Motor operating parameter sensing apparatus

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.

We claim: .[. 
     
       1.  In a motor-operated valve assembly including a valve housing (11) including inlet (12) and outlet (13) openings communicating with a chamber, a valve member (14) mounted in said chamber for movement between open and closed positions for controlling the flow of fluid between the inlet and outlet openings, and synchronous motor means for driving the valve member between its open and closed position; means for controlling the torque exerted by the motor, comprising (a) means (42) for producing a reference frequency signal corresponding with the power supplied to the motor under a given load condition;   (b) means (21, 22, 23, 30) for producing an actual speed signal the frequency of which corresponds with the actual speed of the motor;   (c) comparing means (43) for comparing the frequencies of said reference and actual speed signals to produce an analog torque signal corresponding with the torque developed by the motor;   (d) torque limiting means (46, 47) for comparing the torque signal with a preset value and for providing an output signal when the motor torque exceeds a given value; and   (e) (41, 18) responsive to said output signal for controlling the driving power to said motor means so as to control the motor torque to said given value such that the motor means is prevented from exerting excessive torque on said valve means..]. .[.2. Apparatus as defined in claim 1, wherein said torque limiting means (46, 47) comprises a torque limit switch (46) operable when the torque signal reaches said preset valve..]. .[.3. Apparatus as defined in claim 1, wherein said actual motor speed signal is a cyclic position signal such that successive cycles thereof are indicative of successive incremental units of movement of said valve member by said motor means; and further including counter means (31) for counting the cycles of said position signal to provide an indication of said valve member movement..]. .[.4. Apparatus as defined in claim 3, and further including means (27) for discriminating between forward and reverse movement of said motor means, said discriminating means being operable to increase and decrease the count in said counter means in accordance with the forward and reverse movement of said motor means, respectively..]. .[.5. Apparatus as defined in claim 4, and further including at least one position limit switch (37, 38) operable when the count of said counter means reaches a given value..]. .[.6. Apparatus as defined in claim 5, and further including reduction gearing means (17) connecting said motor means with said valve member, and programmable divider means (32) for reducing the frequency of the cyclic signal supplied to said counter means by a factor that is a function of the reduction gearing ratio..]. .[.7. Apparatus as defined in claim 6, wherein said means for producing said actual speed signal includes at least one permanent magnet (22), means (21) driven by said motor for moving said magnet in a rotary path, and a Hall effect switch (23, 24) mounted adjacent said rotary path for cyclic operation by said magnet during the   
     
     
        rotation thereof..]. .Iadd.8.  A motor-operated fluid valve, comprising: (a) a valve housing (11) including fluid inlet (12) and outlet (13) openings communicating with a chamber;   (b) a valve member (14) mounted in said chamber for movement between open and closed positions relative to said housing to control the flow of fluid between said inlet and outlet openings;   (c) means including a motor (16) for driving said valve member between said open and closed positions;   (d) means supplying driving power to said motor; and   (e) means for controlling the torque exerted by said motor, including (1) means (21-23, 30) for producing a cyclic signal representative of the actual speed of said motor;   (2) means (42,43) for modifying said speed signal to provide a torque signal indicative of the torque exerted by said motor;   (3) torque limiting means (46,47) for comparing said torque signal with a preset valve thereof to provide torque output signal indicative of whether the motor torque exceeds a given value;   (4) means (41, 18) for controlling said driving power supply means as a function of said torque output signal so as to prevent the motor torque from exceeding said given value;   (5) position-signal generating means (31, 32, 34, 35) responsive to said cyclic signal to provide a positive signal representative of the position of said valve member relative to said housing; and     (6) position comprising means (37, 38) for comparing said position signal with at least a preset value thereof to provide a position output signal indicative of said valve member reaching a given position relative to said   
     
     
        housing. .Iaddend. .Iadd.9.  Apparatus as defined in claim 8, and further including gear reduction means (17) for connecting said motor with said valve member, said gear reduction means having a predetermined gear ratio, said position signal generating means including selectively adjustable means (32) for adjusting the valve of the position signal in dependence upon the value of said gear ratio. .Iaddend. .Iadd.10. Apparatus as defined in claim 9, wherein said position-responsive means includes a counter (31) arranged to count cycles of said cyclic signal, and said selectively adjustable means comprises a programmable divider (32) for dividing the frequency of the cyclic signal supplied to said counter. .Iaddend. .Iadd.11. Apparatus as defined in claim 10, and further including means (27) for discriminating between forward and backward movement of the motor, and for varying the count effected by said counter (31) in dependence on whether the motor (16) is performing backward or 
     
     
        forward movement. .Iaddend. .Iadd.12.  Apparatus as defined in claim 10, wherein said position comparing means (37,38) includes at least one position limit switch arranged to be operated when said count established by the counter reaches a given value. .Iaddend. .Iadd.13. Apparatus as defined in claim 8, wherein said means for modifying said speed signal includes means for producing a reference signal indicative of the speed that the motor (16) will achieve under given load conditions; and torque comparing means (43) for comparing said reference signal and said actual speed signal to provide said torque signal. .Iaddend. .Iadd.14. Apparatus as defined in claim 13, wherein said motor (16) operates for given load conditions at a speed determined by a parameter of driving power supplied to the motor, and wherein said references signal providing means (42) includes means responsive to the value of said parameter of the driving power for controlling the value of said reference signal. .Iaddend. .Iadd.15. Apparatus as defined in claim 14, wherein said motor (16) comprises an asynchronous electric motor; wherein said power supplying means comprises an alternating-current voltage source; wherein said signal producing means is operable to produce an electrical signal of a frequency determined by the actual speed of the motor; and wherein said torque comparing means (43 is arranged to compare the frequency of the supply with the frequency of said electrical signal so as to produce said torque signal. .Iaddend. .Iadd.16. Apparatus as defined in claim 15, wherein said torque limit means comprises a torque limit switch arranged to operate in response to said torque signal reaching said preset value. .Iaddend. 
     
     
        .Iadd.7.  Apparatus as defined in claim 8, wherein said cyclic signal producing means includes at least one magnet (22) mounted for movement in a rotary path by said motor, and at least one Hall effect switch (23,24) mounted for cyclic operation in response to successive rotations of said magnet past said switch. .Iaddend.