US2778312A

US2778312A - Fluid pump and controls therefor

Info

Publication number: US2778312A
Application number: US167638A
Authority: US
Inventors: Ward C Suttle; Elmer A Haase
Original assignee: Bendix Aviation Corp
Current assignee: Bendix Aviation Corp
Priority date: 1950-06-10
Filing date: 1950-06-10
Publication date: 1957-01-22
Anticipated expiration: 1974-01-22

Description

Jan. 22, 1957 w c. SUTTLE ETAL FLUID PUMP AND CONTROLS THEREFOR Filed June 10, 1950 INVENTOR. WARD 6'. 507715 EZNER A. l/HASE United States Patent FLUID PUMP AND CONTROLS THEREFOR Ward C. Suttle and Elmer A. Haase, South Bend, ImL, assignors to Bendix Aviation Corporation, South Bend. Ind., a corporation of Delaware Application June 10, 1950, Serial No. 167,638

13 Claims. (Cl. 103-42) This invention relates to pressurizing apparatus.

The invention is concerned primarily with a fluid driven pump for delivering fuel under pressure to a gas turbine engine of the turbo-jet type. The pump herein disclosed is shown in the afterburner system of a jet aircraft engine and is designed to have its output regulated by controlling the inlet fluid pressure.

It is an object of the invention to provide a novel pump apparatus having a single stage air impulse turbine wheel as a prime mover directly connected to a single stage centrifugal pump for supplying scheduled quantities of fuel at predetermined pressures.

It is an important object of the invention to provide pump apparatus capable of having its output regulated within prescribed pressures.

A further object lies in the provision of pump apparatus sensitive or responsive to a predetermined low pressure output for shutting the pump down.

A still further important object of the invention resides in the provision of pump apparatus responsive to a predetermined maximum pressure output for controlling said pressure.

Another object of the instant invention is to provide pump apparatus responsive to overspeeds for maintaining the pump R. P. M. within a safe operating range.

A still further object of the invention resides in the provision of means for rendering pump apparatus temporarily inoperative if the pump outlet pressure does not reach a preselected value within a prescribed time after the apparatus is started.

A very important object of the invention resides in the provision of pump apparatus sensitive to certain conditions for automatically controlling pump delivery and discharge pressures.

The above and other objects and features of the invention will be apparent from the following description of the apparatus taken in connection with the accompanying drawing which forms a part of this specification and in which:

Figure l is a diagrammatic representation of an afterburner system for a jet engine incorporating the device of the invention;

Figure 2 is a schematic diagram of the improved pump apparatus of the invention; and

Figure 3 is an enlarged view of the valve mechanism.

Referring now to Figure 1 of the drawing the reference numeral designates a jet engine with which the pump apparatus 12 is associated for pressurizing fuel to be delivered to the afterburner system of said engine. A conduit 14 connects the inlet of the pump apparatus to a fuel supply source, not shown, and a conduit 16 connects the outlet of said apparatus to an afterburner manifold 18, via afterburner fuel metering control equipment 20. The manifold 18, which is located exteriorly of the tail pipe and hence not subject to the extremely high temperatures prevailing therein, is equipped with a plurality of discharge nozzles 22, terminating upstream of a flame holder 24, the function of which forms no part of this invention 2,778,312 Patented Jan. 22, 1957 and therefore, needs no further explanation. The pressurizing device 12, which is air driven, receives its air supply from the engine air compressor, not shown, via pipe line 30.

With reference to Figure 2 for a more detailed description of the device 12, reference numeral 32 designates a centrifugal pump drivably connected to a fluid driven device, in the form of an air driven turbine 34, the latter of which comprises a nozzle plate 36 and a turbine wheel 38 positioned adjacent the nozzle plate for receiving the high velocity air emitted therefrom, and which impinges upon the turbine wheel blades to thereby drive the same. The pipe line 330 communicates air inlet 40, of the pressurizing device housing 42, with the compressor, not shown.

A valve mechanism 44, the details of which will be more fully described hereinafter, is interposed between the air inlet 40 and chamber 46, one wall of which is formed by the aforementioned nozzle plate 36. It is a function of this valve mechanism to control the air past nozzle plate passages 48, which communicate the chamber 46 with air outlet 50.

The centrifugal pump 32 is provided with an impeller wheel 52, carried on one end of a shaft 53, on the other end of which the turbine wheel 38 is fixedly secured.

Bearings

54 and 55 support the shaft for rotation in the housing 42. The impeller wheel 52 revolves in a chamber 56, having a fuel inlet 58 and an outlet 60; the inlet 53 is adapted to be connected to a fuel supply, not shown, through conduit 14, and the outlet 60 is connected to the conduit 16. The impeller wheel 52 discharges fuel into a volute 62, with which the outlet 60 is in communication.

