation thereof will be described with relation to certain pressure values, however, it is to be realized that such pressure values are illustrative only and do not constitute any required pressure values. Thus, assuming that the compressor 2 is to be initially started at zero pounds per square inch gauge pressure, that is atmospheric pressure, existing in the receiver 8 all the devices described are in the positions as shown in FIG. 1 and the fuel pumps 4 are located to supply the proper quantity of fuel to effect the initial compression of the quantity of air taken in and discharged to the receiver 8. As soon as such initially compressed air is discharged to the closed receiver 8' the pressure in the receiver 8 starts to rise so that the work of compression of the compressor 2 concurrently starts to rise. The pressure rise in the receiver 8 is, however, simultaneously transmitted through the line 32 to the pressure responsive device 16 to cause the spring system 26, 28 and 30 to be compressed and move the rack 5 so that the fuel pumps 4 deliver an increasing quantity of fuel to the compressor 2. Since the work of compression of the compressor 2 increases rapidly as the receiver 8 pressure increases from atmospheric presysure a deflection of the spring system 26, 28 and 30 is provided which results in the proper advance of the fuel pumps 4. In practice a spring system 26, 28 and 30 for controlling the rack 5 from zero to 95 lbs. per square inch gauge pressure within the receiver 8 has been found to be satisfactory. When the receiver 8' pressure is within the range of the spring system the work of compression is constantly increasing so that the fuel pumps 4 must provide an increased amount of fuel to the compressor 2; however, the rate of increase of the work of the compression is not as great as initially existed when the receiver pressure is zero so that the spring system provides for fuel increases at a lower rate as the spring system is deflected.

In the example of a compressor delivering air from 95 to 105 lbs. per square inch gauge the spool 52 is provided with a bias by means of the spring 56 so that no movement thereof can occur until the receiver pressure exceeds 95 lbs. per square inch guage. As soon as the receiver 8 reaches 95 lbs. per square inch gauge the piston rod 14 will achieve its full outward travel towards the lever 12 and be retained in such outward position by the receiver pressure as long as it exceeds 95 lbs. per square inch gauge. As long as the pressure in the receiver 8 is insufficient to overcome the bias of the spring 56, the opening 81 remains closed and the system comprising the lines 78, 80, and 41, the chamber 72, and the chambers of the pressure responsive devices 20 and 38 is at atmospheric pressure. As the receiver 8 pressure starts to rise above the pressure required to move the spool 52, the spool 52 overcomes the bias of the spring 56 and moves downwardly in the bore 51. Such downward movement of the spool 52 causes the opening 81 to be gradually opened and simultaneously gradually closes the opening 79. The vent line 76 is ofsufiicient area so that the chamber 72 remains at atmospheric pressure at all times. Thus, it will be noted that the control valve comprises a chamber 64 connected by a variable orifice (81) to a second chamber ( lines 78, 80 and 41, and the chambers of the devices 20 and 38) which is connected by a variable orifice 79 with the atmosphere (chamber 76). The pressure in the second chamber depends upon the effective openings of the ports 81 and 79 which vary with the pressure in the first chamber.

Initially the pressure in the line 41 is uite low as the greater quantity of air flow will occur through the vent 76; however, as the spool 52 continues to be forced downwardly by increasing pressures in the receiver 8 the pressure in the line 41 gradual-1y increases. Such increase in pressure in the line 41 will occur until the port 81 is open and the port 79 is closed by the side of the spool (FIG. 2). In order to obtain such gradual increase in pressure in the line 41 the vent 76 must be located with respect to the suface 74 so that the vent remains open. It will readily be appreciated that the exact reverse decrease of pressure in the line 41 will occur as the pressure of the receiver 8 drops from its full pressure to a sufficient lower pressure so that the bias of the spring 56 cannot be overcome.

