US2724235A

US2724235A - Magnetic clock movement

Info

Publication number: US2724235A
Application number: US314137A
Authority: US
Inventors: Bauerle Kurt
Original assignee: Gebr Junghans AG
Current assignee: Gebr Junghans AG
Priority date: 1951-10-11
Filing date: 1952-10-10
Publication date: 1955-11-22
Anticipated expiration: 1972-11-22

Description

NOV. 22, K, BAUERLE MAGNETIC CLOCK MOVEMENT I5 Sheets-Sheet 1 Filed Oct. 10, 1952 IN ME NTQR KURT BAUERLE Nov. 22, 1955 BAUERLE 2,724,235

MAGNETIC CLOCK MOVEMENT Filed Oct. 10, 1952 5 Sheets-Sheet 2 Fig.3

44 F194. J a

Nov. 22, 1955 K. BAUERLE 2,724,235

MAGNETIC CLOCK MOVEMENT Filed Oct. 10, 1952 s Sheets-Sheet s NVENTOR KURT U ERLE :87 Mia/ml).

AGENTS United States Patent MAGNETIC CLOCK MOVEMENT Kurt Biiuerle, Schramberg-Sulgen, Germany, assignor to Gebruder Junghans A. G., Schramberg, Geishalde, Germany, a German company Application October 10, 1952, Serial No. 314,137

Claims priority, application Germany October 11, 1951 9 Claims. (Cl. 58--117) The present invention relates to an improvement in and relating to magnetic escapements for clock-movements, more particularly for balance or pendulum clocks.

The advantages of the already known magnetic escapements for clocks consist in the extremely slight friction and in the noiseless operation of the work. Irrespective of these and various other advantages, the escapements heretofore known are characterized by certain deficiences that are in the way of their general employment in practice.

Thus in the known types of escapements, the escape wheel does not drive the escapement with the same rotational impulse in its oscillating movement, the lever arm of the escapement being altered in oscillating. This causes the driving movement, tending in itself to rotate continuously, to be detained at the longer lever arm of the magnetic escapement a longer time than at the short lever arm, whereby an irregular movement and overspeeding respectively of the escape wheel will result.

Moreover the magnetic escapements known heretofore have no possibility of adjusting the magnetic coupling of the escapement and the escape wheel. There is the further disadvantage that the conventional forms and the general design of the mechanical escapements have been dispensed with, which proves unfavourable with respect to space economy and manufacture in pendulum clocks as well as in watches. Thus the watches being provided with a horseshoe-shaped magnetic escapement supported on a tongue spring, are operated at a speed of about 3000 oscillations per minute, thus 20 to 30 times more than usual in watches with mechanical escapements.

In order to remedy these disadvantages, the present invention provides an escape wheel having an undulating periphery of high permeability and cooperating with an oscillating magnetic escapement being so formed as to cause the poles of the magnetic escapement to act upon sections of the escape wheel, said sections being spaced by an odd number of half wave-lengths.

Thus when one pole of the escapement, during the rotation of the escape wheel, is immediately adjacent to the axle of the wheel, acting with the shortest lever arm, the other pole has the greatest distance from the axle, acting with the longer lever arm. In this case the oscillating escapement is formed as an anchor or horseshoe-shaped magnet having suitable poleshoes made of soft iron. The magnetic escape wheel suitably comprises a punched and toothed wheel made of magnetic material of low hysteresis (soft iron), the punched parts and toothing of which form the magnetic undulating or waved path mentioned above. It is useful to arrange the magnetic escapement entirely on one side of the plane of the magnetic escape wheel, thus enabling the magnetic coupling of the escapement and escape wheel to be simply and exactly adjusted. In order to obtain, as far as possible, a uniform operation of the drive system, it is suitable to couple the magnetic escape wheel with the greatwheel not in a rigid torm, but by means of a spiral spring.

Embodiments of the invention are illustrated by some examples in the accompanying drawings, wherein:

Fig. 1 shows the arrangement of the anchor and balance wheel for magnet pendulum escapements in front view;

Fig. 2 shows a side-view of the magnet pendulum escapement, partly in section;

Fig. 3 illustrates the arrangement of anchor, balance wheel and balance for a balance escapement;

Fig. 4 is a side-view of the magnet balance escapement, partly in section;

Fig. 5 shows the arrangement of a regulating lever for the magnet balance escapement according to Figs. 3

Y and 4, in side-view;

Fig. 6 is a front-view of Fig. 5;

Figs. 7 and 8 are details of Figs. 5 and 6.

