Dual tank pneumatic valve

Abstract

A pneumatic actuator is designed to dispense a predetermined volume of compressed air from a main tank to an outlet of a solenoid valve. The actuator includes a secondary tank designed to contain such predetermined volume of compressed air. The secondary tank is placed in communication with the main tank through a narrow duct having a through-flow section much smaller than that of the outlet of the solenoid valve.

Claims

1. A pneumatic actuator comprising: a compressed air tank designed to contain a first predetermined volume of compressed air; a pilot operated valve comprising an inlet connected to a compressed air secondary tank, an outlet for compressed air, and a shutter between said inlet and said outlet; said compressed air secondary tank designed to contain a second predetermined volume of compressed air which has a lower volume than said first predetermined volume of compressed air and placed in communication with said compressed air tank through a narrow duct having a through-flow section smaller than said inlet; said pilot operated valve configured to dispense second predetermined volume of compressed air from said compressed air secondary tank to said outlet when said pilot operated valve is energized; said pilot operated valve configured to open said shutter when said pilot operated valve is energized and eject said second predetermined volume of compressed air contained in said compressed air secondary tank through said outlet; and said pilot operated valve configured to immediately close said shutter before compressed air flow can flow from said compressed air tank to said compressed air secondary tank when said pilot operated valve is de-energised.

2. The pneumatic actuator according to claim 1, wherein said pilot operated valve comprises a main valve which controls the outflow of the compressed air from the compressed air secondary tank, and a pilot solenoid valve for actuating the main valve.

3. The pneumatic actuator according to claim 1, wherein said compressed air tank and said compressed air secondary tank are integrated in a single body.

4. The pneumatic actuator according to claim 1, wherein said outlet is connected to an aerospace release or ejection device.

5. The pneumatic actuator according to claim 4, wherein said through-flow section of said narrow duct has a cross-sectional area about 1/7 of the cross-sectional area of said inlet of said pilot operated valve.

6. The pneumatic actuator according to claim 1, wherein a through-flow section of said narrow duct has a cross-sectional area 1/7 or less than the cross-sectional area of said inlet of said pilot operated valve.

7. The pneumatic actuator according to claim 1, further comprising a spring attached to said shutter, wherein said spring is configured to keep said shutter closed to block an outflow of compressed air from said compressed air secondary tank to said pilot operated valve.

8. The pneumatic actuator according to claim 1, further comprising a spring attached to said shutter, wherein said spring is configured to immediately close said shutter when said pilot operated valve is de-energised.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention will now be described in detail with reference to the attached drawings, provided purely by way of non-limiting example, wherein:

(2) FIG. 1 is a schematic perspective view of an embodiment of the pneumatic actuator according to the invention, and

(3) FIG. 2 is a perspective view in longitudinal section and in enlarged scale of a part of FIG. 1.

(4) FIG. 3 is a block diagram view of the outlet of FIG. 1 connected to an aerospace release or ejection device.

DETAILED DESCRIPTION OF THE INVENTION

(5) Initially referring to FIG. 1, a pneumatic actuator according to the invention comprising a generally cylindrical main tank 2, arranged beside which is a secondary tank 3, positioned on which is a pilot operated valve generally indicated with 4, is illustrated with 1.

(6) The main tank 2 and the secondary tank 3 may be conveniently integrated in a single body.

(7) As better observable in FIG. 2, the valve 4 comprises a main pneumatic valve 5 connected to the secondary tank 3, and a pilot solenoid valve 6 connected to the main valve 5 by means of a duct 8. The main valve 5 is designed to place an outlet 14 of the secondary tank 3 in communication with an outlet 13 of the valve.

(8) In a generally conventional manner, the pilot solenoid valve 6 comprises a solenoid actuator 11 which actuates a shutter 16 which controls the opening of the main valve 5.

(9) The main valve 5 comprises an air outflow section 12 including the outlet 13, and a valve section 10 with a shutter 9 normally kept closed by the action of a spring 15 section and which is opened by the pilot operated valve 6 to control the outflow of the compressed air coming from the secondary tank 3, through the outlet 13.

(10) According to the invention, the main tank 2 is placed in communication with the secondary tank 3 through a narrow duct 7 so that the pressurised air contained in the main tank 2 can flow into the secondary tank 3 as explained hereinafter.

(11) The through-flow section of the duct 7 is considerably smaller than that of the outlet 13: in the embodiment of the invention shown in the figures, such narrow duct 7 has a section that is about 1/7 with respect to that of the air outlet 13, but narrow ducts with smaller or larger narrow sections, depending on the pressures and the compressed air flow rates used by the actuator 1, may be used.

(12) The actuator 1 according to the invention operates as follows.

(13) In the de-energised condition of the solenoid 11, the shutter 9 of the main valve 5 is kept closed by the spring 15 and by the pressure contained in the tank, blocking the outflow of air from the tank 3.

(14) When the solenoid 11 is energised, the pilot operated valve 6 opens the shutter 10 by means of a pneumatic pulse in the duct 8, placing the secondary tank 3 in communication with the outlet 13. In this manner, the predetermined volume of compressed air contained in the secondary tank 3 flows from the outlet 13, actuating, for example, a secondary actuator not shown because it is within the reach of a person skilled in the art. This actuator may consist, for example, of a release or ejection device 113 in the aerospace industry.

(15) After the predetermined volume of compressed air contained in the secondary tank 3 has been ejected, the pilot operated valve 6 is de-energised and the shutter 9 immediately returns to the closed position thanks to the action of a spring 15, and only subsequently does the air contained in the main tank 2 fill the secondary tank 3 again, restoring balance in the pressures between the tanks 2, 3.

(16) It is therefore clear that, if the through-flow section of the narrow duct 7 is sufficiently smaller than that of the outflow of compressed air 13, the air does not have time to flow from the main tank 2 to the secondary tank 3 before the valve 5 closes. In the instants subsequent to the closing of the valve 5, the air flows from the main tank 2 to the secondary tank 3 and the actuator 1 is ready for the subsequent actuation.

(17) Obviously, the construction details and the embodiments may widely vary with respect to what has been described and illustrated, without departing from the scope of protection of the present invention as defined in the claims that follow. Thus, for example, the general conformation of tanks 2, 3 could be different from the one represented in the drawings.