Abstract: An apparatus for determining the spool position of a directional valve is disclosed. A longitudinal valve housing has opposed ends and a plurality of fluid ports, and a spool moves reciprocatingly within the valve housing. A first spring disposed adjacent an end of the spool extends and retracts with the reciprocating movement of the spool. A first oscillator circuit is coupled to the first spring and is adapted to produce a first position signal in response to the inductance of the first spring. Finally, a logic device determines the incremental linear position of the spool relative to the housing in response to the frequency of the first position signal.

Abstract: Electromagnetic actuators having a coil and an armature are used in a number of applications in which it is useful to have an indication of the position of the armature with respect to the coil without the use of external sensors. Accordingly, an actuator control system is provided for determining the position of the armature with respect to the coil in response to the magnitude and rate of change of current flowing in the coil.

Abstract: In one aspect of the present invention a method is disclosed that controls the pressure of actuating fluid supplied to a hydraulically-actuated injector. A target time duration in which fuel is to be injected is determined, and compared to the actual time duration to determine a desired actuating fluid pressure in order to control the fuel injection rate.

Abstract: In one aspect of the present invention, an electronic shift control for a powershift transmission is disclosed. The transmission includes a plurality of speed and direction changing clutches. A plurality of pressure control valves are individually connected to the clutches. A hydraulic pump delivers pressurized hydraulic oil to predetermined pressure control valves to meter hydraulic fluid in response to receiving a clutch command signal. The method produces a shift from a first transmission ratio to a second transmission ratio through disengagement of an off-going clutch associated with the first transmission ratio and engagement of an on-coming clutch associated the second transmission ratio. The method includes filing an on-coming speed clutch, releasing an off-going direction clutch in response to the on-coming speed clutch being filled, and thereafter, gradually increasing the on-coming speed clutch pressure to engage the speed clutch.

Abstract: In one aspect of the present invention, an apparatus for protecting electronic circuit elements from hazardous voltages is provided. The apparatus includes a source of electrical energy that produces electrical energy having a predetermined energy level. An electrical load is connected to the electrical energy source and responsively receives electrical energy. A signaling device receives electrical energy from the electrical energy source and produces an overvoltage signal in response to receiving electrical energy greater than the predetermined energy level. An NMOSFET is connected to the electrical load, and controllably regulates the electrical current flowing through the electrical load. A control device receives the overvoltage signal and responsively controls the operation of the NMOSFET.

Abstract: A control system for automatically controlling a work implement of an excavating machine through a machine work cycle is disclosed. The work implement includes a boom, stick and bucket, each being controllably actuated by at least one respective hydraulic cylinder. A position sensor produces respective position signals in response to the respective position of the boom, stick and bucket. A pressure sensor produces respective pressure signals in response to the associated hydraulic pressures associated with the boom, stick, and bucket hydraulic cylinders. A microprocessor receives the position and pressure signals, and produces a command signal. An electrohydraulic system receives the command signal and controllably actuates predetermined ones of the hydraulic cylinders to perform the work cycle.

Abstract: A control system automatically controls a work implement of an excavating machine through a machine work cycle. The work implement includes a boom, stick and bucket, each being controllably actuated by at least one respective hydraulic cylinder. A position sensor produces respective position signals in response to the respective position of the boom, stick and bucket. A microprocessor receives the position signals, compares at least one of the boom, stick and bucket position signals to a predetermined one of a plurality of position setpoints. A pressure sensor produces respective pressure signals in response to the associated hydraulic pressures associated with the boom, stick, and bucket hydraulic cylinders. The microprocessor receives the pressure signals, and compares at least one of the boom, stick and bucket pressures to a predetermined one of a plurality of pressure setpoints.

Abstract: A method and apparatus for positioning a housing of an excavator housing. A motor receives pressurized fluid to cause rotation of the excavator housing. A motor position sensor determines the rotational position of the housing and responsively produces a housing position signal. A pressure sensor determines the fluid pressure supplied to the motor and responsively produces a pressure signal. A microprocessor produces a signal indicative of a desired rotational position of the housing. The microprocessor receives the position and pressure signals, and responsively controls fluid to the motor in order to rotate the housing to the desired position.

Abstract: In one aspect of the present invention, a method is disclosed that controls the pressure of actuating fluid supplied to a hydraulically-actuated injector. A target engine speed acceleration is determined, and compared to the actual engine speed acceleration to determine a desired actuating fluid pressure in order to control the fuel injection rate to start the engine.

Abstract: In one aspect of the present invention, a method is disclosed that controls the actuating fluid pressure supplied to a hydraulically-actuated injector and the time duration over which the hydraulically-actuated injector injects fuel. The desired actuating fluid pressure and injection duration is swept across a range of values to achieve an optimum combination of values to start an engine.

Abstract: In one aspect of the present invention, an apparatus for determining an extended length of a hydraulic cylinder is disclosed. A piston and rod are contained within a cylindrical housing of the hydraulic cylinder. A coil is wound about the rod and is attached to the piston and an end of the cylindrical housing. The coil extends and retracts with the reciprocating movement of the piston. An oscillator is coupled to the coil and produces a position signal in response to the inductance of the coil. A circuit receives the position signal, and determines the incremental linear position and velocity of the piston and rod relative to the housing in response to the frequency of the position signal.