As the pressure starts to increase in the line 41 above atmospheric the piston rods 18 and 44 are both simultaneously forced outwardly of the cylinders 40 and 47, respectively, so that the levers 12 and 46 cause simultaneous movement of the racks 5 and 7, respectively. As indicated such actuation of the lever 12 causes the rack 5 to move in the reverse direction as that heretofore described with relation to the operation of the pressure responsive device 16 so that the fuel delivered to the compressor 2 is decreased. At the same time rack 7 is moved in a direction to obtain operation of impulse givers 10 so that the quantity of air compressed by the compressor 2 is decreased as the pressure of the receiver 8 increases above the pressure required to operate the control valve. Since the quantity of air compressed is continually decreasing with increasing receiver pressures the work of compression of the compressor 2 is concurrently continually decreasing and accordingly such reduction of fuel supplied to the compressor is required. Since the pressure responsive devices 20 and 38 are both actuated by the same force their operation will be simultaneous to obtain the desired concurrent decrease in fuel and quantity of air compressed. For a more complete under-. standing of the operation of unloading devices in the high pressure operating range of a compressor such as the compressor 2, reference is made herein to the copending application entitled Control Apparatus, Serial No. 697,012, filed November 18, 1957. It will be obvious that as the pressure in the lines 41 increases and decreases a resultant movement of the racks 5 and 7 will simultaneously occur.

In operation the spool valve acts as an amplifier so that a small change in input pressure causes a consider able change in output pressure. Such pressure amplification permits the use of comparatively small springs with a wide working range in the pressure responsive devices which are more accurate, are easier adjustable and are less subject to friction than highly biased systems which inherently have a much smaller Working range. Within the range described an input pressure change of about 2.5 pounds per square inch gauge causes an output pressure change of 58 pounds per square inch gauge whereby an amplification factor of 23 is obtained. In addition, the pressure responsive devices 20 and 30 are subjected to only a portion of the receiver pressure so that the linear amplification range of the spool valve 50 is utilized. I

It is obvious that control pressure changes of this magnitude result in a more accurate control than obtainable when the relative small changes in receiver pressure act immediately on the pressure responsive devices with their resultant limited piston travel. If desired, however, other suitable types of pressure amplifiers may be employed such as a servomotor.

Having described a preferred embodiment of this invent in accordance with the Patent Statutes, it is to be realized that modifications may be made without departing from the broad spirit and scope of the invention. Accordingly, it is respectfully requested that this invention be interpreted as broadly as possible and be limited only by the prior art.

What I claim as new and desire to secure by Letters f Patent is: i

1. A control system for fuel consuming apparatus having an output existing at variable energy levels con1pris' ing, a fuel pumping means including adjustable means for varying the quantity of fuel delivered thereby, means connected to said adjustable means and adapted to be responsive to energy levels below an output determinable energy level to actuate said adjustable means to increase the quantity of fuel delivered by said fuel pumpingmeans to a given maximum, an amplifying means having an output is operatively connected to other means which said other means is connected to said adjustable means for decreas ing the quantity of fuel delivered by said fuel pumping means, and said amplifying means being responsive only to energy levels above said output determinable energy level to actuate said other means to vary the quantity of fuel delivered by said fuel pumping means wherein said other means is operative upon said first mentioned means reaching said output determinable energy level.

2. A control system for fuel consuming apparatus having a variable output existing at variable energy levels including a determinable energy level comprising, a fuel pumping means including adjustable means for varying the quantity of fuel delivered thereby, means connected to said adjustable means and non-linearly responsive to changes in energy levels below said determinable energy level to vary the quantity of fuel delivered by said fuel pumping means, an amplifying means having an output is operatively connected to another means which said other means is connected to said adjustable means, said amplifying means being responsive to changes in energy levels above said determinable energy level to actuate said other means to vary the quantity of fuel delivered by said fuel pumping means, and adjustable control means located at the output end of said fuel consuming apparatus for regulating the output thereof.

3. A control system for fuel consuming apparatus having an output existing at variable energy levels comprising, a fuel pumping means including adjustable means for varying the quantity of fuel delivered thereby, means connected to said adjustable means and responsive to changes in energy levels below a determinable energy level of said output to vary the quantity of fuel delivered by said fuel pumping means, control means located at the output end of said fuel consuming apparatus for regulating the output thereof, an amplifying means having an output is operatively connected to another means which said other means is connected to said adjustable means for decreasing the quantity of fuel delivered by said fuel pumping means, and said amplifying means being responsive to changes in energy levels above said determinable energy level to actuate said other means to vary the quantity of fuel delivered by said fuel pumping means and to further actuate pressure responsive means connected to said control means for controlling the output of such apparatus.

