Purge air system for a combustion instrument
AssigneeRosemont Inc.
InventorsDouglas C. Myhre, David Y. H. Pui, Larry V. Miller
Life of this patent
Estimating the term…
Abstract
A radiation instrument has a purging air flow system for passing air over the lens to keep it clean and free from particulate contaminants and also for providing a positive flow of air away from the lens. The air supply used for such purging is controlled adequately so the flow changes direction and particles are removed from the main flow of purge air by inertial separation prior to the time the air contacts the lens. Such air entrained particles might otherwise deposit on the lens. A flow control orifice provides a secondary flow to carry the particles separated from the main flow out of the flow passageway.
Claims16
An instrument for sensing radiation representative of a parameter in a contaminating suspension and for providing an output indicative of the parameter, the instrument having a housing receiving a supply of pressurized fluid having particles therein, comprising:
- port means formed in the housing and opening to the parameter source for receiving the radiation;
- sensing means supported relative to the housing for sensing the received radiation through the port means and for providing the output;
- lens means supported relative to the housing between the port means and the sensing means for transmitting the radiation therethrough and for shielding the sensing means from the contaminating suspension, the lens means having a lens surface on an opposite side of the lens means from the sensing means which is exposed to the suspension;
- and
- purge means disposed in the housing for maintaining the radiation transmission of the lens means comprising means for establishing a flow path for the pressurized fluid relative to the housing, the means for establishing including means for inertially separating a substantial portion of the particles capable of affecting the radiation transmission from a first portion of the pressurized fluid and for directing such first portion of the pressurized fluid onto the lens surface such that particles from the contaminated suspension are removed from the lens surface by the first portion of the pressurized fluid.
An instrument of the type having a housing with a sensing end, comprising a radiation transmitting surface and wherein said end is directed toward and faces a member, the temperature of which is to be detected, including:
- a tube surrounding the sensing end of said instrument, and defining a first passage for air flow, said tube having an axis extending beyond said radiation transmitting surface in direction toward the member, the temperature of which is to be sensed;
- second means defining a second passageway aligning with the first passageway and within a portion of said tube, and said second means defining, in cooperation with the tube, a third flow passageway surrounding said second means, the second passageway opening to the first passageway and providing a radiation passage from the source of radiation to the radiation transmitting surface;
- and
- said second means including a portion providing fluid flow control, including fluid inlet means to said second passageway adjacent said radiation transmitting surface, the fluid inlet means being positioned to cause a change in direction of fluid flowing from said third passageway to said second passageway such that particles are inertially separated from the air flow, flow from the inlet means flowing across said radiation transmitting surface as the flow enters the second passageway, said second means defining a second constricted outlet from said third passageway to the first passageway spaced from said radiation transmitting surface and controlling fluid flow from said third passageway so that a substantial portion of flow in the third passageway goes through the fluid inlet means and across said radiation transmitting surface such that particles are removed from the radiation transmitting surface, but a second portion of such flow in the third passageway goes through the second constricted outlet.
In an instrument of the type having a housing with a lens, wherein said lens is directed toward and faces a contaminating suspension for detection of temperature of a member, the improvement comprising:
- a first tube extending beyond said lens in direction toward a member which is being sensed;
- a second tube substantially concentric with said first tube and within said first tube, the second tube being shorter than the first tube, the interior of the second tube and a portion of the first tube forming a first passageway, and the space between an outer surface of the second tube and the inner surface of the first tube forming a second passageway;
- and
- said second tube further providing fluid flow control including fluid inlet means leading from said second passageway to said first passageway adjacent said lens positioned to cause a change in direction of fluid flowing from said second passageway to said first passageway and direct such flow across said lens such that particles are removed from the lens surface, and to define a second restricted outlet orifice from said second passageway to the first passageway spaced downstream from said lens in direction toward said source, said second restricted outlet controlling fluid flow from said second passageway so that a substantial portion of the flow in the second passageway flows through the fluid inlet means and across said lens and a second portion of flow goes through the restricted outlet.
Dependencies are inferred from the claim text.