This pressurizing apparatus is summoned into service only when it is desired to employ the afterburner fuel sys tem, whose function is to provide additional fuel for increasing the engine thrust during takeoff, for example. in order that the fuel delivery of the centrifugal pump 32 be maintained at prescribed values for different altitudes, and that the pump R. I. M. be kept at a safe operating speed. the apparatus embraces certain control devices including the valve mechanism 4-4.

The valve mechanism comprises a poppet valve member 64, which seats at 66 to thereby shut off the inlet air pressure to chamber 46. The poppet valve member is carried at one end of a bellows 68, the opposite end of which is supported in the housing 42, to provide a chamber 70 sealed from the chamber 46. A passage 72 connects the chamber 70 with the air inlet 40. The passage 72 is provided with a check valve 74 urged by a spring 76 in a direction which permits air to fiow from the inlet 40 to the chamber 70 but not in the opposite direction. Restricted passages 78 and 80 communicate opposite side of check valve 74 with atmosphere, via aperture 82, controlled by a solenoid valve 84. The opposite sides of poppet valve 64 are of unequal areas, with that side of the valve confined within the chamber 70 being the larger. The poppet valve arrangement is such that with the solenoid valve seated in aperture 82, the air forces acting on the opposite sides of the poppet valve will be slightly unbalanced in a direction tending to seat the valve, assisted by a spring 86. The check valve 74, and restrictions 78 and 80 provide control means for maintaining a fixed loading on the poppet valve. With the opening 82 closed by the solenoid, the restrictions provide a shunt around the check valve, which insures communication between the air inlet and the chamber 7t}. With the solenoid valve unseated from the opening 82 and the inlet air pressure at a value below that required to unseat the check valve 74 against the spring 76. chamber 7% will be vented to atmosphere via opening 82 and restriction 80. When the pressure builds up to a value which unseats the check valve 74 a fixed differential will be established across the poppet valve, regardless of variations in inlet pressure. This latter arrangement insures a fixed predetermined loading on the poppet valve. Thus. for any given air inlet pressure and with the solenoid valve unseatcd from aperture 82, as aforementioned. the air inlet pressure acts in a direction tending to open the poppet valve 64. This provides maximum air flow to the turbine 34 under normal operating conditions of the aircraft. That is, at this time the poppet valve will operate in wide open air inlet position.

However, since the fuel discharge pressure from the pump 32 is not to exceed a predetermined value, means is provided for throttling the poppet valve to maintain the fuel discharge pressure at the desired value. This means includes a bellows 88, one end of which is supported by the housing 42, and sealed thereto, the other end of which carries a button 90 for engagement with an extension 92 of the poppet valve, to thereby limit its movement away from valve seat 66. The underside of the button rests on a sleeve member 94, carried by the housing, thus positioning the button with respect to said extension, which lies directly thereabove and in axial alignment therewith. The spring 86 is interposed between the poppet valve 64 and the button 90. The bellows 88 forms a chamber 96 which communicates with the volute 62, through a restricted passageway 98, and lateral passages 100 in the sleeve member 94.

A spring 102 is interposed between a flange 104, in the upper end of the sleeve 94, and an enlarged end 106, of a stem 108 suspended from the underside of the button 90. thus biasing the latter against the upper end of the sleeve member. A restricted passage 110 communicates the chamber 96 with the fuel inlet 58.

The pressure at which the puppet is to be throttled is determined by control means including a check valve 116, located in the passage 98 between the volute 62 and the chamber 96, and restrictions 112 and 114 formed in the passages 98 and 110 respectively. This throttling pressure, which controls the pump discharge pressure, is dependent upon the force of spring 1.17 of the check valve 116, When the force across button 90 is equal to the force across valve 64, the loading on the button 90 tending to move said button upwardly is balanced by the loading on the poppet which tends to move said poppet downwardly. At this time any further increase in pump discharge pressure will cause the button 90 to move upwardly, and hence throttle the poppet, to thereby lower the pump discharge pressure, which in turn reduces the pressure in the chamber 96. It will be noted that the control means for maintaining a fixed loading on the pop pet is coordinated with the control means for positioning the throttling mechanism. A switch 118 of the normally open type is subjected to the volute pressure and closes when the fuel discharge pressure in the volute 62 attains a predetermined minimum value.

