Abstract: In a grinder having a reciprocating table, a pair of oppositely arranged traverse potentiometers are actuated by the table, and in each direction, the respective potentiometer produces an increasing voltage to reverse the table. A pair of remote potentiometers are arranged respectively opposed to the traverse potentiometers, and are manually set to thereby determine the points of reversing of the table. Signal LED's indicate the position of the table, and these are controlled by signal potentiometer that is driven with the traverse potentiometers. Manual switch means enables the operator to selectively run the table past the normal points of reversal set by the remote potentiometers. Means is provided for slowing the speed of movement of the table at the end of its travel to minimize inertial shock.

Abstract: A motor vehicle has a power roof which can either rotate between a first open position and a closed position or translate between a second open position and the closed position. An electric motor for opening and closing the roof operates from a battery of the vehicle and is connected to the battery by a circuit which can be closed by either of two switches. When the roof is closed, activation of one switch causes the roof to open by rotation while activation of the other switch causes the the roof to open by translation. When the the roof is in an open position, activation of the switch other than that which caused the roof to assume such position effects closing of the roof. The vehicle is equipped with a security system which also operates from the battery and, upon activation, sends a signal to the circuit connecting the motor to the battery.

Abstract: An electrical circuit connected to a drive motor circuit, of a movable sunroof panel containing an electrical field responsive material, for preventing the energization of a power supply prior to the panel being electrically connected to the output of the power supply.

Abstract: A DC motor is supplied, from a motor driver, with a brake voltage constituted by a forward drive voltage, a reverse drive voltage, and a stop voltage of a zero potential level. An operational current of the motor driver is supplied to a low-pass filter whose output is supplied to first and second sample and hold (S/H) circuits. The first S/H circuit performs its sampling operation after a minute period of time in which the brake voltage goes through a polarity inversion from the reverse drive voltage to the forward drive voltage. The second S/H circuit performs its sampling operation after a minute period of time in which the voltage applied is changed from the forward drive voltage to the reverse drive voltage. The outputs or sampled values of both S/H circuits are compared with each other by a comparator. When the sampled values equal each other, i.e., when the number of rotations of the motor becomes zero, the comparator outputs a coincidence pulse. This pulse is supplied to a stop detector.

Abstract: A control circuit for reversible control of a motor including a switch for selecting the rotational direction of a motor, a self-retaining driver circuit for driving the motor in the direction selected by the switch, a timer circuit which is initialized when the switch is actuated irrespective of the selected rotational direction of the motor and resets the driver circuit after the elapse of a certain period of time. The driver circuit may also be connected to a limit switch for resetting the driver circuit when the motor has reached an end of its stroke. Thus, the overloading of the motor is minimized even when the motion of the motor is obstructed at an intermediate point of its stroke, and the motor can reach an end of its stroke without fail even when the switch is actuated repeatedly.

Abstract: A vehicle wiper park mechanism includes a shutoff gear that turns at half the speed and substantially diametrically opposed interrupts that are interconnected randomly, with approximately equal frequency, to park the wipers. The interrupts are offset from an exact diametrical opposition by an angle sufficient to assure that the wiper blades will be randomly flexed in opposite directions when parked, thereby avoiding a permanent blade set with time.

Abstract: The method for monitoring the end positions of a controlling element having a servomotor (1) comprises the recognition of the end position, for instance by interruption of the flow of current to the servomotor by limit switches (4, 5), and the subsequent action of a control pulse of opposite direction on the servomotor in order to brake the servomotor.

Abstract: Variable electrically motorized drive mechanism for gates or similar structure close-off devices that can be installed for the purpose of an assembly operation that is as heavy-duty as possible and without fine adjustments, for which purpose the gate is provided with controls that essentially comprise a position detector, a memory, and a reference-point indicator, the last of which is positioned between the gate-panel limiting positions and outside of any stop positions or defines a corresponding gate-panel reference-point position and synchronizes the position detector at each stroke such that the path that the panel is to travel along from the reference-point position into a particular desired position is dicated or monitored in accordance with a memory output that corresponds to the adjusted position. The system is accordingly continuously self-monitoring and can synchronize itself when the motor is started up again after a power outage and possibly manual operation of the gate.

