05/170582

03/19/1974

08/10/1971

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Robert Bosch GmbH (Stuttgart, DT)

60/39.281

137/613, 123/458, 137/625.650, 415/10

F02C9/08

60/39.28 123/139AW,139E 415/10

Gordon, Clarence R.

Greigg, Edwin E.

That which is claimed is

1. A fuel injection apparatus of the type that continuously delivers metered fuel to a fuel injection nozzle associated with a combustion chamber of a turbine power plant comprising, in combination,

2. a variable flow passage section for the fuel flowing therethrough toward said nozzle,

3. a movable control plunger for varying said flow passage section,

4. a first means exposed to fuel pressure prevailing downstream of the fuel metering valve,

5. a second means exposed to the fuel pressure prevailing upstream of the fuel metering valve,

6. a flow passage section variable as a function of the difference between the pressures upstream and downstream of said fuel metering valve to maintain the pressure drop across said fuel metering valve and said flow passage section constant, and

7. A fuel injection apparatus as defined in claim 1, wherein said electromagnetic fuel quantity control assembly includes a rotary armature affixed to said control plunger, said fuel metering valve includes

8. a longitudinal bore accommodating said control plunger,

9. first lateral opening means communicating with said longitudinal bore to permit admission of fuel thereinto,

10. second lateral opening means communicating with said longitudinal bore and constituting at least one control slot,

11. A fuel injection apparatus as defined in claim 2, wherein said means for rotatably supporting said control plunger includes

12. A fuel injection apparatus as defined in claim 2, wherein said fuel metering valve includes

13. A fuel injection apparatus as defined in claim 4, wherein said means for limiting the maximum angular displacement of said control plunger includes

14. A fuel injection apparatus as defined in claim 5, including a transducer disposed in said housing and having a follower member in continuous engagement with said cam disc, said transducer emitting an electric signal characterizing the actual momentary angular position of said control plunger.

15. A fuel injection apparatus as defined in claim 1, including means for exposing said electromagnetic fuel quantity control assembly to a direct contact with the flowing fuel for cooling purposes.

16. A fuel injection apparatus as defined in claim 1, including a transducer operatively connected to said control plunger to emit an electric signal characterizing the actual momentary position of said control plunger.

17. A fuel injection apparatus as defined in claim 1, including a rapid shut-off valve disposed upstream of said fuel injection pump, said rapid shut-off valve comprises

18. A fuel injection apparatus as defined in claim 9, wherein said valve member is formed as an axially reciprocating plunger.

19. A fuel injection apparatus as defined in claim 1, including

20. a movable valve member adapted to assume a first position in which communication is maintained between said fuel conduit and said fuel injection nozzle and in which communication is blocked between said fuel conduit and said fuel tank; said movable valve member adapted to assume a second position in which communication is blocked between said fuel conduit and said fuel injection nozzle and in which communication is maintained through said discharge conduit between said fuel conduit and said fuel tank,

21. preloaded spring means urging said movable valve member into said second position,

22. electromagnetic means operatively connected to said movable valve member to apply thereto, when energized, a force greater than and opposite to that of said preloaded spring means for urging said movable valve member into said first position.

23. A fuel injection apparatus as defined in claim 1, including a shaft for driving said fuel injection pump from said power plant, said improvement further includes, within said housing, an inductive rpm sensor, having

24. an induction coil,

25. a yoke carrying said induction coil and having at least one toothed portion disposed radially adjacent said toothed disc.

26. A fuel injection apparatus as defined in claim 1, wherein said differential pressure valve includes

27. A fuel injection apparatus as defined in claim 1, wherein said differential pressure valve includes

28. A fuel injection apparatus as defined in claim 1, wherein said electromagnetic fuel quantity control assembly includes a linearly movable armature affixed to said control plunger, said fuel metering valve includes

29. a longitudinal bore for axially slidably supporting said control plunger,

30. first lateral opening means communicating with said longitudinal bore to permit admission of fuel thereinto,

31. second lateral opening means communicating with said longitudinal bore and constituting at least one control slot and

32. A fuel injection apparatus as defined in claim 15, including a transducer disposed in said housing an having an axially displaceable follower member in contact and in axial alignment with said control plunger, said transducer emitting an electric signal characterizing the actual momentary axial position of said control plunger.