The valve mechanism 44, controlled by the solenoid 84, and throttled by the pressure in chamber 96 acting on the button 90, is sensitive to fuel pump overspeed and to a minimum fuel discharge pressure of the pump. The overspeed device includes a normally closed switch 120, connected by linkage 122, to an axially shiftable actuator 124, biased to the right by a spring 126, interposed between the actuator and a stop member 128, the latter of which restricts movement of the actuator to the left, so that balls 130 are confined between a conical surface 132 of the actuator and a vertically disposed flange 134 of a sleeve member 136, concentric with the shaft 53. The spring 126 is so selected that when the pump R. P. M. exceeds a preselected value the centrifugal force of the balls 130 causes them to move outwardly along the conical surface compressing the spring 126, thus urging the actuator to the left and opening the switch 120.

An electrical circuit is provided for the pressurizing apparatus and includes the solenoid valve 84, the minimum discharge pressure switch 118, the overspeed switch 120, a manually operated, normally open, starting switch 140,

a thermal time delay switch 142, a holding switch 144, a manual stop switch 145, holding coil 146, for said holding switch, heater coil 148, for the time delay switch 142, and a source of supply 150. The starting switch 140 is serially connected with the solenoid valve 84 and the overspeed switch 120. The holding coil 146 and heater coil 148 are energized upon closing the starting switch, thus closing the holding switch 144 and subjecting the thermal switch to heat emanating from the coil 148. The holding switch is in parallel with the starting switch and, therefore, maintains the holding coil energized upon release of the latter switch. The thermal time delay switch 142 is in series with the holding switch 144 and is designed to break the holding circuit in a predetermined time after closing the starting switch. It will be noted, however, that the minimum discharge pressure switch 118 shunts the thermal switch and if closed, as a result of the pressure in volute 62, will prevent opening the holding circuit. On the other hand if the pressure in volute 62 has not attained a prescribed value at the time the thermal switch opens the starting switch must be closed again to start the pressurizing apparatus.

Operation and function of the apparatus is as follows: If we assume a condition in which the apparatus is not running, the starting switch 140 is open, and the parts of the apparatus will be as shown in Figure 2. At this time the poppet valve 64 will be closed, solenoid valve 84 will be closed on aperture 82, and the holding switch 144 will be open.

Should it be desired to put the afterburner system into use, the starting switch 140 is closed, thus energizing the solenoid valve 84, to thereby open aperture 82, which communicates the chamber 70 to atmosphere, through restriction 80. A reduction in pressure in chamber 70 permits the poppet valve to be opened under the influence of the air inlet pressure, which flows into the chamber 46, from whence the air expands through the nozzle plate 36 and impinges against the turbine wheel 38, to thereby drive the same. Within a prescribed time after closing the holding switch and releasing the starting switch the thermal switch will open, thus de-energizing the solenoid 84 and closing opening 82, which causes the pressure in chamber 70 to rise, thus urging the poppet valve closed. If, however, the pressure in volute 62 has risen to a predetermined value in a prescribed time, which time is less than that required to operate the thermal switch, the minimum pressure switch 118 will have closed and hence shunted the thermal switch, so that the holding coil 146 will remain energized and its associated switch 144 will stay closed. Under these conditions the pump will continue to deliver fuel as scheduled, subject to throttling as the inlet and discharge pressures of the pump change.

If, for example, the discharge pressure at the outlet 60 exceeds a preselected value, this increase will be communicated to the pressure chamber 96 which will result in moving the button upwardly against the extension 92 of the poppet valve to thereby cut down the flow of air to the turbine wheel 38.

In the event of an overspeed of the pump the switch will open, thus breaking the circuit to the solenoid valve and de-energizing the same which in turn closes aperture 82. As soon as the pump speed drops to the predetermined speed for which it was set the switch 120 will close and the solenoid valve will again open.

To shut down the pressurizing apparatus the manual stop switch 145 is opened. This switch is in the holding circuit in series with the holding switch 144 and interrupts the current to the holding coil 146, when opened. Since this stop switch must be closed before operating the apparatus, the switch is of the normally closed variey.

Although this invention has been described in connection with certain specific embodiments, the principles are susceptible of numerous other applications that will readily occur to persons skilled in the art.

Having thus described the various featuses of the invention, what we claim as new and desire to secure by Letters Patent is:

We claim:

1. The combination with a fluid pump and a fluid device for driving said pump, of means for controlling the fluid to said device comprising a valve mechanism, manual means associated with said mechanism for starting and stopping said device, and electrical means responsive to a predetermined pump discharge pressure for rendering said device inoperative.

2. The combination with a fluid pump and a fluid device for driving said pump. of means for controlling the fluid to said device comprising a mechanism responsive to the discharge pressure of said pump, electrical means including a minimum pump discharge pressure switch, an overspeed switch, and manual switch all of which are operatively connected to said mechanism for controlling said device.