Abstract: The present invention is a safety feature in an automatic garage door operator. In the prior art a single momentary contact push button, either directly connected to the automatic garage door operator or connected via a radio transmitter, is used to control door operation. In accordance with the present invention, closing the garage door requires continuous actuation of the momentary contact push button from the time the operation is begun until the door is fully closed. Any interruption in this continuous operation causes the automatic garage door operator to reverse and fully open the door. Thus continuous attention of the operator is required, thus enhancing safety because of the attention of the operator.

Abstract: Apparatus for remotely controlling the movement of a panning/tilt head motor for a surveillance system is interconnected by a minimum number of conductors with the motor for bi-directional rotation of the panning/tilt head using first and second switching elements to establish manual or automatic control modes of operation and with a four-circuit, double-break switch connected between a remote active control circuit and the field coils of the motor to determine the sector rotation of said motor with engagement with stop elements manually positioned on the panning/tilt head between greater than zero degrees and 360 degrees.

Abstract: An automobile provided with electrically operated windows and electric door lock is provided with a relay circuit which is connected to both the electric door lock and the push button on the car door handle, which works in such a way that when either the electric door lock switch is actuated, or the push button on the external car door handle is pressed, all the windows in the car simultaneously move upward and close.

Abstract: The present invention is a load sensor for use in an automatic portal operator such as an industrial gate operator. An induction motor is employed to move the gate. The power factor of the AC electric power supplied to the induction motor is monitored. A safety operation is triggered when the power factor indicates the motor load is greater than a predetermined amount, as when an obstruction is encountered by the gate.

Abstract: A control device for a movable part, especially a sliding/tilting roof of a vehicle, comprises a motor for driving the movable part, wherein the terminals of the motor can be selectively connected to different poles of a power source by means of make-and-break contacts of corresponding relays, which make-and-break contacts each connect the corresponding terminal of the motor with the negative pole of the power source when the corresponding relay is not excited, and with the positive pole of the power source when the corresponding relay is excited. A first switch is provided, which is actuated through a control member driven by the motor and which interrupts the connection of the motor with the poles of the power source when the movable part reaches its closed position.

Abstract: A control apparatus for a sliding vehicle mounted roof panel controls the movement of the sliding roof panel between fully opened and fully closed positions within a window opening in the vehicle and predetermined intermediate, partially opened positions. The control apparatus includes a sensor for detecting the position of the sliding roof panel and a control apparatus, responsive to the output from the sensor, for activating or de-activating the drive motor controlling the movement of the sliding roof panel. A plurality of sensors may be spaced longitudinally along the longitudinal edge of the roof opening to provide a plurality of intermediate, partially opened stop positions for the sliding roof panel between the fully opened and fully closed positions.

Abstract: The apparatus is provided with a unidirectional motor operatively coupled to the hinged sign through an eccentric drive by a link arm which incorporates a pre-loaded helical compression spring to prevent damage to the link arm should an attempt be made to forcibly swing the sign. Two normally-closed limit switches are associated with the link arm whereby in the course of a motor operating cycle, the stop sign is caused by the link arm to swing out to its outstretched position, at which point one limit switch opens, and then to return to its retracted position, at which point the other limit switch opens. The limit switches are included in a control circuit which supplies power to the motor. The control circuit is responsive to a door switch associated with the bus door so that when the door is open, the door switch is then closed, and power is supplied to the motor through one limit switch until the sign reaches its outstretched position, at which point this limit switch is opened to cut off the motor.

