Patent GB-723460-A (GB)
Title: A device for controlling the operations of a measuring instrument
Inventor: DODEMAN JEAN ARMAND GASTON
IPC: G01D9/34
Filed: 1952-07-14
Abstract: 723,460. Recording-apparatus. PYROMETRIE INDUSTRIELLE. July 14, 1952, No. 17773/52. Class 106 (4). A device for controlling automatically operations to be effected in an instrument adapted for measuring and indicating and/or recording successively conditions in each of a series of apparatus comprises a series of groups each including a ratchet wheel and a notched cam rotatably connected together, a driving pawl associated with each ratchet wheel and a control pawl associated with each notched cam, the pawl for the cam of one group being integral with the pawl for the ratchet wheel of the next group and means, associated with the various groups except the first, for controlling operations to be effected in and by the instrument, the means in the case of one group including means for connecting the instrument successively to the various apparatus. As described, the invention is applied to apparatus for recording on a single sheet successively the temperatures in six ovens and comprises a control device for advancing a commutator switch every 8 secs. to successively connect six thermocouples associated with the six ovens into a potentiometer circuit and for checking and adjusting every 38 2/5 minutes the difference of potential to which the E.M.F. of the thermocouples is opposed. The control device comprises three groups of wheels with transfer mechanism between each. The first group comprises a 24-toothed ratchet-wheel 2 integral with a cam disc 3 having six equallyspaced depressions, the second comprises a pinion 4 integral with a 24-toothed ratchetwheel 5 and with a cam disc 6 having a single depression, and the third comprises a 24-toothed ratchet wheel 7 integral with a cam disc 8 having a single depression and with a ratchetwheel 9 with twelve equally-spaced teeth of the same size and shape as those of the other ratchet-wheels. A series of driving and control pawls 11 to 16 are associated with the ratchet-wheels 2, 5, 7, 9 and cams 3, 6; the pawl 11 being free on a shaft 10, the pawls 12, 13 and 16 being keyed to the shaft 10 and the pawls 14, 15 being integral with one another but free on the shaft 10. The shaft 10 is carried by a rigid frame 18, 19, 20 rotatable about the axis 1 of the wheels 2 to 9 and linked by an arm 21 to a crank-pin on an eccentric 22 driven by a motor so as to oscillate through an arc equal to <1>/24 of a revolution every two seconds and advance the first group by means of pawl 11 and ratchet-wheel 2 so that every eight seconds the pawl 12 enters a depression in the cam 6, allows the pawl 13 to drive the ratchet-wheel 5, thus advancing the pinion 4 a twenty-fourth of a revolution and driving a pinion 27, meshing in gear ratio one to four with the pinion 4, a sixth of a revolution. Every 192 seconds the pawl 14 enters the depression in the cam 6 and allows the pawl 15 to drive the ratchet-wheel 7 a twenty-fourth of a revolution and brings a tooth of ratchet-wheel 9 into the path of the pawl 16 for co-operation next time the pawl 12 enters a depression in the cam 3 so that the cam 8 revolves once in 38 2/5 minutes and once in each revolution rocks an arm 38 when its pawl-shaped end enters the depression in the cam 8. Each time the pinion 27 turns through a sixth of a revolution the commutator switch is advanced through gear-wheels 31, 32, mechanism for changing the recording colour is rotated through sprocket-wheel and chain 29, 37 and printing is caused by the downward movement of a block 34 in sliding off a peg 35 of a wheel 30 before rising on to the next peg 36. When the arm 38 rocks upon entering the depression in the cam 8, it moves under a bar 44 to inhibit printing while moving a set-screw 41 free from a lever 42 to allow it to rock and cause a device to make the necessary connections for checking the potential difference. Other groups may be added for making other cheeks, e.g. for periodically checking the thermo-couples.