Power transmission

Claim 2

An electrohydraulic system with distributed control comprising a plurality of electrohydraulic devices each including means responsive to a pulse width modulated electronic signal for performing an associated hydraulic operation and sensing means for sensing operation of the associated device and providing a sensor signal as a function of such operation, and master control means coupled to all of said devices for coordinating operation of said devices, each of said plurality of devices comprising an assembly having on-board microprocessor-based device control means including means for receiving and storing control signals from said master control means, means for receiving said sensor signal indicating operation of the associated said device, means for comparing said sensor signal to said control signals to generate pulse width modulated error signals, means for operating the associated said electrohydraulic device as a function of said pulse width modulated error signals, means for specifying a communication address unique to each said device control means, said master control means being connected to all of said device control means for communication of said control signals to said device control means individually as a function of associated device address, and a watchdog timer connected to receive said pulse width modulated signals and responsive to absence of such signals to indicate an error condition.

Claim 3

The system set forth in claim 1 wherein each said device control means includes means for bidirectional communication with said master control means, including means for transmitting signals to said master control means indicating status of the associated device.

Claim 4

The system set forth in claim 1 wherein said address-specifying means comprises a plurality of operator switch means, said device control means including means responsive to collective states of said switch means for compiling an address code for the associated device.

Claim 5

The system set forth in claim 1 wherein said error signal-generating means includes memory means for storing predetermined programs for controlling operation of said device, and wherein said microprocessor-based device control means includes means responsive to control signals from said master controller for selecting among said predetermined programs for generating said error signals and thereby controlling operation of said device.

Claim 6

The system set forth in claim 1 wherein each said device controller includes display means for continuously indicating operation of the associated device.

Claim 7

The system set forth in claim 5 wherein said display means comprises first illumination means and means for continuously alternately energizing and de-energizing said first illumination means, such that continuous illumination or continuous extinction of said first illumination means indicates malfunction at said device.

Claim 8

The system set forth in claim 6 wherein said display means further comprises second illumination means for indicating pendency of communication between said master control means and the associated device.

Claim 9

The system set forth in claim 1 wherein said watchdog timer comprises a controlled oscillator responsive to absence of said pulse width modulated signals for a predetermined time duration for resetting said device control means, and to resumption of said pulse width modulated signals for enabling operation of said device control means.

Claim 10

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.

Claim 11

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.

Claim 12

The servo valve assembly set forth in claim 9 wherein said panel is translucent, and wherein said control means further comprises optical display means carried by said one of said printed circuit board assemblies adjacent to said switch means beneath said panel for indicating operation of said servo valve assembly.

Claim 13

The system set forth in claim 10 wherein said optical display means comprises first illumination means and means for continuously alternately energizing and de-energizing said first illumination means, such that continuous illumination or continuous extinction of said first illumination means indicates malfunction at said device.

Claim 14

The system set forth in claim 11 wherein said optical display means further comprises second illumination means for indicating pendency of communication between said master control means and an external source of control signals.

Claim 15

The servo valve assembly set forth in claim 9 wherein said error signal-generating means includes memory means for storing predetermined programs for controlling operation of said servo valve, and wherein said microprocessor-based control means includes means responsive to control signals from an external source for selecting among said predetermined programs for generating said error signals and thereby controlling operation of said servo valve.

Claim 16

The servo valve assembly set forth in claim 9 wherein said servo valve is responsive to pulse width modulated control signals to said stator for controlling position of said valve element, characterized in that said error signal-generating means comprises means for generating said pulse width modulated control signal, and in that said microprocessor-based control means further comprises a watchdog timer connected to receive said pulse width modulated control signals and responsive to absence of such signals to indicate an error condition.

Claim 17

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.

Claim 18

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.

Claim 19

The system set forth in claim 15 wherein said watchdog timer comprises a controlled oscillator responsive to absence of said pulse width modulated control signals for a predetermined time duration for resetting said control means, and to resumption of said pulse width modulated control signals for enabling operation of said control means.

Claim 20

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.

Claim 21

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.

Claim 22

The system set forth in claim 17 wherein said clock comprises clock oscillator and a second counter for providing said sensor signal as a digital signal to said microprocessor-based control means.

Claim 23

The system set forth in claim 18 wherein said microprocessor-based control means comprises a plurality of printed circuit board assemblies mounted in stacked orientation internally of said cover, and wherein said position-determining means is carried on one of said printed circuit board assemblies.

Claim 24

The system set forth in claim 19 further comprising first and second connectors on said cover, said microprocessor-based control means being coupled to said first connector for connection to an external source of said control signals, said position-determining means being coupled to said second connector for connection to said position sensor.

