Fuel systems for engines

Claim 2

A fuel system for an engine, comprising a pump for supplying fuel to the engine, an actuator for controlling the pump, an electronic governor controlling the actuator in accordance with the values of at least two parameters of the system, a supercharger for increasing the supply of air to the engine, the maximum pump output having a first level when the output of the supercharger is below a predetermined level said pump output rising to a second level when the output of the supercharger reaches and exceeds said predetermined level, said maximum pump output being set in the governor by comparing an electrical signal representing pump output with a reference signal which varies in accordance with the output of the supercharger, means for producing said reference signal said means including a transducer comprising transformer means for producing an AC signal having an amplitude dependent upon the output of the supercharger, a peak amplitude detector connected to the transformer means, the peak amplitude detector including a transistor serving to charge a capacitor during alternate halfcycles of the output from the transformer means, the conduction level of the transistor being determined by the amplitude of said a.c. signal.

Claim 3

A system as claimed in claim 1 in which said first level and said second level are set by controlling the minimum and maximum conduction levels respectively of said transistor.

Claim 4

A system as claimed in claim 2 in which the maximum conduction level is set by a diode connected between the base of the transistor and a point of fixed potential.

Claim 5

A system as claimed in claim 2 in which the conduction of the transistor is determined by a second transistor which when conductive removes base current from the first transistor, the minimum conduction level of the first transistor being set by the second transistor.

Claim 6

A system as claimed in claim 4 in which the second transistor has its base connected to the capacitor and its emitter connected through a diode to a point of fixed potential.

Claim 7

A system as claimed in claim 4 in which the second transistor forms with a third transistor a long tailed pair with the transformer means coupled to the base of the third transistor.

Claim 8

A fuel injection system for a diesel engine, comprising in combination a pump for supplying fuel to the engine, an electro-mechanical actuator coupled to the pump to determine the pump output, a drive circuit for controlling the electro-mechanical actuator, first, second and third transducers producing respectively output voltages representing engine speed, pump output and demanded engine speed, a first operational amplifier connected as a summing amplifier and having its inverting input connected through resistors to the first, second and third transducers, said first amplifier producing an output representing the difference between the actual and demanded engine speeds, but the difference being modified in accordance with the input received from the second transducer so as to provide the required engine characteristics, a second operational amplifier connected as a summing amplifier and having its inverting input connected through a resistor to the second transducer, a discriminator coupling the outputs of the amplifiers to the drive circuit, the arrangement being such that until a predetermined pump output is attained, the discriminator couples the first amplifier to the drive circuit, but when said predetermined rate of supply of fuel is reached, the discriminator couples the second amplifier to the drive circuit to limit the maximum rate of supply of fuel, a supercharger which increases the supply of air to the engine, and a fourth transducer for detecting the output of the supercharger and providing a signal to the inverting input of the second amplifier to increase said predetermined rate of supply of fuel. Pg,17

Claim 9

A fuel injection system for a diesel engine, comprising in combination a pump for supplying fuel to the engine, an electro-mechanical actuator coupled to the pump to determine the pump output, a drive circuit for controlling the electro-mechanical actuator, first, second and third transducers producing respectively output voltages representing engine speed, pump output and demanded engine speed, a first operational amplifier connected as a summing amplifier and having its inverting input connected through resistors to the first, second and third transducers, said first amplifier producing an output representing the difference between the actual and demanded engine speeds, but the difference being modified in accordance with the input received from the second transducer so as to provide the required engine characteristics, a second operational amplifier connected as a summing amplifier and having its inverting input connected through a resistor to the second transducer, a discriminator coupling the outputs of the amplifiers to the drive circuit, the arrangement being such that until a predetermined pump output is attained, the discriminator couples the first amplifier to the drive circuit, but when said predetermined rate of supply of fuel is reached, the discriminator couples the second amplifier to the drive circuit to limit the maximum rate of supply of fuel, a supercharger which increases the supply of air to the engine, and a fourth transducer for detecting the output of the supercharger and providing a signal to the inverting input of the second amplifier to increase said predetermined rate of supply of fuel. Pg,17

Claim 10

A fuel injection system for a diesel engine, comprising in combination a pump for supplying fuel to the engine, an electro-mechanical actuator coupled to the pump to determine the pump output, a drive circuit for controlling the electro-mechanical actuator, first, second and third transducers producing respectively output voltages representing engine speed, pump output and demanded pump output, a first operational amplifier connected as a summing amplifier and having its inverting input connected through resistors to the second and third transducers, said first amplifier producing an output representing the difference between the actual and demanded pump outputs, means restricting the maximum pump output to a predetermined value by restricting the demanded pump output, a second operational amplifier connected as a summing amplifier and having its inverting input connected through resistors to the first and second transducers, a discriminator coupling the outputs of the amplifiers to the drive circuit, the arrangement being such that until a predetermined enging speed is attained, the discriminator couples the first amplifier to the drive circuit, but when said predetermined engine speed is reached, the discriminator couples the second amplifier to the drive circuit to limit the maximum engine speed, the maximum engine speed being varied with pump output by the second amplifier, a supercharger which increases the supply of air to the engine, and a fourth transducer for detecting the output of the supercharger and providing a signal modifying the demanded pump output signal so as to increase said predetermined value of the maximum pump output.

Claim 11

A fuel injection system for a diesel engine, comprising in combination a pump for supplying fuel to the engine, an electro-mechanical actuator coupled to the pump to determine the pump output, a drive circuit for controlling the electro-mechanical actuator, first, second and third transducers producing respectively output voltages representing engine speed, pump output and demanded pump output, a first operational amplifier connected as a summing amplifier and having its inverting input connected through resistors to the second and third transducers, said first amplifier producing an output representing the difference between the actual and demanded pump outputs, means restricting the maximum pump output to a predetermined value by restricting the demanded pump output, a second operational amplifier connected as a summing amplifier and having its inverting input connected through resistors to the first and second transducers, a discriminator coupling the outputs of the amplifiers to the drive circuit, the arrangement being such that until a predetermined enging speed is attained, the discriminator couples the first amplifier to the drive circuit, but when said predetermined engine speed is reached, the discriminator couples the second amplifier to the drive circuit to limit the maximum engine speed, the maximum engine speed being varied with pump output by the second amplifier, a supercharger which increases the supply of air to the engine, and a fourth transducer for detecting the output of the supercharger and providing a signal modifying the demanded pump output signal so as to increase said predetermined value of the maximum pump output.