GB2036966A

GB2036966A - Improvements in surface temperature measurement devices

Info

Publication number: GB2036966A
Application number: GB7840681A
Authority: GB
Original assignee: COMARK ELECTRONICS Ltd
Current assignee: COMARK ELECTRONICS Ltd
Priority date: 1978-10-16
Filing date: 1978-10-16
Publication date: 1980-07-02
Also published as: GB2036966B

Abstract

A portable hand-held surface- temperature measuring device has a contact band 21, conveniently of stainless steel, entrained around guides 28 in a housing 15 to prevent an exposed surface for contacting a flat or curved surface of an article, which may be movable or stationary, to measure its temperature. The band 21 is connected to a tension spring 29 which assists the band 21 to conform to the shape of the temperature surface. An additional band 31 or loop of stainless steel strip is retained in the housing 15 and tends to urge the exposed surface of the contact band 21 into good thermal contact with the temperature surface. The contact band 21 supports a thermocouple 27. A film of paint or the like between the bands 21, 31 prevents direct electrical conduction between the bands 21, 31. <IMAGE>

Description

SPECIFICATION Improvements in surface temperature measurement devices The present invention relates to portable surface-temperature measurement devices.

In many industrial processes it is necessary to ascertain the temperature of the surface of an article. Where the surface is stationary and substantially flat and the temperature is not in excess of about 5000, there is no difficulty in measuring surface temperature with a portable device with a simple temperature-sensitive probe.

However, problems do occur where the surface, the temperature of which is to be ascertained, is not flat such as with a cylinder or drum and it has hitherto been difficult to establish adequate thermal contact with a curvilinear surface over a reasonable area. In some processes it is desirable to ascertain the temperature of a moving surface and this also presents problems.

A general object of this invention is to provide an improved form of portable surface temperature measurement device.

According to the present invention a portable surface-temperature measuring device employs a flexible resilient thermally-conductive contact band for contacting the surface of an article the temperature of which is to be ascertained and said contact band, which is capable of adopting a flat or a curvilinear profile in accordance with the temperature surface in question, carries temperature sensitive means which provides a signal representing the temperature of the surface.

Normally, the temperature sensitive means would be a simple thermocouple junction and the device would be used with a separate compatible temperature measuring and/or display instrument and connected thereto with a cable. Further, according to the invention, a separate pressure means exerts pressure on the contact band to urge the latter into good thermal contact with the temperature surface in question. In one preferred form the pressure means is a further band or loop of resilient material. The pressure band and the contact band can conveniently be made from stainless steel strip. To provide additional flexibility, one end of the contact band can be subjected to the tension force of a spring, capable of extending to permit the contact band to adopt a reasonably small radius of curvature commensurate with that of a curvilinear surface the temperature of which is to be measured.It is desirable to locate the contact band with its pressure means in a protected position within a housing. It is useful to connect this housing preferably by way of a pivotable connection -- to some form of handle or grip capable of being hand held.

According to a further preferred feature of the invention, the contact band and the pressure means or band establish pressure contact through the contact band and the temperature sensitive means, e.g. the thermocouple junction and its electrical connection lead, via a substance exhibiting high thermal conductivity but low electrical conductivity. A film or coating of suitable paint or thin tape can generally be used for this purpose.

Where the surface the temperature of which is to be measured is in motion, it is desirable to provide the device with rotatable guide wheels or rollers which can contact the surface and revolve while the device is otherwise held stationary with the contact band in sliding contact with the surface. Conveniently, these wheels can be supported on the aforementioned housing.

A preferred embodiment of a device made in accordance with the invention comprises a housing supporting wheels or rollers for contacting a temperature surface during use, a flexible elongate thin thermally-conductive contact band, preferably subjected to tensile spring force in the longitudinal direction, partly retained in the housing and having a reasonably extensive exposed surface facing outwardly of the housing for contacting the temperature suface, a flexible pressure band located in the housing to subject the contact band to force tending to urge the exposed surface outwardly against the temperature surface, and a thermocouple or the like supported by the contact band to yield a signal indicative of the temperature of the temperature surface.

