GB1591038A

GB1591038A - Temperature sensing device

Info

Publication number: GB1591038A
Application number: GB1304277A
Authority: GB
Original assignee: Individual
Current assignee: Individual
Priority date: 1978-05-04
Filing date: 1978-05-04
Publication date: 1981-06-10

Description

(54) A TEMPERATURE SENSING DEVICE (71) I, SIMON JOHN WILSON, a British subject of 30, Comberton Avenue, Kidderminster, Worcestershire, DY10 3EG do hereby declare the invention, for which I pray that a patent may be granted to me, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to a temperature sensing device for mounting on a pipe or other member, the temperature of which is to be sensed.

According to the invention, there is provided a temperature sensing device comprising a body and temperature sensing means mounted in the body, wherein the body has limbs which, together with the sensing means, define an opening in which there is received in use a member whereof the temperature is to be sensed, the limbs extend from the sensing means in opposite directions around the boundary of the opening, and convergent free end portions of the limbs are resiliently displaceable in respective directions to increase the size of the opening, whereby the limbs are adapted to establish pressure contact between the sensing means and a member fitted in the opening where the device is in use.

The sensing means preferably comprises a thermal conductor which forms said part of the boundary of the opening and a temperature sensitive element spaced from the opening, the temperature sensitive element being in thermally conductive engagement with the conductor and the body having a thermal conductivity less than that of the conductor.

The temperature sensitive element may be disposed in a pocket or aperture of the body.

The temperature sensitive element may be disposed in a further opening formed in the body. Said further opening may lead from the opening defined by the limbs and sensing means to a face of the body remote from the limbs, the sensing means being disposed in said further opening.

The invention will now be described, by way of example, with reference to the accompanying drawing wherein: Figure 1 shows a plan view of a device in accordance with the invention fitted on a pipe, Figure 2 shows the device and pipe as viewed along the length of the pipe, Figure 3 shows a cross section of the device on the line III-III of Figure 1, Figure 4 is a view similar to Figure 2 of a further device in accordance with the invention fitted on a pipe, and Figure 5 is a cross section, similar to Figure 3, of the device shown in Figure 4 but on an enlarged scale.

The device shown in Figures 1, 2 and 3 of the accompanying drawing comprises a body 10 having a pair of limbs 11 and 12, which are integral with a connecting portion 13 of the body. The limbs are of substantially arcuate form, having respective concave faces 14 which are presented towards each other. When the body is substantially unstressed, the faces 14 have a common axis of curvature 15.

The body 10 is formed of a resiliently deformable material, for example polypropylene or nylon. Accordingly, the limbs 11 and 12, particularly free end portions thereof, can be displaced relative to the connecting portion 13 in a direction away from the axis 15 to increase the size of the opening 18 between the limbs. Between the free end portions of the limbs there is a gap 16 through which a pipe 17, to which the device is to be fitted, can enter the opening 18 between the limbs. The body subtends at the axis 15 an angle greater than 1800 so that the body will grip a pipe which just fits in the opening 18. The body may consist of a known type of moulded plastics pipe-clip.

The body 10 is formed with a bore 19 which extends from the opening 18 to a face 20 of the body remote from the limbs 11 and 12. At the end of the bore 19 adjacent to the opening 18 there is a counterbore 21, which, together with bore 19, forms a further opening in addition to the opening 18. In the bore 19 and counterbore 21, there is disposed temperature sensing means for sensing the temperature of a pipe to which the device is fitted. The temperature sensing means comprises a temperature sensitive element 31 which, in the particular example illustrated, is a thermistor. The thermistor is situated in the counterbore and, when the device is fitted to a pipe is spaced somewhat from that pipe. The temperature sensing means further comprises a thermal conductor 22 for conducting heat from the pipe 17 to the thermistor.The conductor 22 consists of a bolt 23 and a pair of nuts 24 and 25 which are threadedly engaged with a shank of the bolt. The shank of the bolt extends along the bore 19 and through a bore in a terminal block 26 which rests on the face 20 of the body. The head of the bolt is engaged with the terminal block so that the bolt holds on the body 10.