Abstract: Electromagnetic actuators that include a coil and an armature are used in a number of applications. It is desirable to determine the position of the armature with respect to the coil without the use of external sensors. Accordingly, an apparatus is provided that determines the position of the armature with respect to the coil in response to the coil current and voltage.

Abstract: A non-contacting joystick includes a control shaft being universally movable about a Z-axis. A spherical conducting body is attached to an end of the control shaft. A plurality of conducting plates are disposed circumjacent to the spherical body. A charging power supply supplies electrical energy of a first polarity to the spherical body and electrical energy of a second polarity to the plurality of conducting plates. Each conducting plate forms a variable capacitor with the spherical body. The capacitance value of each variable capacitor is a function of the displacement of the spherical body relative to the Z-axis. A circuit produces a plurality of position signals, each position signal being responsive to a capacitance value of a respective variable capacitor. The position signals indicate the relative position of the spherical body.

Abstract: An apparatus for measuring torsional vibrations of rotating machinery is provided. A wheel having a plurality of spaced apart teeth is connected to the rotating machinery. A sensor detects the speed of wheel rotation and responsively produces a speed signal that has a frequency proportional to the rotational wheel speed. A timing device receives the speed signal, determines the period of the most recent pulse of the speed signal, and responsively produces an instantaneous period signal that has a value representative of the determined period. A microprocessor receives the instantaneous period signal, determines an instantaneous speed value of the rotating wheel and an average speed value of the rotating wheel based on previous wheel rotations.

Abstract: 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.

Abstract: In one aspect of the present invention, an apparatus for analyzing a plurality of events of an internal combustion engine is provided. A crankshaft sensor monitors the rotational position of the crankshaft and responsively produces a crankshaft pulsetrain. A cylinder pressure sensor senses the pressure produced in the engine cylinder and responsively produces a cylinder pressure signal. A memory device stores previously calculated values representing engine cylinder volumes at predetermined crankshaft positions. A microprocessor determines the start of combustion for an occurring engine cycle in response to a cylinder pressure signal magnitude, P.sub.2, at a current crankshaft position being equal or greater than the relationship:P.sub.1 (V.sub.1 /V.sub.2).sup.nwhere, P.sub.1 equals the cylinder pressure corresponding to a previous crankshaft position, V.sub.1 equals cylinder volume corresponding to the previous crankshaft position, V.sub.

Abstract: In one aspect of the present invention, an apparatus determines the rotational speed and direction of a rotating object. The apparatus includes a sensor adapted to detect the speed and direction of the rotating object and responsively produce a frequency signal indicative of the speed of the rotating object and a direction signal having a voltage value indicative of the rotational direction of the rotating object. A distinguishing stage receives the frequency and direction signals, and determines the voltage value of the portion of the direction signal that coincides with the falling edge of the frequency signal. Responsively the distinguishing stage produces a control signal having a voltage level responsive to the determined voltage value of the direction signal. A converting stage receives the frequency signal and responsively produces an output signal having a DC voltage proportional to the frequency of the frequency signal.

Abstract: An electrohydraulic assembly for actuating a moveable control element is provided. A valve body has two fluid ports, and a central bore. A core is disposed in spaced proximity from the valve body. An armature is rectilinearly translatable between first and second positions relative to the core. First and second electromagnetic coils produce respective electromagnetic forces in response to being energized to cause the rectilinear movement of the armature. A linearly shiftable spool is rigidly connected to the armature. The armature movement causes the spool to displace, which controls fluid flow for actuating the control element. First and second springs provide respective biasing forces to the armature to assist the rectilinear movement of the armature upon the appropriate energization of either of the electromagnetic coils.

Abstract: In one aspect of the present invention, an apparatus for measuring the height of liquid contained in a storage tank is disclosed. A tube is disposed inside the tank. A float is disposed inside the tube and is buoyed on the surface of the liquid. An ultrasonic transducer is disposed inside the tube. The ultrasonic transducer emits ultrasonic pulses toward the float, receives the reflected ultrasonic pulses, and responsively produces an echo signal. The float has a top portion and a bottom portion separated by a cylindrical portion. The bottom portion including an spherical surface which receives the ultrasonic pulses. The spherical surface has a predetermined radius which is a function of the inside diameter of the tube, the height of the cylindrical portion of the float and the outside diameter of the cylindrical portion of the float. A temperature sensor monitors the temperature of the liquid and produces a thermometric signal in response to the liquid temperature.

Abstract: A system is disclosed that performs a plurality of measurements based on a set of preprogrammed instructions. The system includes a central processing unit (CPU) that has an internal primary and expansion bus. The internal primary bus includes a program memory and the internal expansion bus includes an I/O memory. The set of preprogrammed instructions resides in the program memory and defines a predetermined type of measurement. A standard bus couples the internal primary bus to one or more standard external devices, while a custom bus couples the internal expansion bus to one or more custom external devices. The custom bus includes an analog bus that provides for analog signal transmission to one or more custom external devices. At least one of the custom external devices receives a test signal, conditions the test signal and delivers data representing the conditioned test signal to the I/O memory.