FR2847371A1 - Method for detecting drowning, uses detection unit having deformable chamber, with inflow of fluid into chamber measured to detect duration of immersion - Google Patents

Abstract

The drowning is detected after a duration T of immersion at a depth greater than a threshold L. The method involves penetrating a fluid in a deformable chamber and to limit the deformation of this chamber when this latter is disposed at a depth lower to a threshold L. The next step includes controlling and measuring the flow of fluid at the interior of the chamber in order to determine the duration T of immersion at a depth greater than the threshold L.

Description

he

  METHOD OF DETECTION OF DROWNING AND DEVICE FOR THE SAME

IMPLEMENTATION

  The present invention relates to a method for detecting drowning as well

  than a device for its implementation.

  Devices for detecting drowning are described in documents US-5,097,254 and FR-2,199,111. They make it possible to trigger an alarm or a rescue device when the swimmer remains immersed at a depth greater than a determined threshold for a certain period. To this end, these devices comprise on the one hand a pressure sensor with a deformable membrane on which the water is likely to exert a pressure, ensuring the measurement of the depth, and on the other hand, an electric type delay

  or electronic measuring the duration of immersion at a certain threshold.

  Taring means at the membrane level make it possible to determine the triggering threshold for measuring the pressure corresponding to the depth. Thus, as soon as the swimmer is immersed to a certain depth greater than the set threshold, the water exerts on the membrane sufficient pressure to deform it and close a contact. Closing this contact arranged in series with the time delay does not trigger the alarm or the rescue device

  only after a certain duration depending on the setting of said time delay.

  These devices are not satisfactory because of their complexity because they combine a mechanical type device for measuring the pressure and an electric type device for measuring the duration. Furthermore, the operation of this type of device is not safe because it varies according to the surrounding conditions, in particular the temperature, which is prohibitive.

for a safety device.

  Also, the present invention aims to provide a simple and reliable method and device for detecting drowning, while allowing deep immersion for a short time, for example during a dive. To this end, the subject of the invention is a method of detecting drowning, said drowning being detected after a duration T of immersion at a depth greater than a threshold L, consisting in causing a fluid to penetrate into a deformable chamber and to limit the deformation of said chamber when the latter is disposed at a depth less than a threshold L, characterized in that it consists in monitoring and measuring the flow of the fluid inside the chamber in order to determine the duration T d immersion at a depth greater than the threshold L. The invention also provides a device for detecting drowning comprising at least one deformable chamber when a fluid is introduced inside said chamber, as well as means for limiting deformation of said chamber when the latter is disposed at a depth less than a threshold L, characterized in that it comprises means for controlling and measuring the coulement fluid inside said chamber to determine an immersion time T to a depth greater than the threshold L.

  Other characteristics and advantages will emerge from the description which follows.

  follow the invention, description given by way of example only, opposite

  of the accompanying drawings in which: - Figure 1 is a section through the device in the "no drowning detected" position, - Figure 2 is a section through the device when a drowning is detected, - Figure 3 is a schematic view illustrating the Principe of fonctionment. Drowning is characterized by a certain time of immersion. According to the principle of the invention, drowning will be detected after an immersion time greater than a threshold T and for a depth greater than a threshold L. L and T are determined empirically, T representing an average value of apnea and L being the average distance separating the device from the surface of the water in normal operation, that is to say without risk of drowning. For example, the average distance L is of the order of 50 to 60 cm and the duration T

on the order of a minute.

  The drowning detection device of the invention is described with regard to

Figures 1 and 2.

  It comprises in a shell 10 two chambers 12 and 14 separated by a partition 16, at least one nozzle 18 being provided at the level of the partition allowing the flow of a fluid 20 from one chamber to the other. Chambers 12 and 14 include at least a portion of deformable surface capable of being

  deform depending on the volume of said chambers.

  According to a preferred embodiment, the chambers 12 and 14 are delimited on the one hand by the partition 16 and on the other hand each by a flexible membrane 22,

  the partition 16 dividing the shell 10 into two compartments 24 and 26.

  At one of its faces, the shell 10 includes orifices 28 allowing the passage of water in one of the compartments 24 in which the

flexible membrane of the chamber 12.

  The membrane of the other chamber 14 is connected to an actuator 30, return means 32, in the form of a spring, resistant to the deformation of said membrane, tending to maintain or return the device to the "non-drowning" position.

  detected "corresponding to Figure 1.

  According to a characteristic of the invention, the nozzle is capable of having two states, a first state called "non-passing" in which it prevents or greatly restricts the flow of the fluid from the first chamber 12 to the second chamber 14 when the device is disposed at a depth less than the threshold L and a second state known as passing in which it allows the flow of fluid from the first chamber 12 to the second chamber 14 when the device is disposed at a depth greater than the threshold L. According to the embodiments, this change of states can be obtained either by using the spring 32 which opposes the deformation of the chamber 14 and therefore prevents the flow of fluid to said chamber when the pressure is not sufficient that is to say when the device is disposed at a depth below the threshold L, or either by incorporating a non-return valve at the nozzle, the latter being triggered from a c ertaine pressure when the device is disposed at a depth equal to or greater than the threshold L. According to another variant, this change of state can be induced due to the characteristics of the fluid, in particular its viscosity, said fluid flowing at

  through the nozzle 18 from a certain pressure.