The thermistor 31 is disposed between the nuts 24 and 25 and is in good thermally conductive engagement with both nuts. During assembly, the nuts can be adjusted along the shank of the bolt to establish any required contact pressure between the nuts and the thermistor. The nuts and thermistor may then be encapsulated in a curable resin which prevents subsequent movement of the nuts relative to the body. The nut 25 lies nearer to the opening 18 than does the nut 24 and the tip of the bolt 23 projects through the nut 25 towards that space. As shown in Figure 2, when the device is fitted to a pipe, the limbs 11 and 12 and the tip of the bolt 23 engage the pipe but neither the nut 25 nor the connecting portion 13 of the body engages the pipe since the tip of the bolt is slightly closer to the axis 15 than is the connecting portion 13 of the body.

The tip of the bolt 23 is closer to the axis 15 than are the faces 14 of the limbs 11 and 12 when the device is substantially unstressed. In consequence of this, when the device is fitted to a cylindrical pipe having an external radius of curvature approximately equal to the radius of curvature of the faces 14 when the device is unstressed, the axis 27 of the pipe 17 is offset from the axis 15 in a direction away from the connecting portion 13 of the body. The limbs 11 and 12 are therefore stressed and occupy positions slightly further from the axis 15 than is the case when the device is unstressed. Accordingly, the limbs 11 and 12 engage the pipe under pressure and maintain the tip of the bolt 23 in pressure contact with the pipe.

Since the surface area of the bolt which is in contact with the pipe is relatively small, the pressure between the bolt and pipe is relatively high. This ensures that the conductor 22 is maintained in good thermal communication with the pipe.

Electrical leads 28 and 29 extend from the thermister to the terminal block 26. These leads are disposed in respective slots which extend from the opening 18 to the terminal block 26 and are adjacent to one of the axially presented faces of the body. Accordingly, the slots are separated from the bore 19 by a part of the body and the leads are therefore insulated from the bolt 23. After the leads have been inserted into their respective slots, these may be filled with a curable resin to encapsulate the leads and so insulate them electrically and protect them from mechanical damage. In a case where a known moulded pipe clip is used for the body 10, the slots for receiving the leads 28 and 29 may be cut in the pipe clip after the latter has been moulded.

The bolt 23 and nuts 24 and 25 are formed of a material which has a higher thermal conductivity than the material of which the body 10 is formed. The bolt and nuts are preferably formed of brass, steel or some other metal.

Turning now to the device shown in Figures 4 and 5, certain parts shown in these Figures which correspond to parts already described with reference to Figures 1, 2 and 3 are indicated in Figures 4 and 5 by like reference numerals with the prefix 1 and the preceding description is deemed to apply, except for the differences hereinafter mentioned.

The temperature sensing means of the device shown in Figures 4 and 5 comprises a temperature sensitive element 131 and a thermal conductor 122. When the device is fitted to a pipe, the element 131 is spaced somewhat from the pipe and the conductor 122 conducts heat between the pipe and the element 131. The conductor comprises a bolt 123 having a head 132 which projects into the opening 118 adjacent to the counterbore 121. A screw threaded shank of the bolt extends from the head through the counterbore 121, through the bore 119 and projects beyond the face 120 of the body. On this projecting end portion of the shank, there is fitted a nut 133 which prevents the head 132 moving further into the opening 118, before the device is fitted to the pipe.

A pair of nuts 134 and 135 which are threadedly engaged with the shank of the bolt 123 are disposed in the counterbore 121, these nuts having a diameter greater than the diameter of the bore 119 so that the nut 134 prevents the bolt 123 moving along the bore 119 in a direction away from the opening 118. The nuts 134 and 135 grip firmly between them an electrically conductive tag 136. The temperature sensitive element 131 is gripped between a pair of washers 137 and 138 carried on the shank of the bolt 123. The washer 137 is engaged by the nut 135 and the washer 138 is engaged by the head 132 of the bolt. During assembly of the device, the nut 135 is screwed along the shank towards the head 132 to establish the required contact pressure between the washers and the element 131.The nut 134 is a lock nut which prevents vibration or other environmental factors causing subsequent movement of the nut 135 along the shank in a direction away from the head 132.

