Patent GB-867080-A (GB)
Title: Improvements in or relating to measuring instruments such as liquid meters
IPC: G01F1/38
Filed: 1958-01-30
Abstract: 867,080. Indicating-apparatus. SCHOPPE & FAESER G.m.b.H. Jan. 30, 1958 [Feb. 1, 19'57; Nov. 2, 1957], No. 3116/58. Class 106 (4). In a meter linkage for use in flow meters &c. a deflection s is produced by a primary force G applied to a deflectable hinge 3 of a toggle joint suspended between pivots 4, 5 of which at least the pivot 5 is shiftable and is opposed by a restoring force P proportional to the square of the deflection s. The hinge 3 operates a pointer, pen, &c. In the embodiment shown in Fig. 1, arms 1, 2 form the toggle joint, the arm 2 being hinged to one arm r 1  of a bell-crank lever 8 working on a fixed hinge 9. The other arm r2 of the lever is connected to the hinge 3 by a tension spring c so that deflection of the hinge causes a restoring force to be transmitted to the pivot 5 through the spring C and bell-crank lever 8. By suitable choice of the rate of the spring C, the force G and the length of the arms 1, 2, the restoring force P may be made proportional to the square of the deflection s. In the embodiment shown in Fig. 2 the force G is applied by a tension-spring C G  tending to extend the hinge 3 which is connected by a yoke 13 to the displaceable cover 11 of a bellows diaphragm 12. A tension-spring C extends between the arm r 2  of the bell-crank lever 8 to the cover 11. The deflection s of the hinge 3 is transmitted to a pointer 16 by a rack 14 and a pinion 15. In a modification, Fig. 3 (not shown), the toggle joint hinge is suspended between two shiftable pivots each loaded by a like compression spring and hinged to a like bell-crank lever of which the longer arm is connected through a tensionspring with the cover of a bellows diaphragm. The cover is connected to the toggle joint hinge by a rod. In a further modification, Fig. 4, the toggle joint 3 is suspended between two shiftable pivots 19, 20 on link rods 22, 21 respectively, each deflectable about a fixed fulcrum. The pivots 19, 20 support a second toggle joint 23 with its arms 24, 25 longer than the arms 1, 2. The centre hinges 3, 23 of the toggle joints are connected by a tension-spring C and the pivots 19, 20 are loaded by compression-springs C 1 <SP>1</SP>, C 1 <SP>11</SP>, respectively. By a suitable choice of constants the deflection of the point 23 may be made proportional to the square root of the force applied to a diaphragm 17. In a still further modification, Fig. 5 (not shown), the tension spring C is replaced by a compression spring and the springs C 1 <SP>1</SP> and C 1 <SP>11</SP> are replaced by a single compression-spring acting between the hinge 23 and a fixed point of the anchorage to counteract the reactive forces generated in the spring C. In another modification, Fig. 6, the arms 1, 2 are hinged at points 29, 30 to arms 31, 32, respectively, which pivot on a fixed hinge 33. Compression springs C 3 <SP>1</SP>, C 3 <SP>11</SP> act on the pivots 29, 30 in a direction normal to the arms 1, 2 when the hinge 3 is fully extended. In an alternative construction, Fig. 7, the arms 1, 2 are each hinged at 10 to an elbow lever 20, 21 connected through a double-armed lever 23 to a tension spring C 1 . The other arm of lever 23 is connected to the point 10 by a spring steel ribbon 27 connected at its centre 28 to strut 30 fixed to arms 1, 2 at 29.