  The operating principle of the device is now described.

  In immersion, water enters the compartment 24 via the orifices 28 and exerts a pressure on the membrane 22 of the chamber 12. Consequently, the fluid tends to flow from the chamber 12 towards the chamber 14 via the nozzle 18 and the membrane 22 of the second chamber 14 is deformed. The deformation of the

  membrane of the second chamber 14 generates a translation of the actuator 30.

  When the pressure P exerted by the water on the membrane of the first chamber 12 is insufficient, in particular when the device is placed at a depth less than L, the fluid does not flow or flows very

  weak from the first to the second bedroom.

  When the pressure P exerted by the water on the membrane of the first chamber 12 is sufficient, when the device is arranged below the threshold depth L, the fluid flows from the first to the second chamber. The detection of drowning occurs after a certain duration, depending in particular on the nozzle, the viscosity of the fluid and the pressure, when the deformation of the chamber 14 has reached a certain threshold, the actuator 30 then triggering a

  inflatable buoy or an alarm for example.

  When the duration is too short, for example during a dive, the membrane of the second chamber 14 has not had time to deform sufficiently, and

drowning is not detected.

  The adjustment of thresholds L and T can be carried out by adjusting the spring setting

32 and nozzle 18.

  According to a first variant, one could provide a single deformable chamber 14, the water entering it via the nozzle 18. Two chambers are preferred for providing a determined fluid flowing from one chamber to the other with

substantially stable properties.

  According to another variant, the nozzle 18 can be replaced by a porous wall,

  the membrane 16 being partly or entirely porous.

  In all cases, the means for measuring the duration of immersion at a depth greater than or equal to the fixed threshold comprise means for measuring or controlling the flow of a fluid through a nozzle, a porous wall or the like. , characterized by a flow resistivity, said fluid being either water in the simplified variant or a separate fluid having stable properties, almost insensitive to the environment, in the variant

illustrated by the figures.

  The device of the invention has the main advantages of being reversible and of returning to the non-triggered position as soon as the swimmer returns to the surface, of authorizing an immersion for a short time, of being simple in providing

  means for measuring pressure and duration in hydraulic form.

  According to another characteristic of the invention, the device is safe because

  almost insensitive to external conditions.

  The detection device of the invention is preferably coupled either to a rescue device such as an inflatable buoy or to a signaling device such as an alarm and attached to a belt 34 as illustrated

by figure 3.

Claims (12)

  1. Method for detecting drowning, said drowning being detected after a duration T of immersion at a depth greater than a threshold L, consisting in causing a fluid to enter a deformable chamber and in limiting the deformation of said chamber when the latter is disposed at a depth below a threshold L, characterized in that it consists in controlling and measuring the flow of the fluid inside the chamber in order to determine the duration T of immersion at a depth greater than the threshold L . 2. Detection method according to claim 1, characterized in that it consists in causing a fluid to flow from a first deformable chamber to a second deformable chamber, a second fluid, in particular water, being capable of exerting pressure on the deformable wall of one of the two chambers. 3. Detection method according to claim 1 or 2, characterized in that the duration T of triggering is adjusted by adjusting the characteristics of the fluid and the resistivity to the flow of control and measurement means of fluid flow.   4. Detection method according to one of the preceding claims,   characterized in that the threshold L is adjusted by adjusting the calibration of return means provided to limit the deformation of one of the chambers or the   triggering of a valve provided at the nozzle.   5. A drowning detection device comprising at least one deformable chamber (12, 14) when a fluid is introduced inside said chamber, as well as means for limiting the deformation of said chamber when the latter is disposed at a depth less than a threshold L, characterized in that it comprises means for controlling and measuring Sq the flow of the fluid inside said chamber in order to determine a duration T of immersion at a depth greater than threshold L. 6. Device according to claim 5, characterized in that it comprises two deformable chambers (12, 14), means being provided to allow the flow of a fluid from one chamber to another. 7. Device according to claim 5 or 6, characterized in that the means   fluid flow control and measurement devices include a nozzle (18).   8. Device according to claim 5 or 6, characterized in that the means for controlling and measuring the flow of the fluid comprise a wall porous.   9. Device according to claim 7 or 8, characterized in that the nozzle (18) or the porous wall is capable of occupying two states, a first state called "non-passing" when said chamber is arranged at a depth less than a threshold L and a second state known as passing when said chamber is arranged at a depth greater than the threshold L.   10. Device according to any one of claims 5 or 9, characterized   in that it comprises a shell (10) in which the deformable chamber or chambers (12, 14) are arranged, orifices (18) being provided to allow   the introduction of water inside said hull.   11. Device according to any one of claims 1 to 10, characterized   in that it comprises an actuator (32) connected to the deformable part of the chamber. 12. A rescue device capable of being worn by a user comprising a device for detecting drowning according to any one of claims 5 to 11.