The invention may be understood more readily, and various other features of the invention, may become more apparent from consideration of the following description.

An embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings, wherein Figure 1 is a side view of a device made in accordance with the invention; Figure 2 is an inverted plan view of the device; Figure 3 is a cross-sectional view of the device taken along the line Ill-Ill of Figure 2; Figure 4 is a sectional side view of the device taken along the line IV-IV of Figure 2; Figure 5 is an enlarged plan view of the contact band of the device; Figure 6 is a side view of the contact band shown in Figure 5; and Figure 7 is an enlarged plan view of part of the contact band showing the probe or thermocouple thereof.

The device represented in the drawings is especially adapted for use in measuring the surface temperature of drums or cylinders or similar curvilinear structures and can cope with moving surfaces as with revolving drums or cylinders. The device is composed of a handle assembly 10 pivotably secured with pivot joints 11 to a base assemly 12. The handle assembly 10 employs a shaped member or members 1 3 to which is mounted a rod 14 intended to be held in the hand of user.

The base assembly 12 is composed of a housing defined by a main wall member 1 5 supported by the pivot joints 11 and side wall members 16 fixed to inner webs 1 7 of the member 15 with the aid of screw-threaded elements 18 and spacers 18'. A further screw threaded element 1 9 and spacer 19' extends between the side wall members 16 at the central region of the assembly 1 2. Rotatable wheels or rollers 20 are mounted at the outside of the side wall members 1 6 as shown.

A contact band 21 is retained inside the housing 1 5, 1 6 and extends along the open lower part of the assembly 12. This contact band 21 shown separately in Figures 5-7, can be a stainless steep strip. As shown in Figures 5 and 6 one end 22 of the band 21 is formed into a bifurcated loop 23 and spot welded at 24 and the other end 25 is spot welded to double-thickness and has a hole 26 therein.

A temperature sensitive probe, here in the form of a thermocouple junction 27, is spot-welded to the central region of the band 21 as shown in Figure 7. The junction 27 is connected to respective electrical conductors of a cable 40 passing through grommets 41,42 in the member 15,13. The cable 40 would normally be connected at the other end to a suitable measuring or display instrument which may display directly a temperature reading of the surface with which the band 21 is in thermal contact. The band 21 is entrained around cylinrical guides 28 coaxial with the rollers 20 and extending between the side wall members 16. The looped end 22 of the band 21 is retained by the fixing element 19 or more particularly by the spacer 19' mounted thereon.

The hole 26 at the other end of the contact band 21 is coupled to a tension spring 29 again located by the spacer 19'. The band 21 is inherently resilient but the spring 29 enables the band 21 to effectively stretch to adopt a small radius of curvature. This stretching facility is also especially usefu! where the device is used to ascertain the temperature of a moving surface of an article such as a rotating drum. One or both side wall members 1 6 and the rod 14 are provided with visual indicia 3Q denoting the orientation of the device when used with a moving surface. The band 21 is thus particuiariy adapted to take up a curvilinear shape corresponding to the surface (moving or stationary) the temperature of which it is desired to measure.To maintain adequate thermal areal contact between the band 21 and the surface the base assembly employs a pressure band 31 which may be in the form of a further stainless steel strip.

The strip has its ends fixed together to thus render band 31 endless. As shown in Figure 3, the band 31 is held freely in the housing of the assembly 12 i.e. between the side wall members 1 6 and the guides 28 and extends beneath the spring 29. The band 31 lies against a region of the inner surface of the band 21. At the contact zone between the bands 31,21 there is a film or layer of material which permits thermal conductivity but is practically electronically non-conductive at the small e.m.f. present across the thermocouple. One or both bands 31, 21 can be conveniently coated with a film of suitable paint although a thin tape may be suitable. In one practical design based on the illustrated embodiment the bands 31,21 are made from stainless steel ASS1 302 of thickness 0.002 inches and the band 21 has a film 45 of paint (Figures 5 and 7) (type PFU aluminium heatresisting P298 cured at 2500F,) exhibiting the properties mentioned above. The thermocouple junction or probe 27 can be standarrd NiCr, NiAl type K By2437.