Referring now to the drawings, 1 denotes the anchor or locking member and 2 the pole wheel. The anchor 1 is formed as a permanent magnet. Its two ends are provided with two pole pieces 3 and 4 made of soft iron.

During the vibration of the anchor 1, the constantly altered lever arms are approximately balanced by one pole being moved radially outwards, while the other pole is moved radially inwards, or to put it in other words: When one lever arm is reduced, the other lever arm is extended, the resulting force thus being kept nearly constant. Two

safety pins

5 and 6 are provided, alternately passing over the teeth of the escape wheel without touching them and stopping the escape wheel when the clock or watch is wound up and its hands set.

A further advantage of this arrangement is the possibility of adjusting the air gap between the escape wheel and the pole wheel. In Fig. 2 the air gap is designated as a. The air gap is controlled by screws 7 and 8 by which cap plates 9 and 10 are pressed. The cap plates 9 and 10 are preferably made of hardened and polished steel. The pivot ends limited by the cap plates are rounded off. In principle, the form is similar to that of a watch balance staff being limited by means of a steel cap plate or a cap jewel. In the magnetic escapement of the invention it is not absolutely necessary to provide both the anchor staff and the pole wheel arbor with cap plates at both pivot ends, as due to the magnetic forces the opposite pivot ends of both arbors are automatically limited. The adjustment of the air gap is of special importance in mass production, because the manufacturing tolerances may introduce differences in the tension spring force, friction, magnetic force etc.

It will be appreciated that the cap plates for adjusting the air gap between the escape wheel and the escapement also do much towards reducing the friction. Even one cap plate, such as the plate 9, would be sufficient for the adjustment of the air gap. This, however, would cause an increased friction, as the anchor staff with the pivot shoulder would then be pressed against the plate.

As will be seen from the drawing, the magnetic escapement for pendulum clocks according to the invention has the classical form of the mechanical anchor escapement.

I The ends of the anchor or the magnetic poles 3 and 4 respectively may be compared with the entering and the exit pallet of an anchor. In this case the mechanical escapement of the anchor would have to be replaced by the magnetic escapement having the corresponding form.

As is shown in Fig. 2, a normal anchor staff 11, an anchor staff box 12 and an adjusting rod 13 may be used. Instead of a plate or massive hook, the magnet anchor 1 is mounted on the arbor. Instead of the normal greatwheel the pole wheel 2 is riveted on to the normal greatwheel arbor 14. The pendulum spring as well as the pendulum itself (not shown) are of normal type.

It may be repeated that the pendulum spring, the complete pendulum, the adjusting rod thereof, the anchor journal box and the anchor staff as well as the great-wheel arbor of normal clocks may be used; only the great-wheel, the plate anchor, massive anchor or Graham anchor are to be replaced by the magnet anchor with poles and the pole wheel, the latter parts retaining the classic forms of the known trains. Similar features characterize a magnetic escapement for alarm clocks and watches (see Figs. 3 and 4). The known types of such magnetic escapements use tongue springs. The invention provides a balance the number of vibrations of which is greater than that of pocket or wrist watches, but smaller than that of said tongue spring. The magnet has the concentric form of a balance ring 1%, its ends being provided with pole pieces 161 and 192 made of soft iron and positioned unilaterally in opposite pole paths of the pole wheel. The magnet or balance ring 1% and the balance staff 1&4- with its journal box 105 are mounted on a bridge 163 made of non-magnetic metal. A spiral spring 166 is positioned on the balance staff 104 in a known manner, the end thereof being secured to a spiral pillar or pin 167. The magnet 100 is preferably made of magnetic steel in a punching operation. The distance of the poles may be varied by twisting owing to the effects of the hardening process. Such distance variations may be eliminated by riveting the parts 1%, 1G1, 102 and 1513 together. The bridge 193 thus serves not only as a support of the balance ring but also for adjusting the distance of the poles. Of course the balance may also be made by a pressed method or of sintered magnetic steel.

