Abstract: A fuel control system (11) for a gas turbine engine (10) is disclosed. The proportional control regulates the fuel flow Wf from a hydromechanical unit (36) based upon an error signal E representing the difference between a demanded speed signal Nd and an actual speed signal Ng. The demanded speed signal Nd is generated by an integrator (32) as the time integral of the difference between the demanded signal Nd and a scheduled speed signal Ngs. Additionally, the difference signal is limited between an upper limit Al and a lower limit Dl prior to the integration by a comparator (28) and limited circuit (30).

Abstract: A fuel control apparatus (34) for a gas turbine engine (10). The fuel control apparatus (34) meters fuel flow Wf according to an electrical signal (Wf/Pc, E) indicative of the desired fuel/air ratio of the engine as scheduled from the power lever angle (PLA) by a closed loop acceleration based electronic governor (26). The apparatus (34) mechanically multiplies the electrical signal (Wf/Pc, E) by the compressor discharge pressure (Pc) of the engine (10) to yield the fuel flow (Wf).

Abstract: A pressure transducer (26) is disclosed. A multiplicity of signal plates (Cs, Cr, Csf, Crf) are disposed on a first quartz disc (88). Opposing the signal plates (Cs, Cr, Csf, Crf) across a gap formed by an annular frit (92) is a common plate (94) disposed on a second quartz disc (86). The signal plates (Cs, Cr, Csf, Crf) and common plate (94) form capacitors which are operable to modulate alternating excitation signals applied to the signal plates. The capacitances vary the modulation during deflections of the discs (86, 88) as a result of pressure changes, and the common plate (94) algebraically sums the modulated excitation signals into a single output from the transducer (26).

Abstract: A quartz capacitive pressure transducer including a sensing plate and a reference plate disposed on one quartz substrate which are opposed across a gap by a common plate on another quartz substrate to form capacitances. The substrates are maintained in their opposing relationship by an annular frit which seals a chamber between the substrates to a reference pressure. The reference plate is disposed in the area occupied by the frit annulus to provide a reference capacitance that has a zero pressure gradient.

Abstract: A fuel/air ratio control apparatus for a reciprocating engine used in light aircraft including a fuel metering apparatus (32) and an electronic fuel/air ratio control (39). The control (39) generates an electrical signal (Wf/Wa) indicative of a desired fuel/air ratio based upon the flight condition of the aircraft and the metering apparatus (32) meters fuel flow (Wf) according to the mass airflow (Wa) ingested by the engine. The fuel metering apparatus (32) positions a metering valve (348) by means of a force balance of opposing forces developed by an air diaphragm (330) and a fuel diaphragm (336). The fuel diaphragm (336) is subjected to the differential pressure of a metering head pressure (Pu) and a fuel output pressure (Pm). The output pressure (Pm) is regulated by a controlled orifice (343) influenced by a proportional solenoid (406) whose armature valve (341) is positioned by the electrical signal (Wf/Wa).

Abstract: An automatic speed control for a heavy duty vehicle includes a controller which regulates communication between a compressed air source and an air actuated throttle mechanism. The controller generates a control signal which is a function of a speed error signal and the position of the air actuated throttle to regulate the compressed air source. The speed error signal is calculated as the difference between a commanded speed signal and an actual speed signal. To generate the control signal, the error signal and throttle position signal are operated on by different lead-lag transfer functions. These lead-lag terms are thereafter combined with a proportional speed error term to yield the desired control signal. The system further includes a throttle control feature for powering auxiliary equipment when the actual speed signal is zero. Another feature of the control limits the commanded speed signal to a set value when it exceeds a predetermined limit.

Abstract: A fuel control apparatus (34) for a gas turbine engine (10). The fuel control apparatus (34) meters fuel flow Wf according to an electrical signal (Wf/Pc, E) indicative of the desired fuel/air ratio of the engine as scheduled from the power lever angle (PLA) by a closed loop acceleration based electronic governor (26). The apparatus (34) mechanically multiplies the electrical signal (Wf/Pc, E) by the compressor discharge pressure (Pc) of the engine (10) to yield the fuel flow (Wf).