Two electrical leads emerge from the temperature sensitive element 131. One of these leads is connected to the tag 136 and accordingly is maintained in an electrically conductive relation with the bolt head 132. The other lead 139, is connected to an electrical conductor 140 which extends through an opening in the connecting portion 113 of the body. As shown in Figure 5, the opening containing the conductor 140 may be parallel to the bore 119.

When the device is in use, means for measuring the electrical conductivity or some other electrical parameter of the element 131 is connected both to the conductor 140 and the pipework which includes the pipe 117. The pipework may constitute an electrical conductor which is common to a number of devices similar to or identical with that shown in Figures 4 and 5.

The head 132 of the bolt is nearer to the axis 115 than are the surfaces 114 of the limbs 111 and 112. Accordingly, when the device is fitted to a pipe, the head 132 of the bolt is maintained in pressure contact with the pipe. The bolt 123, the washers 137 and 138 and the nut 135 provide a path along which heat can readily be conducted between the element 131 and the pipe.

WHAT I CLAIM IS: 1. A temperature sensing device comprising a body and temperature sensing means mounted in the body, wherein the body, which, together with the sensing means, define an opening in which there is received in use a member whereof the temperature is to be sensed, the limbs extend from the sensing means in opposite directions around the boundary of the opening, and convergent free end portions of the limbs are resiliently displaceable in respective directions to increase the size of the opening, whereby the limbs are adapted to establish pressure contact between the sensing means and a member fitted in the opening when the device is in use.

2. A device according to Claim 1 wherein the sensing means comprises a thermal conductor which forms a part of the boundary of the opening, and a temperature sensitive element spaced from the opening, the temperature sensitive element being in thermally conductive engagement with the conductor and the body having a thermal conductivity less than that of the conductor.

3. A device according to Claim 2 wherein the temperature sensitive element is disposed in a further opening formed in the body.

4. A device according to Claim 2 or Claim 3 wherein the temperature sensitive element is also connected electrically with the thermal conductor.

5. A temperature sensing device substantially as herein described with reference to and as shown in Figures 1, 2 and 3 of the accompanying drawing.

6. A temperature sensing device substantially as herein described with reference to and as shown in Figures 4 and 5 of the accompanying drawing.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. pair of washers 137 and 138 carried on the shank of the bolt 123. The washer 137 is engaged by the nut 135 and the washer 138 is engaged by the head 132 of the bolt. During assembly of the device, the nut 135 is screwed along the shank towards the head 132 to establish the required contact pressure between the washers and the element 131. The nut 134 is a lock nut which prevents vibration or other environmental factors causing subsequent movement of the nut 135 along the shank in a direction away from the head 132. Two electrical leads emerge from the temperature sensitive element 131. One of these leads is connected to the tag 136 and accordingly is maintained in an electrically conductive relation with the bolt head 132. The other lead 139, is connected to an electrical conductor 140 which extends through an opening in the connecting portion 113 of the body. As shown in Figure 5, the opening containing the conductor 140 may be parallel to the bore 119. When the device is in use, means for measuring the electrical conductivity or some other electrical parameter of the element 131 is connected both to the conductor 140 and the pipework which includes the pipe 117. The pipework may constitute an electrical conductor which is common to a number of devices similar to or identical with that shown in Figures 4 and 5. The head 132 of the bolt is nearer to the axis 115 than are the surfaces 114 of the limbs 111 and 112. Accordingly, when the device is fitted to a pipe, the head 132 of the bolt is maintained in pressure contact with the pipe. The bolt 123, the washers 137 and 138 and the nut 135 provide a path along which heat can readily be conducted between the element 131 and the pipe. WHAT I CLAIM IS:

1. A temperature sensing device comprising a body and temperature sensing means mounted in the body, wherein the body, which, together with the sensing means, define an opening in which there is received in use a member whereof the temperature is to be sensed, the limbs extend from the sensing means in opposite directions around the boundary of the opening, and convergent free end portions of the limbs are resiliently displaceable in respective directions to increase the size of the opening, whereby the limbs are adapted to establish pressure contact between the sensing means and a member fitted in the opening when the device is in use.