The air gap between the magnet poles 101, 1i't2 and the pole wheel is designated as b. The air gap may be conveniently adjusted by means of center screws 109. The illustrated support is only to be regarded as an example. Any other suitable hearing, such as a pivoted bearing illustrated in Fig. 2 may be used.

Safety pins 119, 111 are riveted into the bridge 103. The function of said pins is similar to that in the above described pendulum escapement.

Also in this magnetic escapement for alarm clocks and watches etc. the design is generally adapted to the mechanical balance escapements. All parts of the train are mounted on parallel arbors similar to any mechanical escapement.

A further important characteristic of the magnetic esca ements, particularly for rapidly vibrating systems, is the provision of an elastic coupling. In Fig. 4 the coupling spring is denoted as 112. The pole wheel 193 with the bearing box 113 is rigidly mounted on the arbor The driver 115 is supported on the shoulder 114a of the arbor 114 in a loose form and axially locked against displacement by a small disc 116. The two ends of the spring 1E2 bent up at right angles are coupled with the journal box 113 and the driver 115, i. e. one end engages a borehole of the box 113 between two pinion teeth. Due to the intercalated screw spring 112 the escape wheel is always elastically driven and a step-by-step movement of the escape wheel is made possible without suddenly stopping the whole train. The elastic coupling may also be inserted in the magnetic anchor escapement for pendulum clocks; in said escapements, however, it will not be absolutely necessary, the movements of the pole wheel of the pendulum escapement being slower.

Furthermore, it is proposed for better starting the rapidly vibrating magnetic escapement, to provide the teeth of the pole wheel with abutting or lifting faces, in order to mechanically vibrate the balance through the safety pins until the magnet poles are enabled to follow the waved path of the pole wheel, the further drive being magnetic.

Fig. 3 shows the pole wheel with the abutting faces 10312. Vhen the clock is wound up, the resulting recoil may cause the abutments or end supports 108a of the pole wheel 108 to strike on the safety pins 110/111, thus vibrating the balance 1%. Furthermore it will be useful, to provide the extension of the follower arbor 117 engaging the pole wheel pinion with a small knurl. Thus the movement may be started by hand.

The anchor forms illustrated by the drawings are only examples. In Fig. 1 the poles 3 and 4 embrace 3 /2 teeth. The poles could be spaced to such an extent as to embrace 4 /2 teeth. Moreover the anchor 1 may be made of nonmagnetic metal and an elongated permanent magnet may be riveted on the rearside of the anchor 1, said magnet having soft iron poles. in this case the anchor 1 would only serve as a support for the magnet and the poles. The anchor 1 and the poles 3 and 4 may be made in one piece of magnetic steel, e. g. of sintered magnet steel in the pressed method. Also in the quick vibrating magnetic cscapement according to Figs. 3 and 4 the magnet may have any form, i. c. it need not be formed as a balance ring 109. in this case the magnet may have a form similar to that of the anchor in Fig. 1, the center of gravity being balanced by means of a counterweight made of non-magnetic metal.

The adjustment in quickly vibrating escapements may be performed in a similar manner as in balance escapements, i. e. by means of a spiral adjuster reducing or ex tending the length of the spiral in a known manner. As the magnetic escapement is characterized by an elevated number of oscillations compared with that of a mechanical balance escapement, the adjustment by reducing and extending the spiral is not highly sensitive, the spiral of a magnetic escapement having, as a rule, a reduced length.

Adjustments on a magnetic base are already known, said adjustments using iron screws or plates to be adjusted adjacent to the magnet. A suitable adjusting means having in principle the same form as a spiral adjuster is shown in Figs. 5 to 8, said means, however, not being supported in the balance center but in the pole wheel center. The adjusting lever 29% may be adjusted by hand at the arm 200a bent up at right angles. Within reach of the pole wheel a concentric lap Ztltlb bent up at right angles is positioned, said lap bearing two poles 2690 and 2960'. When the poles 2000 and 230:! face the

poles

101 and 102, as shown in Figs. 5 and 6 (the distance of the poles 290a and 260d being equal to that of the poles 101 and 102) the greatest deflection of the lines of force takes place, or, to put it in other words: All lines of force starting from the

poles

101, 102 pass not only through the pole wheel, but also to a great extent through Ztltlc, 29012 and 200d. Fig. 5 is a diagrammatic view of the flow of the lines of force.

