Patent GB-456068-A (GB)
Title: Improvements in or relating to automatic control mechanism
IPC: G05D13/00
Filed: 1935-05-03
Abstract: 456,068. Fluidpressure servomotorcontrol systems. KENT, Ltd., G., 199, High Holborn, London, and HOWARD, G. P. E., and IVANOFF, A., Biscot Road Works, Luton, Bedfordshire. May 3, 1935, No. 13292. [Class 135] An automatic control mechanism for controlling a variable condition such as temperature, pressure, flow, level, or the moisture content of manufactured articles such as paper and of the kind in which the movement of the control member is compounded of a movement the extent of which is proportional to the deviation of the variable condition from the desired value and a movement the velocity and sense of which is dependent upon the extent of the deviation, has this second component obtained through a mechanical infinitely variable speed mechanism preferably of the type comprising a sphere supported by three discs. In the form shown in Fig. 1, the apparatus is controlled by a float 3 connected to a cranked lever 1, 2, 4, provided with a pin 5 engaging a slot in a lever 7 rotatable about an adjustable fulcrum 8. The fulcrum is mounted on a lever 34 adjusted by toothed pinions 36 and coupled by a link 37 to an indicating pointer 38. The arm 4 is coupled by a link 31 to a pen arm 32 adapted to record on a moving chart 33 the variations of the controlling condition. An intermediate point on the lever 7 is coupled by a link 9 to an arm 10 freely mounted on a shaft 11 and having a projection 39 adapted to bear against an adjustable screw 40 carried by an arm 41 fixed to the shaft 11. One end of the shaft 11 carries an arm 12 coupled by a link 13 to an intermediate point on a floating lever 14, while the other end carries an arm 20 engaging a slot in a link 21 pivoted to a lever 22. This lever is formed with a bracket 23 supporting the adjustable disc 24 of the variable speed gear which is driven by an electric or pneumatic motor 28 acting through gearing and a disc 25. A third disc 26 is coupled through gearing to an arm 15 pivoted to one end of the floating lever. As the disc 24 is turned the axis of rotation of the sphere resting on the three discs is altered so altering the speed and direction of rotation of the arm 15. The other end of the floating lever 14 is coupled by a link 16 to an arm 17 on a shaft 18 carrying a baffle adapted to move between discharge and receiving jets 87, 88 to control the operation of a diaphragm power device connected to a valve or other regulating member. In a modification the adjusting screw 40 is replaced by a cam on the arm 10 adapted to engage the arm 41. In order to adjust the relative values of the two components, the floating lever may be made adjustable, a carriage pivoted to the lever being adjustably clamped to the arm 12 while the arm 15 has an adjustable carriage having a roller working between flanges on the lever and located by a clamping screw working in a slot. In another modification, Fig. 5, variations in the controlling impulse rotate a cam engaging a roller 79 carried by a lever 76 pivoted at 77 to a lever 78. This lever turns about an axis coincident with the pin 75 and is held by a weighted arm 84 with a pin 83 pressing against a toothed adjusting sector 81. This sector is operated by a pinion 82 under manual or time control. The free end of the lever 76 acts through a member 74, adjustably supported by a friction-held arm 86 and link 85, on a cam surface formed on a lever 55. The floating lever 59 is pivoted to this lever and is coupled by a link 60 and arm 61 to the spindle 18 and by a link 63 and arm 64 to the spindle 30. The lever 55 acts through a member 67 adjustably supported by a link 71 and friction-held arm 72 on an arm 69 mounted on the control spindle 11 of the variable speed gear. In a modification of this form the cams and associated members are replaced by a link and slotted lever.