Crown Equipment Corporation

Solaria Research Enterprise, Ltd.

John R Harman

Robert Gordon Lankin

Christopher M Killian

Joseph K Hammer

David B Stang

Ned E Dammeyer

Nathan L Blake

Randall D Plaugher

James L Hoying

Carl H Pohl

A system is provided that evaluates an energy state. The system comprises a sensor, bins, and a processor. The sensor is communicatively coupled to at least one cell that is powering an electric load. The sensor is operative to collect samples, each representing a measure of current discharged from the at least one cell during a discharge event. The bins are stored in a memory, and are accessible by the processor. The processor is programmed to sort the collected samples into bins based upon sample value. The processor is also programmed to create a use estimate based upon samples sorted into their corresponding bins. Yet further, the processor is programmed to determine a fractional depletion for each bin, each fractional depletion being a quotient that is computed by dividing an expected value for that bin by the use estimate for that bin.

Fractional depletion estimation for battery condition metrics

Evaluation of a battery state comprises transforming a time based history of the load on the battery into a spectral representation of that history in a load domain, e.g., the current domain. The method also comprises comparing the spectral representation to an expected battery capability for the load represented by each line in the spectra and calculating the fraction of the expected capability used at each spectral line. The method still further comprises aggregating the calculated fractions into a total fraction that represents the estimated fraction of the expected battery capability associated with that particular time history.

A motor control system is provided comprising an electrically charged battery, an electrical motor, a battery voltage sensor, a motor speed sensor, an armature voltage sensor, an armature current sensor, and a microprocessor. The magnitude of the armature current applied to the motor is a function of a predetermined armature current setpoint signal and the magnitude of the field current applied to the motor is a function of a predetermined field current setpoint signal, a field current correction signal, and a field current de-boost signal. The microprocessor programmed to generate an armature current setpoint signal, a field current setpoint signal, and an armature voltage reference signal. Further, the microprocessor is programmed to (i) compare the armature voltage reference signal to the measured armature voltage signal and generate an armature voltage error signal based on the comparison; (ii) generate the field current correction signal as a function of the armature voltage error signal; (iii) generate an armature-to-field current check function, wherein the check function defines a set of armature current to field current ratio values as a function of armature current; (iv) calculate a ratio of the measured armature current signal to the field current setpoint signal to establish an operating ratio value, (v) compare the operating ratio value to a corresponding armature current to field current ratio value of the armature-to-field current check function, and (vi) establish the field current de-boost signal, wherein the magnitude of the field current de-boost signal is a function of the measured armature current signal and the comparison of the operating ratio value to the corresponding ratio value.

Separately excited DC motor with boost and de-boost control

In accordance with one embodiment of the present invention, a motor control system is provided comprising an electrical motor, a motor speed sensor, a speed command generator, an armature voltage sensor, and a microprocessor. The electrical motor includes an armature assembly and a field assembly. The armature assembly is responsive to an armature current, the magnitude of which is a function of a predetermined armature current setpoint. The field assembly is responsive to a field current, the magnitude of which is a function of a predetermined field current setpoint and a field current correction signal. The motor speed sensor is arranged to generate an actual motor speed signal representative of an actual speed of the electrical motor. The speed command generator is arranged to generate a speed command signal indicative of a desired speed of the electrical motor. The armature voltage sensor is arranged to generate a measured armature voltage signal from an electrical potential of the armature assembly. The microprocessor is programmed to: (i) generate an armature voltage reference signal, the field current setpoint, and the armature current setpoint, wherein the armature voltage reference signal, the field current setpoint, and the armature current setpoint as a function of the speed command signal and the actual motor speed signal; (ii) compare the armature voltage reference signal to the measured armature voltage signal and generate an armature voltage error signal based on the comparison; and, (iii) generate the field current correction signal as a function of the armature voltage error signal.

Compensated field current control for a separately excited DC motor

A lift truck provided with a fixed mast section, several moveable mast sections and a carriage supporting load carrying forks and operator's platform is hydraulically raised and lowered. Mast chains interconnect the fixed mast section and the moveable mast sections and the moveable mast sections and the carriage. One pair of cushioning devices is placed between the fixed mast section and lower most moveable mast section and a second pair of cushioning devices is placed between the uppermost moveable mast section and the carriage. Each cushioning device two spring elements, one with a relatively soft spring rate, the other with a relatively stiff spring rate. The cushioning devices and a common hydraulic connection between hydraulic cylinders combine to reduce the shock and jerk felt by the operator during mast staging while raising or lowering the mast in either an empty or loaded condition.

Mast staging cushion apparatus

A brake control apparatus for controlling the application of braking torque to a permanent magnet brake of the type wherein a permanent magnet creates a magnetic flux path for applying a braking torque and an electromagnet provides a continuously variable flux in opposition to the permanent magnet. Braking torque is controlled in response to a braking command signal from an operator controlled floor pedal or hand grip which varies in relation to the amount of braking desired. A control circuit responsive to the braking command signal causes braking torque to be generated in direct proportion to the amount of braking desired. The control circuit including a device for applying either direct current or pulses of current to the electromagnet, the pulse width of which varies from a minimum pulse width representing maximum braking to a maximum pulse width representing no braking. The pulses are monitored to insure proper operation. The current in the pulses is used as an indication of brake temperature and is used to control the pulse width of any given desired brake torque. A tachometer monitors the direction and speed of rotation of the braked wheel and an anti-skid algorithm modifies the pulses applied to prevent wheel lockup. The brake is fail safe since removal of current to the electromagnet either by operation of the control circuit or by an emergency removal of power will cause the permanent magnet to apply full braking torque.

Proportional control of a permanent magnet brake

A materials handling vehicle or fork lift truck may be equipped with either cushion or pneumatic tires. When converting the vehicle from cushion to pneumatic tires, the front axle is moved downward and the mast assembly is moved forward to provide adequate clearance. The rear axle is also moved downward and backward. Changing configurations requires the addition of only one component; all of the other axle mounting hardware can be either repositioned or its orientation reversed in order to accommodate the change.

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Versailles, OH, United States of America

John R Harman