US3381466A - Alarm-bell mechanism for an alarm timepiece - Google Patents

Description

May 7, 1968 JEAN-CLAUDE SCHNEIDER 3,331,466

"BELI MECHANISM FOR AN ALARM TIMEPIECE ALARM 4 Sheets-Sheet 1 Filed Oct. 4, 1965 JEAN'CLAUDE SCHNEIDER 3,381,466

BELL MECHANISM FOR AN ALARM TIMEPIECE May 7, 1968 ALARM- Filed Oct. 4, 1965 4 Sheets-Sheet 2 JEAN-CLAUDE SCHNEIDER 3,381,466

ALARM-BELL MECHANISM FDR AN ALARM TIMEPIECE Filed Oct. 4, 1965 May 7, 1968 4 Sheets-Sheet 5 May 7, 1968 JEAN-CLAUDE SCHNEIDER ALARM-BELL MECHANISM FOR AN ALARM TIMEPIECE 4 Sheets-Sheet 4 Filed Oct. 4, 1965 United States Patent 3,381,466 ALARM-BELL MECHANISM FOR AN ALARM TIMEPIECE Jean-Claude Schneider, La Chaux-de-Fonds, Switzerland, assignor to Fabrique dHorlogerie Chs. Tissot et Fils S.A., Le Locle, Neuchatel, Switzerland, organized under the laws of Switzerland Filed Oct. 4, 1965, Ser. No. 492,384 Claims priority, application Switzerland, Oct. 9, 1964, 13,130/64; Sept. 8, 1965, 12,516/65 15 Claims. (Cl. 58-16) In alarm timepieces, the alarm-bell mechanism generally comprises an alarm-bell wheel provided with ratchet teeth driving the hammer. The latter is secured to an escapement comprising two projections which slide altenratively on the inclined flanks of the teeth of the alarm-bell wheel when the latter is freed, in such manner that the hammer oscillates and strikes the bell.

According to the present invention we provide an alarm-bell mechanism for an alarm timepiece comprising an alarm-bell provided with teeth, a spring for the en tr'ainment of the alarm-bell wheel and an oscillating escapement provided with an impulsion member for urging an oscillating hammer from an equilibrium position, an input projection and an output projection, the said projections engaging alternately in the teeth of the alarmbell wheel, the input projection locking the wheel whereas the output projection is urged out by the teeth thereof, the hammer being arranged to return to its equilibrium position, the hammer striking a bell in the course of its oscillation.

The accompanying drawings show, by way of example, two embodiments of the mechanism according to the invention.

FIGURE 1 is a plan view of the first embodiment in a first operating position,

FIGURE 2 is a similar view in a second operating position,

FIGURE 3 is a view in partial section of the mechanism shown in FIGURES 1 and 2,

FIGURE 4 is a partial plan view of the second form of embodiment, and

FIGURE 5 is a view in section along the line VV of FIGURE 4.

The mechanism shown in the drawings is intended to be lodged in a small alarm clock provided with a circular bell 1 and in its upper portion, with a rod 2 for stopping the ringing action, the rod being vertically movable and adapted to be displaced into different positions, as will be explained later. A hammer 3 having the form of an arc of a circle is suspended within the bell 1 for free pivoting about a horizontal arbor 4. In the inoperative position, its center of gravity is located in a vertical plane extending through the axis of the arbor 4. Thus, the hammer occupies a position of equilibrium in which one of its ends contacts the bell 1.

An alarm-bell wheel 5 secured to a driving pinion 6 is driven in rotation in the clockwise direction seen in FIG- URE 1, when the alarm-bell mechanism is tripped. To this end, the pinion 6 engages with a wheel 7 which turns through rather less than a complete rotation during the unloading of an alarm spring 8. FIGURE 3 shows that the wheel 7 is mounted idly on an arbor 9 and has Breguet form teeth on its upper face. These teeth mesh with corresponding teeth 10a formed in the lower face of a cam .11 to which the inner end of the spring 8 is attached. The outer end of the said spring is secured to 'a post 12 which is attached to a frame element 13. The cam 11 rotates clockwise during the loading of the alarm spring and anti-clockwise during the unloading thereof, the Breguet coupling 10 being designed in such manner that the wheel 7 is entrained only during the unloading. The cam 11 is keyed to the arbor 9, by means of a central aperturehaving a rectilinear edge co-operating with a corresponding flat 14 on the arbor 9. The latter is driven in rotation during the loading period by means which are not described and is then freed at the instant of tripping of the alarm mechanism. It then rotates in the anti-clockwise direction as seen in FIGURE 1.

