| 摘要 |
The present invention concerns an arrangement for generating a pulsating underpressure in a line 7 intended to be connected to a breathing vest A, which arrangement comprises an underpressure line 6 connected to an underpressure source 1. According to the invention, the arrangement comprises a tube 9 which is open at both ends and which, at its first end, is connected to the underpressure line 6 and which comprises first, second and third ports 10, 8 and 11 which are arranged axially one after the other and which connect the insides and outsides of the pipe 9 to each other, a valve body 12 which can be axially displaced inside the tube between a first position, in which the valve body closes the connection through the inside of the tube between the first and second ports 10, 8 without completely closing any of the ports, while the connection between the second and third ports 8, 11 is open, and a second position, in which the connection through the inside of the tube 9 between the first and second ports 10, 8 is open while the connection between the second and third ports 8, 11 is closed, a control cylinder 13 which is arranged in the continuation of the tube outside its second end and comprises a control piston 14 connected in an axially fixed manner to the valve body 12, a by-pass line 16 which connects the third port 11 to that of the two control cylinder chambers located farthest from the second end of the tube 9, which chambers are delimited by the control piston 12 and comprise an air inlet opening, members 17 for closing the connection of the by-pass line 16 to the third port 11, members 18 for closing the air inlet opening of the by-pass line 16, and members 25 for controlling the members 17, 18 for closing the connection of the by-pass line to the third port 11 and the air inlet opening of the by-pass line, the first and second ports 10 and 8 being connected to the line 7, intended to be connected to a breathing vest A, and to the atmosphere, respectively. <IMAGE> |