Abstract: A driving mechanism, preferably provided for a high-voltage isolating switch (T), contains a driving motor (M) which acts upon a moving contact of the switch via a shaft (W) and is provided with a rotor winding (R) and a stator winding (S), connected in series. To control a direction of rotation of the driving motor (M) in dependence on the position of the switch, the driving mechanism also contains a control circuit. In this driving mechanism, it is intended to keep the number of cores of a connecting cable (L) from the driving mechanism housing (K) to a control cabinet (N) as small as possible.

Abstract: A vehicle windshield wiper, whereby a blade is supported on a lever member hinged to a fixed support and designed to swing about a pin by virtue of a linear actuator, an output member of which consists at least partially of a screw connected to an electric motor having a hollow shaft, by means of a circirculating-ball screw-nut screw coupling, and extending through the motor itself.

Abstract: Control apparatus for a hinged stop sign mounted on the side of a school bus to cause the sign to swing out to an outstretched position when the bus door is opened to load or unload passengers and to return the sign to its retracted position when the door closes. The apparatus is provided with a unidirectional motor operatively coupled to the hinged sign through an eccentric drive by a link arm having associated therewith two normally-closed limit switches, whereby in the course of a motor operating cycle, the stop sign is caused to swing out to its outstretched position, at which point one limit switch opens, and then returns to its retracted position, at which point the other limit switch opens. The limit switches are included in a control circuit which supplies power to the motor.

Abstract: A domestic ice-cream maker comprises a refrigerated bowl-shaped container for an ice-cream mass; a rotatable stirring tool associated with such container for scraping off ice-cream freezing at a refrigerated surface of the container; and a single-phase synchronous motor for rotating the stirring tool, such motor having a maximum permissible operating temperature for making the ice-cream. A transmission path including a reduction mechanism extends between the synchronous motor and the stirring tool. Backlash is provided in the reduction mechanism as overload protection for the synchronous motor, the backlash acting in both directions of rotation of the motor and corresponding in each such direction of rotation to at least 10 revolutions of the motor, the motor, upon being blocked in either direction of rotation, reversing its direction of rotation and passing through the range of the backlash without exceeding its maximum permissible operating temperature.

Abstract: A control device for a car wiper apparatus is disclosed, in which the wiper apparatus is driven in forward or reverse directions by the function of an electronic circuit. The control electronic circuit is so configured as to minimize the number of connection brushes for controlling the forward and reverse operations of the wiper motor which reciprocates the wiper blade. The reduced number of the connection brushes, which are arranged in the wiper motor, realizes a compact shape of the wiper motor as a whole. The electronic circuit functions to drive the wiper motor in forward and reverse directions within a predetermined angle thereby to rotate the crank arm connected with the wiper motor and the wiper blade with a small predetermined angle for reciprocal wiping operating, thus making it possible to mount the wiper apparatus in the small internal space of the car.

Abstract: A windshield wiper system includes two windshield wipers of which each is mounted on a separate wiper shaft and may be driven to and fro by a separate motor between an inner reversing position and an outer reversing position, which windshield wipers are at least partially superposed in their inner reversing position and rotate in opposite directions through one wiping cycle. The two windshield wipers are moved without collision even though they wipe an overlapping area. The first windshield wiper is driven by its associated motor with a greater angular velocity of the output shaft than the second windshield wiper is driven by its motor. In addition the first windshield wiper is stopped for a predetermined time in its inner reversing position between two wiping cycles.

Abstract: A controller for controlling the movement of a member such as a sliding door driven by a motor. The door is controlled by the use of a motion detector coupled with the door. Pulses from the motion detector are counted by control circuitry, and the door is moved at a reduced speed in the region of its limits of travel. The limits are defined by the number of pulses from the motion detector equalling a predetermined value. The motor is de-energized if a stationary state of the door is detected in the low speed region, and reversed if a stationary condition is detected in the remainder of its movement.