Abstract: A fluid filter (10) of the spin-on automotive type has a housing with a unitary closure member (18). The unitary, or one-piece, closure member (18) includes provision for mounting of the filter and for fluid flow therethrough. Two opposed annular flanges (78, 80) of the closure member receive between them the marginal edge (72) of the filter shell in a fluid-tight crimped engagement. This arrangement facilitates manufacture of the filter by providing support to the shell wall (68) during the crimping operation and also provides an exceptionally strong joint between the shell (12) and closure member (18). Another embodiment of the filter has a closure member (18) with a marginal edge (76) having a portion of reduced thickness which facilitates its crimped engagement with the filter shell (12). Methods of making such closure members attain a unitary closure member without welding operations.

Abstract: An automatic speed control for a heavy duty vehicle includes a controller which regulates communication between a compressed air source and an air actuated throttle mechanism. The controller generates a control signal which is a function of a speed error signal and the position of the air actuated throttle to regulate the compressed air source. The speed error signal is calculated as the difference between a commanded speed signal and an actual speed signal. To generate the control signal, the error signal and throttle position signal are operated on by different lead-lag transfer functions. These lead-lag terms are thereafter combined with a proportional speed error term to yield the desired control signal. The system further includes a throttle control feature for powering auxiliary equipment when the actual speed signal is zero. Another feature of the control limits the commanded speed signal to a set value when it exceeds a predetermined limit.

Abstract: An actuator particularly adapted to control a plurality of bleed air valves of a gas turbine engine is disclosed. The actuator comprises n solenoid pilot valves where 2.sup.n is the number of actuation positions and 2.sup.n -1 is the number of bleed air valves to be actuated. The actuator receives as n bit digital signal corresponding to the number of bleed air valves to be actuated for a particular operating condition of the engine and the actuator converts this number into a correct mechanical position. The conversion is accomplished by a series of telescoping cylinder and piston assemblies each having an expandable chamber. Each chamber is independently contracted or expanded by an associated pilot valve controlling a pressure source in response to the presence or absence of a particular bit in the digital word. The size of the expandable chamber of each assembly is related to the others by ascending powerts of two and correspond to a bit position in the digital input signal.

Abstract: A control system 54 for a doser type hydraulic actuator 56 is disclosed. The doser actuator includes a pair of unequal area pistons 18, 20 on a common shaft 16 which are moved incrementally by injecting into or removing from a control pressure chamber metered quantities or doses of fluid. The doses are metered by timed openings of solenoid valves 32, 34 connecting the control pressure chambered to a supply 44 or return 48 pressure sources. The control system includes a base pulse width signal generator 106 which pulse modulates the solenoids as a function of the error between a requested position and an actual position. The base pulse width is modified by a correction means 108, 110, 112 when the error is within a predetermined band width. The correcting means compensates for the reaction of the actuator when its response is uncertain with respect to the base pulse width.

Abstract: A vibration adjustable spacer (10) is disclosed. In a preferred implementation spacers 10, 10', 10" are used to damp the vibrational resonance of a number of printed circuit boards (42, 44, 46) in an assembly (40). The spacer (10) has an adjustable snubbing means (30) which extends to abut an essentially stationary surface (7) when the board is accelerated in one direction and a pivotable means (22) operating such that retraction of the snubbing means is impeded when the board is accelerated in the opposite direction.

Abstract: An automatic speed control for a heavy duty vehicle includes a controller which regulates communication between a compressed air source and an air actuated throttle mechanism. The controller generates a control signal which is a function of a speed error signal and the position of the air actuated throttle to regulate the compressed air source. The speed error signal is calculated as the difference between a commanded speed signal and an actual speed signal. To generate the control signal, the error signal and throttle position signal are operated on by different lead-lag transfer functions. These lead-lag terms are thereafter combined with a proportional speed error term to yield the desired control signal. The system further includes a throttle control feature for powering auxiliary equipment when the actual speed signal is zero. Another feature of the control limits the commanded speed signal to a set value when it exceeds a predetermined limit.

Abstract: A control system 54 for a doser type hydraulic actuator 56 is disclosed. The doser actuator includes a pair of unequal area pistons 18, 20 on a common shaft 16 which are moved incrementally by injecting into or removing from a control pressure chamber metered quantities or doses of fluid. The doses are metered by timed openings of solenoid valves 32, 34 connecting the control pressure chambered to a supply 44 or return 48 pressure sources. The control system includes a base pulse width signal generator 106 which pulse modulates the solenoids as a function of the error between a requested position and an actual position. The base pulse width is modified by a correction means 108, 110, 112 when the error is within a predetermined band width. The correcting means compensates for the variations of the actuator when its response is uncertain with respect to the base pulse width.