4. A control system for fuel consuming apparatus having an output of a flowable medium existing at variable energy levels comprising, a fuel pumping means including adjustable means for varying the quantity of fuel delivered thereby, means connected to said adjustable means and responsive to changes in energy levels below a determinable energy level of said output to vary the quantity of fuel delivered by said fuel pumping means, an amplifying means having an output is operatively connected to another means which said other means is connected to said adjustable means, said amplifying means being responsive to changes in energy levels above said determinable energy level to actuate said other means to vary the quantity of fuel delivered by said fuel pumping means, and said amplifying means including adjustable biased movable means to control said determinable energy level.

5. A control system for a fuel consuming gaseous fluid compressor which discharges compressed fluid at various pressures from an inlet pressure to a maximum pressure, a fuel pumping means including adjustable means for varying the quantity of fuel delivered to such a compressor, means connected to said adjustable means wherein said means is responsive to changes in discharge pressure from the compressor inlet pressure to a determinable pressure below the maximum pressure to vary the quantity of fuel delivered by said fuel pumping means, an amplifying means actuated by changes in discharge pressure above said determinable pressure, another pressure responsive means connected to said adjustable means to vary the quantity of fuel delivered by said fuel pumping means and connected to said amplifying means, and said amplifying means including a member operable to control actuation of said other device by fluid discharged by such a compressor which fluid has a range of pressures greater than the range of discharge pressures which causes actuation of said first mentioned device.

6. A control system for a fuel consuming gaseous fluid compressor which discharges compressed fluid at various pressures from an inlet pressure to a maximum pressure comprising, a fuel pumping means including adjustable means for varying the quantity of fuel delivered thereby, a device connected to said adjustable means which is responsive to changes in discharge pressure from the compressor inlet pressure to a determinable pressure below the maximum pressure to vary the quantity of fuel delivered by said fuel pumping means, an amplifying device actuated by changes in discharge pressure above said determinable pressure and having a pair of outlets, another pressure responsive device connected to said adjustable means to vary the quantity of fuel delivered by said fuel pumping means and connected to said outlets, and said amplifying means including a member simultaneously cooperable with said outlets to vary the opening thereof to control actuation of said other device by fluid discharged by such a compressor which fluid has a range of pressures greater than the range of discharge pressures which causes actuation of said first mentioned device.

7. A control system for a fuel consuming gaseous fluid compressor which discharges compressed fluid at various pressures from an inlet pressure to a maximum pressure comprising, a fuel pumping means including adjustable means for varying the quantity of fuel delivered thereby, a device connected to said adjustable means which is responsive to changes in discharge pressure from the compressor inlet pressure to a determinable pressure below the maximum pressure to vary the quantity of fuel delivered by said fuel pumping means, an amplifying device actuated by changes in discharge pressure above said determinable pressure, a pair of pressure responsive devices connected to said amplifying means one of which is also connected to said adjustable means to vary the quantity of fuel delivered by said fuel pumping means and the other of which is also connected to means for controlling output of such a fluid compressed by such a compressor, and said amplifying means including a member operable to control actuation of said pair of devices by fluid discharged by such a compressor which fluid has a range of pressures greater than the range of discharge pressures which causes actuation of said first mentioned device.

8. A control system for a fuel consuming gaseous fluid compressor which discharges compressed fluid at various pressures from an inlet pressure to a maximum pressure comprising, a fuel pumping means including adjustable means for varying the quantity of fuel delivered thereby, a device connected to said adjustable means which is responsive to changes in discharge pressure from the compressor inlet pressure to a determinable pressure below the maximum pressure to vary the quantity of fuel delivered by said fuel pumping means, an amplifying device actuated by changes in discharge pressure above said determinable pressure, another pressure responsive device connected to said adjustable means to vary the quantity of fuel delivered by said fuel pumping means and actuated by said amplifying means, said amplifying means including a member operable to control actuation of said other device by fluid discharged by such a compressor which fluid has a range of pressures greater than the range of discharge pressures which causes actuation of said first mentioned device, and said amplifying means member being movable to obtain a linear pressure amplification throughout the greater part of its movement.