Abstract: A power window device has an arrangement to automatically invert the movement direction of a windowpane when an upward movement of the windowpane is prevented in the automatic drive mode by some reason before it reaches its proper upper limit, and also has an arrangement activated to invalidate the automatic inverting function of the arrangement for a predetermined time.

Abstract: A portable electric heater/fan which can oscillate from side to side over a distance of 45 degrees or 90 degrees or remain stationary and which can also be tilted backward or forward so as to provide a beam of hot or cold air whose lateral extent and direction can be adjusted over two mutually perpendicular axes includes a compartment containing a heater/fan assembly and being slidably mounted for back and forth tilting movement on a neck joint fixed to a main gear carried by a shaft mounted for rotation about a vertical axis on a base. The main gear is coupled by a drive gear to the shaft of a synchronous electric motor mounted on the base. A first and a second set of cooperable limit stops are provided on the base and main gear for limiting the rotation of the main gear by the motor to either 90 degrees for the first set or 45 degrees for the second set.

Abstract: Signal apparatus including an assembly for producing a signal beam and another assembly for sweeping the beam in at least one zone of rotation. A control circuit connected to the sweeping assembly causes it to sweep the signal beam in periodically reversed motion at a substantially constant angular velocity across the zone of rotation between preselected endpoints thereof.

Abstract: An obstruction sensing and control arrangement for door or gate opening-closing mechanisms. The arrangement compares the operating rate of change of a predetermined characteristic with a preset rate of change and stops or reverses the motor in the opening/closing mechanism. The characteristic preferred is motor body temperature which is monitored indirectly. The control arrangement also includes a back up static control threshold to sense a second static operating characteristic of the motor and a second comparator means set at a preset threshold level to stop or reverse the motor. A common motor sensor is used for both the dynamic and static control thresholds. The invention also includes means to sense operating temperature and to alter the preset static threshold level automatically in response to temperature changes.

Abstract: A washing apparatus for an automotive vehicle having at least one washing brush with a substantially vertically oriented rotation axis, a brush mechanism for guiding and transporting the washing brush on a course over and around the automotive vehicle to be washed, and a control mechanism including a reversing drive for the washing brush and for the control of the washing apparatus. To avoid damage of the washing brush, a sensing element connected to the control mechanism is provided which responds to a damaging catching of the washing brush during rotation and travel over its course and reverses the rotation direction of the washing brush by acting on the control mechanism. Any of various criteria, including decrease of rotational motion of the brush, changes in brush orientation and torque, and drive-motor current changes are used by the sensing element in determining when to respond, and thus to reverse at least temporarily the rotation direction of the washing brush.

Abstract: A power window control for a motor vehicle provides express or one-touch movement in response to short activations of a control element and traditional power window movement during activation of the control element for longer periods. The control provides for automatic window closing with activation of a power door lock element, as long as the ignition is off unless the ignition key is in the ignition switch and the driver's door is open. This allows single touch vehicle locking but helps prevents the operator from locking himself out of the vehicle with the key still inside. Window movement, once initiated in the open or close direction, is stopped in response to motor stall when the open or closed limit is reached.

Abstract: When it is detected that the motor for rotating the agitator of the machine is locked, the motor is turned in the forward direction and/or in the reverse direction a predetermined number of times. If the motor is still locked, an indicating unit is operated to indicate the occurrence of the abnormal condition. When the motor locked by an excessively large quantity of wash and the motor is not unlocked after the motor is turned in the opposite direction, the occurrence of the abnormal condition is indicated by an alarm unit. Therefore, the operator, informed of the presence of the abnormal condition immediately upon its occurrence, can rectify the problem, for instance, by decreasing the size of the washing load.

Abstract: An electrical power steering apparatus includes a vehicle velocity sensor for detecting a vehicle velocity, a steering torque sensor for detecting a steering torque of a steering wheel, comparators for receiving the voltage signal from the steering torque sensor and detecting a steering direction, a motor drive mechanism, a vehicle wheel declination sensor for detecting a declination of a vehicle wheel, a nonsteering state detecting unit including an absolute value converter, a reference voltage generator and a comparator to detect a nonsteering state, and a controller for supplying a current of a magnitude corresponding to the declination of the vehicle wheel to the motor so as to decrease the declination during the nonsteering state.

