Caterpillar Inc.

James A Antone

Fred C Lee

Martin Leo Willi

Paul C Gottshall

Michael R Verheyen

William J Love

Wojciech A Tabisz

Errol W Davis

Brian W Mann

Liliana Grajales

Kenneth D Gihring

A current mirror circuit is provided including a first and second transistors of a first conductivity type, the first transistor having a base connected to a base of the second transistor forming a base junction. A third transistor which is of a second conductivity type is connected in series with the first transistor and a collector of the third transistor is connected to the base junction of the first and second transistors. A fourth transistor which is of the second conductivity type is connected in series with the second transistor and has a base connected to a base of the third transistor forming a base junction. A collector of the second transistor is connected to the base junction of the third and fourth transistors. A first resistor is connected between an emitter of the third transistor and ground and a second resistor is connected between an emitter of the fourth transistor and ground. The circuit provides current matching over the first and second resistors where such resistors have about the same resistance values.

Current mirror circuit with improved correction circuitry

In one aspect of the present invention a gate drive circuit is disclosed. The gate drive circuit includes a first voltage source, a power transistor, a first and second switching device, and a controller. The power transistor has a drain connected to the first voltage source and a source connected to a load. The first switching device is connected to the power transistor gate and biases the power transistor ON to transfer energy from the first voltage source to the load. The second switching device is connected to the power transistor gate and biases the power transistor OFF to block the transfer of energy from the first voltage source to the load. The controller is connected to the first and second switching device and controls the power transistor at a first state where the first switching device biases the power transistor ON, controls the power transistor at a second state where the second switching device biases the power transistor OFF and provides a signal path from the power transistor gate to ground, and controls the power transistor at a third state where the second switching device biases the power transistor OFF to protect the second switching device from short circuit voltages in response to the controller detecting a short circuit condition in the power transistor.

Gate drive circuit that controls a power transistor in three states

A method of prolonging the life of glow plugs comprises the steps of providing a variable displacement pump rotatably connected to a internal combustion engine; driving a hydraulic motor at a generally constant speed with the hydraulic output of the variable displacement pump and directly connecting an alternator to the hydraulic motor to energize the glow plugs with an AC current and voltage and controlling the AC current to maintain a generally constant glow plug temperature from startup and throughout the entire operating range of the internal combustion engine.

Method of prolonging the life of glow plugs

The present invention is directed toward a circuit for receiving an input current and for producing an output voltage proportional to the input current. The circuit includes a first transistor which receives the input current, and a second transistor connected to the first transistor, wherein the first and second transistors comprise a current mirror topology. A third transistor is connected in series with the first transistor, and an operational amplifier has an output which is connected to the base of the third transistor. The third transistor has a collector coupled to a base junction of the current mirror. The operational amplifier has a positive input terminal coupled to a collector of the second transistor through a first resistor, and a negative input terminal coupled to an emitter of the third transistor through a second resistor, the first and second resistors having substantially similar impedance values.

Current mirror correction circuitry

In one aspect of the present invention, an apparatus for controlling the temperature of a plurality of glow plugs of a multi-cylinder internal combustion engine is disclosed. A voltage sensor produces a signal relative to the magnitude of the sensed voltage across a glow plug. A microprocessor compares the magnitude of the sensed signal with a preselected magnitude indicative of a predetermined temperature glow plug and responsively produces a current command signal. An alternator receives the current command signal and responsively delivers alternating current to the glow plugs.

Alternating current control apparatus and method for glow plugs

A solenoid driver circuit is controlled by an electronic control module ('ECM') and eliminates many components required for a high voltage power supply required by the prior art. The solenoid driver circuit includes a high voltage select switch, a select switch and a modulation switch that are controlled by the ECM. The ECM causes the switches to be opened and closed so that the back EMF created by the solenoid coil when the modulation switch is opened can be recaptured by charging a capacitor. That energy can then be used to energize the solenoid coil.

Solenoid injector driver circuit

In one aspect of the present invention a gate drive circuit is disclosed. The gate drive circuit includes a high voltage and low voltage energy source, a power transistor, a switching transistor, and a charging capacitor. The charging capacitor stores energy from the low voltage energy source. The gate drive circuit further includes a circuit that biases the switching transistor OFF which causes the low voltage energy stored in the capacitor to bias the power transistor ON to transfer high voltage energy to the load. The circuit additionally biases the switching transistor ON which biases the power transistor OFF to block the transfer of high voltage energy. Finally, a protection device is included to limit the power transistor voltage to a maximum voltage level in response to the power transistor being biased ON.

Gate drive circuit

A circuit includes a high voltage energy source, a power transistor having a drain connected to the energy source and a source connected to a load, and a first capacitor connected between the power transistor gate and source. Also included is a first P-channel transistor connected in parallel with the first capacitor, and a second capacitor connected between the first P-channel transistor gate and drain. A transformer delivers positive voltage to the first capacitor to bias the power transistor ON, and delivers negative voltage to the second capacitor to bias the first P-channel transistor ON, which causes the energy stored in the first capacitor to discharge; thereby biasing the power transistor OFF.

An apparatus that drives a piezoelectric actuator in response to charging and discharging command signals is disclosed. The apparatus includes an energy source that supplies electrical energy to the piezoelectric actuator. A charging circuit includes: a charging transistor connected to the energy source to control the amount energy supplied to the piezoelectric actuator, a charging inductor connected to the charging transistor to limit the rate of change of energy supplied to the piezoelectric actuator, and a charging thyristor disposed between the charging circuit and the piezoelectric actuator. A selecting circuit receives the charging command signal and responsively biases the charging thyristor ON to connect the piezoelectric actuator to the charging circuit. A comparator determines the magnitude of voltage applied to the piezoelectric actuator. A control circuit receives the charging command signal, and responsively biases the charging transistor alternately ON and OFF to control the amount of energy supplied to the piezoelectric actuator in response to the piezoelectric actuator voltage being less than an upper desired voltage value. Finally, the selecting circuit biases the charging thyristor OFF to disconnect the piezoelectric actuator from the charging circuit in response to the piezoelectric actuator voltage being greater than or equal to the upper desired voltage value.

Apparatus for driving a piezoelectric actuator

An apparatus is provided for controllably connecting and disconnecting a piezoelectric actuator to and from an energy source to effect the displacement of a piezoelectric actuator for a fuel injector. Precise control of the timing and duration of the piezoelectric actuator is necessary to ensure that a proper quantity of fuel is delivered to each cylinder of an internal combustion engine. A charging and discharging means monitors the voltage level of the piezoelectric actuator, and the charging and discharging current of the piezoelectric actuator. Further, a smoothing means aids in leveling the charging and discharging current to better approximate a constant current to control the piezoelectric actuator providing a precise quantity of fuel to be delivered.

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Edwards, IL, United States of America

James A Antone