BACKGROUND OF THE INVENTION

This invention relates to a continuously operating fuel injection apparatus particularly adapted for a gas turbine used as a power plant in an automotive vehicle. The apparatus is of the type that comprises a continuously operating fuel injection pump and control means to regulate the injected fuel quantities. The apparatus includes a fuel quantity control mechanism which affects the position of a control plunger metering the fuel quantities to be advanced to the fuel injection nozzles. To ensure a constant pressure drop across a fuel metering valve containing the control plunger, in the fuel flow there is positioned a differential pressure valve. Further, the fuel injection apparatus includes means for the rpm-dependent control of the fuel quantities as well as means for limiting the pressure within the hydraulic system and means for protecting the apparatus against excessive rpm's and temperatures.

With a fuel injection apparatus of the aforeoutlined type it is sought to obtain a variation of a flow passage section for the fuel by means and as a function of an operational variable of the gas turbine. It is further sought to obtain, by means of a constant pressure drop across the aforenoted flow passage section, a uniformly exact fuel metering which corresponds to the open flow passage section and which is independent from the pressures upstream and downstream of the fuel metering means. For this purpose, the fuel injection apparatus itself must operate very reliably and should include safety devices to counteract effects of excessive rpm's or excessive temperatures.

In fuel quantity regulating devices of the aforenoted type, it is known to provide in the fuel line a metering valve which is controlled as a function of a deviation of a predetermined rpm from an actual value and at which the pressure drop is maintained at a constant value by means of a differential pressure valve. Devices of this type serve to regulate deviations of an operational magnitude to a zero value whereby safety devices, responding, for example, to excessive rpm's or excessive temperatures, shut off the power plant by cutting off the supply of fuel. It is, however, extremely difficult to design mechanical regulators which satisfy the requirements of modern gas turbines and which respond in a sufficiently rapid manner to variations in the operational conditions to effect the necessary corrections.

OBJECT AND SUMMARY OF THE INVENTION

It is an object of the invention to provide an improved fuel quantity regulating assembly which satisfies the requirements of modern gas turbines and which operates in a reliable manner.

Briefly stated, according to the invention, the flow passage section of the fuel metering valve is variable by means of an electromagnetic system which is disposed in the housing of the fuel injection apparatus and which is directly connected with the control plunger of the fuel metering valve.

The invention will be better understood, as well as further objects and advantages become more apparent, from the ensuing detailed specification of several exemplary embodiments taken in conjunction with the drawing.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a diagrammatic representation of the arrangement of a fuel injection apparatus associated with a two-shaft gas turbine, including an electronic regulator for controlling the injected fuel quantities and a gate mechanism associated with the turbine;

FIG. 2 is a longitudinal sectional view of one embodiment of the fuel injection apparatus according to the invention;

FIG. 3 is a sectional view taken along line III -- III of FIG. 2;

FIG. 4 is a top plan view of the same fuel injection apparatus with its top closure removed;

FIG. 5 is a sectional view along line V--V of FIG. 2;

FIG. 6 is a sectional view along line VI--VI of FIG. 2;

FIG. 7 is a longitudinal sectional view of an embodiment of a rapid shut-off valve disposed upstream of a fuel injection nozzle and forming part of the apparatus according to the invention;

FIG. 8 is a simplified representation in elevation of two serially connected components shown in more detail in FIG. 2;

FIG. 9 is a schematic representation, in side elevation, of another embodiment of a differential pressure valve; and

FIG. 10 is a longitudinal sectional view of another embodiment of the fuel control assembly shown in FIGS. 2, 3, 4 and 8.

DESCRIPTION OF THE EMBODIMENTS

Turning now to FIG. 1, there is shown schematically the arrangement of a fuel injection apparatus KA serving a two-shaft gas turbine adapted to constitute the power plant of an automotive vehicle. The gas turbine includes a compressor V for the intake air, a compressor turbine VT, a gate mechanism L hydraulically actuated by a control mechanism LV and disposed upstream of the work turbine AT, as well as a heat exchanger WT in which the intake air is heated by means of exhaust gases.