In order to drive the hammer 3, the mechanism comprises an escapement 15 which pivots on a pin 16 secured to a frame element 17. The escapement has two projections .18 and 19 which co-operate with the teeth of the wheel 5 in the manner of the pins on a conventional escapement. The projeceion 19 constitutes an input projection which, when it is engaged in the teeth of the wheel 5 locks it, whereas the projection 18 constitutes an output projection which, when it is engaged in the teeth of the wheel 5, is expelled therefrom whilst rocking the escapement 15. A stud 20, constituting an impulsion member and fixed in the escapement opposite the projections 18 and 19 then communicates a pulse to the hammer 3.

FIGURE 1 shows, in broken lines the position into which the hammer 3 rises under the effect of the impulses of the escapement. When removed from its position of equilibrium, it drops back under the effect of its own weight and the front edge of the 'arm of the hammer brings about, at the end of travel, the disengagement of the escapement which recovers the position shown in FIGURE 1, at the same time, the hammer 3 strikes the hell 1.

Instead of the hammer oscillating freely when it receives the impulse from the escapement, it may also be braked, and then recalled by a resilient element 21 which consists of a rectilinear arm of a wire spring wound about a cylindrical post 22 on the frame element 13. The said wire spring is normally in the position shown in full lines of FIGURE 1. However, it can be displaced into the position 21' shown in broken lines, in which case it bears constantly against a stud 23 fixed in the arm of the hammer. It is clear that the wire spring, in its position 21, is loaded as soon as the impulse is imparted to the hammer, in such manner that the latter ascends to a lower level than when it is free and the disengagement of the escapement 15 is brought about more rapidly. The striking rate is thus accelerated. This variation in the striking rate may be obtained automatically during the alarm-bell action due to a rocker 24 consisting of a thin blade pivoting on a stud 25. Fixed in the said rocker are two parallel pins 26 which embrace the limb 21 of the wire spring at a point very near the post 22.

A rotation of the rocker 24 in the clockwise direction sulfices to displace the wire spring from the position 21 to the position 21. This rotation is brought about by the cam 11. The latter has in its upper face a series of grooves 27, 28 and 29. Furthermore, the rocker 24 has, at its lower part, an arm at the end of which is secured a pin 30 which, in the position shown in FIGURE 1, is engaged in the groove 27. The rocker 24 is resilient, in such manner that the pin 30 bears slightly against the bottom of i 3 the groove 27. The resilience of the rocker 24 permits furthermore displacements of the cam 11 in the axial direction when it is entrained clockwise during windingup, the Breguet coupling 10, 10a being freed.

As will be seen in FIGURE 1, the grooves 27, 28 and 29 have a V-shaped profile. They extend in concentric arcs of a circle centred on the axis of the arbor 9. The grooves 27 and 29 extend in an arc of substantially 330. The groove 28 comprises two segments 28 and 28a and begins in the groove 27 at approximately 80 from its commencement. It extends along a chord of a circle having its centre on the axis of the arbor 9 then has a portion comprising an arc of a circle centred on the axis of the arbor 9, and then a second portion on the chord by means of which it reaches the groove 27. The segment 28a also commences in the groove 27. It has a rectilinear chordal portion and a portion forming an arc of a circle centred on the axis of the arbor 9. The ends of the grooves 27. 28a and 29 are joined by a radial groove 31. At the commencement of the alarm action, the cam 11 is in the position shown in FIGURE 1. If the pin 30 is in the inlet of the groove 27, the rocker being in a position illustrated in FIGURE 1, it will be seen that the cam 11 maintains the said rocker immobile for as long as the pin is in the groove 27. At the inlet of the groove 28, the pin is drawn towards the axis of the arbor 9, thus pivoting the rocker 24 clockwise and displacing the resilient wire 21 into the position 21'. From this instant on, the hammer rate is accelerated. 7

When the pin follows the portion of the groove 28 approaching the groove 27, the rocker pivots anti-clockwise and the pins 26 return the resilient wire 21 into its normal position. The rate of the hammer is slowed down once more. The same phenomenon of acceleration of the rate is reproduced when the pin 36 reaches the groove 28a.

It will be noted that the device described also comprises a mechanism (not shown) which brings about the momentary stopping of the rotation of the cam 11 and of the wheel 7 at the instant at which the pin leaves the groove 28 to return into the groove 27, in such manner that the actuation of the alarm mechanism, when it takes place as described hereinabove, is eifected in two stages which may follow each other with an interval of greater or lesser length and each of which comprises as low-rate period and a rapid rate period.