9. A control system for a fuel consuming gaseous fluid compressor which discharges compressed fluid at various pressures from an inlet pressure to a maximum pressure comprising, a fuel pumping means including adjustable means for varying the quantity of fuel delivered thereby, a device connected to said adjustable means which is responsive to changes in discharge pressure from the compressor inlet pressure to a determinable pressure below the maximum pressure to increase the quantity of fuel delivered by said fuel pumping means, an amplifying device actuated by changes in discharge pressure above said determinable pressure, another pressure responsive device connected to said adjustable means to decrease the quantity of fuel delivered by said fuel pumping means and connected to said outlet through said amplifying device, said amplifying means including a movable member responsive to said determinabl pressure to actuate said other device by fluid discharged by such a compressor which fluid has a range of pressure greater than the range of discharge pressures which causes actuation of said first mentioned device, and means operable by changes in pressure above said determinable pressure to reduce the work of compression of such a compressor when said discharge pressure is above said determinable pressure.

10'. A control system for a fuel consuming gaseous fluid compressor which discharges compressed fluid at various pressures from an inlet pressure to a maximum pressure comprising, a fuel pumping means including adjustable means for varying the quantity of fuel delivered thereby, a device connected to said adjustable means which is responsive to changes in discharge pressure from the compressor inlet pressure to a determinable pressure below the maximum pressure to increase the quantity of fuel delivered by said fuel pumping means, an amplifying device actuated by changes in discharge pressure above said determinable pressure, another pressure responsive device connected to said adjustable means to decrease the quantity of fuel delivered by said fuel pumping means and connected to said outlet through said amplifying device, said amplifying means including a movable member to responsive to said determinable pressure to actuate said other device by fluid discharged by such a compressor which fluid has a range of pressure greater than the range of discharge pressures which causes actuation of said first mentioned device, and means operable by changes in pressure above said determinable pressure to reduce the work of compression of such a compressor when said discharge pressure is above said determinable pressure, at least one of said devices being operable to cause operation of said fuel pumping means at said determinable pressure, and said first mentioned device including means to obtain a non-linear increase in fuel injected.

11. A control system for fuel consuming apparatus having an output comprising, a fuel pumping means operative to control the amount of fuel delivered to such an apparatus, means for regulating the quantity of fuel delivered by said fuel pumping means, a lever device having one end operatively connected to said regulating means, said lever device having two spaced pivot points, one of which is located at the other end thereof, wherein the other of said spaced pivots is located intermediately the ends thereof, a first pressure responsive device operatively connected to said output of such an apparatus for controlling the position of said intermediately spaced pivot point to increase the quantity of fuel delivered thereby, said first pressure responsive device operative to a predetermined pressure output of such an apparatus, a second pressure responsive device operatively connected to said output of such an apparatus responsive to pressures above said predetermined pressures to actuate said pivot point located at said other end to decrease the quantity of fuel delivered thereby while said intermediately located pivot remains stationary, and means operatively connected to said second control member for adjusting said predetermined pressure.

12. Fuel control means comprising a first movable member for adjusting the quantity of fuel delivered by said fuel pump, a second movable member connected to said first movable member for controlling the position thereof, a first control member connected to said second movable member wherein said first control member is responsive to a first range of pressures to move said second movable member in a first direction to increase the quantity of fuel delivered thereby, a second control member operatively connected to said second movable member wherein said second control member is operative over a pressure range greater than said first range to move said second movable member in a direction opposite to said first direction to decrease the quantity of fuel delivered thereby, and means operatively connected to said second control member for adjusting said pressure ranges.

13. Control means for the supply of fuel to an engine having an output wherein said engine output has a first range of values and a second range of values with said second range of values being greater than said first range of values, fuel pumping means for delivering fuel to the engine, adjusting means operatively connected to said fuel pumping means for regulating the amount of fuel delivered by said fuel pumping means a first control member connected to said output and responsive to said first range output for actuating said regulating means in a first direction to increase the fuel supplied thereby, a second control device responsive only to said second range output for actuating said adjusting means in a second direction opposite to said'first direction to decrease the fuel supplied thereby, and said first and second control members being sequentially operable.

References Cited in the file of this patent UNITED STATES PATENTS 1,203,315 De Wein Oct. 31, 1916 1,240,531 Banner Sept. 18, 1917 1,594,959 Huff Aug. 3, 1926 1,792,255 Standerwick Feb. 10, 1931 1,863,406 Hudson June 14, 1932 2,161,743 Heinrich et a1 June 6, 1939 2,463,364 Dustin Mar. 1, 1949 2,755,988 Wachsmuth July 24, 1956 2,841,322 Wachsmuth July 1, 1958 FOREIGN PATENTS 896,275 Germany Nov. 9, 1953

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