Claim 25

The system set forth in claim 18 wherein said servo valve is characterized by a predetermined gain increase over a specified temperature range, and wherein said armature comprises electronic coil means having at least one coil constructed of an electrical conductor having an increasing electrical resistance characteristic over said temperature range which substantially complements said predetermined gain increase, such that overall gain of said system remains substantially constant over said temperature range.

Claim 26

The system set forth in claim 21 wherein said valve driver means comprises a voltage-controlled amplifier, such that current to said armature coil means and force applied thereby to said armature and valve element vary with resistance of said coil means.

Claim 27

The system set forth in claim 22 wherein said conductor comprises a 60-alloy copper wire.

Claim 28

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, 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, and means responsive to said control signals from said external source and coupled to said stator for generating said valve control signals, and valve drive means for generating said valve control signals as voltage-controlled pulse width modulated signals, said valve drive means comprising a differential amplifier having power inputs coupled to positive and negative supply voltages, a control input for receiving control signals, and a reference input coupled to ground, such that output of said amplifier is at ground in the absence of such control signals.

Claim 29

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, 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, and means responsive to said control signals from said external source and coupled to said stator for generating said valve control signals, and valve drive means for generating said valve control signals as voltage-controlled pulse width modulated signals, said valve drive means comprising a differential amplifier having power inputs coupled to positive and negative supply voltages, a control input for receiving control signals, and a reference input coupled to ground, such that output of said amplifier is at ground in the absence of such control signals.

Claim 30

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, 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, and means responsive to said control signals from said external source and coupled to said stator for generating said valve control signals, and valve drive means for generating said valve control signals as voltage-controlled pulse width modulated signals, said valve drive means comprising a pair of solid state switches having control electrodes for receiving valve control signals, and power electrodes for alternately connecting positive and negative voltage supplies to said armature as a function of said valve control signals.

Claim 31

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, 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, and means responsive to said control signals from said external source and coupled to said stator for generating said valve control signals, and valve drive means for generating said valve control signals as voltage-controlled pulse width modulated signals, said valve drive means comprising a pair of solid state switches having control electrodes for receiving valve control signals, and power electrodes for alternately connecting positive and negative voltage supplies to said armature as a function of said valve control signals.

Claim 32

The system set forth in claim 25 further comprising an inverter connected between said control electrodes, whereby said switches are both responsive to a single control signal to said inverter.

Claim 33

The system set forth in claim 26 wherein said switches comprise power MOSFETs.

Claim 34

An electrohydraulic servo 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 including electronic coil means mounted on said manifold for receiving valve control signals, an armature coupled to said valve element and responsive to said stator coil means for variably positioning said valve element within said manifold, said servo valve being characterized by a predetermined gain increase over a specified temperature range, and valve driver means for supplying said valve control signals to said stator, characterized in that said electronic coil means comprises at least one coil constructed of an electrical conductor having an increasing electrical resistance characteristic over said temperature range which substantially complements said predetermined gain increase, such that overall gain of said system remains substantially constant over said temperature range.

Claim 35

An electrohydraulic servo 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 including electronic coil means mounted on said manifold for receiving valve control signals, an armature coupled to said valve element and responsive to said stator coil means for variably positioning said valve element within said manifold, said servo valve being characterized by a predetermined gain increase over a specified temperature range, and valve driver means for supplying said valve control signals to said stator, characterized in that said electronic coil means comprises at least one coil constructed of an electrical conductor having an increasing electrical resistance characteristic over said temperature range which substantially complements said predetermined gain increase, such that overall gain of said system remains substantially constant over said temperature range.

Claim 36

The system set forth in claim 28 wherein said valve driver means comprises a voltage-controlled amplifier, such that current to said armature coil means and force applied thereby to said armature and valve element vary with resistance of said coil means where the coil resistance sensitivity to temperature changes is controlled in a manner whereby the effect of temperature on coil current is compensated for.

Claim 37

The system set forth in claim 29 wherein said conductor comprises a low temperature coefficient of resistance wire.

Claim 38

The system set forth in claim 29 wherein said voltage-controlled amplifier comprises a differential amplifier having power inputs coupled to positive and negative supply voltages, a control input for receiving control signals, and a reference input coupled to ground, such that output of said amplifier is at ground in the absence of such control signals.

Claim 39

The system set forth in claim 29 wherein said voltage-controlled amplifier comprises a pair of solid state switches having control electrodes for receiving valve control signals and power electrodes for alternately connecting positive and negative voltage supplied to said armature as a function of said valve control signals.

Claim 40

The system set forth in claim 32 wherein said amplifiers further comprises an inverter connected between said control electrodes.

Claim 41

The system set forth in claim 33 wherein said switches comprises power MOSFETs.