CA2118863A1 - Temperature sensor - Google Patents

Temperature sensor

Info

Publication number
CA2118863A1
CA2118863A1 CA002118863A CA2118863A CA2118863A1 CA 2118863 A1 CA2118863 A1 CA 2118863A1 CA 002118863 A CA002118863 A CA 002118863A CA 2118863 A CA2118863 A CA 2118863A CA 2118863 A1 CA2118863 A1 CA 2118863A1
Authority
CA
Canada
Prior art keywords
thermistor
terminals
sensor
distal end
probe
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Abandoned
Application number
CA002118863A
Other languages
French (fr)
Inventor
John R. Hart
Lowell F. Kline
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Emerson Electric Co
Original Assignee
Therm O Disc Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Therm O Disc Inc filed Critical Therm O Disc Inc
Publication of CA2118863A1 publication Critical patent/CA2118863A1/en
Abandoned legal-status Critical Current

Links

Classifications

    • GPHYSICS
    • G01MEASURING; TESTING
    • G01KMEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
    • G01K7/00Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements
    • G01K7/16Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements using resistive elements
    • G01K7/22Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements using resistive elements the element being a non-linear resistance, e.g. thermistor
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01KMEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
    • G01K7/00Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements
    • G01K7/16Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements using resistive elements

Abstract

TEMPERATURE SENSOR

ABSTRACT OF THE DISCLOSURE

A thermistor positioned within a tubular probe adjacent its closed distal end has lead wires connected with terminals by both crimp and weld connections that are independent of one another. A
non-rigid heat transfer medium fills the distal end portion of the probe in surrounding relationship to the thermistor. An opening in the sensor housing leads to the interior of the probe and receives a dielectric sleeve in which tail end portions of the terminals are positioned.

Description

211~863 Background of the Invention This application relates to the art of sensors and, more particularly, to sensors of the type having a thermistor positioned within a tubular ~ ;~
probe. The invention is particularly applicable to ~-temperature sensors for sensing the temperature of a 10 fluid and will be described with specific reference ~ ~ -thereto. However, it will be appreciated that the invention has broader aspects and can be used for other purposes such as sensing liquid levels by supplying sufficient current to the thermistor to cause self-heating.
Temperature sensors commonly include a thermistor positioned within a tubular probe. It is common to pot the thermistor in a rigid heat transfer medium such as epoxy. Damage to the thermistor, and to the lead wires and their connections to plug-in terminals, may occur due to thermal expansion and contraction during use of the device or by curing of the potting medium. It would be desirable to improve the integrity of the connections between the lead wires and the terminals, and to minimize damage or failure caused by expansion and contraction during use of the device.
' .

Summary of the Invention A temperature sensor of the type described has the thermistor lead wires connected to the terminals with both crimp ccnnections and weld 2ll8863 connections. This redundant connection arrangement between the thermistor lead wires and the terminals provides very high reliability of the temperature sensor.
In a preferred arrangement, the crimp connection s located closer to the thermistor than the weld connection.
In accordance with another aspect of the application, a non-rigid heat transfer medium such - -~
as silicon grease completely fills the distal end portion of the probe in surrounding and encapsulating relationship to the thermistor.
The terminals are shaped with grooves and embossed depressions for enhancing the crimp connection to the lead wires. The terminals are also shaped to minimize leakage of air or liquid therepast, and to securely lock same in a molded plastic connector.
An opening in the sensor housing communicates with the interior of the tubular probe.
The opening is enlarged and receives a dielectric sleeve in which the lead wire-to-terminal connections are positioned.
The cylindrical bore in the probe has two different diameters intersecting at a shoulder and the dielectric sleeve has one end abutting the shoulder.
It is principal object of the present invention to provide an improved sensor having redundant connections between terminals and lead wires.
It is also an object of the invention to provide a sensor having improved terminals.