In general the device as illustrated and described is suitable for measuring surface temperature over a range -400C to +3000C with a fast response time and with reasonable accuracy. The device is robust and can be used in most industrial plants in their normal working environments.

Claims

1. A portable surface-temperature measuring device which employs a flexible, resilient, thermally-conductive contact band for contacting the surface of an article, the temperature of which is to be ascertained, said contact band being capable of adopting a flat or curvilinear profile according to the temperature surface and temperature sensitive means carried by said contact strip for providing a signal indicative of the temperature of said surface during use.

2. A device according to claim 1 , wherein the contact band is a stainless steel strip.

3. A device according to claim 1 or 2, wherein the temperature-sensitive means is at least one thermo-couple junction welded or otherwise fixed to the contact band.

4. A device according to any one of claims 1 to 3, wherein a tension spring is also connected with the contact band.

5. A device according to any one of claims 1 to 4, and further comprising pressure means for exerting pressure on the contact band to urge the latter against the temperature surface during use.

6. A device according to claim 5, wherein the pressure means is a further band or loop of resilient material.

7. A device according to claim 6, wherein the pressure means is a stainless steel strip.

8. A device according to claim 5, 6 or 7, wherein the contact band and the pressure means or band establish pressure contact over a zone where the temperature sensitive means is located and via a substance therebetween which exhibits high thermal conductivity but low electrical conductivity.

9. A device according to claim 8, wherein the substance between the contact band and the pressure means or band is at least one film or coating of paint or a tape.

10. A device according to any one of claims 1 to 9, and further comprising a housing, the contact band being partly retained in the housing with an exposed surface for directly contacting the temperature surface.

11. A device according to any one of claims 1 to 9, and further comprising rotatable guide wheels or rollers for contacting the temperature surface during use.

1 2. A device according to claim 10 and further comprising rotatable guide wheels or rollers supported by the housing for contacting the temperature surface, during use.

13. A device according to claim 10 and 12, wherein the housing is pivotably connected to a handle or grip capable of being held in the hand of a user.

14. A device according to claim 10, 12 or 13, wherein the contact band is entrained around cylindrical guides mounted to the housing.

1 5. A device according to claim 12, wherein the contact band is entrained around cylindrical guides coaxial with the wheels or rollers.

16. A device according to claim 14 or 15, when appended to claim 4, wherein one end of the contact band is fixed within the housing, while the other end is coupled to said tension spring.

1 7. A device according to any one of claims 10 to 16, when appended indirectly or directly to claim 5, wherein the pressure means is a closed loop of resilient material held freely within the housing to act on the contact band.

1 8. A portable surface-temperature measuring device comprising a housing supporting rotatable wheels or rollers for contacting the surface of an article, the temperature of which is to be ascertained, a flexible, elongate, thin thermallyconductive contact band partly retained in the housing and having an exposed surface facing outwardly of the housing for contacting the temperature surface, a flexible pressure band located in the housing to subject the contact band to a biasing force tending to urge the exposed surface thereof outwardly of the housing into a a real contact with the temperature surface and temperature-sensitive means supported by the contact band for yielding a signal indicative of the temperature of the temperature surface.

19. A device according to claim 18, wherein the contact band is subjected to tensile spring force in its longitudinal direction.

20. A device according to claim 18 or 19, wherein the contact and pressure bands are both stainless steel strips which physically contact one another over a region where the temperature- sensitive means in the form of a thermocouple junction is welded to the contact band and one or both strips are treated over said region to electrically isolate one band from the other while permitting thermal conduction.

21. A measuring device substantially as described with reference to, and as illustrated in, the drawings accompanying U.K. patent application 40681/78.