DE1808170A1 - Shock protection for watches - Google Patents

Description

Shock protection in clocks It is known to work in clocks, preferably in wristwatches, to be secured against impact by making the movement free-floating and elastic hangs in the housing. up to now either metallic or flexible springs have been used for this purpose Materials, for example rubber or plastic, the latter preferably used as a pinge. The purpose of these arrangements was to keep the acceleration at impact so low that that the endangered parts of the movement, especially the balance shaft with the thin bearing journal, can withstand the resulting acceleration forces. It is also known, and Fabric tests on wristwatches have clearly proven that everyone is shockproof Movement parts is necessary if the functionality of a wristwatch after a Shock should be received. That the principle of shock protection for the entire work was rarely used in the housing, is due to the fact that the previous elastic work suspensions had the following disadvantages: a) poor centering with aging ouer bending of the springy work suspensions; b) for flexible ones Materials require a large amount of space because of their great resilience, or the destruction of the impact energy must take place at fixed stops; c) at short braking distances, very high spring stiffnesses are necessary, which in turn leads to leads to great accelerations; d) occur in the elastic work suspension as a result the reversal of acceleration on high impact forces.

Computational and metrological studies have shown that with elastic Resilience of the work after its deflection by the shock protection is significant higher acceleration forces occur than if the impact movement along the same Deflection fo is braked inelastically. Therefore aie shock load is aes Work when using elastic locking elements much larger than for shock-absorbing materials with the lowest possible impact elasticity. This is shown schematically in Fig. 1. Figure 1 a shows the sequence of movements with elastic Movement suspension (damped sine function), Figure 1 b with shock-absorbing movement suspension (aperiodic damping and slow reversal of the deformation in the shock-absorbing Slaterial). Both theoretically and practically it follows that in the second If the acceleration force is only about half as great.

To achieve the desired shock absorption, z.ß. plastic Viton has proven its worth, which has an impact elasticity below 10 a.

The effect of such a shock-absorbing work suspension lies in this in a shock pulse conversion, the short shock pulse with high peak acceleration into a long pulse with a smaller impact force peak and creeping regression the impact deformation and the impact energy is largely converted into the deformation energy of the shock-absorbing material is destroyed.

The advantage here is that this device is simple and cheap, and that if the balance pivot is dimensioned appropriately, you can use the expensive balance shock protection bearings can do without. The latter are now almost generally used as alternative bearings with a conical Stone lining made. Their recentering often leaves something to be desired. aside from that they require a narrow bumper gap that is easily oily or dirty can and then cause undefined additional attenuation.

In Fig. 2 the invention is shown in its principle. Fig. 2 a shows a movement with the usual attachment to the case. Fig. 2 b shows a work under Interposition of a shock-absorbing ring, e.g.

a Viton ring.

According to the invention, this shock protection can by a shock-absorbing Work suspension additionally through an insight into the dimensioning of the shock-prone balance pivot can be improved.

up to now a radial impact has been attempted with rigid journal bearings to be caught by a pin that is as long as possible, so that the impact force is destroyed the natural oscillation time of the balance shaft is as long as possible compared to the peak time and after bending the pin, the impact energy is completely destroyed in a bumper. will.

Even with impact-protected bearings with evasive bearing lining the balance pins are relatively long for reasons of tolerance and ease of manufacture, i.e. a ratio of loaded pin length 1a to pin diameter was chosen dz greater than 1.

Theoretical considerations combined with practical results (see table below) have now shown that it is advantageous to treat the burdened Part (1a)) of the balance pivot with a continuous transition (1v) to the thick one Corrugated part (corrugated tree) with diameter dv 60 as short as possible to make both the ligament oscillation time of the balance shaft compared to the peak time is as small as possible and to increase the maximum (static) bending stress. By Both measures increase the impact resistance of the pin. So it is possible to use thinner pins, which in a known manner the influence of the location improved on the cang.

In Fig. 3 a, a common balance pin is shown as an average between 38 different normal tenons for men's wristwatches. In Fig. 3 b is a pin proposed according to the invention shown in the the pin length 1z has been significantly shortened, so that the ratio 1a / dz is smaller 1 will.

In the table below are practical measurements on devices listed after the discovery. The impact test was carried out in accordance with DIN 8308. The effect on the movement was enjoyed by the resulting imbalance, which in turn from the maximum path difference with a horizontal balance wheel axis can be grasped. During the tests, the shock-absorbing ring according to Fig. 2 b was also used an immediate suspension of the work without any shock protection according to Fig. 2 a compared. As was to be expected, a blow to steel occurred in particular significant advantage of the Viton ring. There is also a clear improvement with shortened tenon length. This is particularly important when the journal diameter is decreased.

Watches with shock protection according to the invention with shock-absorbing movement suspension and with a shortened balance pivot held a case from 1 irtheight on steel supports and concrete floor several times, whereas here the "classic designs with the usual Shock protection through evasive lining, both through broken tang and through Failure to damage parts of the movement.

The shock absorption aer movement of the suspension according to the invention can both take place in the radial as well as in the axial direction.

If the latter is excluded by this type of suspension, the axial shock protection can be provided in a known manner by an elastically movable cap stone, which, however, ensures precise recentering after the shock. o QI 0 ca c tenon tong E cc $ d OOCO ~ ca TO Xl ts NU} N ~~ u, s N normal case a 9 0.3 QJ6 VT blow to O 5 steel b a> 9 0> NT change of 6 b9 83 3J6 NT 22 6 2 a 9 Q3 0, t6 VS stachejfln 6 202. bg 0.3 w NS Brl ch a 9 427 0.13 tl S o 6 3 b 9 Q27 0! 13 NT 6 10 ~ c 9 426 0.12 NS 22 » a 7 A3 0J6 VT 6 2 pcs 4 b 7 C5 0.11 VT 12 2 c 7 425 0.11 VS L0 24 5 ~ 6 0, Sb 0.10 VT 120 80

Claims (4)

Claims: 1. Shock protection for watches, preferably for wristwatches, with a flexible suspension of the movement in the case, characterized in, that the work suspension is made of a shock-absorbing material. 2. Shock protection according to claim 1), characterized in that in addition a balance shaft with a short journal is used. 3. Shock protection according to claim 1.) and 2.), characterized in that that Viton is used as a shock-absorbing material. 4. Shock protection according to claim 1.) to 3.), characterized in that that a work ring made of shock-absorbing material is used as a suspension.