Safety valve for watches

Abstract

A safety valve for a watch including a head that is movably mounted on a tube and able to move between an open position and a closed position, the tube including in its internal volume a first spring and wherein the tube is provided on an external face with a cam surface allowing a manual movement and an automatic movement of the head into its open position, after the first spring, the tube includes a second spring having a higher stiffness than that of the first spring.

Claims

1. A safety valve comprising: a tube configured to be fixed to a watch case and a hollow head provided with a shaft extending into a hollow part of the head, said head being movably mounted on the tube and able to move along an axis defined by the shaft between an open position, wherein a fluid overpressure inside the watch case is capable of escaping, and a closed position wherein fluid is prevented from escaping, said tube comprising, in its internal volume, a first spring wound around the shaft, the tube being further wherein: an external face of said tube is provided with a cam surface, respectively, allowing a manual movement of the head to its open position following intervention by a user and an automatic movement of the head towards its open position in response to a critical overpressure inside the watch case, and the tube includes a second spring wound around the shaft with the second spring separated from the first spring by a step portion traversed by the shaft and integral with the tube, the first spring being dimensioned so that the valve is active in response to an overpressure Px inside the watch case after manual movement of the head into its open position, the second spring being sized so that the valve is active in response to an overpressure Py inside the watch case causing automatic movement of the head into its open position, the second spring having a higher stiffness than that of the first spring so that overpressure Py is higher than overpressure Px.

2. The valve according to claim 1, wherein the cam surface is formed of one or more ramps cooperating with recesses of complementary shape made in the inner wall of the head.

3. The valve according to claim 2, comprising to ramps each extending over an arc of less than or equal to 180.

4. The valve according to claim 2, wherein the ramps are arranged in an equidistant manner.

5. The valve according to claim 2, wherein each ramp comprises stop notches at its ends.

6. The valve according to claim 5, wherein the stop notches or stops are used to set, in a reproducible manner, the position of an inscription or of a logo arranged on the head in the closed and/or open position.

7. The valve according to claim 1, wherein the tube includes in its internal volume two chambers, separated by the step portion with, in succession starting from the head, a first chamber housing the first spring and a second chamber housing the second spring.

8. The valve according to claim 1, wherein the valve includes a gasket arranged facing one end of the tube inside an annular housing arranged in the head and another gasket, also called the first gasket, intended to be supported on the step portion when overpressure Px and overpressure Py are substantially equal to 0.

9. The valve according to claim 8, wherein the first chamber includes a ring arranged between the first spring and the first gasket, one end of the first spring being supported under the head and the other end of the first spring being supported on the ring intended to compress the first gasket against the step portion when overpressure Px and overpressure Py are substantially equal to 0.

10. The valve according to claim 1, wherein one end of the second spring is supported on the step portion and the other end of the second spring is supported on a shoulder arranged at a base of the shaft.

11. The valve according to claim 1, wherein the step portion includes a stop cooperating with the shaft to limit the axial movement of the head towards its open position.

12. The valve according to claim 1, wherein the first spring and the second spring are crest-to-crest springs.

13. The valve according to claim 1, wherein Px is higher than or equal to 1 bar and wherein Py is higher than or equal to 3 bar.

14. The valve according to claim 1, wherein the tube includes a mark on its external face.

15. A watch comprising: a case formed of a case middle, a back cover and a crystal delimiting a sealed volume in which is mounted a timepiece movement provided with a means for displaying time information, and including a valve including a tube intended to be fixed to a watch case and a hollow head provided with a shaft extending into a hollow part of the head, said head being movably mounted on the tube and able to move along an axis defined by the shaft between an open position, wherein a fluid overpressure inside the watch case is capable of escaping, and a closed position wherein fluid is prevented from escaping, said tube comprising in its internal volume a first spring wound around the shaft, the tube being further wherein: an external face of said tube is provided with a cam surface, respectively, allowing a manual movement of the head to its open position following intervention by a user and an automatic movement of the head towards its open position in response to a critical overpressure inside the watch case, and the tube includes a second spring wound around the shaft with the second spring separated from the first spring by a step portion traversed by the shaft and integral with the tube, the first spring being dimensioned so that the valve is active in response to an overpressure Px inside the watch case after manual movement of the head into its open position, the second spring being sized so that the valve is active in response to an overpressure Py inside the watch case causing automatic movement of the head into its open position, the second spring having a higher stiffness than that of the first spring so that overpressure Py is higher than overpressure Px, said valve being mounted on the case.

