Valve devices for use in sorting apparatus ejectors

• US 5,628,411 A
• Filed: 12/01/1994
• Issued: 05/13/1997
• Est. Priority Date: 12/01/1994
• Status: Expired due to Term

• Current Assignee: Buhler Sortex Ltd. (Buhler Holding AG)
• Original Assignee: Sortex Ltd. (Buhler Holding AG)
• Inventors: Henderson, Kenneth C., Mills, Stewart J.
• Primary Examiner(s): Terrell, William E.
• Assistant Examiner(s): Nguyen, Tuan
• Application Number:
  US08/347,957
• Time in Patent Office: 894 Days
• Field of Search: 209/638, 209/639, 209/644, 251/24, 251/129.01, 251/129.03, 251/129.05, 251/129.06, 251/368
• US Class Current: 209/644
• CPC Class Codes: B07C 5/3425 of granular material, e.g. ore particles, grain investigation moving fluids or granular solids using optical means G01N21/85
• CPC Class Codes: B07C 5/366 during free fall of the articles
• CPC Class Codes: F16K 11/022 comprising a deformable member
• CPC Class Codes: F16K 31/005 Piezoelectric benders
• CPC Class Codes: F16K 7/12 with flat, dished, or bowl-shaped diaphragm

Abstract

A valve device is disclosed for controlling the delivery of gas from a pressurised source suitable for use in a pneumatic ejector in particle sorting apparatus. It uses a diaphragm as a valve member disposed over an output port from a chamber which is in substantially continuous communication with a source of gas or air under pressure. Both sides of the diaphragm are exposed to pressurised gas or air in the chamber. For this reason, and because the diaphragm itself engages the output port to close it, when the input pressure is applied there is a differential pressure which elastically deforms the diaphragm to close the output port. The diaphragm has a piezoelectric element, and the valve device includes an electric circuit operable to selectively activate the piezoelectric element and withdraw the valve member from the output port to admit pressurised gas or air thereinto.

Claims

1. A pneumatic ejector for sorting apparatus in which material to be sorted is directed in a stream following an aerial path, and rejected material is removed from the stream by air pulses from such ejectors, which ejector has a housing defining a pressure chamber;

a diaphragm mounted in the housing and comprising a piezoelectric element;

an input for connection to a source of pressurised gas, which input communicates with the chamber on both sides of the diaphragm; and

an output port connecting the chamber on one side of the diaphragm to a delivery duct terminating in an ejector nozzle, an area of the diaphragm being disposed in juxtaposition with the output port and the diaphragm being elastically deformable by differential input gas pressure over said area thereof such that said area closes the output port with said differential pressure balanced by elastic forces in the diaphragm such that the exerting pressure between the diaphragm and the periphery of the output port is substantially zero, the ejector including an electric circuit selectively operable to activate the piezoelectric element to withdraw said area of the diaphragm from the output port to the admit gas from the pressure chamber to the output port, and thence to the ejector nozzle.

2. A pneumatic ejector according to claim 1 wherein the housing is formed with a bleed duct from the chamber permitting a steady flow of gas through the chamber for controlling the temperature thereof.

3. A pneumatic ejector according to claim 2 including a valve in the bleed duct for controlling the flow of gas therethrough.

4. A pneumatic ejector according to claim 1 wherein the pressure chamber has the shape of a cylinder with said diaphragm traversing the axis thereof and the output port substantially on said axis, and wherein the input is disposed on the periphery of the cylinder.

5. A pneumatic ejector according to claim 1 wherein the output port is mounted on a resiliently flexible section of the housing.

6. A pneumatic ejector according to claim 1 wherein the position of the output port in the housing is adjustable to establish an engagement pressure between the diaphragm and the periphery of the output port in the closed position of substantially zero under a given input pressure.

7. A pneumatic ejector according to claim 1 wherein a piezoelectric portion of said diaphragm is in juxtaposition to the output port.

8. A pneumatic ejector according to claim 1 wherein the housing is formed with a stop behind said diaphragm for limiting the extent of its withdrawal from the output port in response to activation of the piezoelectric element.

9. A pneumatic ejector according to claim 1 wherein the pressure chamber has the shape of a cylinder with said diaphragm traversing the axis thereof and the output port substantially on said axis, the diaphragm dividing the pressure chamber into discrete sections, and the housing including means communicating the input to both sections.

10. A pneumatic ejector according to claim 1 including an electronic damping circuit for the piezoelectric element.

11. A pneumatic ejector unit for sorting apparatus in which material to be sorted is directed in a stream following an aerial path, and rejected material is removed from the stream by air pulses from such ejectors, which ejector has a housing defining a pressure chamber with a plurality of output ports each connected to an ejector nozzle;

a diaphragm disposed in juxtaposition with each output port and comprising a piezoelectric element; and

an input for connection to a source of pressurised gas, which input communicates with the chamber on both sides of the diaphragm, wherein an area of each diaphragm is disposed in juxtaposition with its respective output port and each diaphragm is elastically deformable by differential input gas pressure over said area thereof such that said area closes the respective output port with said differential pressure balanced by elastic forces in the diaphragm such that the exerting pressure between the diaphragm and the periphery of the output port is substantially zero, the ejector unit including an electric circuit selectively operable to activate the piezoelectric elements to withdraw the diaphragms from the output port to admit gas from the pressure chamber to the ejector nozzles.

12. A pneumatic ejector unit according to claim 11 wherein the housing is formed with a bleed duct from the chamber permitting a steady flow of gas through the chamber for controlling the temperature thereof.

13. A pneumatic ejector unit according to claim 11 having two output ports each in a discrete region of the pressure chamber with the sides of the diaphragms facing their respective output ports and the said regions and the regions between the diaphragms being in communication with the input.

14. A pneumatic ejector unit according to claim 13 wherein the diaphragms define a central chamber region with output port regions on either side thereof.

15. A pneumatic ejector according to claim 14 including a stop disposed in the central region for limiting the extent of withdrawal of each diaphragm from its adjacent output port in response to activation of the respective piezoelectric element.

16. A pneumatic ejector according to claim 15 wherein the pressure chamber is substantially cylindrical with the output ports and the stop substantially aligned on the axis thereof.

17. A pneumatic ejector according to claim 13 further having a plurality of ejectors arranged side by side in an array with space therebetween.

18. A pneumatic ejector according to claim 11 wherein the position of each output port in the housing is adjustable to establish an engagement pressure between the diaphragm and the periphery of the output port in the closed position of substantially zero under a given input pressure.

19. A pneumatic ejector according to claim 11 including an electronic damping circuit for the piezoelectric element.

20. A pneumatic ejector for sorting apparatus in which material to be sorted is directed in a stream following an aerial path, and rejected material is removed from the stream by air pulses from such ejectors, which ejector has a housing comprising a central section and two side sections, each side section having a respective output port formed therein, and being attached to the central section by an adjustable mounting mechanism, the housing defining a pressure chamber;

a diaphragm mounted in the housing and comprising a piezoelectric element;

an input for connection to a source of pressurised gas, which input communicates with the chamber on both sides of the diaphragm; and

an output port connecting the chamber on one side of the diaphragm to a delivery duct terminating in an ejector nozzle, an area of the diaphragm being disposed in juxtaposition with the output port and the diaphragm being elastically deformable by differential input gas pressure over said area thereof such that said area closes the output port, whereby the closure pressure between an output port and a respective diaphragm is altered by adjustment of said mounting mechanism, the valve device including an electric circuit selectively operable to activate the piezoelectric element to withdraw said area of the diaphragm from the output port to the admit gas from the pressure chamber to the output port, and thence to the ejector nozzle.