US5545073A — Silicon micromachined CO2 cleaning nozzle and met…

Claim 1

Independent Claim 177 words

An apparatus for cleaning a workpiece with abrasive CO 2 snow, comprising a nozzle for creating and expelling the snow, including; an upstream section for receiving CO 2 gas at a first pressure, said upstream section having a first contour optimized for subsonic flow of the CO 2 gas at said first pressure, a downstream section for directing the flow of the CO 2 gas and the snow toward the workpiece, said downstream section having a second contour optimized for supersonic flow of the CO 2 gas at a second pressure, and throat means, coupled to and for cooperating with said upstream and downstream sections, for changing the CO 2 gas from the gaseous phase generally along a constant entropy line at least partially into snow within said downstream section at a speed of at least Mach 1.1, whereby increased kinetic energy is imparted to the abrasive snow particles by delaying the conversion of the CO 2 gas into the solid phase until the gaseous CO 2 reaches supersonic speeds in said downstream section of said nozzle.

Claim 2

Independent Claim 177 words

An apparatus for cleaning a workpiece with abrasive CO 2 snow, comprising a nozzle for creating and expelling the snow, including; an upstream section for receiving CO 2 gas at a first pressure, said upstream section having a first contour optimized for subsonic flow of the CO 2 gas at said first pressure, a downstream section for directing the flow of the CO 2 gas and the snow toward the workpiece, said downstream section having a second contour optimized for supersonic flow of the CO 2 gas at a second pressure, and throat means, coupled to and for cooperating with said upstream and downstream sections, for changing the CO 2 gas from the gaseous phase generally along a constant entropy line at least partially into snow within said downstream section at a speed of at least Mach 1.1, whereby increased kinetic energy is imparted to the abrasive snow particles by delaying the conversion of the CO 2 gas into the solid phase until the gaseous CO 2 reaches supersonic speeds in said downstream section of said nozzle.

Claim 3

Dependent Claim 28 words

The apparatus as described in claim 1 wherein said second contour is optimized for minimizing turbulence and focusing the flow of the snow as it exits the nozzle.

Claim 4

Dependent Claim 43 words

The apparatus as described in claim 1 wherein said second contour is shaped to achieve a parallel flow of the CO 2 gas and snow exiting said downstream section, thereby focusing the snow in a small footprint for abrasive application to the workpiece.

Claim 5

Dependent Claim 21 words

The apparatus as described in claim 1 wherein said throat, upstream and downstream sections of said nozzle comprise silicon micromachined surfaces.

Claim 6

Dependent Claim 19 words

The apparatus as described in claim 1 wherein the cross-section of said throat section is generally rectangular in shape.

Claim 7

Dependent Claim 24 words

The apparatus as described in claim 1 wherein the speed of the CO 2 gas in said downstream section is at least Mach 2.0.

Claim 8

Dependent Claim 20 words

The apparatus as described in claim 1 wherein said first pressure is in the range of 100 to 800 psi.

Claim 9

Dependent Claim 23 words

The apparatus as described in claim 1 wherein a contour of said throat section accelerates the CO 2 gas as it passes therethrough.

Claim 10

Dependent Claim 51 words

The apparatus as described in claim 1 wherein said throat and downstream sections of said nozzle are formed by surfaces of a silicon material for controlling the footprint of the exhausted CO 2 gas and snow and for minimizing the resulting electrostatic charge of the exhausted CO 2 gas and snow.

Claim 11

Dependent Claim 36 words

The apparatus as described in claim 1 wherein said throat and downstream sections of said nozzle produce a mix of exhausted CO 2 gas and snow in the approximate ratio of 5 to 1 by mass.

Claim 12

Independent Claim 157 words

A method for cleaning a workpiece with abrasive CO 2 snow, comprising: receiving CO 2 in a gaseous form in an upstream section of a nozzle having a first contour shaped for subsonic flow of the CO 2 gas, passing the CO 2 gas through a throat section of the nozzle shaped for delaying the phase change of the CO 2 from the gaseous phase along a constant entropy line into a mixture of CO 2 gas and snow within a downstream section spaced from the throat section, passing the CO 2 gas through the downstream section of the nozzle having a second contour for directing the flow of the CO 2 gas and snow toward the workpiece at a speed greater than Mach 1.1, whereby increased kinetic energy is imparted to the snow by delaying the conversion into the solid phase until the gaseous CO 2 reaches supersonic speeds in the downstream section of the nozzle.