3. in combination, a pump for putting fluid under pressure, a fluid driven device drivably connected to said pump, a fluid connection to the device, means for controlling the fluid to said device comprising a valve in the connection subject to the fluid pressure in the connection on one side and a variable pressure on the other side, a mechanism or rativcly connected to said valve and to the discharg si e of said pump for throttling said valve, means communicating the discharge side of said pump to said mechanism, and electrical means including an electrically operated valve for controlling said variable pressure acting on the other side of said first named valve.

4. In combination, a pump for putting fluid under pressure, a fluid actuated device drivably connected to said pump, means for controlling the fluid to said device comprising a throttling mechanism, means communicating the discharge side of said pump to said mechanism, and means including an overspeed responsive device and a minimum pump discharge pressure device operatively connected to said mechanism.

5. in combination. a pump for putting fluid under pressure, a fluid actuated device connected to said pump to drive the same, means for controlling the fluid to said device comprising a throttling mechanism, a passage connecting the discharge side of said pump to said mechanism, an electrical circuit embracing a solenoid valve, and an overspeed device in said circuit.

6. In combination, a pump for putting fluid under pressure, a fluid actuated device connected to said pump for driving the same, means for controlling the fluid to said device comprising a throttling mechanism, a passage connecting the discharge side of said pump to said mechanism, an electrical circuit embracing a solenoid valve, an overspeed device, and a device responsive to a predetermined minimum pump discharge pressure.

7. In combination, a pump for putting fluid under pressure, a. fluid actuated device connected to said pump for driving the same, for controlling the fluid to said device comprising a throttling mechanism, means communicating the discharge side of said pump with said mechanism, an electrical circuit embracing a solenoid valve, and means for rendering said mechanism inoperative if the pump discharge pressure does not reach a predetermined value in a prescribed time.

8. In combination, a centrifugal fuel pump, an air turbine drivably connected to said pump, a valve mechanism for controlling the air to said turbine and including a valve member movable from a normally closed position to a plurality of open positions under the influence of a diiferential pressure, means for positioning said valve member in any one of its open positions, said last named means being responsive to the pump dis charge pressure, an electrical circuit including a solenoid valve for creating a differential pressure on said valve member, an overspeed device in said circuit, a device responsive to a predetermined minimum pump discharge pressure in said circuit, and manual means in the circuit for starting and stopping said air turbine.

9. The combination with a fluid pump and a fluid actuated device for driving said pump, of a valve mechanism for said device comprising a poppet valve, control means for said poppet valve including a control circuit having a solenoid valve therein, switches in said circuit controlled by pump speed and discharge pressure respectively, and means for throttling said poppet valve in accordance with the pump discharge pressure.

it). The combination with a fluid pump and a fluid actuated device for driving said pump, of a valve mechanism for said device comprising a valve member, control means for said valve member, said control means including a passage connecting the opposite sides of said valve member, a check valve in the passage, a passageway connected to the passage at points anterior and pos terior to the check valve, restrictions in said passageway at the points where connected to said passage, means connecting the passageway between said restrictions to atmosphere, and means sensitive to variations in pump discharge pressure for throttling said valve member including a device arranged in the path of movement of the valve member.

11. For use in the fuel supply engine having a compressor, a liquid fuel pressurizing apparatus comprising a pump, an air actuated device arranged to drive the pump, a conduit connecting the inlet side of said device to a stage of the compressor, valve mechanism in said conduit having a normally closed valve member directly subjcctabie to a differential air pressure, means for releasing the air pressure on one side of said valve member, and mechanism operatively connected to said valve member and to pump discharge pressure and being arranged to cause said valve member to throttle the air to said air actuated device according to the pump discharge pressure.

12. For use in the fuel supply system of a gas turbine engine having a compressor, a liquid fuel pressurizing apparatus comprising a centrifugal pump, an air driven turbine arranged to drive the pump, a conduit connecting the inlet side of said air turbine to a stage of the compressor, valve mechanism in said conduit including a valve member directly subjectable to a differential air pressure, and mechanism operatively connected to said valve member and to pump discharge pressure and being arranged to cause said valve member to throttle the air to said air actuated device according to the pump discharge pressure.

13. For use in the fuel supply system of a gas turbine engine having a compressor, a liquid fuel pressurizing apparatus comprising a pump, an air actuated device arranged to drive the pump, a conduit connecting the inlet side of said device to a stage of the compressor, valve means in said conduit for varying the air pressure to the inlet of said device, means connecting one side of said valve means with a source of low pressure fluid, said means including valvular means for releasing the air pressure on said one side of said valve means, and mechanism operatively connected to said valve means and to the pressure at the discharge side of said pump for varying the position of the valve means in said conduit.

system of a gas turbine References Cited in the tile of this patent UNITED STATES PATENTS (Other references on following page)