When the adjusting lever or the poles Ztlllc, 200d respectively are turned away from the poles 191, 102, the lines of force are not so deflected as to influence the time of oscillation.

In said adjusting system the effective element of the adjusting lever has thus two poles corresponding to the distance of the magnetic pole so that in the maximum position, i. e. the poles being opposite, a full flow of the lines of force with only small air gaps takes place. Thus a coarse and a fine adjustment will be attained, according to whether the poles Ethic and 209d of the adjusting lever are distant from the

poles

101 and 102 or face them. This is not the case with the conventional adjusting systems characterized by a considerable diffusion of magnetic flux.

There is another possibility of adjusting by introducing, from off the plate 120 (Fig. 4), a soft iron pin in the stray field of the magnet by screwing it in, so that said pin may more or less approach the magnet in the symmetrical plane determined by the

arbors

104 and 114. It increases then the effect of the spring 106 according to its adjustment, an additional force resulting from it tending to force the vibrating'magnet 100 into a symmetrical position, i. e. its rest position.

It will be appreciated that in the new magnetic escapement with a high-speed balance the sensitivity to abnormal positions is eliminated, said sensitivity existing in the known magnetic balances with tongue spring. In case the clock with tongue spring is not in its normal position, the correct vibration of the tongue spring will be effected because of its own weight and the corresponding displacement.

We claim:

1. A magnetic escape mechanism for clock-movements, more particularly for pendulum and balance controlled clocks, comprising an escape wheel having at its periphery a wavy path of high magnetic permeability and a cooperating magnetic locking member oscillatable about: an axis parallel to that of said escape Wheel and having poles and pole pieces spaced to engage sections of said wavy path of the escape wheel separated by an odd number of a half wave-length of said path.

2. A magnetic escape mechanism as claimed in claim 1, wherein the escape Wheel is a punched and toothed wheel of a magnetic material, the poles of the locking member being spaced by an odd number of a half tooth pitch.

3. A magnetic escape mechanism according to claim 1 comprising a time-controlling element including an adjustable magnetic body for magnetically regulating the period of oscillation of said magnetic locking member.

4. A magnetic escape mechanism for clock-movements, more particularly for pendulum and balance controlled clocks, comprising an escape wheel having at its periphery a wavy path of high magnetic permeability and a cooperating flat magnetic locking member extending in a plane parallel to the plane of the escape wheel and oscillatable about an axis parallel to that of the escape wheel and having poles and pole-pieces of opposite polarity spaced to engage sections of said wavy path of the escape wheel separated by an odd number of half wave-lengths of said wavy path.

5. A magnetic escape mechanism as claimed in claim 4 the escape wheel of which is a punched and toothed wheel of a magnetic material and the locking member of which is of horseshoe shape.

6. A magnetic escape mechanism according to claim 5 comprising pins at the horseshoe shaped locking member, said pins engaging the exterior parts of the teeth of the escape wheel in the extreme positions of the locking member and thus locking the escape Wheel in the winding operation.

7. A magnetic escape mechanism according to claim 5 wherein the balance ring comprises a horseshoeshaped magnet forming the magnetic locking member said magnet having a bridge of non-magnetic material extending from the poles of the magnet to the balance staff to connect the magnet to the latter.

8. A magnetic escape mechanism according to claim further comprising means to relatively displace the escape wheel and the locking member to provide for adjusting the distance of the poles from the magnetic escape wheel.

9. A magnetic escape mechanism according to claim 4 comprising a time-controlling adjustable magnetic element displaceable with respect to the oscillatable mag netic locking member and altering the retracting force of the member for magnetically regulating the period of oscillation of the same.

References Cited in the file of this patent UNITED STATES PATENTS 1,825,382 Baker Sept. 29, 1931 2,554,523 Clifiord May 29, 1951 2,571,085 Clifford Oct. 9, 1951 FOREIGN PATENTS 139,783 Great Britain June 2, 1921