CA1163827A - Temperature sensing device - Google Patents
Temperature sensing deviceInfo
- Publication number
- CA1163827A CA1163827A CA000371540A CA371540A CA1163827A CA 1163827 A CA1163827 A CA 1163827A CA 000371540 A CA000371540 A CA 000371540A CA 371540 A CA371540 A CA 371540A CA 1163827 A CA1163827 A CA 1163827A
- Authority
- CA
- Canada
- Prior art keywords
- temperature sensing
- temperature
- sensing device
- contact
- contact body
- 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.)
- Expired
Links
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
- G01K1/00—Details of thermometers not specially adapted for particular types of thermometer
- G01K1/16—Special arrangements for conducting heat from the object to the sensitive element
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
- G01K1/00—Details of thermometers not specially adapted for particular types of thermometer
- G01K1/14—Supports; Fastening devices; Arrangements for mounting thermometers in particular locations
- G01K1/146—Supports; Fastening devices; Arrangements for mounting thermometers in particular locations arrangements for moving thermometers to or from a measuring position
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
- G01K13/00—Thermometers specially adapted for specific purposes
- G01K13/04—Thermometers specially adapted for specific purposes for measuring temperature of moving solid bodies
- G01K13/08—Thermometers specially adapted for specific purposes for measuring temperature of moving solid bodies in rotary movement
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- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Measuring Temperature Or Quantity Of Heat (AREA)
Abstract
\
ABSTRACT OF THE DISCLOSURE
Disclosed is a temperature sensing element for sensing the temperature of a moving surface, com-prising a contact body of self-lubricating material, such as graphite, having an exterior contact surface shaped to conform to the surfaces whose temperature is to be sensed, with the contact body having an internal recess therein; a temperature sensing element positioned in the internal recess of the contact body;
and a cast body of a high-temperature resistant casting material, such as silicone rubber, firmly bonded to the contact body of self-lubricating material.
ABSTRACT OF THE DISCLOSURE
Disclosed is a temperature sensing element for sensing the temperature of a moving surface, com-prising a contact body of self-lubricating material, such as graphite, having an exterior contact surface shaped to conform to the surfaces whose temperature is to be sensed, with the contact body having an internal recess therein; a temperature sensing element positioned in the internal recess of the contact body;
and a cast body of a high-temperature resistant casting material, such as silicone rubber, firmly bonded to the contact body of self-lubricating material.
Description
63~
TEMPERATURE SENSING DEVICE
BACKGROUND OF THE INVENTION
The present invention relates to a temperature sensing device which has a sensing element located in its interior, the outward surface of which is shaped in accordance with the shape of the surface whose temperature is to be measured.
In various technical fields it is necessary to measure the surface temperature of rolls, rollers or of other curved or flat surfaces.
Temperature sensing devices are, e.g., known from the fixing stations of electrophotographic copiers, and are, e.g., described in U.S. Patent No. 3,888,622.
Temperature sensing devices of that type are constituent parts of temperature measuring circuits for determining and controlling the surface temperatures of the fixing rolls. Among other elements, such a measuring circuit comprises a probe shoe containing at least one tem-perature sensing element, the probe being arranged close to the moving surface of the heated fixing roll, but without touching it. Within the air gap between the heated fixing roll and the probe shoe, an induction field is produced and a magnetic, preferably fluid medium is introduced into this gap. This medium pos-sesses a relatively high coefficient of thermal con-ductivity, whereby a rapid and effective heat flow 3 ~ 3.8Z;I
. -
TEMPERATURE SENSING DEVICE
BACKGROUND OF THE INVENTION
The present invention relates to a temperature sensing device which has a sensing element located in its interior, the outward surface of which is shaped in accordance with the shape of the surface whose temperature is to be measured.
In various technical fields it is necessary to measure the surface temperature of rolls, rollers or of other curved or flat surfaces.
Temperature sensing devices are, e.g., known from the fixing stations of electrophotographic copiers, and are, e.g., described in U.S. Patent No. 3,888,622.
Temperature sensing devices of that type are constituent parts of temperature measuring circuits for determining and controlling the surface temperatures of the fixing rolls. Among other elements, such a measuring circuit comprises a probe shoe containing at least one tem-perature sensing element, the probe being arranged close to the moving surface of the heated fixing roll, but without touching it. Within the air gap between the heated fixing roll and the probe shoe, an induction field is produced and a magnetic, preferably fluid medium is introduced into this gap. This medium pos-sesses a relatively high coefficient of thermal con-ductivity, whereby a rapid and effective heat flow 3 ~ 3.8Z;I
. -
- 2 -from the surface to be measured to the temperature sensing element is obtained.