16. The valve according to claim 1, wherein Px is higher than or equal to 2 bar and wherein Py is higher than or equal to 4 bar.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a front view of one part of the helium escape valve according to the invention.

(2) FIG. 2 represents the same view of the whole of the helium escape valve provided with the head, with the ramps arranged in said head transparently visible.

(3) FIG. 3 is a perspective view of the helium escape valve according to the invention.

(4) FIG. 4 represents a wave spring which, in a preferred variant of the invention, can be used in the helium escape valve.

(5) FIGS. 5 and 6 are cross-sectional views of the helium escape valve of the invention fixed to a watch case. In FIGS. 5 and 6 the head is in the closed position. In FIGS. 7 and 8 the head is in the open position following intervention by the user. In FIG. 8 a difference in pressure between the interior and exterior of the watch case results in gas escaping towards the exterior of the watch case. In FIG. 9, the head is in the open position without intervention by the user, following significant overpressure inside the watch case.

(6) FIGS. 10 and 11 represent a watch case provided with a helium escape valve according to the invention, with the head respectively in the closed position and in the open position.

DETAILED DESCRIPTION OF THE INVENTION

(7) The present invention relates to a helium escape valve, which will also be referred to as a safety valve.

(8) Valve 1 represented, amongst others, in FIGS. 2, 3 and 5, includes a hollow cylindrical head 3 mounted on a tube 4 intended to be fixed to watch case 5, for example by screwing down. Valve 1 includes a shaft 6 integral with head 3, which extends inside the volume delimited by the hollow head and by the tube. According to the invention, head 3 is movably mounted on tube 4 and moves axially between a closed position and an open position respectively represented in FIGS. 5 and 7. The head can move axially in a purely translational motion or move axially via a rotational motion transformed into a translational motion by a cam type contact between the head and the tube. To this end, tube 4 is provided, on its upper external face, and more specifically on its external face outside the watch case, with a cam surface 7 formed of one or more ramps on which head 3 slides when the user imparts a rotational movement to the latter (FIGS. 1 and 2). The tube can be provided with a single ramp occupying an arc comprised between 15 and 360. Preferably, the tube is provided with at least two ramps to ensure that the head rests on the tube at several points when the head is in the open position. These different ramps have the same geometry (same length, same height) and, preferably, they are arranged in an equidistant manner so that the seat of the head is perpendicular to the longitudinal axis formed by the tube when the head is open. Where there are two ramps, each ramp occupies an arc of less than or equal to 180. Where there are three ramps, each ramp occupies an arc of less than or equal to 120. In the example illustrated in FIGS. 1 to 3, tube 4 is provided on its upper external face with two ramps 7, each occupying an arc of slightly less than 180. Each ramp cooperates with recesses 8 of complementary shape made in the inner wall of head 3, as illustrated in FIGS. 2, 3 and 5. Preferably, each ramp comprises, at its ends, notches or stops 9, which inform the user that he has reached end of travel. It is evident that these notches or stops can also be used to position the inscription on valve head 3 in a precise and reproducible manner, so that the piece is always read in the same manner and has the same aesthetics in the closed and/or open position.

(9) As represented in FIG. 5, valve 1 has a double seal with, on the one hand, an O ring gasket 10 disposed opposite the upper end of tube 4 inside an annular housing 12 provided in head 3 and, on the other hand, another gasket 11, referred to below as the first gasket, arranged inside tube 4. According to the invention, the internal volume of the tube is divided into two chambers 4a, 4b, separated by a step portion 13 traversed by shaft 6. There is a first chamber 4a under head 3, followed, in the direction of the base of shaft 6, by a second chamber 4b. The first 4a and second 4b chambers respectively house first spring 14 and second spring 16. The two chambers are separated by step portion 13 serving as support for first O ring gasket 11 arranged in first chamber 4a. This step portion may be in the shape of a truncated cone, as in the examples, or possibly flat. It includes a vertical extension 13a extending towards the base of shaft 6 and cooperating with a shoulder 6a made in shaft 6 to limit the translational motion of the head in the open position.