Abstract: A window wiper control system provides accurate regulation and/or profiling of wiper speed. A desired interval corresponding with the preselected speed or speed profile is stored; a reference signal is provided to indicate a reference position of the wiper and is used to measure the actual interval of a wiper stroke or cycle. The actual interval is compared with the desired interval and an appropriate adjustment is made in a pulse-width modulation signal for effecting a desired speed and interval. The pulse-width modulation signal preferably has a relatively-low repetition rate. The wiper speed may be profiled to include acceleration and deceleration, and the intervals of acceleration and deceleration may be lengthened substantially to provide an apparent dwell.

Abstract: A control apparatus for an automotive power-operated convertible roof includes means for detecting movement of a vehicle, drive means for opening and closing the automotive convertible roof, a relay for preventing the opening and closing of the convertible roof and roof opening/closing controlling means for controlling the relay to inhibit the opening and closing of the convertible roof when the velocity of the vehicle detected by the movement state detecting means is not below a predetermined speed level. As a result, is unlikely that the convertible roof will be opened or closed erroneously during movement of the vehicle, nor is there the possibility of damage to the roof caused by an excessive wind pressure during opening or closing of the roof. In addition, no special consideration is needed about the possibility of floating or vibration of the vehicle body caused by wind pressure acting on the roof, and vehicle stability is enhanced.

Abstract: Motor control apparatus is disclosed for a motor driven vehicle power window mechanism including a flexible drive element, such as a drive tape, adapted to drive the window in a predetermined direction by being placed in tension by the motor. The tension of the flexible drive element is relieved by automatically reversing motor direction for a short time when the window reaches the desired position. The reverse motor rotation is accurately controlled to an amount sufficient to relieve drive tension but insufficient to produce unwanted reverse movement of the window by detecting the pulses of the armature ripple current as the successive commutator bars pass the brushes during reverse motor rotation, integrating these pulses and stopping the reverse motor operation when the integrated value reaches a predetermined reference.

Abstract: A system is disclosed for energizing an electric motor for forward or reverse rotation, which motor operative to open or close a side window pane of a door or a sun roof panel of an automobile. The motor is energized for forward or reverse rotation in accordance with the status of a pressure sensitive switch which is mounted on a window frame to detect the presence of an object or hand and an operation of up/down command changeover switches. If the presence of an object is detected by the sensor during the forward rotation of the motor which is effective to close the window pane, a self-hold circuit is triggered or set, and the motor is energized for reverse rotation. The motor is deenergized at a given time interval after the sensor has ceased to detect the object. The motor remains at rest as long as the self-hold circuit is set. In certain embodiments, the self-hold circuit is reset when up command changeover switch is moved from its up position to its non-operative position.

Abstract: This invention relates to closure retention apparatus for automatic doors, and more particularly to an electrical circuit for providing a reduced amount of electrical power to the motor which controls the opening and closing of the door. The circuitry includes first circuit means for applying a first level of power temporarily to said motor for operating the door from open toward closed position, and a second circuit for applying a second, reduced level of power continuously to the application of the first level power thereto for a preselected period of time for operating said door toward closed position also.

Abstract: A motor drive system and method for driving a cast bell or similar object, comprising a motor and cam switches driven by the motor which operate relays in accordance with a duration angle and a start angle respectively, the circuit of the drive system supplying power to normally provide drive energy to the bell when it is swinging through the duration angle, and to provide power to the bell following system initiation as long as the bell is within the start angle. The start angle is set to be greater than the duration angle so as to optimize steady state power delivery while ensuring power delivery at the time of initial system energization.