Abstract: A digital resolver processor measures the angle of a rotatable device. A resolver connected to the rotatable device generates sinusoidal signals as a function of an excitation signal and of the resolver angle. A phase shift network receives the sinusoidal signals and generates leading and lagging phase shifted signals with a relative phase shift proportional to resolver angle. A counter is enabled by the leading signal and inhibited by the lagging signal so that the contents of the counter represents the relative phase shift, and thus, the angle of the rotatable device. The angular position of the resolver is limited so that the contents of the counter is maintained within a predetermined range in the absence of a fault condition of the resolver terminals. The contents of the counter is forced outside the predetermined range in response to short or open circuit conditions of the resolver terminals, so that misleading angle representations may be recognized as such.

Abstract: An aircraft low or flat tire flight deck warning system monitors the rotational speed and thus, the condition of the tires. A differential tire rotational speed signal is compared to a variable reference by a comparator which generates a warning signal when the differential signal is greater than or equal to the reference. The reference signal is derived from one of the tire rotation signals or from an independent ground speed signal and is therefore proportional to the rotational speed of a properly inflated tire and to the aircraft ground speed. Separate references and comparators cooperate to generate separate warning signals for distinct dangerous tire conditions. The warning signals are inhibited under a variety of conditions.

Abstract: An electrical resistance apparatus adapted for the measurement of the position of the throttle blade of an internal combustion engine is disclosed. The apparatus includes a generally annular housing which has an inside surface that supports a flexible resistive element. The resistive element comprises a flexible web on which two parallel resistive tracks have been overlaid. A generally cylindrical rotor mounts within the housing and electrically couples the two tracks by means of a U-shaped conductive wiper that bridges the separation between the resistive tracks. The rotor is mechanically connected to the throttle blade of the internal combustion engine and rotates therewith. By applying the leads of a power supply to one resistive track and reading a voltage signal from the other resistive track, a potentiometric signal related to the position of the throttle blade is developed.

Abstract: A fluid filter (10) of the spin-on automotive type has a housing with a unitary closure member (18). The unitary, or one-piece, closure member (18) includes provision for mounting of the filter and for fluid flow therethrough. Two opposed annular flanges (78, 80) of the closure member receive between them the marginal edge (72) of the filter shell in a fluid-tight crimped engagement. This arrangement facilitates manufacture of the filter by providing support to the shell wall (68) during the crimping operation and also provides an exceptionally strong joint between the shell (12) and closure member (18). Another embodiment of the filter has a closure member (18) with a marginal edge (76) having a portion of reduced thickness which facilitates its crimped engagement with the filter shell (12). Methods of making such closure members attain a unitary closure member without welding operations.

Abstract: A digital pressure measuring system with nonlinear resolution is disclosed. The system includes a capacitive pressure transducer with a pressure variable sensing capacitor and a substantially invariable reference capacitor. The capacitors of the transducer are excited by out-of-phase signals and their outputs combined at a summing junction. The output of the summing junction controls the incrementation of a counter whose output is converted to a nonlinear negative feedback signal. A closed loop is formed by applying the feedback signal to the summing junction through a feedback capacitor. The counter is incremented in a direction to null the loop such that its output is representative of the measured pressure.

Abstract: A voltage controlled oscillator for the conversion of a ratiometric analog signal into a digital signal is disclosed. The oscillator generates a square wave whose frequency is a function of the magnitude of the analog signal input. The variable frequency wave is generated by a comparator receiving high and low threshold levels from a network for comparison with a ramping voltage developed by a timing element. An increasing ramp is provided by a current source whose output is proportional to the analog signal and a decreasing ramp rate is provided by a current sink whose output is similarly proportional to the analog input signal. Because the analog input signal is ratiometric with variations in the power supply voltage, the ramp rates change with these variations, however the high and low threshold levels also change with variations in the supply voltage thereby the comparator generates a square wave output at a frequency independent of these variations.