|Publication number||USRE38686 E1|
|Application number||US 10/057,218|
|Publication date||Jan 11, 2005|
|Filing date||Jan 24, 2002|
|Priority date||Oct 6, 1997|
|Publication number||057218, 10057218, US RE38686 E1, US RE38686E1, US-E1-RE38686, USRE38686 E1, USRE38686E1|
|Inventors||Norton M. Loblick|
|Original Assignee||Star Envirotech, Inc.|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (7), Referenced by (5), Classifications (4), Legal Events (2)|
|External Links: USPTO, USPTO Assignment, Espacenet|
The present invention relates to a smoke generating apparatus.
U.S. Pat. No. 5,107,698 which issued to Gilliam in 1992 discloses a smoke generating apparatus. Smoke generating apparatus, such as those disclosed by Gilliam, are used to test for hairline cracks and similar leaks that are not detectable by visual inspection. The location of the leak is detected by observing smoke exiting from the leak. The Gilliam apparatus has a container in which is disposed a heating element. The container is filled with a smoke producing liquid until the liquid level reaches, without submerging, the heating element. An air pump forces a flow of air to bubble up through the smoke producing liquid, propelling the smoke producing liquid into contact with the heating element. Any of the smoke producing liquid coming in contact with the heating element is vaporized. When the smoke producing liquid is vaporized, it becomes smoke. As the flow of air exits the container it carries the smoke. The flow of air can be directed as required for testing purposes.
The Gilliam apparatus has limitations due to incomplete combustion. Particles of partially burned solution and unburned solution become entrained in the air flow and potentially can temporarily plug the leaks that the apparatus is supposed to be detecting.
What is required is a smoke generating apparatus that has improved combustion.
According to the present invention there is provided a smoke generating apparatus which includes a combustion chamber having an air flow inlet and an air flow outlet. A helical heating element is disposed in the combustion chamber. The helical heating element has a central flow axis. A smoke generating fluid injection tube is positioned along the central flow axis of the helical heating element. Means is provided for conveying smoke generating fluid to the smoke generating fluid injection tube. Means is provided for generating an air flow from the air flow inlet to the air flow outlet.
The smoke generating apparatus, as described above, with co-axial injection into a helical heating element provides more efficient combustion. Smoke generating fluid is injected onto the helical heating element, with the injection preferably angled upwardly toward an upper segment of the helical heating element. Any smoke generating fluid that is not immediately vaporized upon contact with the helical heating element falls by force of gravity onto a lower segment of the heating element. In addition, the helical heating element increases the surface area of heating element to which the smoke generating fluid is exposed. As will be hereinafter further described, it is preferred that the outer contact surface of the heating element be insulated, so that there is no direct contact between the smoke generating fluid and the current carrying core of the heating element.
Although beneficial results may be obtained through the use of the smoke generating apparatus, as described above, having the smoke generating fluid in the same chamber as the helical heating element unavoidably results in a heat build up which raises the temperature of the smoke generating fluid over time. This can cause operation problems by altering the viscosity of the smoke generating fluid. This can also cause safety concerns as heat builds in the chamber. Fuel to support combustion is present in the form of the smoke generating fluid, as is the oxygen to support combustion in the air flow through the combustion chamber. Another concern is that of fluid levels. The heating element will not work as intended if it is submerged. Care must, therefore, be taken to ensure that the heating element is not submerged as a result of overfilling or movement during use. Even more beneficial results may, therefore, be obtained when the smoke generating fluid is retained in a separate fluid reservoir.
Although beneficial results may be obtained through the use of the smoke generating apparatus, as described above, too much flow can flood the helical heating element. The preferred means for conveying smoke generating fluid from the reservoir to the smoke generating fluid injection tube includes a source of pressurized air, the pressurized air forces the smoke generating fluid along the injection tube to the helical heating element.
Although beneficial results may be obtained through the use of the smoke generating apparatus, as described above, only a small percentage of the smoke generating fluid vaporizes immediately upon contacting the helical heating element. The balance of the smoke generating fluid requires a few seconds to reach vaporizing temperature. It is, therefore, preferred that the means for conveying smoke generating fluid to the smoke generating fluid injection tube includes means for intermittent injection sequencing. This can be done in a number of ways, beneficial effects have been obtained through the use of a timing means to time an on phase and an off phase of an injection cycle.
