Tennant Company

Richard F Milun

Robert Erko

Bruce Phillip Bushey

Paul Leonard Groschen, Jr

John Peter Haeg

Terry B Schwartz

Musibau O Alowonle

Peter Alexander Loring

Steven Vincent Feeny

Craig Daniel Block

A control system for a linear actuator having an electric motor drawing a variable current level during operation. The control system includes a current level sensor for determining an operational current level of the linear actuator and a controller for generating a drive signal and a force request signal representative of a desired current level of the linear actuator. The drive signal remains constant during a predetermined time interval of the controller. The control system further includes a current limiting component for receiving the force request signal, the current level of the linear actuator and the drive signal. The current limiting component minimizes the current level of the electric motor in response to a comparison between the force request signal and the desired current level within a time interval substantially smaller than the predetermined time interval of the controller.

Linear actuator control structure

A rider surface maintenance vehicle with variable dynamic braking, in contrast to a mechanically-engaged braking system that uses a brake cable. A brake pedal engages a sensor that encodes the pedal position as an electronic signal. The electronic signal, along with the vehicle velocity, determines a machine deceleration rate, or braking rate, either by calculation, lookup table, or a combination of the two. The braking rate may be tuned so that the of the brake mimics or approximates the feel of a conventional mechanically-engaged brake that uses a brake cable. During stopping, once the vehicle passes below a threshold velocity, a parking brake is automatically engaged. The braking rate is converted to a duty cycle, and the braking is preferably accomplished by pulse width modulation (PWM) of an electrical load applied in parallel to the motor.

By wire control of braking and acceleration

A control system for estimating the approximate relative position of an electric linear actuator on a surface maintenance machine. The control system includes device for selectively coupling the electric motor of the linear actuator to the electric power source, device for measuring or estimating the current and voltage of the electric motor, device for estimating the motor speed based on the measured values of current and voltage, and storage device for storing values of estimated motor speed and integrating device for determining approximate linear actuator position, wherein the integrating device integrates the motor speed over time to determine the approximate position of the linear actuator position.

Back EMF actuator control

A power management system for a surface maintenance machine, such as a street sweeper is disclosed. The system includes a variable speed engine for transporting the surface maintenance machine, a hydraulic pump powered by the engine, a vacuum fan motor powered by the hydraulic pump, an engine speed sensor coupled to the engine, an electric proportional valve coupled between the hydraulic pump and the vacuum fan motor, said valve for selectively restricting a flow rate to the vacuum fan motor, and a control unit operatively coupled to the engine speed sensor and the proportional valve, said control unit receiving engine speed information from the engine speed sensor and communicating a predetermined signal to the proportional valve to control the flow rate to the vacuum fan motor as a function of engine speed. A method of managing engine power from a single-engine street sweeper is also disclosed.

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Corcoran, MN, United States of America

Richard F Milun