Claim 13

Independent Claim 157 words

A method for cleaning a workpiece with abrasive CO 2 snow, comprising: receiving CO 2 in a gaseous form in an upstream section of a nozzle having a first contour shaped for subsonic flow of the CO 2 gas, passing the CO 2 gas through a throat section of the nozzle shaped for delaying the phase change of the CO 2 from the gaseous phase along a constant entropy line into a mixture of CO 2 gas and snow within a downstream section spaced from the throat section, passing the CO 2 gas through the downstream section of the nozzle having a second contour for directing the flow of the CO 2 gas and snow toward the workpiece at a speed greater than Mach 1.1, whereby increased kinetic energy is imparted to the snow by delaying the conversion into the solid phase until the gaseous CO 2 reaches supersonic speeds in the downstream section of the nozzle.

Claim 14

Dependent Claim 45 words

The method as described in claim 11 further including the step of minimizing boundary layer buildup through the throat and downstream sections of the nozzle as the CO 2 passes therethrough, thereby minimizing turbulence in the flow of the snow as it exits the nozzle.

Claim 15

Dependent Claim 41 words

The method as described in claim 11 further including the step of creating a generally parallel flow of CO 2 gas and snow exiting the downstream section, thereby focusing the snow into a small footprint for abrasive application to the workpiece.

Claim 16

Dependent Claim 29 words

The method as described in claim 11 further including the step of accelerating the CO 2 gas to a speed of at least Mach 2.0 in the downstream section.

Claim 17

Dependent Claim 25 words

The method as described in claim 11 further including the step of accelerating the CO 2 gas as it passes out of the throat section.

Claim 18

Dependent Claim 52 words

The method as described in claim 11 further including the step of focusing the flow of the CO 2 gas and the snow flowing through the downstream section of the nozzle for controlling the shape of the abrasive footprint generated by the exhausted CO 2 gas and snow acting on the workpiece.

Claim 19

Dependent Claim 32 words

The method as described in claim 11 further including the step of generating a mix of exhausted CO 2 gas and snow in the approximate ratio of 5 to 1 by mass.

Claim 20

Independent Claim 161 words

A method for ablating a workpiece with abrasive CO 2 snow, comprising: receiving CO 2 in a gaseous form in an upstream section of a nozzle having a first contour shaped for subsonic flow of the CO 2 gas, passing the CO 2 gas through a throat section of the nozzle shaped for delaying the phase change of the CO 2 from the gaseous phase along a constant entropy line into a mixture of CO 2 gas and snow within a downstream section spaced from the throat section, passing the CO 2 gas and snow through the downstream section of the nozzle having a second contour shaped for directing the flow of the CO 2 gas and the snow toward the workpiece at a speed greater than Mach 1.1, whereby increased kinetic energy is imparted to the snow by delaying the conversion into the solid phase until the gaseous CO 2 reaches supersonic speeds in the downstream section of the nozzle.

Claim 21

Independent Claim 161 words

A method for ablating a workpiece with abrasive CO 2 snow, comprising: receiving CO 2 in a gaseous form in an upstream section of a nozzle having a first contour shaped for subsonic flow of the CO 2 gas, passing the CO 2 gas through a throat section of the nozzle shaped for delaying the phase change of the CO 2 from the gaseous phase along a constant entropy line into a mixture of CO 2 gas and snow within a downstream section spaced from the throat section, passing the CO 2 gas and snow through the downstream section of the nozzle having a second contour shaped for directing the flow of the CO 2 gas and the snow toward the workpiece at a speed greater than Mach 1.1, whereby increased kinetic energy is imparted to the snow by delaying the conversion into the solid phase until the gaseous CO 2 reaches supersonic speeds in the downstream section of the nozzle.

Claim 22

Dependent Claim 48 words

The method as described in claim 18 further including the step of accelerating the CO 2 gas to a speed of at least Mach 2.0 in the downstream section of the nozzle before the CO 2 gas is converted into a mixture of CO 2 snow and gas.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1999-08-13	2000-02-12	2000-08-13	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	2003-08-13	2004-02-12	2004-08-13	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	2007-08-13	2008-02-12	2008-08-13	$7700.00	Window Closed / Lapsed

Silicon micromachined CO2 cleaning nozzle and method

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