Yale Materials Handling Corporation

Eaton Corporation

Bernard W Jalbert

Eugene P Finger

Thomas A Penkalski

David H Albanesius

James A Wahl

Gerald W Skulley

A proximity switch including an inductor having an actuator rod movable in proximity thereto to affect the inductance thereof. An electrical pulse of relatively short duration is applied to the inductor and the current from the inductor is measured at a selected time interval after the initiation of the pulse. When a selected value of the current is exceeded, the switch is triggered. A plurality of inductors may be sequentially interrogated by one electronic circuit, thus requiring low power and affording smooth operation. Calibration of the trigger point is accomplished electronically after mechanical installation, thus inherently compensating for mechanical tolerances and proximity effects.

Inductive proximity switch means and method

Apparatus for inhibiting high torque created by the application of reverse voltage to a conventional motor with a field coil and armature operating in the opposite direction comprising a pair of drive resistors in series with the motor, a corresponding normally open contact connected in parallel to each respective drive resistor, an energizing coil corresponding to each contact, a timing circuit and an inhibitor circuit. During high speed forward operation, both coils are energized, closing both contacts, shorting out both drive resistors and maximizing motor voltage. When reverse operation is desired, a reverse voltage is applied across the armature, resetting the timing circuit and activating the inhibitor circuit. The inhibitor circuit will deenergize the coils, opening the contacts and remove the short across the drive resistors and thus reduce the reverse voltage being applied and permit gradual deacceleration. When armature speed nears zero, the inhibitor circuit deactivates and the energizing coils reenergize, increasing reverse motor voltage upon the expiration of the time delay of the timing circuit.

High torque inhibitor

A motion sensor which includes, in a basic embodiment, two sensing elements of any type disposed so as to detect the relative passing thereby of perturbations. The sensing elements are disposed so that they are offset with respect to the perturbations, such that the sensing elements cannot both be activated simultaneously. When one sensing element is activated, thus indicating motion, timing means starts counting and, if the other sensing element is activated within a predetermined length of time, the sensor infers that purposeful motion has been detected and may, for example, activate a power steering assist unit. The spacing of the perturbations determines the minimum degree of motion required for the motion sensor to provide an output and the timing mechanism determines how rapidly that degree of motion must occur for the motion sensor to provide the output. Thus, the spacing and time parameters may be set so that purposeful motion may be discriminated from random motion such as vibration. The sensing elements may be photodetectors, microswitches, pressure sensors, reed switches, or conductive, inductive, or capacitive proximity sensors, or of any other type. The corresponding perturbations may be arrayed on either a rotating or a linearly moving member.

Motion sensor useful for power assisted steering systems

A multiple function control for an electric lift truck which facilitates moving the truck while the load carriage is being raised or lowered. Two vehicles speeds in forward and reverse can be selected by means of a pair of pushbuttons (34, 36) located on the load carriage lift control handle (32), independent of the normal vehicle travel control (28). Circuit means are provided to prevent simultaneous selection of both forward and reverse drive motor directions and to prevent adverse results from simultaneous operation of the normal vehicle travel control and the pushbutton control.

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Richboro, PA, United States of America

Bernard W Jalbert