The fuel injection apparatus KA comprises a fuel injection pump 3 which is driven by the compressor turbine VT and which delivers fuel from a fuel tank K to nozzles D in a combustion chamber BK through a fuel metering valve 13 across which a differential pressure valve 36 maintains a constant pressure drop. The fuel metering valve 13 has a control plunger which, according to the invention, is directly actuated by an electromagnetic quantity control assembly 17. The desired operational condition of the gas turbine is arbitrarily set by means of an accelerator pedal A, the position of which determines a desired value fed into an electronic regulator ER. Signals characterizing the actual operational condition of the gas turbine are fed into the electronic regulator ER, on the one hand, from an inductive transducer 32 which is connected with the control plunger of the fuel metering valve and which responds to the position thereof and, on the other hand, from an inductive rpm sensor 48 connected with the shaft 2 of the fuel injection pump. In case of a deviation from the predetermined desired value a correction of the flow passage section at the fuel metering valve is effected by means of a corresponding signal from the electronic regulator ER. Further, the electronic regulator ER monitors the maximum permissible rpm and the maximum permissible temperature T, so that in case the limit value of either variable is exceeded, the electric feed circuit of the magnetically controlled rapid shut-off valve 67, disposed upstream of the fuel injection pump, is interrupted, whereby fuel admission to the fuel injection pump 3 is cut off. Simultaneously, the hydraulic system is depressurized downstream of the fuel injection pump. An excess-pressure valve 100 disposed between the pressure and suction side of the fuel injection pump 3 limits the maximum pressure in the fuel injection apparatus KA.

The use of an electronic regulator rather than a mechanical regulator has, among others, the significant advantage that characteristics of different turbines may be set therein in a simple manner. In contradistinction, in case of a mechanical regulation, for each different type of gas turbine the basic mechanical regulator has to be complemented with a special regulator or complex additional mechanisms.

Turning now to FIG. 2, there is shown in section a fuel injection apparatus according to the invention, comprising a regulator housing 1 in which there is supported a gear pump 3 driven from the compressor turbine by the drive shaft 2. The gear pump 3 delivers fuel through bore 4 to a fuel metering valve 13. More particularly, the fuel flows from the bore 4 into an annular groove 5 of a guide sleeve 6 wherefrom the fuel is admitted through bores 7 into an annular chamber 8 which is formed by a control plunger 11 and the axial bore 14 of the sleeve 6. If desired, the bore 4 may be designed as a hydraulic damping element (accumulator). The two control edges 12 of the control plunger 11 and the corresponding control slots 15 cooperating therewith form a fuel metering valve, the flow passage section 21 of which is variable by means of a quantity control assembly 17 directly connected with the control plunger 11. The quantity control assembly 17 includes a rotary magnet 18 which is turnably disposed between two solenoids 19 (only one seen in FIG. 2) arranged on a core 20. In this manner -- as better seen in FIG. 4 -- through the magnet 18 and the core 20 there may be formed a closed magnetic circuit. The rotary magnet 18 is affixed to the control plunger 11 which is axially supported by point bearings 23. The axial immobilization of the control plunger 11 is effected by an adjusting screw 24 urging the plunger 11 against an abutment 25 which, in a top closure 27, is supported by a spring 26. Above the rotary magnet 18, the control plunger 11 carries a cam disc 30 which, in response to the rotation of the control plunger 11, actuates the inductive transducer 32 through a follower pin 31.