Although beneficial results may be obtained through the use of the smoke generating apparatus, as described above, more precise control can be obtained over when the means for generating an air flow includes a source of pressurized air, a pressure regulator to limit the pressure in terms of pounds per square inch and a flow control regulator to control the flow to a specified number of litres per minute at a specified pressure.
Although beneficial results may be obtained through the use of the smoke generating apparatus, as described above, to the extent that there is incomplete combustion, it is preferred measures be taken to limit the products of incomplete combustion exiting the combustion chamber in the smoke. Even more beneficial effects may, therefore, be obtained when an outlet tube and an inlet tube are provided. The outlet tube extends from the air flow outlet into the combustion chamber terminating in a smoke receiving end. The inlet tube extends from the air flow inlet into the combustion chamber terminating in an air discharge end. The inlet tube has an inner diameter that is smaller than the inner diameter of the outlet tube. The inlet tube and the outlet tube are co-axially aligned. The positioning of the air discharge end of the inlet tube and the smoke receiving end of the outlet tube is configured to create a venturi effect to draw smoke from the combustion chamber. The only point of entry into the outlet tube is by means of the venturi. Products of incomplete combustion, therefore, tend to fall to the bottom of the combustion chamber after encountering the exterior of the outlet tube or the inlet tube.
Although beneficial results may be obtained through the use of the smoke generating apparatus, as described above, the majority of units tested do not leak. Even more beneficial results may, therefore, be provided when three operating modes are provided. A first operating mode provides power only to the means for generating an air flow from the air flow inlet to the air flow outlet and includes means for measuring pressure loss. This enables the unit to be tested for leaks without generating smoke. If the unit leaks there will be a pressure loss. It is only when a pressure loss is noted indicating the presence of a leak, that smoke need be used to locate the leak. A second operating mode provides power to the helical heating element to preheat said helical heating element. Of course, the smoke generating fluid will only turn to smoke when subjected to heat. If smoke generating fluid is being pumped into the combustion chamber onto a helical heating element that has not, as yet, reached its vaporizing temperature, injected fluid could eventually submerge the heating element rendering the unit non-functional. A third operating mode provides power to all systems to heat the helical heating element, inject smoke generating fluid by means of pressurized air onto the helical heating element and create an air flow of pressurized air to draw smoke out the outlet of the combustion chamber.
Although beneficial results may be obtained through the use of the smoke generating apparatus, as described above, there remains a safety hazard should a short occur. Even more beneficial results may, therefore, be obtained when the helical heating element is insulated. When helical heating element is insulated it will not short out. When helical heating element is insulated a larger diameter wire may be used and the surface area exposure of the smoke generating fluid to heat is further increased.
These and other features of the invention will become more apparent from the following description in which reference is made to the appended drawings, wherein:
The preferred embodiment, a smoke generating apparatus generally identified by reference numeral 10, will now be described with reference to
The use and operation of smoke generating apparatus 10 will now be described with reference to
In the illustrated embodiment, the solenoid actuated valve 34, in conjunction with the timer 36, regulates the impulse rate of pressurized air into the reservoir 12. The advantage of this configuration is generally one of physical space requirements. The disadvantage is that the inherent compressibility of air under pressure makes it somewhat more difficult to accurately regulate the fluid flow from the reservoir. It will be apparent to one skilled in the art that the solenoid valve could alternatively be positioned on the connecting flow conduit. This alternative, while preferable from a fluid regulation standpoint, has limitations due to larger space requirements.
It will be apparent to one skilled in the art that modifications may be made to the illustrated embodiment without departing from the spirit and scope of the invention as hereinafter defined in the Claims.
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|Citing Patent||Filing date||Publication date||Applicant||Title|
|US8307848 *||Nov 13, 2012||Aerocontrolex Group, Inc.||Freeze resistant manifold assembly and system|
|US8827208 *||Sep 12, 2008||Sep 9, 2014||Airbus||Smoke generation device for aircraft and aircraft fitted with such a device|
|US20090072095 *||Sep 12, 2008||Mar 19, 2009||Airbus||Smoke generation device for aircraft and aircraft fitted with such a device|
|US20100310733 *||Nov 25, 2008||Dec 9, 2010||Steve Hoffman||Pressurized cooking oven|
|US20100313966 *||Jun 12, 2009||Dec 16, 2010||AeroControlex Group,Inc.||Freeze Resistant Manifold Assembly and System|
|Jul 10, 2007||FPAY||Fee payment|
Year of fee payment: 8
|Jul 7, 2011||FPAY||Fee payment|
Year of fee payment: 12