:

~ -It is another object of the invention to provide a sensor with a non-rigid heat transfer medium surrounding the thermistor. : :

Brief Description of the Drawing Figure 1 is a side elevational view showing one side of a temperature sensor constructed in accordance with the present application;
Figure 2 is a side elevational view similar to Figure 1 and showing the opposite side of the temperature sensor;
Figure 3 is a top plan view thereof;
Figure 4 is a cross-sectional elevational view taken generally on line 4-4 of Figure 3;
Figure 5 is a cross-sectional elevational view of the metal housing portion of the temperature sensor in Figures 1-4;
Figure 6 is a plan view of a terminal;
Figure 7 is a side elevational view of the terminal of Figure 6;
Figure 8 is an end elevational view showing the bottom crimp connecting portion of the terminal subsequent to forming thereof into a generally 25 U-shaped configuration; -~
Figure 9 is a plan view of another ::~
terminal; and Figure 10 is an end view showing the bottom :
crimp connecting portion of the terminal of Figure 9 ~ :
subsequent to forming thereof into a generally U-shaped configuration.

, 2~188G3 Description of a Preferred Embodiment Referring now to the drawing, wherein the showings are for purposes of illustrating a preferred embodiment of the invention only and not for purposes of limiting same, the figures show a metal housing A assembled to a plastic connector B.
Housing A includes an elongated tubular probe 10 having a closed distal end 12 and an enlarged head 14 that is externally shaped for cooperation with a tool to facilitate installation and removal of the sensor. Tubular probe 10 has external threads 16 thereon beneath enlarged head portion 14 along about one-half of the length of the 15 probe for reception in a tapped hole. When ~ -installed, the unthreaded portion of tubular probe 10 and its closed distal end 12 are immersed in the fluid whose temperature is to be sensed.
Housing A has an enlarged entrance opening 20 in enlarged head portion 14 opposite from closed distal end 12 for providing access to the hollow interior of probe 10. Opening 20 is of generally inverted frustol-conical shape to facilitate insertion of components into the probe.
Referring to Figure 5, the interior of tubular probe 10 has first and second different diameter cylindrical portions 30, 32 that intersect at a shoulder 34. The first and larger diameter cylindrical portion 30 has a length substantially less than the second smaller diameter cylindrical portion 32. Preferably, the smaller diameter portion is at least about three times the length of ~