The temperature sensing elements are arranged in the interior of the cylindrical probe shoe made of a non-magnetic material. The probe shoe is fastened to a free end of a support arm which is also made of a non-magnetic material, such as, e~g., aluminum, plastic or the like. The other end of the support arm is fastened to the frame of the apparatus. In the back side of the support arm, i~e., opposed to the fixing roll, a cut out is provided in which a circular magnet is installed which is divided into two halv~s along a vertical centerline. Each half of the magnet comprises a number ~f north and south pole pieces, with opposite pole pieces belng located adjacent to each other.
There is no direct contact between the sur-face to be measured of the fixing roll and the probe shoe containing the temperature sensing elements.
The toner fixing device known from German Offenlegungsschrift No 2,420,161 comprises a temperature measurin~ device for measuring the surface temperature of a roll and for controlling the heating of the roll.
This temperature measuring device is composed of a photosensitive cell with fiber optics which is arranged close to the fixing roll, and of a light source illumi-nating a fluorescent strip on the circumferential surface of the fixing roll. The intensity of the light emitted by the fluorescent strip is in indirect proportional ratio to the temperature of the strip, i.e., to the temperature of the surface of the fixing roll. The light is led to the photosensitive cell via the fiber optics. The output signal of the cell is amplified and led to a control unit controlling the current supply of a quartz lamp whichproduces the fusing of the toner on 1~6~8Zi a fusing roll of the fixing device.
In this temperature measuring unit, too, there is no direct contact between the temperature sensing element and the surface to be measured. This device is quite complicated, however, since a photosensitive cell with fiber optics and a light source for illuminating the fluorescent strip on the surface of the fixing roll to be measured are required, and it is rather accident-sensitive, because the fiber optics is easily contam-inated by toner which then causes failure of the temperature measuring device.
SUMMAR~ OF THE INVENTION
It is therefore an object of the present invention to provide an improved temperature sensing device.
Another object of the invention resides in providing an improved temperature sensing device which over a longer period of time is maintenance-free and makes possible a rapid measurement of the temperature of a moving surface.
It is also an object of the invention to provide such a temperature sensing device which is technically uncomplicated, can be inexpensively built and is relatively free of wear.
In accomplishing the foregoing objects, there has been provided in accordance with the present invention a temperature sensing element for sensing the temperature of a moving external surface, comprising: a contact body of a self-lubricating material having an exterior contact surface shaped to conform to the surface whose temperature is to be sensed, said contact body having an internal recess therein; a temperature sensing element positioned in the internal recess of said contact body;
B
a cast body of a high-temperature resistant casting material, said cast body being firmly bonded to said contact body of self-lubricating material; a contact area between said contact body and said cast body having at least one blind bore into which a reinforcing metal sleeve is inserted; a supportin~ bracket having at least one end inserted into said metal sleeve; a supporting member running parallel to the surface to be measured, said bracket being attached to said supporting member; and biasing means cooperating with a pin and connected to said supporting member for exerting a torque on said supporti.ng member for pressing the contact surface against the surface to be measured. In one preferred embodiment, the contact body is comprised of graphite, the temperature sensing element is sealed in a glass pearl which is inserted into the internal recess of the contact body, and the internal recess is lined with a heat-conductive paste to ensure a good thermal contact between the contact body and the glass pearl containing the temperature sensing element, Further objects, features and advantages of the present invention will become apparent from the detailed description of preferred embodiments which follows.
'- ix~
'BRIEF DESCRIPTION OF THE;D~A~XNGS
In the drawings:
Figure 1 is a sectional view of the temperatu,re sensing device according to the present invention;
Figure 2 is a side view of the temperature sensing device, seen in the direction of the arrow A
in Figure l;
Figure 3 is a schematic view, partly in section,-illustrating the mounting of the temperature sensing de-vice of the invention by means o~ a bracket and a support pipe; and Figure 4 is a schematic view of the arrangement of the temperature sensing device contacting the surface whose temperature is to be measured.
DETAILED DESCRIPTION OF PREFE~RED EMBODIMENTS
The invention pertains to a temperature sensing device of the type described in the introduction of the application, which is composed of a body of a self-lubricati,ng material having an outward surface which serves as the contact surface, and of a cast body of a high-temperature resistant casting material, which after casting and setting is firmly bonded to the body of self-lubricating material. The body of self-lubri-cating material serves as the fixture for the sensing element.
