Power transmission

An electrohydraulic servo valve assembly comprising a servo valve including a manifold having openings for connection to a source of hydraulic fluid and to a load, a valve element variably positionable in said manifold for controlling flow of fluid among said openings, a stator mounted on said manifold for receiving valve control signals, an armature coupled to said valve element and responsive to said stator for variably positioning said valve element within said manifold, and a cover mounted on said manifold for enclosing said armature and stator, and

• microprocessor-based control means mounted on said manifold within said cover, said control means including means for receiving and storing control signals from an external source, means for receiving signals from a sensor coupled to said load to indicate operation at said load, means for comparing said sensor signals to said control signals for generating error signals, and means responsive to said error signals for generating said valve control signals to said stator,
• said microprocessor-based control means comprising a plurality of printed circuit board assemblies mounted in stacked orientation internally of said cover, said means for receiving and storing said control signals from an external source comprising switch means carried by one of said printed circuit board assemblies adjacent to said cover and means responsive to collective states of said switch means for establishing a numerical address associated with said control means for communication with such external source, said cover including a removable panel adjacent to said switch means for affording access thereto.

An electrohydraulic servo valve assembly comprising a servo valve including a manifold having openings for connection to a source of hydraulic fluid and to a load, a valve element variably positionable in said manifold for controlling flow of fluid among said openings, a stator mounted on said manifold for receiving valve control signals, an armature coupled to said valve element and responsive to said stator for variably positioning said valve element within said manifold, and a cover mounted on said manifold for enclosing said armature and stator, and

• microprocessor-based control means mounted on said manifold within said cover, said control means including means for receiving and storing control signals from an external source, means for receiving signals from a sensor coupled to said load to indicate operation at said load, means for comparing said sensor signals to said control signals for generating error signals, and means responsive to said error signals for generating said valve control signals to said stator,
• said servo valve being responsive to pulse width modulated control signals to said stator for controlling position of said valve element,
• said error signal-generating means comprising means for generating said pulse width modulated control signal, and said microprocessor-based control means further comprising a watchdog timer connected to receive said pulse width modulated control signals and responsive to absence of such signals to indicate an error condition.

An electrohydraulic servo and actuator system comprising a servo valve including a manifold having openings for connection to a source of hydraulic fluid and to a load, a valve element variably positionable in said manifold for controlling flow of fluid among said openings, a stator mounted on said manifold for receiving valve control signals, an armature coupled to said valve element and responsive to said stator for variably positioning said valve element within said manifold, a cover mounted on said manifold for enclosing said armature and stator, a hydraulic actuator operatively coupled as a load to said manifold openings, and a position sensor coupled to said actuator for providing sensor signals as a function of operation at said load,

• said position sensor comprising magnetic means coupled to said actuator for motion conjointly therewith, waveguide means adjacent to said magnetic means in fixed position relative to travel of said magnetic means, means for launching current pulses in and receiving acoustic return pulses from said waveguide means, and means for determining position of said magnetic means with respect to said waveguide means and thereby determine position of said actuator, and
• microprocessor-based control means mounted on said manifold within said cover, said control means including means for receiving and storing control signals from an external source, means for receiving said sensor signals to indicate operation at said load, means for comparing said sensor signals to said control signals for generating error signals, and means responsive to said error signals for generating said valve control signals to said stator,
• said position-determining means comprising a counter, means responsive to a measurement signal from said microprocessor-based control means for resetting said counter and launching an initial current pulse in said waveguide means, means responsive to acoustic return pulses from said waveguide means for incrementing said counter and relaunching current pulses in said waveguide means, means coupled to said counter for indicating a preselected count in said counter corresponding to a preselected number of launch/return cycles at said waveguide means and for generating an interrupt signal to said microprocessor-based control means, a clock responsive to said measurement signal and to said interrupt signal for measuring time duration therebetween, and means responsive to a read signal from said microprocessor-based control means for transmitting output of said clock to said microprocessor-based control means as said sensor signal.