Abstract: A method for operating an internal combustion engine includes monitoring engine parameters using an electronic controller, determining a surge speed limit for the engine based on a compressor map, determining an offset engine speed based on a margin between the surge speed limit and an engine speed, determining a minimum engine speed based on the margin, applying the offset engine speed to an engine speed signal to provide an adjusted engine speed, and applying the adjusted engine speed to a desired engine speed when a speed of the engine approaches the surge speed limit.

Abstract: A method for operating an internal combustion engine includes monitoring engine parameters using an electronic controller, determining a surge speed limit for the engine based on a compressor map, determining an offset engine speed based on a margin between the surge speed limit and an engine speed, determining a minimum engine speed based on the margin, applying the offset engine speed to an engine speed signal to provide an adjusted engine speed, and applying the adjusted engine speed to a desired engine speed when a speed of the engine approaches the surge speed limit.

Abstract: An apparatus and method for providing a detent function on a hydraulic system. The hydraulic system includes a hydraulic implement movable between first and second implement positions. The apparatus and method receives a control input signal generated by an electronic control handle in response to operator input, monitors the control input signal, and actives a detent function if the control input signal follows a preset pattern. The preset pattern includes moving the handle to a detent area, between first and second positions, and then back to neutral, within a given time period. There is also a force feedback to the handle, opposing operator movement; which is proportional to the distance moved from neutral, and which has different attributes within and outside the detect area.

Abstract: A displacement controlled hydraulic proportional valve has a spring retainer and a force feedback spring serially disposed between a pilot valve spool and a main valve spool in a control chamber. An arcuate convex end portion on the pilot valve spool extends into a cylindrical pocket in the spring retainer essentially defining a contact point through which force is transferred between the pilot valve spool and the retainer. The point contact minimizes side loading on the pilot valve spool due to buckling of the feedback spring to minimize tendency of the pilot valve spool to stick during operation.

Abstract: Centering spring devices are useful in hydraulic control valves for returning the valve to the neutral position under both normal and abnormal operating conditions. Since the actuator moving the valve spool must work against the spring centering device, electrically actuated hydraulic valves have been limited to small sizes. The subject hydraulic control valve incorporates a centering spring device that can be controllably disabled so that the valve spool can be freely moved between the neutral and operating positions. In one embodiment, a centering spring is disabled by hydraulically moving the spring retainers toward each other to compress the spring with hydraulic fluid controlled by a solenoid valve. Maintaining the spring in a compressed condition permits the valve spool to be moved with a smaller actuator thereby making it feasible to control the valve position with an electrical actuator.

Abstract: An apparatus, is adapted to controllably position a movable element in a hydraulic motor. A controller receives a request signal and velocity and/or position signals from sensors. The controller, in accordance with a control scheme using velocity and/or position feedback, determines the flow of hydraulic fluid to the cylinder needed to reduce velocity and/or position errors. A directional valve, actuated by an electrohydraulic pilot system, delivers hydraulic fluid to the hydraulic motor.

Abstract: Vehicles having implements are typically used to perform repetitive functions in work cycles. An implement control system raises and lowers an implement relative to the vehicle and reduces the stresses applied to the vehicle from abruptly stopping the motion of the implement. A lever pilot signal is produced in response to the pivotal position of a control lever. An electrohydraulic pilot signal is also produced. The pilot signal having the greater pressure is directed to a main valve for controlling the position of the implement. The method and apparatus of the instant invention are applicable to a number of vehicles having a hydraulically operated implement.

Abstract: An apparatus is provided for controllably positioning a movable element within a hydraulic motor in response to a flow request signal. An electric circuit receives the flow request signal and responsively produces an energization signal. An electromagnetic actuator has a core, and a coil with a plurality of windings wound as a helix around the core. The coil is adapted to receive the energization signal and responsively produce a magnetic force proportional to the magnitude of the energization signal forcing the core to move bidirectionally relative to the coil. A mechanical coupling has one end connected to and movable with the core. A directional valve includes a spool connected to the other end of the mechanical coupling. The directional valve precisely meters pressurized fluid to the motor causing the movable element to move in response to the movement of the core.