Abstract: An electro-mechanical oscillator has a DC motor with an output shaft coupled to a ball screw. A ball nut riding on the ball screw is coupled to an output sleeve which moves linearly with the ball nut. When the ball nut reaches one of two extreme positions its direction of movement is reversed by reversing the polarity of the voltage supplied to the motor. A control board is provided for monitoring the position of the ball nut, for reversing the motor and for controlling the speed of the motion.

Abstract: In a grinder, the table carrying the workpiece to be ground reciprocates to carry it past a grinding wheel. The table moves armatures oppositely into and out of respective coils, inducting voltage therein for driving the reversible motor that moves the table. Remote coils with manually settable armatures therein oppose the first coils for determining the range of movement of the table. A control circuit includes right and left halves corresponding to the directions of movement of the table. Right and left SCR's control the current from first coils to the drive motor, transistors control the gating current to the SCR's; triacs control the current from the transistors, and other triacs control the current from the main source to the drive motor.

Abstract: A device for driving a motor-operated closure part for an opening, especially on a motor vehicle, having a protective circuit for interrupting the closing movement when there is an indication that an object may be obstructing closure of the opening. A speed transmitting means exists that detects the adjusting speed of the closing part on at least one range of the adjusting path of the closure part that is critical with respect to the engagement of an obstruction. In addition, an evaluating stage is provided that responds to the speed signal and/or its rate of change with respect to time, for producing an obstruction signal that activates a control means of the circuit to interrupt the closing movement.

Abstract: A control circuit for a one-touch vehicle window control uses a pair of switches, each switch actuating a still window for movement in one of two opposite directions but being effective to stop a window moving in the opposite direction from that which it initiates. The motor is in an H-switch bridge with SCRs and FETs, with each switch providing actuating signals to an SCR and FET for one armature current direction and further providing an actuating signal through an impedance to a discharge transistor connected across a capacitor connected to the gate of the FET for the opposite armature current direction. The base of each discharge transistor is connected to another capacitor and through another impedance to the junction of a FET and a motor armature terminal.

Abstract: A multiposition controller includes a first switching element for switching on and off in accordance with a position of a movable object to be controlled and a second switching element for detecting the direction of movement of the object. The second switching element switches off when the object is positioned at one side from an initial position of the object, while it switches on when the object is positioned at the other side from the initial position of the object. Furthermore, the second switching element remains off or on when the object is positioned at the initial position. By such a simple structure, an accurate position control can be achieved.

Abstract: A stop-position controlling device for an electric windshield wiper is disclosed, which comprises an oscillation means for a wiper blade and a switch mechanism provide with armature shortcircuiting contacts for forcedly stopping the wiper blade at a predetermined position under a turn-off state of a wiper switch. In this device, the armature shortcircuiting contacts are shifted at plural positions for forcedly stopping the wiper motor at different positions and a turnover means is further arranged therefor, or a contact moving means is disposed for displacing the armature shortcircuiting contacts to plural positions.

Abstract: A control unit for operating the motor of a motor driven headlamp carrier mechanism includes oscillator circuitry for generating a series of pulses for energizing the motor, voltage responsive means for sensing a motor counter-EMF related voltage as an indication of motor rotation, output circuitry for interrupting motor energization when the voltage responsive circuitry senses motor stall, and start circuitry for energizing the motor independent of the oscillator circuitry for a period of time sufficient to produce motor counter-EMF. Such control permits sensing of the engagement of the headlamp carrier with fixed mechanical stops without the use of position or torque limit switches.

Abstract: In an agitating type washing machine a washing drive motor is run reciprocally in opposite directions to rotate an agitating wheel within a washing tank alternately in one and the other directions to perform intended washing. The washing machine comprises a rotational angle detector for detecting an angle of rotation of the agitating wheel, and a control for controlling the motor in response to a detection signal from the rotational angle detector. The control controls such that an angle of rotation of said agitating wheel by energization of the motor during running under a load is made smaller than that during no load running and that changing over between running under a load and no load running is automatically effected in response to a detection signal from the rotational angle detector, and controls rotation of said agitating wheel to an angle equal to or less than 360 degrees including rotation by energization of the motor and rotation by inertia whether during running under a load or no load.