(10) In first chamber 4a, first spring 14 is wound around shaft 6. This first spring 14 is supported, at one end, under head 3 and, at the other end, on a ring 15 that compresses first gasket 11 against step portion 13. In second chamber 4b, second spring 16 is wound around shaft 6. It is supported, at one end, on step portion 13, and at the other end, on a second shoulder 6b provided at the base of shaft 6. This second spring 16 is sized to exert a return force on the head and to maintain sufficient closure pressure to ensure the sealing of the valve. According to the invention, it has a stiffness that is higher than that of the first spring, the stiffness of the two springs being calculated as a function of the pressure thresholds above which the valve must be operative. By way of example, first spring 14 can be dimensioned so that the overpressure value Px inside the valve that releases first gasket 11 is higher than or equal to 1 bar, preferably to 2 bar, whereas second spring 16 can be dimensioned to release gasket 10 under head 3 at a delta pressure Py between the interior and exterior that is higher than or equal to 3 bar, preferably to 4 bar. The springs may be helical springs. In a preferred variant, they may be crest-to-crest springs, also known as wave springs, as represented in FIG. 4, which offer the advantage of occupying less space compared to a helical spring of equivalent stiffness. The superposition of Schnorr or Belleville washers is also envisaged.

(11) FIGS. 5 to 9 illustrate the operation of the valve according to the invention. In FIGS. 5 and 6, the head is in the closed position, i.e. the user has not rotated the head. If there is no difference in pressure between the interior of the watch case (pressure P2) and the external environment (pressure P1=P2), the two gaskets 10, 11 are compressed and the valve is completely sealed (FIG. 5). In the presence of moderate overpressure inside the watch case (P2>P1), shaft 6 is held in the low position by the return force of second spring 16, whereas first gasket 11 is no longer active due to the helium pressure lifting the latter (FIG. 6). Nonetheless, the sealing of the valve is ensured by gasket 10 under the head. In the presence of significant overpressure inside the watch case (P2>>P1), the return force of second spring 16 is no longer able to counteract the internal pressure (FIG. 9). Consequently, shaft 6 rises up, releasing the two gaskets 10, 11 and thereby allowing gas to escape through the two chambers and the space between the external face of the tube and the inner circumference of the head.

(12) When the user rotates the head to place it in the open position as shown in FIGS. 7 and 8, the head moves axially by a distance D corresponding to the height of the ramp, which makes gasket 10 inactive under head 3. If the internal pressure is equal to the external pressure (P1=P2), first gasket 11 remains compressed against support step 13 and consequently the valve remains sealed (FIG. 7). Conversely, when the internal pressure exceeds the external pressure (P2>P1) by a predefined value sufficient to counteract the return force of first spring 14, first gasket 11 also becomes inoperative, which allows gas to escape outside the watch case to balance the pressures (FIG. 8).

(13) Finally, FIGS. 10 and 11 illustrate watch case 5 comprising valve 1 according to the invention in the closed and open positions respectively. Optionally, tube 4, which is visible when head 3 is in the open position, can be marked on its external face with a logo or colour to indicate to the user that the head is in the open position.

LIST OF PARTS

(14) (1) Valve

(15) (3) Head

(16) (4) Tube (4a) First chamber (4b) Second chamber

(17) (5) Watch case

(18) (6) Shaft (6a) First shoulder (6b) Second shoulder

(19) (7) Cam surface or ramp

(20) (8) Recess in the head

(21) (9) Notch on the ramp

(22) (10) Gasket under the head

(23) (11) Other or first gasket

(24) (12) Housing

(25) (13) Step portion (13a) Stop

(26) (14) First spring

(27) (15) Ring

(28) (16) Second spring

(29) (17) Distinct push-piece for the valve according to the invention