Fuel level sensors

Figure 1.176 shows a carbon fiber prototype mold for a 400-liter fuel tank with a simplified frame and screwed form flanges. The attachment of required fixtures like a fuel-level sensor, threaded fittings, inserts, etc. enables the rotation of prototypes in production-based design. 

The single largest application for ECTEE has been as primary insulation and jacketing [62] for voice and copper cables used in building plenums [63]. In automotive applications, ECTEE is used for jackets of cables inside fuel tanks for level sensors, for hookup wires, and in heating cables for car seats. Chemically foamed ECTEE is used in some cable constructions [64]. In the chemical process industry, it is often used in chlorine/caustic environment in cell covers, outlet boxes, lined pipes (Eigure 4.26), and tanks. 

Fuel- as well as oil-level sensors using capacitive and thermal principles are state of the art and are thus not further discussed in this contribution. 

Propellant utilization systems have been used to attain minimum propellant residual at engine cutoff by controlling outflow of one of the propellants within the limits of mixture ratio tolerances. Signals from point level sensors, which are spaced at various percent full levels in both the fuel and oxidizer tanks, can be compared on a time basis and processed through a computer. The computer may then provide the necessary mixture ratio control commands to a flow control valve. Such a system is presently used on the Atlas Standard Space Launch Vehicle (SSLV) and has been proposed for upper stages of Saturn. 

An internal power supply module provides the power needed by certain components within a fuel cell system. The components include sensors, control boards, pumps, fans, blowers, compressors, solenoid valves, contactors, switches, and so on. The IPM also provides the power to start the fuel cell system and helps carry some load when the fuel cell stack is inadequate to handle a sudden load jump. There are many types of sensors in a fuel cell system, such as the H2 concentration sensors, the H2 pressure sensors, the fluid flow rate sensors, the coolant-level sensors, the temperature sensors, the current sensors, the voltage sensors, the door-open sensors, the vibration sensors, and the flooding sensors. These sensors monitor the corresponding parameters to indicate the situation of the entire fuel cell system. The control boards may include a main board for controlling the system and several sub-boards for controlling various modules discussed in this chapter. Pumps, fans, blowers, compressors, solenoid valves, contactors, and switches all require power to perform the corresponding functions. 

The FLD-system provides an estimate of the fuel volume in the fuel tank to the driver along with a warning if the fuel volume drops below a predefined value. The functionality provided by the FLD-system is distributed across three Electronic Control Unit (ECU)-systems, i.e. an ECU with sensors and actuators, in the Electronic/Electrical (E/E)-system Engine Management System (EMS), Instrument Cluster (ICL), and Coordinator (COO). The ECU-systems also interact with the fuel tank that is outside of the E/E-system. COO estimates the fuel volume in the tank by relying on the output of a Kalman filter that, in turn, relies on a signal of a sensor measuring the fuel level in the tank and an estimate of the current fuel consumption provided by EMS, as inputs. The estimated fuel... 

The oxygen sensor closed loop system automatically compensates for changes in fuel content or air density. For instance, the stoichiometric air/fuel mixture is maintained even when the vehicle climbs from sea level to high altitudes where the air density is lower. 

Some tanks are installed with permanent leak identification sensors, which can check for leaked fuel vapor or liquid as it comes into contact with the sensors.21 However, these, as well as all the environmental sign tests (visual or instrumental) may be triggered by a spill instead of a leak. The success of external systems depends on the sensitivity of the sensor, the ability of the sensor to distinguish the stored chemical from other chemicals, the ambient background noise level of the stored chemical, the migration properties of the chemical, and the sampling network. 

These modern computer controlled ignition systems use multiple sensors to determine optimum firing. This may include double pick-up sensors on the flywheel to determine rpms under acceleration and deceleration, intake and atmospheric pressure compensation, oxygen sensor levels to maximize combustion, temperature sensors and exhaust emission sensors. All this data is constantly fed into the on-board computer and processed using complex algorithms to determine optimum firing and fuel consumption levels. 

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