~ ~:
~ ''" '' .~

the larger diameter portion. A thin deformable attaching ring 40 extends upwardly from the flat upper end 42 of enlarged head portion 14.
Referring to Figure 4, an elastomeric gasket 46 is positioned on flat upper end 42 of housing enlarged head portion 14. A flat end of connector B is positioned against gasket 46 and pressure is applied thereto for compressing the gasket. Deformable housing ring 40 is then deformed inwardly over a circular flange 50 on connector B to seal opening 20 and the interior of probe 10. A
locking projection 52 on connector B adjacent flange 50 thereof interlocks with inwardly deformed ring 40 on housing A to prevent rela~ive rotation between connector B and housing A.
Connector B has opposite side projections 56, 58 for cooperation with latches on a socket in a known manner. Connector B also has a longitudinal projection 60 for properly orienting connector B
with a socket and guiding same into the socket.
Connector B has a cavity 62 surrounding portions of -~
terminals C, D that are molded into connector B.
The portions of terminals C, D within cavity 62 are receivable in sockets in a known manner.
A thermistor E having a negative temperature coefficient of electrical resistance is positioned within tubular probe 10 adjacent closed distal end 12 thereof. The inner end portion of ~ probe 10 adjacent distal end 12 thereof is completely filled with a non-rigid heat transfer medium 70 such as silicon grease. The amount of heat transfer medium 70 is preferably ~ust sufficient to insure complete encapsulation of thermistor E therein 80 that the major length of the interior of 2ll8863 "
. - 7 -.
probe 10 remains free of heat transfer medium to minimize transfer of heat toward enlarged head 14.
The wall thickness of the unthreaded portion of probe 10 and distal end 12 is preferably not greater -:
than about 0.032 inch to insure rapid transfer of heat to thermistor E.
Lead wires attached to thermistor E are connected with tail end portions of terminals C, D
by both crimp connections 76, 78 and weld 10 connections 80, 82. The crimp and weld connections ~ .
are longitudinally spaced-apart from one another along the longitudinal axes of terminals C, D.
Crimp connections 76, 78 are located closer to thermistor E than weld connections 80, 82. A
dielectric sleeve 84 is received in enlarged opening 20 and closely received within the first larger diameter inner cylindrical portion of the probe.
The bottom end of dielectric sleeve 78 abuts :~
shoulder 34 formed by the intersection of the first 20 and second large and smaller inner cylindrical :
portions of the probe.
Figures 6 and 7 show terminal C having a flat blade portion 90 with a longitudinal axis 92 and parallel opposite sides 94, 96. Blade portion 90 intersects a flat tail portion 98 having a reduced width and being laterally offset relative to longitudinal axis 92. Opposite sides 102, 104 of tail portion 98 are laterally offset from sides 94, 96 of blade portion 90. The shoulder 106 formed by 30 the intersection of blade side 94 with tail side 102 provides a tortuous path to inhibit leakage of fluid along the terminal. A rectangular notch 107 in side :-" 2l~8863 96 of blade 90 adjacent tail portion 104 serves the same purpose. These irregularities in the sides of the terminal also enhance interlocking of the terminals with the molded plastic connector.
Tail portion 98 is formed with a curved transversely extending embossment 110 on which a wire lead is positioned to form a weld connection.
A crimp connection portion 112 is shown in its flat configuration in Figure 6 prior to lateral bending of same into a generally U-shaped configuration. A
plurality of spaced- apart longitudinal generally V-shaped grooves 120-122 are formed on the surface of crimp connection portion 112 to facilitate bending of same into a generally U-shaped configuration and to enhance flattening of the generally U-shaped portion when it is crimped closed with a wire received therein. A generally rectangular recess 130 is embossed in crimp connection portion 112 in alignment with weld embossment 110. The fine wire lead extends across embossed depression 130 and makes good contact with the upper and lower edges thereof when the crimp connection is crimped closed. Figure 8 shows the crimp connection portion 112 after it has been formed into a generally U-shaped configuration for receiving a wire therein. Grooves 120-122 and embossed recess 130 are located within the interior surface of the generally U-shaped crimp portion.
After a wire is inserted within the generally U-shaped portion of Figure 8, it is crimped closed to securely lock the wire therein. The same wire is also welded to transverse embossment 110.
-, 2ll8863 ~:, - 9 - :

Figure 9 shows terminal D having a flat blade portion 140 with a longitudinal axis 142 and opposite sides 144, 146. A narrower width tail portion 148 is laterally offset from longitudinal axis 142 so that its opposite sides 150, 152 are offset laterally from blade sides 144, 146. A
shoulder and notch 154, 156 serve the same purposes as shoulder and notch 106, 107 of terminal C. A
transverse weld embossment 160 is formed in tail 10 portion 148 and a crimp connection portion 162 is provided at the lower end thereof. A plurality of spaced-apart longitudinally extending generally V-shaped grooves 163-165 are provided in crimp connection portion 162 to facilitate the bending and closing of same. A generally rectangular depression 170 is embossed in crimp connection portion 162 in alignment with weld embossment 160. Figure 10 shows crimp connection portion 162 after it has been bent into a generally U-shaped configuration for 20 receiving a wire lead. Grooves 163-165 and depression 170 are located within the interior surface of the generally U-shaped portion. The crimp connection portions are curved into generally U-shaped configurations such that the pocket in the U-shaped portion is on the same side of the terminal as the outwardly curved portion of weld embossment 160. The generally U-shaped pocket and the weld embossment are also longitudinally aligned.
Thermistor E and wire leads 72, 74 are preferably coated with a dielectric material that is removed from the end portions of the wire leads that are crimp and weld connected to the terminals. The wire leads are crimped and welded to the terminals of a connector and a dielectric sleeve is positioned 2ll8863 over the connections. This assembly is then mated with a metal housing by extending the thermistor attached to the wire leads down into the tubular probe. With the parts positioned as shown in Figure 4, deformable ring portion 40 on housing A is then deformed inwardly to lock the assembly together.
Although the invention has been shown and described with respect to a preferred embodiment, it is obvious that equivalent alterations and modification will occur to others skilled in the art upon the reading and understanding of this specification. The present invention includes all such equivalent alterations and modifications, and is limited only by the scope of the claims.