The rocker 24 further comprises an arm 32 extending in the direction of the axis of the hammer and having an abutment face 33 at its free end. In the position illustrated in FIGURE 1, the said abutment face 33 is disposed in such manner that the stud 23 of the hammer reaches a point very near this face at the instant at which the hammer impinges against the bell. In this position, the face of the abutment 33 is thus inactive. It is also inactive when the rocker has pivoted towards the right so as to accelerate the hammer movement. On the contrary, it becomes active if the rocker pivots anti-clockwise out of the position shown in FIGURE 1 and passes into the position shown in FIGURE 8. The abutment 33 then locks the hammer 3 in a raised position, spaced-apart from the bell 1. n

the other hand, the studs 26 remove the wire spring 21 from the stud 23 but bring up a further resilient element consisting of a shorter arm 34 of the wire spring 21 contacting a stud 35 projecting from the projection 19 of the escapement 15. The resilient arm 34, under these conditions, causes disengagement of the escapement. The wheel is able to rotate clockwise and the escapement 15 oscillates regularly without the hammer being actuated. Ifreference is again made to FIGURE 1, it will be seen that it suflices to pivot the rocker in such manner that the pin 30 passes from the groove 27 or from the groove 28 to the groove 29, so as to put the mechanism in the position illustrated in FIGURE 2. The alarm-bell movement then develops idly until the pin 30 reaches the height of the groove 31 (FIGURE 2).

In this position, the alarm-bell mechanism is stopped.

Furthermore, the weight of the hammer 3 exerted through intermediary of the stud 23 on the rocker 24 pivots the latter clockwise, the pin 30 sliding in the groove 31, and the rocker returns into the rapid-operation position. A winding-up mechanism then entrains the cam 11 in the clockwise direction and restores it finally to the starting position shown in FIGURE 1.

The passage of the pin from the groove 27 to the groove 29 may be manually controlled, at will. For this purpose, the rocker 24 has a third arm 38 terminating in an abutment face 36 extending under the control rod 2. The lower end of the said rod extends normally to a height such that the abutment 36 just contacts it when the rocker is in the rapid-operation position. In the slowoperation position, a small space therefore extends between the rod 2 and the abutment 36 (position shown in full lines in FIGURE 1). However, a pressure may be exerted on the rod 2 at any desired instant and it causes the rocker to pass from one of the two operating positions into the idle-travel position. The rod 2 is carried on an annular member provided with an abutment which can be screwed into a support on the time-piece. By screwing this support, it is possible to displace the lower end of the rod 2 into the position shown in broken lines in FIGURE 1. It will be seen that the rocking of the rocker 24 in the clockwise direction at the instant of passage of the pin 30 at the inlet of the groove 28 is then prevented by this rod.

The inclined flank of the groove 28 passing through the groove 27 at this point tends to entrain the pin 30 toward the axis of the arbor 9, but since the rocker is prevented from pivoting, the pin 30 ascends the said oblique flank and drops back into the groove 27. The same phenomenon takes place when the groove 28 reaches the groove 27 and at the commencement of the groove 28a. In other words, by screwing the support of the knob 2, the rocker is compelled to remain constantly in the slow-operation position.

No acceleration of the rate'of the hammer during the ringing action is produced.

The screwed or unscrewed position of the support of the knob 2 does not of course have any influence on the pivoting of the rocker which displaces the pin in the groove 29. In other words, the knob for stopping the ringing action, on the rod 2 may be actuated whatever the position of the support. On thecontrary, if the latter is in the screwed position, the pin 30, instead of sliding in the groove 31 as far as the inlet of the groove 28a, at the end of the ringing action, will only slide as far as a point opposite the end of the groove 27. For this purpose, an inclined ramp 37 is formed at the outlet of the said groove, so as to permit the pin to enter it readily at the instant of winding-up of the alarm-bell mechanism. The cam 11 could also have only two grooves instead of three, if no variation in the operational rate is desired. It could also have only a single groove 28 instead of two grooves 28 and 28a, so as to produce only one variation in the striking rate during the complete ringing action.

Furthermore, the mechanism described could also be utilised with a device for winding'up the alarm-bell action which differs from that shown in the drawings.

The projections on the escapement could be inverted, in such manner that the inlet projection provides the impulse and the outlet projection serves as an abutment.