The fuel metered at the control slots 15 flows through an annular groove 16 and a channel 34 into a first chamber 35 of the differential pressure valve 36. Thus, the pressure in the chamber 35 equals the pressure immediately downstream of the fuel metering valve (i.e. subsequent to metering). A membrane 37, constituting the movable valve component, is clamped between the regulator housing 1 and the valve housing 38 coplanar with a stationary flat valve seat 39. A coil spring 41, having a spring characteristic of flat course, is secured to the valve housing 38 by means of an intermediate ring 40 and exerts a force on the membrane 37 through a spring seat disc 42 in the direction of opening. Thus, the differential pressure valve 36 is in an open position when not in operation. From the annular groove 5 provided in the sleeve 6, the fuel flows unthrottled through the bore 9 into a second chamber 10 of the pressure differential valve 36. Thus, the pressure in the chamber 10 equals the pressure immediately upstream of the fuel metering valve (i.e. prior to metering). The two chambers 10 and 35 are separated from one another by the membrane 37. From the chamber 35 the metered fuel, as regulated by the valve membrane 37, flows through a pressure conduit 113 to the injection nozzle D associated with the combustion chamber BK. The course of fuel from upstream of the fuel metering valve 13 to the injection nozzle D may be particularly well followed in FIG. 8 which schematically illustrates the fuel metering valve 13 and the differential pressure valve 36 connected directly downstream thereof.

A certain amount of excess fuel is directed from the chamber 10 through a throttle bore 44 into a space 45 where, together with leakage fuel quantities, it directly contacts and thus effectively cools the magnet system 17, the inductive transducer 32 and the inductive rpm sensor 48. From the space 45 the fuel is returned to the tank K through the return port 46 provided in the closure 27.

As further seen in FIG. 2 and also illustrated in FIG. 6, to the pump drive shaft 2 there is keyed a toothed disc 49 of the inductive rpm sensor 48. The latter also includes stationary yokes 50 having arcuately extending toothed portions immediately adjacent the toothed disc 49. The latter, with each yoke 50, forms a magnetic circuit, the magnetic flux of which varies in a pulsating manner as a function of the angular velocity of the toothed disc 49. On each yoke 50 there is mounted an induction coil 51 in which there are induced voltage pulses as the flux changes. The rpm-responsive signal transmitters 54, each formed of a yoke 50 and an induction coil 51, are secured to a support body 52 carrying contact terminals 56 to which there are connected the terminals of the induction coils 51. As well seen in FIG. 6, the two rpm-responsive signal transmitters 54 are disposed at opposite sides of the toothed disc 49. In this manner the rotational tolerances in the air gap formed between the toothed disc 49 and the yokes 50 compensate one another and also, there is attained, by redundancy, an increased reliability of operation. The lid 27, closing off the top of the regulator housing 1, has an extension 57 serving as an electric plug. Along the inside wall of the lid 27 there is disposed a conductor plate 58 which carries contact springs 59 and contact faces which, in operation, are urged against the contact springs 60. All electric connections within the regulator housing are made on the conductor plate 58. The terminals which have to be situated externally of the regulator housing, are formed as prongs 62 within the plug 57. The conductors connecting the prongs 62 with the internal pins 61 extend into the regulator housing through fluid tight and heat insulating means.

Turning now to FIG. 3 there is shown a cross section of the fuel injection apparatus taken axially through the electromagnetic quantity regulating mechanism 17 and showing the fuel metering valve 13 with the control slot 15 and the control edge 12 in elevation. For the purposes of pressure equalization, the chamber 71 is connected with the chamber 45 through a port 70.

FIG. 4 shows a top plan view of the fuel injection apparatus of FIG. 2 with the closure 27 removed. There is seen, as previously described, the yoke 50 with the induction coil 51 of the inductive rpm signal transmitter 48. Above the rotary magnet 18 there may be observed the cam disc 30 which actuates the follower pin 31 of the inductive transducer 32. The rotary magnet 18 is limited in its angular displacement by the cooperation between abutment faces 75 and 76 of the cam disc 30 on the one hand and the abutment plate 74 on the other hand. In the de-energized condition of the electromagnetic quantity control mechanism 17, a return spring 77 sets the control plunger 11 into a zero position in which the flow passage section 21 (FIGS. 2 and 3) has a zero area. To the inductive transducer 32 there are mounted contact faces 79 which, when the closure 27 is in place, are pressed against the contact springs 59 of the conductor plate 58. The solenoids 19 are supplied with current through the contact springs 60.

