GB1425893A - Clock mechanism - Google Patents

Abstract

1425893 Electric clocks KIENINGER & OBERGFELL 19 March 1973 [17 March 1972] 13144/73 Heading G3T [Also in Divisions F2 and G4] In a clock mechanism having an electric motor (3), Figs. 1 and 2 (not shown) energized intermittently to wind a spring 13 which is in tension between an escapement train driving wheel 12 and a winding wheel 9, the motor being switched on to drive the wheel 9 through a certain angle when the relative angular positions of the wheels 9, 12 have changed by a corresponding amount, the motor is coupled to the wheel 9 via an indexing mechanism which transmits rotary motion from a driving wheel 101 to a driven wheel 102 during a part only of each revolution of the drive wheel. Overrun of the motor after opening of switch contacts 39, 40 therefore has no effect either on the position of the wheel 9 and the spring tension after winding, or on time indicators e.g. of digital type which are driven directly by the shaft 8 of the wheel 102, thus ensuring proper positioning of the indicators. The drive wheel 101 coupled to the motor has four indexing teeth 107 and a circular locking portion 104 which can engage tangentially with the sides of spaced teeth 108 of the wheel 102 during over-run. Teeth 109, 110 of the wheel 102 are axially shortened to clear the portion 104, and a further short tooth 111 on the wheel 101 aids the initial motion of the driven wheel. The overlap ratio between the wheels is greater than one, so that the effective ratio between the four indexing teeth 107 and the twenty teeth of the wheel 102 is 1:4. The switch contacts are operated by a first switching wheel 21 fast with the wheel 9 and a second switching wheel 22 which is loosely pivoted and coupled to the wheel 12 by means of an arm with portions 30, 32 extending through an arcuate slot 31 in the wheel 22. A further slot 28 in the wheel is engaged by a pin 27 fixed to the wheel 21. Figs. 4a, b show the positions immediately after a winding operation, the end 44 of spring contact arm 24 lying in a gap between teeth 50 of the wheel 21 while a tooth 51 of the wheel 22 holds up the end 43 of the other contact arm 23 to separate the contacts. As the wheel 12 and the arm 30, 32 move clockwise under the pull of the spring 13, the arm comes up against the end of the slot 31 and rotates the wheel 22 allowing the contact arm 23 to drop and the contacts to close. The motor is thus energized to drive, via the indexing mechanism, the digital time indicators and the wheels 9 and 21, tensioning the spring 13. As the wheel 21 advances, the pin 27 engages the edge of slot 28 and also displaces the wheel 22. As the contact arm 24 is raised by the next tooth 50 of the wheel 21, the contacts remain closed, but they are opened after the tooth clears the arm end, by the next tooth 51 of the wheel 22 engaging the arm 23.