The alarm-bell mechanism shown in FIGURES '4 and 5 is similar, in broad outline, to that of FIGURES'I to 3. It comprises an alarm-bell wheel 40 which is capable of rotating in the direction of the arrow 41 under the' action of an alarm-bell spring (not shown), an escapement consisting of the two members 42 and 43 and a hammer 44 actuated by the escapement.

The main element 42 of the escapement is mounted on a pivot rod 45 (FIGURE 5) which is secured at its lower end in a boss 46 forming a part of a frame element of the alarm mechanism. The element 42 has a stud 47 projecting from its upper face coaxially with the rod 45 and terminating in a pivot 48 of reduced diameter, which is freely engaged in a seating formed in a frame element located immediately above the escapement. The element 43 is mounted on the stud 47. It comprises a sleeve portion 49 which guides it relatively to the stud 47. As can be seen from FIGURE 4, the element 43 forms the input projection 50 of the escapement whereas the element 42 forms, at one of its ends, the output projection 51. This latter member is prolonged beyond the pivoting point of the escapement in the form of an arm one of the sides 52 of which cooperates with the stud projecting from the hammer 44. The member 42 has furthermore a lateral finger 53 forming, with the side 52, a notch in which a projection portion 54 of the member 43 is engaged. The portion 54 limits the possible angular movement between the two elements of the escapement.

In order to improve the cooperation between the teeth 55 of the alarm mechanism wheel 40 and the projections 50 and 51 on the escapement, the latter each have a rectilinear side 56, 57 and the teeth 55 each have a plane, oblique face 58 extending from their apex in the direction of the arrow 41.

The improvement in the functioning obtained due to the special construction of the escapement as just described results, on the one hand, from the fact that the members 42 and 43 which carry the entry and outlet projections are articulated relatively to each other and, on the other hand, from the fact that the teeth of the alarm mechanism wheel are able to act by communicating an impulse to the outlet projection 51 during the time that the sides 58 of the said teeth slide on the tip of the projection.

During the impulse, i.e. during the time that a tooth 55 bears on the side 56 of the projection 51 and the side 52 of the escapement urges the hammer 44, the member 43 only begins to engage in the teeth of the wheel 40 when its stud 54 contacts the side 52 of the member 42. The depth of penetration of the said projection is thus diminished. Furthermore, the action of the face 58 on the teeth 55 on the tip of the projection 51 prolongs the impulse to the maximum extent.

On the contrary, during the return movement of the hammer, when the latter rocks the member 42, by bearing on the side 52, the member 43 which contacts a tooth 55 and retains the alarm mechanism wheel remains immobile until the finger 53 entrains it by contacting the stud 54. The angular travel of the two parts of the escapement therefore retards the disengagement to the maximum extent. The penetration of the outlet projection in the teeth may be increased in such manner that the impulse commences as soon as the disengagement has terminated, i.e. as soon as the tip of the projection 50 has reached the front end of the face 58 of the tooth which it retains.

The mechanism of FIGURES 4 and 5 permits an improvement in the efiiciency of the escapement by approximately 30% relative to the arrangement of FIGURES 1 to 3.

It will be noted furthermore that the rocker provided for modifying the functioning conditions of the escapement and the spring adapted to be put into contact with one of the projections on the escapement so as to permit the rotation of the alarm mechanism wheel when the hammer is immobilised, have not been shown.

I claim:

1. An alarm bell actuating mechanism comprising:

an alarm bell wheel provided with teeth;

an alarm spring for entraining the alarm bell wheel;

an oscillating hammer adapted to strike the bell in the course of its oscillation, said hammer having an equilibrium position and being arranged to return to its equilibrium position;

an oscillating escapememnt having an input projection and an output projection, said input and output projection alternately engaging the teeth of the alarm bell wheel, said output projection being located at the trailing side of the escapement with respect to the direction of rotation of the alarm bell wheel and being shaped so as to lock said wheel when it en-, gages the teeth thereof, said input projection being located at the leading side of said escapement with respect to the direction of rotation of the alarm bell wheel, said input projection being urged out of said wheel when it engages the teeth thereof whereby said escapement will rotate in a first direction;

a driving member mounted on said escapement, said driving member contacting said hammer and urging the hammer from its equilibrium position when said escapement oscillates in said first direction, said oscillation in said first direction causing said output projection to lock in engagement with the teeth on said alarm bell wheel, return of said hammer to its equilibrium position urging said output projection out of engagement with the teeth of said alarm bell wheel and permitting said hammer to strike the bell.

2. A mechanism according to claim 1, wherein the hammer is caused to return to its equilibrium position by a horizontal pivot.