Abstract: An improvement for a controller (C) for controlling the idle speed of an engine. A logic circuit (1) is responsive to the position of switches (S1, S2) and the direction in which an extendible and retractable member (T) is to be driven by a motor (M) to energize the motor. The logic circuit includes logic gate (3) responsive to both switches being open when the member is at its extreme extended position and the member is to be retracted to energize the motor to retract the member. The logic circuit also includes a logic gate (5) responsive to both the switches being open when the member is at its extreme retracted position and the member is to be extended to energize the motor to extend the member. The motor is thus energized to move the member in the appropriate direction even though a switch which should be closed is open due to dust or debris preventing switch closure.

Abstract: The central locking system for motor vehicles comprises a plurality of catch drives reversibly driving between a locking position and an unlocking position. The catch drives are switched on for a pre-determined time duration in the locking direction by drive signals of a first time control circuit. The catch drives are energized in the unlocking direction by a second time control circuit for a pre-determined time duration. The time control circuits can be triggered alternately through a triggering control switch actuatable by means of a door key from outside the vehicle, or by means of a press-button switch actuatable from within the motor vehicle. The trigger inputs of the time control circuits are connected through separate trigger paths to the press-button switch.

Abstract: In an agitating type washing machine a washing drive motor is run reciprocally in opposite directions to rotate an agitating wheel within a washing tank alternately in one and the other directions to perform intended washing, the washing machine comprises a rotational angle detector for detecting an angle of rotation of the agitating wheel, and a control for controlling the motor in response to a detection signal from the rotational angle detector. The control interrupts energization of the motor when the angle of actual rotation of said agitating wheel or the number of rotations of the motor reaches a predetermined value, the control means controlling the motor to run in a reverse direction when rotation of the agitating wheel by inertia in one direction is almost stopped.

Abstract: A microprocessor based control system for establishing the optimum points of motor turn on and turn off for an oscillatory pumping system. The power to the motor is disabled at a point calculated to return the maximum stored mechanical energy to the system after turn-around. The motor is restarted at either a predetermined motor speed which may be different in the up and down stroke directions, or when the speed peaks. Safeguards are also provided under control of the microprocessor for disabling pump operation in the event of pump overtravel, overload or pump off. The control permits dynamic changes to the operating parameters of the pumping system in order to optimize the power required by the motor over a wide range of operating conditions.

Abstract: A drive arrangement for the shaft of a turbo molecular pump comprises a motor supply, including a chopper which controls a voltage source, and a motor with two phase windings connected via a current measuring resistor to the neutral point of the voltage source. The voltage drop at the resistor is proportional to the motor current and so influences the width of the control pulses of a pulse-width modulator connected to control the chopper that the motor current remains constant. Switching transistors for the motor have parallel oppositely-connected diodes which, upon disconnection of a phase winding, supply residual energy to capacitors in the circuit.

Abstract: A motor operated valve, typically a butterfly valve driven by .[.a synchronous.]. .Iadd.asynchronous .Iaddend.electric motor (16), is provided with a torque sensing arrangement wherein an cyclic electrical signal representative of the rotational speed of the motor is produced by magnets (22) on disc driven by the motor and Hall effect switches (23,24). The frequency of this signal is compared in a circuit (43) with the frequency of current supplied to the motor to provide an indication of motor torque. Switches (46,47) define preset torque limits for the valve. If the limits are exceeded, a signal is fed to control logic (41) which operates switches (18) to control the supply current to the motor. The speed signal from the Hall effect switches is also fed to a counter (31) to develop a count representative of movement of the valve. The output of counter (31) is compared with preset valves defined by switch circuits (37,38) to define limits of travel for the valve.