Low-Cost High-Purity Vacuum Pumps and Systems

Patent metadata

Field	Value
Publication number	US-2023114036-A1
Application number	US-202117802722-A
Country	US
Kind code	A1
Filing date	Mar 1, 2021
Priority date	Feb 28, 2020
Publication date	Apr 13, 2023
Grant date	—

Abstract

Disclosed is a pumping system with reduced contamination. A vacuum pump system includes a mechanical vacuum pump mechanism within a hermetic pump that hermetically isolates the pump mechanism from ambient air. A pump inlet is hermetically sealed to the hermetic pump housing. A pump outlet is hermetically sealed at one end to the hermetic pump housing and at the other end to an inlet of a Peclet seal tube. The vacuum pump system produces a vacuum in a vacuum processing chamber. A sweep gas source injects a sweep gas into at least one of (i) the hermetic pump housing and (ii) the inlet of the Peclet seal tube. The sweep gas and a process gas flow through the Peclet seal tube to substantially isolate against the backflow of the ambient air through the Peclet seal tube.

First claim

What is claimed:

1 . A pumping system with reduced contamination, comprising:
a vacuum pump system including a mechanical vacuum pump mechanism within a hermetic pump housing configured to hermetically isolate the mechanical vacuum pump mechanism from ambient air outside the hermetic pump housing; a pump inlet hermetically sealed to the hermetic pump housing and configured to serve as an inlet path to the vacuum pump mechanism; a pump outlet hermetically sealed to the hermetic pump housing and configured to serve as an outlet path from the mechanical pump mechanism; wherein the vacuum pump system is configured to produce a vacuum in a vacuum processing chamber; wherein the pump outlet is hermetically sealed to an inlet of a Peclet seal tube; and at least one of: (1) a sweep gas source configured to inject a sweep gas into at least one of (i) the hermetic pump housing and (ii) the inlet of the Peclet seal tube; and (2) a process gas source configured to inject a process gas into the vacuum processing chamber; such that at least one of the sweep gas and a process gas flow through the Peclet seal tube from the inlet of the Peclet seal tube towards an outlet of the Peclet seal tube to substantially isolate against the backflow of the ambient air through the Peclet seal tube.

2 . The pumping system of claim 1 wherein the sweep gas includes at least one of argon, nitrogen and a combination of nitrogen and hydrogen.

3 . The pumping system of claim 1 wherein the gas source is configured to inject at least a portion of the sweep gas directly into the hermetic pump housing.

4 . The pumping system of claim 1 wherein at least a portion of the process gas is injected into the vacuum processing chamber and flows into the vacuum pump system through the pump inlet.

5 . The pumping system of claim 1 wherein the gas source is configured to inject at least a portion of the sweep gas into the inlet of the Peclet seal tube.

6 . The pumping system of claim 1 wherein the vacuum pump system includes a ballast volume arranged in gaseous communication with the inlet of the Peclet seal tube such that the ballast volume can reduce pressure fluctuations caused by pump ripple.

7 . The pumping system of claim 1 wherein the mechanical vacuum pump mechanism is a displacement pump and wherein a motor outside the hermetic pump housing is coupled to the displacement pump inside the hermetic pump housing via a hermetic rotary coupler.

8 . The pump system of claim 7 wherein the hermetic rotary coupler is a magnetic hermetic rotary coupler.

9 . The pumping system of claim 1 wherein the vacuum pump system has a base pressure selected from the group consisting of 0.001 Torr to 1 Torr, 1-10 Torr, 10-100 Tor, 100-300 Torr and 300-750 Torr.

10 . The pumping system of claim 1 wherein the Peclet seal tube is a metal Peclet seal tube.

11 . The pumping system of claim 1 wherein the outlet of the Peclet seal tube includes a valve configured to seal the Peclet seal tube from the ambient air at times when the sweep gas input is not flowing.

12 . The pumping system of claim 1 wherein the mechanical vacuum pump mechanism is a displacement pump selected form the group consisting of a piston pump, a diaphragm pump and a scroll pump.

