Patent GB-843743-A (GB)
Title: Improvements in or relating to indicators for mechanically propelled vehicles
IPC: B60Q1/38
Filed: 1958-10-10
Abstract: 843,743. Road traffic signals on vehicles. BOSCH G.m.b.H., R. Oct. 10, 1958 [Oct. 12, 1957], No. 32356/58. Class 118 (2). A signalling system on a road vehicle comprises two switching circuits controlling a direction indicator of the winking-light type and causing flashing-light signals to be given by the vehicle's headlamps respectively, the two switching circuits being controlled in part by a common electromagnetic switching device having at least one winding one a magnetic core and provided with at least two spring-loaded movable switch contacts, one of which is arranged in series with a thermally-expansible wire which is mechanically attached thereto and so arranged as to cause the contacts to make and break periodically. In the arrangement illustrated in Fig. 1 closure of the directionindicating switch 47 to left or right causes a current to flow through switch armature 18, thermally expansible wire 26, current-limiting resistor 29 and core 13. The wire 26 expands and the armature 18 is spring urged in the direction of the arrow until contact is made with fixed contact 27 whereupon wire 26 and resistor 29 are short-circuited and a heavy current flows through the core 13 and lights the appropriate ones of the direction-indicating lamps 14. The magnetic core 11 is energized by the current flowing through core 13 and attracts an armature 20 which completes the circuit of a tell-tale lamp 32. The energization of the core is however insufficient to attract the armature 24. The wire 26, now short-circuited, cools thereby withdrawing the armature 18 from the contact 27 thus switching the lamps 14, 32 off and causing current to flow once more through the wire 26 whereupon the wire commences to expand once more and the cycle of operations is repeated. The lamps 14, 32 consequently flash for as long as the switch 47 is closed. On closing switch 39 with switch 47 open current flows through switch armature 22 and coil 15 thereby energizing core 11 which attracts armature 24 to complete the circuit of headlamps 16. Current also flows through thermally expansible wire 33 which expands breaking the circuit at contacts 23, 34 and so extinguishing the headlamps. The wire 33 then cools and contracts until the circuit is again completed and the cycle of operation described above repeated. The circuit may be modified in a number of ways. Fig. 5 shows a modification in which the core is provided with a single winding 63 and the thermally expansible wire 68 controls the flashing both of the direction indicators and of the headlamps. On closing the direction-indicator switch 73 current flows through the wire 68 and armature 64 which is electrically connected to the core 62 until the expansion of the wire causes the armature to engage fixed contact 69 whereupon the indicator lamps light and the wire commences to contract to break the contact between the armature 64 and contact 69 to recommence the switching cycle. On closing switch 76, the circuit of the thermally expansible wire 68 is completed as before so that a heavy current periodically flows through the winding 63 to attract the armature 66 thus causing the circuit of the headlamps 74 to be periodically made and broken.