Turning now to FIG. 5, there is shown in section that part of the fuel injection apparatus that contains the rapid shut-off valve 67. From the fuel tank K the gear pump 3 (not shown in FIG. 5) aspirates fuel through a supply port 81, as well as bores 82 and 83. Between the supply port 81 and the bore 82 there is disposed the rapid shut-off valve 67 which comprises a piston plunger 88 reciprocably disposed in a guide sleeve 95. The piston plunger 88 is connected with the armature 90 of an electromagnet 66 through a clutch 89. The moment the solenoid of the electromagnet 66 is de-energized, the piston 88 of the rapid shut-off valve 67, by virtue of a preloaded spring 91 (FIG. 7) closes the bore 82 which is connected to the fuel pump 3 by means of the bore 83. Simultaneously with this occurence, the pressure and suction side of the fuel pump 3 are interconnected, while the fuel flows through a return bore 85, an annular groove 93 and bores 94 in the guide sleeve 95 into the annular chamber 96 of the piston plunger 88. The annular chamber 96 is, in the closed position of the piston plunger 88, in communication with the annular groove 97 and bores 98 which, in turn, are continuously connected with the supply port 81.

In a bore 84 parallel with the gear pump 3 there is arranged a pressure limit valve 100 which opens in case of overpressure to establish communication between the pressure side 4 and the suction side 83 of the gear pump 3. This opening is effected by lifting the piston 101 against the force of a spring 102 from the abutment member 103. As a result, an annular groove 104 in the valve body 105 is exposed, permitting a fuel flow through the bores 106 into the annular chamber 107, which, in turn, is in communication with the bore 83. The pressure limit valve 100 thus maintains a predetermined pressure level in the hydraulic fuel circuit.

The embodiment of the fuel injection apparatus described in connection with FIGS. 1-6 operates as follows:

By means of the electronic regulator ER to which there are applied, among others, the signals characterizing the position of the accelerator pedal A, and by means of a control apparatus contained in the electronic regulator, an electric setting magnitude is generated which is amplified in such a manner that it tends to turn the rotary magnet 18 counterclockwise (as viewed in FIG. 4) against the force of the return spring 77. Signals characterizing the momentary position of the rotary magnet 18 are transmitted by the inductive transducer 32 to the electronic regulator ER.

To the electronic regulator ER there are further applied magnitudes characterizing the temperature T of the gases in the combustion chamber BK and the pressure of the ambient atmosphere.

The rotary magnet 18, angularly displaced by the magnetic force of the energized solenoid 19, moves, by means of the cam disc 30, the follower pin 31 of the inductive transducer 32. The latter includes two serially connected inductive components which are formed as coils and which surround an axially displaceable ferrite core. This coil-and-core assembly is not shown in FIGS. 1-6; it is illustrated in FIG. 10 which relates to a modified structure to be described later. Thus, the motion of the cam disc 30 is transmitted to the ferrite core by means of the follower pin 31. The reproducibility of the output magnitude of the inductive transducer 32 is enhanced by a play compensating spring which continuously and slightly urges the ferrite core against the follower pin 31 and the latter against the cam disc 30.

The fuel is delivered from and by the gear pump 3 to the fuel metering valve 13 at which the fuel metering is effected while a constant pressure drop through the differential pressure valve 36 is maintained. In this manner the magnitude of the flow passage section 21 is a measure for the throughgoing fuel quantities.

In case there is a breakdown in the electronic circuitry, or an excessive rpm or excessive temperature appears, the coil of the electromagnet 66 is de-energized and the spring 91 abruptly displaces the armature 90 and the piston plunger 88 upwardly whereby the admission of fuel to the gear pump 3 is suddenly interrupted. Simultaneously, the hydraulic system is depressurized at the pressure side of the gear pump 3 and thus, fuel may flow through the return bore 85 and the annular groove 96 into the supply port 81 which is at the suction side of the gear pump 3.