13 . The pumping system of claim 1 further comprising:
a first stage vacuum pump disposed between the chamber and the mechanical vacuum pump mechanism such that an inlet of the first stage pump provides vacuum withing the vacuum processing chamber and the mechanical vacuum pump mechanism is configured to pump on an outlet of the first stage vacuum pump.

14 . The pumping system of claim 13 wherein the first stage vacuum pump is a turbomolecular pump having an oxygen compression ratio selected from the group consisting of less than 1E6, less than 1E5, less than 1E4 and less than 1E3.

15 . A furnace system for powder metallurgy with reduced contamination, comprising:
a vacuum processing chamber configured to perform a debinding cycle at a debinding temperature sufficient to debind at least one part such that debinding by-products are off-gassed from the least one part, wherein the debinding cycle can be followed by a sintering cycle at a sintering temperature that is higher than the debinding temperature, the vacuum processing chamber having a pumping tube having an inlet end that is sealed to the vacuum processing chamber and an outlet end that is separated from the vacuum processing chamber by the pumping tube; a heating system including at least one heater configured to heat the pumping tube at least during the debinding cycle to at least a temperature sufficient to reduce condensation of contaminants within the pumping tube, including the debinding by-products outgassed from the vacuum processing chamber during the debinding cycle, to a predetermined threshold; a pumping system sealed to the outlet end of the pumping tube and configured to produce a vacuum in the vacuum processing chamber; and a process gas source configured to inject a sweep gas into the vacuum processing chamber at least during the sintering cycle such that the pumping tube provides an amount of Peclet sealing during sintering.

16 . The furnace system of claim 15 wherein the vacuum is greater than 10 Torr and the pumping tube has a diameter selected from the group consisting of less than ¼″, less than ½″ and less than 1″.

17 . The furnace system of claim 16 wherein the sweep gas flow is injected at a rate selected from the group consisting of 0.1 slm to 1 slm, 1 slm to 10 slm and greater than 10 slm.

18 . The furnace system of claim 15 wherein pumping system includes:
a vacuum pump system including a mechanical vacuum pump mechanism within a hermetic pump housing configured to hermetically isolate the mechanical vacuum pump mechanism from ambient air outside the hermetic pump housing;
a pump inlet hermetically sealed to the hermetic pump housing and configured to serve as an inlet path to the vacuum pump mechanism;
a pump outlet hermetically sealed to the hermetic pump housing and configured to serve as an outlet path from the mechanical pump mechanism;
wherein the vacuum pump system is configured to produce a vacuum in a vacuum processing chamber;
wherein the pump outlet is hermetically sealed to an inlet of a Peclet seal tube; and
a sweep gas source configured to inject a sweep gas into at least one of (i) the hermetic pump housing and (ii) the inlet of the Peclet seal tube and such that the sweep gas and a process gas flow through the Peclet seal tube from the inlet of the Peclet seal tube towards an outlet of the Peclet seal tube to substantially isolate against the backflow of the ambient air through the Peclet seal tube.

19 . The furnace system of claim 15 further comprising:
a first stage vacuum pump disposed between the chamber and the mechanical vacuum pump mechanism such that an inlet of the first stage pump provides vacuum withing the vacuum processing chamber and the mechanical vacuum pump mechanism is configured to pump on an outlet of the first stage vacuum pump.

20 . The pumping system of claim 19 wherein the first stage vacuum pump is a turbomolecular pump having an oxygen compression ratio selected from the group consisting of less than 1E6, less than 1E5, less than 1E4 and less than 1E3.

21 . The furnace system of claim 15 wherein the chamber is extended by way of a chamber extension having a cross sectional area substantially the same as a cross sectional area

Assignees

• Desktop Metal Inc

Inventors

• Woodard Nathan

Classifications

• F27B2005/163

  Controlled openings, e.g. orientable · CPC title

• F27B5/04 Primary

  adapted for treating the charge in vacuum or special atmosphere · CPC title

• F27B2005/161

  Gas inflow or outflow · CPC title

• B22F2999/00

  Aspects linked to processes or compositions used in powder metallurgy · CPC title

• F27B5/16 Primary

  Arrangements of air or gas supply devices · CPC title