Abstract: In one aspect of the present invention, a method for detecting an electrical fault condition of a driver circuit is disclosed. The driver circuit is used to energize an electrohydraulic device that regulates fluid pressure. The method detects the fault condition, and responsively switches from a normal fluid pressure control strategy to a fault mode fluid pressure control strategy in order to continue to control the fluid pressure during the fault condition.

Abstract: A method and apparatus for determining a leak in an HC fluid supply of an exhaust purification system for an engine is disclosed. The fluid supply includes an injector that injects an amount of a NOx reducing fluid, a tank that holds the NOx reducing fluid, and a pump that pressurizes the NOx reducing fluid. The system fluid pressure is read before and after the pump is shut off. The pressure readings are compared and the exhaust purification system is turned off in response to the difference between the pressure readings being greater than a predetermined value.

Abstract: An apparatus for controllably moving a work implement is disclosed. The implement is connected to a work machine and is moveable in response to operation of a hydraulic cylinder. The apparatus includes an operator controlled joystick. A joystick position sensor senses the position of the joystick and responsively generates an operator command signal. An implement position sensor senses the position of the work implement and responsively produces an implement position signal. A microprocessor based controller receives the implement position and operator command signals, modifies the operator command signal, and produces an electrical valve signal in response to the modified operator command signal. An electrohydraulic valve receives the electrical valve signal, and controllably provides hydraulic fluid flow to the hydraulic cylinder in response to a magnitude of the electrical valve signal.

Abstract: A method for reducing the brake pressure commanded by a traction control system of a machine is disclosed. The method includes the steps of estimating the instantaneous heat energy associated with an applied brake, estimating the accumulated heat energy associated with the applied brake during the time period that the brake is applied in response to the instantaneous heat energy; comparing the accumulated heat energy to a maximum allowable heat energy value; and reducing the magnitude of the braking command signal to reduce the applied brake pressure in response to the accumulated heat energy being greater than the maximum allowable heat energy value.

Abstract: An apparatus controls the movement of a ripper for a machine. Tilt and lift cylinders controllably actuate the ripper. Hydraulic control valves control the flow of hydraulic fluid to the respective cylinder. An auto-return button produces an auto-return signal in response to being depressed by the machine operator. A controller receives the auto-return signal and delivers a ripper control signal to the hydraulic control valves to automatically raise the ripper to a predetermined position.

Abstract: A control system for automatically controlling a work implement of an excavating machine through a machine work cycle in disclosed. The work implement including a boom, stick and bucket, each being controllably actuated by at least one respective hydraulic cylinder. A plurality of command signal magnitudes associated with at least one hydraulic cylinder are stored. The command signal magnitudes are represented by a plurality of control curves, where each control curve is responsive to a material condition setting that is representative of a predetermined condition of the excavating material. A microprocessor selects one of the plurality of control curves and responsively produces a command signal having a magnitude dictated by the selected control curve. A electrohydraulic system receives the command signal and controllably actuates predetermined ones of the hydraulic cylinders to perform the work cycle.

Abstract: Apparatus and method for controlling dither in a solenoid actuator. Circuitry produces a frequency command signal in response to a measured dither parameter and produces a current command signal. A solenoid actuator input signal is delivered to a solenoid actuator, said solenoid actuator input signal having a frequency determined in response to the frequency command signal and a magnitude of current determined in response to a current command signal.

Abstract: An apparatus for measuring the flow rate of a liquid in a line includes a capacitor formed by a pair of electrodes. A charging circuit produces a charging current of constant magnitude. The charging current is used to charge the capacitor to a predetermined voltage. A timing circuit measures the time between the time at which the charging circuit begins to produce the charging current and the time at which the capacitor has been charged to the predetermined voltage. The timing circuit produces a pulse width modulated signal. The magnitude of the pulse width modulated signal is indicative of the time difference.

Abstract: An apparatus for measuring the pressure of a liquid in a container includes a capacitor formed by a pair of electrodes. A charging circuit produces a charging current of constant magnitude. The charging current is used to charge the capacitor to a predetermined voltage. A timing circuit measures the elapsed time between the time at which the charging circuit begins to produce the charging current and the time at which the capacitor has been charged to the predetermined voltage. The timing circuit produces a pulse width modulated signal. The magnitude of the pulse width modulated signal is indicative of the time difference and thus, the pressure within the container.

Abstract: An apparatus for sensing the level of fluid, including a two electrode device being disposed in the fluid and a microprocessor. The microprocessor being connected to the two electrode device and delivering alternating current thereto. The microprocessor reads the voltage across the device, compares the voltage to a predetermined voltage level, and produces a warning signal in response to the fluid level being below a predetermined fluid level.