FIG. 7 illustrates an embodiment of a rapid shut-off valve 67a disposed upstream of the nozzle D in the valve housing 110. The metered fuel passing through the bore 111 flows, in the case the rapid shut-off valve 67a is open, through an injection channel 113 directly to the nozzle D. The piston plunger 115 which, in a de-energized condition of the magnet coil 119 of the electromagnet 66, is pressed by spring 91 to the valve seat 114 to close channel 113, carries at its frontal face oriented towards the valve seat a packing ring 117 and has at its frontal face oriented toward the magnet coil 119 an armature 118. In the closed condition of the rapid shut-off valve 67a, the fuel flows from the chamber 112 through the slots 120 and the annular groove 121 of the guide sleeve 122 into an annular chamber 124 which is formed between the piston plunger 115 and the inner bore 123 of the guide sleeve. The annular chamber 124 is, through bores 125 and an annular groove 126, in communication with a return conduit 127 leading to the fuel tank K. The bore 128 permits a pressure equalization between the chamber 129 above the armature 118 and the chamber 112 below the guide sleeve 122. The advantage of this embodiment resides in the fact that by virtue of arranging of the rapid shut-off valve immediately upstream of the nozzle D, the delay of response of the turbine is decreased because the length of the hydraulic conduit between the injection nozzle D and the shut-off valve 67a has been substantially shortened. At the same time, the return conduit downstream of the fuel pump decreases the danger of a scoring of the pump, because the latter, as long as the turbine rotates, does not run dry.

FIG. 9 shows a modified differential pressure valve 36a. Here, the membrane 37 actuates, as a function of the fuel pressures upstream and downstream of the fuel metering valve 13, a control plunger 133 affixed to the membrane 37. The fuel flowing into an annular groove 136 of the plunger 133 through a channel 131 communicating with the chamber 35, is admitted as a function of the position of a control edge 132 of the plunger 133 to the injection channel 113 and thus to the nozzle D. The frontal face of the control plunger 133 remote from the membrane 37 is exposed to the force of a spring 134 in the opening direction of the valve. The fuel quantity leaking through the control plunger 133 is returned through a leakage channel 135 to the fuel tank K. It is thus seen that while in the differential pressure valve 36 according to FIGS. 2 and 8 the membrane 37 directly cooperates with a flat valve seat 39 to maintain the pressure drop across the fuel metering valve 13, in the differential pressure valve 36a according to FIG. 9 such a control is achieved by the membrane 37 indirectly by shifting the control plunger 133. This latter structure has the advantage that pressure variations in the conduit 113 have a smaller feedback effect on the differential pressure.

FIG. 10 shows in longitudinal section a fuel metering valve 13a of the axially sliding type in contradistinction to the rotary structure described in connection with FIGS. 2, 3 4 and 8. The fuel metering valve 13a shown in FIG. 10 is directly associated with a plunger-type magnet assembly 158. The fuel flows from the pressure side of the fuel injection pump 3 (not shown in FIG. 10) through bores 4 and 142 into an annular groove 143 of the guide sleeve 144 and therefrom into an annular chamber 146 which is formed between an axially slidable control plunger 145 and the axial bore 150 of the sleeve 144. The metering of the fuel occurs by means of a cooperation between the control edge 147 of the plunger 145 and control slots 148 provided in the sleeve 144. From the control slots 148 the fuel flows into an annular groove 149 also provided in sleeve 144 and therefrom through a channel 152 into a chamber of the differential pressure valve. The connection to the other chamber of the differential pressure valve is established by means of a bore 151. The armature 155 of the plunger magnet assembly 158 is directly connected with the control plunger 145. When the magnet coil is energized, the armature 155 is drawn into the magnet, as a function of the current intensity, against the force of a return spring 156 which engages the core 157. The latter simultaneously serves as an abutment for the position of the control plunger 145. Longitudinal grooves 154 in the armature 155 serve to equalize the pressure at the armature.

The axial position of the control plunger 145 is transmitted directly by its frontal face 160 to a follower rod 31a integral with the axially slidable ferrite core 163 of an inductive transducer 165. The latter further includes two serially connected solenoids 161 and 162 surrounding the ferrite core 163. The reproducibility of the output magnitude of the inductive transducer 165 is increased by a play equalizing spring 164 which urges the ferrite core 163 continuously and slightly against the follower rod 31a.