PRESSURE-REGULATING DEVICE FOR THE SECOND STAGE OF REDUCTION OF AN AIR BREATHING APPARATUS

Abstract: A floating piston member (8) formed with an axial conduit (408) communicating with the air-feeding conduit (7) from the first stage of reduction of an air bottle, is provided at one end with a valve seat (508). The said piston member (8) may be displaced between a first operative position, in which it is pushed by air pressure against the seal (403) of a valve member (3) against the action of a spring (608), and a second position wherein it is separated and moved away from the seal (403) of said valve member (3) by the action of said spring (608). The valve member (3) is controlled by the manostat diaphragm of the breathing apparatus, through a suitable trasmission (2) and is urged constantly toward said valve seat (508) by a spring (503).

Description: This invention relates to a pressure-regulating device which is intended, for example, to equip the second stage of reduction of a two-stage pressure regulator of an air breathing apparatus, particularly an underwater breathing apparatus. In the conventional air pressure-regulating devices for the second stage of reduction of an air breathing apparatus, the valve member of the second-stage valve is urged constantly by a calibrated spring with a considerable force against its valve seat. This valve-closing force is present as well when the valve is in its rest condition, and in the course of time this fact causes a permanent distortion of the resilient seal on the valve member, which alters the calibration of said valve. Inasmuch as the rest periods of this device are by far much longer than the periods of actual operation, it has been proposed, for example, as described in US-A- 4,094,314, to avoid any contact between the valve member and valve seat in the second-stage valves during the non-operative periods of said valves, by mounting the valve seat on a freely-floating member or piston, whereby the valve seat is matched against the valve member only when compressed air is operative upstream of said valve seat, whereas when the supply of compressed air is discontinued said piston is pushed back into a neutral position due to the resiliency of the seal on said valve member. The device according to said US-A-4,094,314 however, has some disadvantages and does not grant always a constant and reliable operation; moreover, the force which matches the valve member against its seat cannot be adjusted. Furthermore, all the conventional regulators mentioned above have the serious disadvantage to require the user, during the step of air supply to him, to make an inhaling effort growing progressively with his air requirements, so that considerable breathing difficulties are often encountered by a user who, for example, is temporarily in a panting or gasping condition, i.e. is struggling for breath. The breathing functions of this user, in fact, are not facilitated by the conventional regulators. From FR-A-2288346 a pressure regulating device is known, comprising a floating piston member formed with an axial conduit communicating with the air-feeding conduit from the first stage of reduction of an air bottle, and provided at one end with a valve seat. The said piston member may be displaced between a first operative position, in which it is pushed by air pressure against the seal of a valve member against the action of a spring, and a second position wherein it is separated and moved away from the seal of said valve member by the action of said spring. The said device is however intended for use on breathing apparatuses for aircraft pilots and is not suitable for use in an underwater breathing apparatus. This invention provides a pressure-regulating device for the second stage of reduction of an underwater air breathing apparatus comprising a floating piston member formed with an axial conduit communicating with the air feeding conduit from the first stage of reduction of the pressurized air feeding bottle or bottles, and provided at one end with a valve seat, and capable of displacing between a first operative position in which it is pushed by the air pressure against the seal of a valve member against the action of a spring, and a second operative position wherein it is moved away from the seal of said valve member by the action of said spring under the control of the manostat diaphragm of the air breathing apparatus, characterized by the fact that in the rest position of the device the valve seat and the valve member are spaced one from another so as to exclude any contact between said parts. According to its main characteristic, the floating piston of the device according to the invention, which mounts said valve seat, moves through an exactly-established stroke between an operative position wherein it is pushed by the pressure of the compressed air against the seal of the valve member, and a rest position, defined by a stop member, wherein said valve seat is spaced from the seal of the valve member by the action of a spring, so as to ensure a prompt separation of these two members in any operational condition. By virtue of this characteristic, it is possible to calibrate accurately and in an exactly reproducible manner both the force for matching together said two members, i.e. the second-stage valve seat and valve member, and the force for separating them. Due to said calibrated spring acting on the floating piston, said piston and the valve seat mounted thereon are separated from said valve member at the beginning of the breathing activity as a result of the pressure drop upstream of said piston during the inhalation step, so that an increased amount of air will be fed to the user at a parity of breathing effort, with resulting easier breathing, which is particularly important in case of increased need of oxigen of the user. Further characteristics and advantages of this invention will become apparent from the following description of a preferred embodiment thereof, illustrated in the accompanying drawing, which diagrammatically shows a longitudinal sectional view of a second-stage pressure regulating device according to the invention. With reference to the drawing, the numeral 1 indicates diagrammatically the mouthpiece of a breathing apparatus, the numeral 2 indicates the control lever for a valve member 3, said lever being controlled, in a manner known per se , by a manostat diaphragm (not shown) of the breathing apparatus. The regulating valve for the second stage of the regulator comprises a valve body indicated generally at 4 communicating at one end thereof, through a conduit 5, with the conduit leading to the mouthpiece 1, and closed at the other end thereof by a screwed cap 6 comprising an axial tubular union 7 which is connected to the first-stage reduction valve (not shown) associated with the bottle which feeds the compressed air. The valve body 4 comprises interiorly a first cylindrical chamber 104 and a second cylindrical chamber 204 having a larger diameter than the chamber 104. The two chambers 104 and 204 freely communicate with each other. The chamber 104 communicates at one end thereof with said conduit 5, while the chamber 204 is closed at the opposite end thereof by said screwed cap 6. The chamber 104 accommodates the valve member 3 comprising a cylindrical body 103 connected at one end thereof to a stem 203 which extends with a radial clearance through said conduit 5 and is associated with an end of said control lever 2. The body 103 is provided at the other end thereof with a member 303 accommodating the resilient seal 403 of the valve member. The outer diameter of the member 303 is smaller than the inner diameter of the chamber 104 so as to form an annular gap between these two members to permit the air to flow therethrough. The valve member 3 is urged constantly in the axial direction towards the chamber 204 by a spring 503 abutting against the bottom of the chamber 104 and the bottom of the member 303. The axial displacement of the member 3 in said direction is limited by a stop member 603 arranged on the end portion of the stem 203. The chamber 204 accommodates, in an axially slidable manner, the valve-seat mounting member. This member, indicated generally at 8, comprises a cylindrical body 108 accommodated in the chamber 204, provided at one end thereof with a cylindrical extension 208 protruding into the conduit 7. A toroidal seal 308 is arranged between the outer wall of the extension 208 and the inner wall of the conduit 7 to ensure a sealed co-operation therebetween. A through-conduit 408 is formed axially in the body member 8 and communicates at one end thereof with said conduit 7, and at the other end thereof with the valve seat 508. The body member 8 is urged constantly away from the valve member 3 by a spring 608 abutting against the bottom of the chamber 204 and against an annular shoulder on the body member 8. The operation of the device described above is now apparent. As soon as the airflow from the first stage is activated, the air pressure acting on the end of the extension 208 pushes the body member 8 against the action of the spring 608 and matches the valve seat 508 against the valve member 403. When the user starts breathing, the valve member 403 is moved away from the valve seat 508, against the action of the valve spring 503, by the action of the lever 2 under the control of the manostat diaphragm. As a result, an airflow is established from the conduit 7, through the conduit 408, the valve seat 508 and conduit 5 to the mouthpiece 1. Such an airflow causes a pressure drop in the conduit 7, upstream of the piston 8, so that the floating piston 8 is again moved away from the valve member 403 (the illustrated position), thus increasing the distance between the valve seat 508 and valve member 403, which causes an increase in the amount of air fed to the user at a parity of inhaling effort. This characteristic makes breathing easier, which is particularly important in case of panting conditions or lack of oxigen. Of course, as soon as the inhaling act is over, pressure will increase upstream of the piston 8 and will match it back against said valve member 403, thus discontinuing the airflow to the user. Finally, when the regulator is at rest, i.e. when the airflow is discontinued from the first stage to the second stage of the regulator, the piston 8 together with the valve seat 508 are kept away from the valve member 403 by the action of the spring 608.