Claims (12)

1. A temperature sensor including a metal housing having an elongated tubular portion with a closed distal end, said metal housing having an opening opposite said distal end for providing access to the interior of said tubular portion, said tubular portion having an internal shoulder intermediate said opening and said distal end, a larger first diameter internal cylindrical surface extending from said shoulder to said opening and a smaller second diameter internal cylindrical surface extending from said shoulder to said distal end, a dielectric sleeve extending through said opening along said first diameter internal cylindrical surface and having a sleeve end abutting said shoulder, a thermistor positioned within said tubular portion adjacent said distal end, an electrical connector attached to said housing and closing said opening, said connector including a molded plastic body having a pair of electrical terminals molded therein, said electrical terminals having blade portions projecting from said body on the opposite side thereof from said metal housing and tail portions projecting from said body into said opening in said metal housing, said tail portions of said terminals including terminal end portions projecting at least partly into said dielectric sleeve, and a pair of conductors extending between said thermistor and said terminal end portions, each said conductor being connected to one of said terminal end portions.
2. A temperature sensor including a thermistor positioned within a tubular probe adjacent a closed distal end thereof, said sensor including terminals for connecting said thermistor in an electrical circuit, lead wires connecting said thermistor with said terminals, and a non-rigid heat transfer medium encapsulating said thermistor, said heat transfer medium substantially filling said tubular probe adjacent said closed distal end thereof for transferring heat therethrough from the walls of said probe to said thermistor, the major length of the interior of said tubular probe between said thermistor and said terminals being void of said heat transfer medium to minimize sinking heat away from said thermistor through said probe.
3. The sensor of claim 2 including a dielectric sleeve in said tubular probe adjacent said terminals around the connections between said terminals and said lead wires, said sleeve extending over only a portion of the length of said probe adjacent said terminals such that the length of said probe occupied by said thermistor is unoccupied by said sleeve so that heat transfer through said heat transfer medium from the walls of said probe to said thermistor is uninhibited by said sleeve.
4. The sensor of claim 1 wherein said smaller second diameter internal cylindrical surface that extends between said shoulder and said closed distal end has a length substantially greater than the length of said larger first diameter internal cylindrical surface.
5. The sensor of claim 4 wherein said opening in said metal housing has a generally inverted frusto-conical shape.
6. The sensor of claim 1 wherein the length of said smaller second diameter internal cylindrical surface is at least three times the length of said larger first diameter internal cylindrical surface.
7. The sensor of claim 1 including a sufficient amount of non-rigid heat transfer medium in said tubular portion adjacent said closed distal end thereof to completely encapsulate said thermistor while leaving the major length of the interior of said tubular portion free of said heat transfer medium.
8. The sensor of claim 1 wherein said blade portions and tail portions are laterally offset relative to one another within said plastic body to define a shoulder on each said electrical terminal within said plastic body.
9. The sensor of claim 8 wherein each said blade portion on each of said electrical terminals has a notch therein within said plastic body on the opposite side of each said blade portion from said shoulder.
10. The sensor of claim 1 wherein each said terminal end portion on said tail portions of said electrical terminals has a transverse boss therein and said conductors have conductor end portions welded to said bosses.
11. The sensor of claim 10 wherein each said terminal end portion includes a generally U-shaped crimp portion spaced from said transverse boss in a direction toward said closed distal end of said tubular portion of said housing, each said crimp portion having an internal surface with longitudinal grooves therein, and each said crimp portion being crimped closed on one of said conductor end portions.
12. The sensor of claim 11 wherein said internal surface of each said crimp portion has a depression embossed therein and each of said conductor end portions extends across said depression.
CA002118863A 1993-04-02 1994-03-11 Temperature sensor Abandoned CA2118863A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US08/041,856 US5302934A (en) 1993-04-02 1993-04-02 Temperature sensor
US08/041,856 1993-04-02