3. A mechanism according to claim 1 wherein the hammer is caused to return to its equilibrium postiion by resilient element loaded by the hammer when the latter moves away from the equilibrium position, in one direction.

4. A mechanism according to claim 3, wherein the said resilient element is adjustable between two positions in one of which it remains constantly out of contact with the hammer whereas in the other it is loaded with each oscillation of the hammer.

'5. A mechanism according to claim 4, wherein the resilient element is controlled by a rocker.

6. A mechanism according to claim 5, wherein the said rocker comprises a sensing means co-operating with a guide element driven in rotation simultaneously with the alarm-bell wheel, the said guide element being disposed in such manner as to bring about a rotation of the rocker and the displacement of the resilient element from one of the said positions to the other during the ringing action.

7. A mechanism according to claim 3, wherein a second adjustable resilient element is provided, which is adapted to be displaced to a position wherein it co-operates with the escapement so as to bring about the disengagement thereof without the intervention of the hammer.

8. A mechanism according to claim 7, wherein the second resilient element is also controlled by the rocker and the latter has an abutment which, in the position wherein the second resilient element co-operates with the escapement, locks the hammer.

9. A mechanism according to claim 8, wherein the rocker further comprises an arm for manual control permitting the rocker and the second resilient element to be selectively disposed in the position for rocking the hammer.

10. A mechanism according to claim 1 wherein the escapement comprises two members which are articulated to each other and which are capable of moving through a limited angle relatively to each other, each of them having one of the projections.

11. A mechanism according to claim 10, wherein the output projection has a rectilinear side along which the teeth of the alarm-bell wheel are able to slide so as to impart to the escapement an impulse to actuate the hammer.

12. A mechanism according to claim 10 wherein the teeth of the alarm-bell wheel have an oblique face co-operating with the output projection in such manner as to prolong the duration of the impulse until the rear end of the said oblique face leaves the tip of the projection.

13. A mechanism according to claim 10, wherein the articulation pivot between the two said members coincides with the pivoting axis of the escapement.

14. A mechanism according to claim 10, wherein the member which carries the output projection is secured to 7 an arm extending beyond the escapement pivoting point References Cited and carrying the said impulse member. UNITED STATES PATENTS 15. A mechanism according to claim 10, wherein one 720 801 2/1903 Hauser 5821 12 l of the sad members constituting the escapement has :1 15911081 11/1928 Pierce 58 21.12

projecting portion and the other a recess the dimensions 5 of which are larger than those of the said projecting por- RICHARD B. WILKINSON, Primary Examiner. tion, the latter being engaged in the recess in such manner as to limit the angular displacements of the two members GERALD BAKER Exammer' relatively to each other. M. LORCH, EDITH C. SIMMONS, Assistant Examiners.

Claims (1)

1. AN ALARM BELL ACTUATING MECHANISM COMPRISING: AN ALARM BELL WHEEL PROVIDED WITH TEETH; AN ALARM SPRING FOR ENTRAINING THE ALARM BELL WHEEL; AN OSCILLATING HAMMER ADAPTED TO STRIKE THE BELL IN THE COURSE OF ITS OSCILLATION, SAID HAMMER HAVING AN EQUILIBRIUM POSITION AND BEING ARRANGED TO RETURN TO ITS EQUILIBRIUM POSITION; AN OSCILLATING ESCAPEMENT HAVING AN INPUT PROJECTION AND AN OUTPUT PROJECTION, SAID INPUT AND OUTPUT PROJECTION ALTERNATELY ENGAGING THE TEETH OF THE ALARM BELL WHEEL, SAID OUTPUT PROJECTION BEING LOCATED AT THE TRAILING SIDE OF THE ESCAPEMENT WITH RESPECT TO THE DIRECTION OF ROTATION OF THE ALARM BELL WHEEL AND BEING SHAPED SO AS TO LOCK SAID WHEEL WHEN IT ENGAGES THE TEETH THEREOF, SAID INPUT PROJECTION BEING LOCATED AT THE LEADING SIDE OF SAID ESCAPEMENT WITH RESPECT TO THE DIRECTION OF ROTATION OF THE ALARM BELL WHEEL, SAID INPUT PROJECTION BEING URGED OUT OF SAID WHEEL WHEN IT ENGAGES THE TEETH THEREOF WHERBY SAID ESCAPEMENT WILL ROTATE IN A FIRST DIRECTION; A DRIVING MEMBER MOUNTED ON SAID ESCAPEMENT, SAID DRIVING MEMBER CONTACTING SAID HAMMER AND URGING

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