Claims: 1. A pressure-regulating device for the second stage of reduction of an underwater air breathing apparatus comprising a floating piston member (8) formed with an axial conduit (408) communicating with the air feeding conduit (7) from the first stage of reduction of the pressurized air feeding bottle, and provided at one end with a valve seat (508), and capable of displacing between a first operative position in which it is pushed by the air pressure against the seal (403) of a valve member (3) against the action of a spring (608), and a second operative position wherein it is moved away from the seal (403) of said valve member (3) by the action of said spring (608) under the control of the manostat diaphragm of the air breathing apparatus, characterized by the fact that in the rest position of the apparatus the valve seat (508) and the valve member (3) are spaced one from another so as to exclude any contact between said parts. 2. A device according to claim 1, wherein the force exerted by said spring (608) of said floating piston (8) in said second operative position is such as to move said piston (8) away from said valve member (3) as soon as a pressure drop occours upstream of said piston (8) due to the creation of an airflow through the valve seat (508) of said piston (8) and the valve member (3) co-operating therewith, when the valve member (3) is moved away from the valve seat (508) as a result of an inhalation act of the user of the regulator.

Inventors: GAROFALO, GIOVANNI
Applicants: THE SUMITOMO BANK, LIMITED
Application year: 1988
Main classification: B63C11
IPC codes: A62B9, B63C11