Abstract: An electrical transmission control mechanism for shifting a transmission of a machine is provided. The control mechanism includes a control assembly that has rotational motion. A plurality of contactless sensors detect the amount of rotational movement of the control assembly and responsively produce signals that are indicative of a desired speed and/or direction of the transmission. A coupling arrangement couples the rotational motion of the control assembly to the contactless sensors to isolate the contactless sensors from mechanical loading that is imposed on the control assembly.

Abstract: An electromagnetic actuator is disclosed. The actuator includes a core having an inner and outer pole that defines a pole face. A coil of windings is disposed in the core and produces a magnetic field. An armature is moveable between first and second positions in response to the force produced by the magnetic field. A stroke elongation device is disposed adjacent to the outer pole piece and closely spaced from the armature. The stroke elongation device increases the pull-in force of the electromagnetic actuator.

Abstract: In one aspect of the present invention, an apparatus and method for calibrating an electrohydraulic system is disclosed. In accordance with the present invention, a hydraulic valve that is responsive to an electrical valve signal controllably provides hydraulic fluid flow to a hydraulic actuator. A position sensor senses the position of the hydraulic actuator and responsively produces an actuator position signal. A microprocessor based controller receives the actuator position signal and determines when the hydraulic actuator begins movement, and associates the magnitude of the electrical valve signal to a first predetermined joystick position. Thereafter, the microprocessor based controller determines when the hydraulic actuator movement reaches terminal velocity and associates the magnitude of the electrical valve signal to a second predetermined joystick position.

Abstract: An electrohydraulic control device for a drive train of a machine including an engine, a transmission, a torque converter, and an impeller clutch is disclosed. A manually operated impeller clutch pedal produces an impeller clutch pedal signal in response to the position of the impeller clutch pedal. An impeller clutch electrohydraulic valve produces fluid flow to the impeller clutch to controllably engage and disengage the impeller clutch. An impeller clutch pressure curve that is responsive to the impeller clutch pedal position is stored in memory. A rotary position switch selects a desired rimpull setting indicative of a desired reduction in rimpull and produces a desired rimpull signal. An electronic controller receives the desired rimpull signal and reconfigures the impeller clutch pressure curve.

Abstract: In one aspect of the present invention, an automatic screed temperature control is disclosed. The control senses the screed temperature and compares the screed temperature to a lower set point. In response to the screed temperature being less than the lower set point, the control causes fuel to dispense into the combustion chamber and subsequently causes the fuel to ignite in order to heat the screed. The screed is heated until the screed temperature becomes greater than an upper set point.

Abstract: In one aspect of the present invention, an apparatus for detecting particles within a fluid is disclosed. A bobbin defines a debris collection chamber. A first coil is wound in a helix about the bobbin in the proximity of the debris collection chamber, wherein the induction of the first coil is responsive to the particle accumulation within the collection chamber. A reference coil is wound in a helix about the bobbin to compensate for changing fluid temperature. An oscillator is coupled to the first and reference coils for selectively energizing the coils with an oscillating waveform at a frequency that induces eddy currents in the particles. The frequency of the oscillating waveform is indicative of the amount of accumulation of both the ferrous and nonferrous particles.

Abstract: In one aspect of the present invention, an apparatus for detecting particles within a fluid is disclosed. A bobbin defines a debris collection chamber. Spaced apart first and second coils are wound about the bobbin in the proximity of the debris collection chamber, wherein the inductance of the coils are responsive to the particle accumulation within the collection chamber. An electromagnet is wound about the second coil to attract ferrous particles into the proximity of the second coil. A reference coil is wound about the bobbin to compensate for the changing temperature of the fluid. An oscillator is coupled to the first, second and reference coils for selectively producing an oscillating waveform at a frequency that induces eddy currents in the particles. The frequency of the oscillating waveform is indicative of the amount of accumulation of both the ferrous and non-ferrous particles.

Abstract: In one aspect of the present invention, a zero crossing detecting circuit is disclosed. The circuit includes a first comparator having an inverting and non-inverting input connected to an input signal. The non-inverting input of the first comparator is further connected to the first comparator output to provide a feed forward path. A second comparator is additionally included having an output connected to the first comparator inverting input. This provides the inverting input of the first comparator with a reference voltage that is substantially equal to that of the first comparator non-inverting input; thereby, providing the first comparator with balanced inputs.

Abstract: 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.

Abstract: In one aspect of the present invention, a joystick is disclosed. The joystick includes a control shaft and a pivotal mount for the control shaft. A plurality of centering springs bias the control shaft to a neutral position, and extend and contract in response to pivotal movement of the control shaft. An oscillator circuit is coupled to the centering springs and produces an output signal having a frequency responsive to the inductance of the centering springs.