Thermocouple with out-of-line aspiration holes
The response time of a thermocouple is improved by offsetting the outlet aspiration opening or openings in the thermocouple protective housing from the gas flow axis and the inlet opening. The outlet aspiration opening is located substantially at the gas separation point which is a point of minimum gas pressure. The degree of offset is thus chosen to maximize the pressure differential, .DELTA.P, between the inlet and the outlet openings. This increases the gas flow rate through the housing and past the thermocouple junction thereby substantially improving the thermocouple response time.
Latest Amespace, Inc. Patents:
Claims
1. A thermocouple assembly for measuring the temperature of a fluid stream comprising:
- (a) a casing,
- (b) at least one pair of dissimilar wires disposed in said casing and forming a thermocouple junction,
- (c) insulation dispersed in said casing and separating said dissimilar wires from said casing and from each other,
- (d) a protective housing spaced apart from and surrounding at least a portion of said casing containing a thermocouple junction,
- (e) means to allow a part of the heated stream to flow through said protective housing and past said casing in the area of the thermocouple junction, including:
- (1) an inlet opening in said housing positioned essentially along the flow axis of the stream,.Iadd.said inlet opening in axial alignment with said thermocouple junction, and.Iaddend.
- (2) at least one outlet opening in said housing downstream from the inlet opening to establish a flow path through said housing,.Iadd.and.Iaddend.
- (f) means for increasing the flow rate of the fluid through said housing by locating the outlet opening at a minimum fluid pressure point, thereby maximizing the pressure difference between inlet and outlet openings to provide rapid response of the thermocouple to changes in fluid stream temperature.
2. The thermocouple assembly according to claim 1 wherein said outlet opening is radially offset from the axis of said inlet opening.
3. The thermocouple according to claim 2 wherein an outlet opening in the housing is located either 75.degree. or 285.degree. from the downstream side of the fluid stream flow axis.
4. The thermocouple according to claim 2 wherein an outlet opening in the housing is located within a band extending either from 45.degree.-85.degree. or 275.degree.-315.degree. from the downstream side of the fluid stream flow axis.
5. The thermocouple according to claim 2 wherein offset outlet openings are located on both sides of said axis.
6. The thermocouple according to claim 5 wherein the offset outlet openings are respectively located 75.degree. and 285.degree. from the downstream side of the fluid stream flow axis.
7. The thermocouple according to claim 5 wherein the offset openings are respectively located within bands extending from 45.degree.-85.degree. and from 275.degree.-315.degree. from the downstream side of the fluid stream flow axis.
8. The thermocouple according to claim 5 wherein the outlet openings are axially offset from the plane of the inlet opening.
9. The thermocouple according to claim 8 wherein the outlet openings are respectively located above and below the plane of the inlet openings.
10. The thermocouple according to claim 6 wherein the outlet openings are axially offset from the plane of the inlet opening.
11. The thermocouple according to claim 6 wherein the outlet openings are respectively located above and below the plane of the inlet opening.
12. The thermocouple according to claim 7 wherein the outlet openings are axially offset from the plane of the inlet opening.
13. The thermocouple according to claim 7 wherein the outlet openings are respectively located above and below the plane of the inlet opening.
14. A thermocouple assembly for measuring the temperature of a gaseous stream including at least one thermocouple junction positioned in a casing surrounded by a protective housing spaced from said casing,
- (a) means to expose the thermocouple junction in said housing to a gaseous stream including an inlet opening and at least one outlet opening in said housing,.Iadd.the inlet opening and thermocouple junction being axially aligned,.Iaddend.
- (b) said outlet opening being.Iadd.radially.Iaddend.offset from the inlet opening, the degree of off-set being chosen to locate the outlet opening in a minimal pressure area on the outside of the housing to maximize the pressure difference across said openings and the gas flow rate through said housing.
3075387 | January 1963 | Rademacher |
3159032 | December 1964 | Rademacher et al. |
3284246 | November 1966 | Macatician |
3451862 | June 1969 | Burgess, Jr. et al. |
3459598 | August 1969 | Cole et al. |
4131756 | December 26, 1978 | Smith |
4132114 | January 2, 1979 | Shah et al. |
4162929 | July 31, 1979 | Finney |
4244222 | January 13, 1981 | Hoyer et al. |
4485263 | November 27, 1984 | Itoyama et al. |
1084989 | September 1967 | GBX |
- Distribution of Local Pressure and Skin Friction Around a Circular Cylinder in Cross-Flow Up to Re=5.times.10.sup.6 by E. Achenbach, Journal of Fluid Mechanics, pp. 625-639, Apr. 1969.
Type: Grant
Filed: Dec 22, 1994
Date of Patent: Dec 2, 1997
Assignee: Amespace, Inc. (Wilmington, DE)
Inventor: Robert A. Pustell (Andover, MA)
Primary Examiner: Charles T. Jordan
Assistant Examiner: Chrisman D. Carroll
Law Firm: Ratner & Prestia
Application Number: 8/361,574
International Classification: H01L 3502;