Publications (1)

Publication Number Publication Date
CA2118863A1 true CA2118863A1 (en) 1994-10-03

Family

ID=21918710

Family Applications (1)

Application Number Title Priority Date Filing Date
CA002118863A Abandoned CA2118863A1 (en) 1993-04-02 1994-03-11 Temperature sensor

Country Status (3)

Country Link
US (1) US5302934A (en)
EP (1) EP0618433A1 (en)
CA (1) CA2118863A1 (en)

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US5449234A (en) * 1993-11-29 1995-09-12 Caterpillar Inc. Air temperature sensor
DE69613213T2 (en) * 1995-02-02 2001-10-04 Keystone Thermometrics Corp TEMPERATURE PROBE
DE19542516C1 (en) * 1995-11-15 1997-04-17 Heraeus Sensor Gmbh Temperature sensor
JP4085828B2 (en) * 2003-01-31 2008-05-14 株式会社ジェイテクト Torque detection device
US20060290370A1 (en) * 2004-02-27 2006-12-28 Wells-Cti, Llc, An Oregon Limited Liability Company Temperature control in ic sockets
US7123037B2 (en) * 2004-02-27 2006-10-17 Wells-Cti, Llc Integrated circuit temperature sensing device and method
US7394271B2 (en) * 2004-02-27 2008-07-01 Wells-Cti, Llc Temperature sensing and prediction in IC sockets
US7042240B2 (en) * 2004-02-27 2006-05-09 Wells-Cti, Llc Burn-in testing apparatus and method
US7722362B2 (en) * 2006-06-22 2010-05-25 Watlow Electric Manufacturing Company Sensor adaptor circuit housing incapsulating connection of an input connector with a wire
US7665890B2 (en) 2006-06-22 2010-02-23 Watlow Electric Manufacturing Company Temperature sensor assembly and method of manufacturing thereof
US8162541B2 (en) * 2009-04-06 2012-04-24 Roxanne P. Ostlund, legal representative Two-terminal temperature sensor with electrically isolated housing
US8734012B2 (en) * 2009-08-21 2014-05-27 Therm-O-Disc, Incorporated Temperature sensor
DE102009028850A1 (en) * 2009-08-24 2011-03-03 Endress + Hauser Flowtec Ag Manufacturing method of a sensor of a thermal flow meter
GB0918042D0 (en) * 2009-10-15 2009-12-02 Delphi Tech Inc Connector assembly and method of manufacturing same
US8562091B2 (en) * 2010-03-09 2013-10-22 Xerox Corporation Apparatus and method for detecting ink in a reservoir using an overdriven thermistor and an electrical conductor extending from the thermistor
US20140230545A1 (en) * 2013-02-21 2014-08-21 Amphenol Corporation Sensor and method of making a sensor
US10663931B2 (en) * 2013-09-24 2020-05-26 Rosemount Inc. Process variable transmitter with dual compartment housing
CN115014412A (en) 2013-09-30 2022-09-06 罗斯蒙特公司 Process variable transmitter with dual compartment housing
JP6383181B2 (en) * 2014-05-30 2018-08-29 矢崎総業株式会社 connector
JP6303937B2 (en) * 2014-09-10 2018-04-04 住友電装株式会社 Wheel speed sensor
US10015899B2 (en) 2015-06-29 2018-07-03 Rosemount Inc. Terminal block with sealed interconnect system
JP7151369B2 (en) * 2018-10-22 2022-10-12 株式会社デンソー temperature sensor

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Also Published As

Publication number Publication date
EP0618433A1 (en) 1994-10-05
US5302934A (en) 1994-04-12

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Legal Events

Date Code Title Description
EEER Examination request
FZDE Discontinued