Patent GB-1308091-A (GB)
Title: Fluid logic switching circuits
IPC: G05B19/46
Filed: 1971-04-23
Abstract: 1308091 Fluid logic and switching circuits PHILIPS GLOEILAMPENFABRIEKEN N V 23 April 1971 [25 April 1970] 11021/71 Heading F1P Selective transmission of pneumatic fluid e. g. air pressure from a common command line S Fig. 1 through one of a plurality e. g. ten of similar fluidic elements 5 only four of which are shown to the outlet 17 of the selected element which comprises at least two series-arranged fluid interrupters 11, 13 individually controlled by a control signal applied thereto is effected by connecting the control input of each interrupter of one element to one of a plurality e.g., 5 control pressure lines a--c and connecting the remaining elements to the control lines in a different combination. Each interrupter may comprise an annular chamber 23 Fig. 2 having a supply input 29, an output 31 and separated by a resilient diaphragm 25 from a larger area chamber 21 having a control input 27. Such an interrupter is referred to as a straight way valve which closes when the control input is 1 and the supply input is 1 or 0 and which valve opens when the control input is 0 and the supply input is either 1 or 0. To select any one of the elements 5 say the topmost element and with a command pressure at level 1 the control pressure in lines a, b to which the selected element is connected by lines 7, 9 must be at level 0 whilst c--d are at 1 whereby the valves of all the non-selected elements remain closed whilst those of the selected element remain open for the transmission of command pressure. Alternatively if command pressure is 0 then both control pressures for the selected element must be at level 1 which closes both valves and thus ensures the desired low output being held. In a second embodiment each of eight identical fluidic elements 35 Fig. 3 comprises three seriesarranged straight way valves 37, 39, 41 having their control inputs supplied through lines p, q, r, to common control pressure lines a, c, d and having the output 45 connected not only to the device e.g., an electric switch being actuated but to one side of each of three further interrupters 47, 49, 51 connected at their other sides through lines s, t, u to control pressure lines b, d, f. Each interrupter 47, 49, 51 is referred to as an automatic air relief valve and has an inlet 63 connected to 45 and separated by centrally apertured resilient diaphragm 59 from a chamber 57 having a control pressure inlet 65. The diaphragm is urged against a stop 67 to isolate 63 from 65 when pressures at 63, 65 and 1 and 0 respectively. In operation and to maintain the pressure level unity at 45 each valve 47, 49, 51 is held open by connecting control pressure lines b, d, f, at level 1 to inlets 65. The output of none of the non-selected elements is 1 because at least one straight way valve of each element is closed as is at least one air relief valve. When having selected say element 35 depicted in Fig. 5 it is desired to select another element, say the next one above 35 the pressure levels in pairs of control lines a, b and c, d are retained at 0, 1 and 0, 1 respectively but those of e, f are reversed so that e=1, f=0. As a result the previously open valve 41 of element 35 closes thus amplifying the output 45 whilst all the straight way valves of the newly selected element open to provide a 1 output. In a third embodiment each element (71) Fig.6 (not shown) of a system of eight identical fluidic elements comprises three series arranged straight way valves (73, 75, 77) each having its control inlet connected to one side of an associated air relief valve (79, 81, 83); the other side of all the relief valves being connected to the output (87) of the element. In a fourth embodiment each of eight elements (89) Fig. 8 (not shown) has three series arranged straight through valves (91, 93, 95) each controlled by a separate control pressure line and each valve is associated with a further straight through valve (97, 99, 101) having a common supply branched from the output (105) of the selected element. The control inlet of each valve (97, 99, 101) is connected to a further separate control line and the output of each valve (97, 99, 101) is connected to a common auxiliary command line (S) at an inverse pressure level to that of the main command line (S). In operation a 1 output from the selected element is held by virtue of closure of valves (97, 99, 101). In a fifth embodiment wherein each of eight elements 121 Fig. 10 comprises straight way valves 123, 125, 127 associated with air relief valves 129, 131, 133 as in Fig. 3, three further series-arranged straight way valves 139, 141, 143 and referred to as restoring valves are supplied at 145 from the command line S common to all eight elements. Valves 139, 141, 143 have their control inlets connected to the control inlets of valves 123, 125, 127 and have the output 147 connected to one side of an air relief valve 153 to close the same. The output 137 of valves 123, 125, 127 is also connected through a store control line 159 and an air relief valve 161 to the output 151. In operation and with S=l and a, b, c, d, e, f being 0, 1, 0, 1, 0, 1, respectively a 1 output at 137 is transmitted through open valve 161 to output 151. An output 1 at 147 is transmitted through open valve 153 to lines 149, 151. On selecting one of the remaining elements e. g. by changing control pressure levels at a--c to 1, 0, 0,1, 0,1, valves 123, 139 of the first selected element 121 shown close and valve 129 opens to relieve the store control line 159 as for a valve 161 which is now closed. Although valve 139 is now closed line 149 is not vented and a pressure 1 is transmitted through open valve 153 to output 151 which is thus maintained at pressure 1. In a sixth embodiment Fig. 11 (not shown) the third and fifth embodiments are combined. The foregoing circuits may be formed by a unit of layer construction and may serve to actuate an electrical contact switch of an automatic telephone system.