In one embodiment of the invention, the sensing element is sealed in a glass pearl which has been in-serted into a bore of the body of a self-lubricating material. This bore contains a heat-conductive paste ensuring a good thermal contact between the body of self-lubricating material and the glass pearl in which the sensing element is sealed~ Thus a rapid temperature measurement is made possible, since the temperature present at the contact surface of the body of self-lubricating material is led, via the heat-conductive paste, through the body of self-lubricating material and to the sensing element in the glass pearl with practically no delay. It is advisable to connect the sensing ele-ment to connecting wires which are embedded in the cast body. Via these connecting wires, the ends of which project from the cast body, the sensing element is connected to an electrical circuit containing, inter alia, an amplifier for amplifying the output signal of the sensing element to the strength required.
In a further embodiment of this invention, wired parallel to the sensing elements are circuit ele-ments which are connected to the connecting wires and embedded in the cast body~ In the area of the contact surface between the cast body and the body of self-lubricating material, bores are provided in the body of self-lubricating material which are reinforced by means of metal sleeves. Into these bores, the ends of a bracket are introduced which is supported in a pipe, parallel to the surface whose temperature is to be measured. This embodiment makes it possible to pivot the temperature sensing device around the bracket, in order to bring the contact surface of the temperature sensing device into the correct position with respect to the surface to be measured. The sensing element preferably is a negative-temperature coefficient re-sistor. The casting material used may, e.g., be sili-cone rubber.
The present invention will be explained in more detail by way of an exemplary embodiment in the attached figures of drawing.
1~6385~J
The temperature sensing device 1 which is schematically shown in Figure 1 is composed o~ a body 2 of a self-lubricating material and of a cast body 5.
Graphite is preferably used as the self-lubricating material for the body 2, but it is also possible to use a sintered material containing finely divided graphite particles, intercalated polytetrafluoro-ethylene or an alloy of soft metals, such as, e.g., bronze. In the body 2 of self-lubricating material, a bore 9 is provided into which a glass pearl 7 is inserted having its upper end extending into the cast body 5~ A sensing element 6, e.g., a negative-temperature coefficient resistor, is sealed in the glass pearl 7. Any sensing element causing either a current change or a voltage change as a reaction to temperature variations detected by the temperature sensing device 1 can be used as the sensing element in the present invention.
The outward surface of the body 2 forms a contact surface 10, the shape of which is adapted to the surface whose te~perature is to be measured, as shown in Figures 2 and 4.
The body 2 of a self-lubricating material serves as the fixture for the sensing element 6. In the bore 9, a heat-conductive paste 4 is contained which ensures a good thermal contact between the body 2 and the glass pearl 7 in which the sensing element 6 i5 included. Connecting wires 11 and 12, which are embedded in the cast body 5, lead from the sensing element 6 to the outside. It is advisable to form the ends of these connecting wires 11 and 12 as plug wires. Thus a simple plug-and-socket connection can be created between the temperature sensing device 1 and an electronic circuit for the further processing -` ~16;~827 , of the electric output signals of the sensing element 6.
This electronîc circuit is conventional and is not shown in the figures of drawing.
T~e cast body 5 is made of a high-temperature resistant casting mass, such as, e.g., a silicone rubber or a similar material having a thermal conductivity of less than a.5 W m l K l.
The thermal conductivity of the casting mass for the body 5 is low compared with the thermal con-ductivity of the materials used for producing the body 2,the thermal conductivity of the latter varying between about 4 and 250 W m l K l Due to the fact that the body 2 possesses a large contact surface lO and a small massl an excellent thermal contact is made possible between the temperature sensing device l and the moving surface 17 (Figure 4) whose temperature is to be measured, i.e., the tempera-ture chan~es of the moving surface 17 are registered with practically no delay. Since the thermal conducti-vity of the cast body 5, or respectively of the castingmass used for its production, is low, the cast body S
hardly contributes to the undesired, detrimental total thermal capacitance of the temperature sensing device l, and thus its influence on the temperature measurement is kept very small.
Due to the self-lubricating properties of the body 2, and, in the preferred embodiment, especially to the anti-friction proQerties of graphite, it is not necessary to apply a special anti-friction layer onto this body 2, which would be necessary if a conventional metal body was used as the fixture for the sensing ele-ment 6. Another disadvantage which can be avoided by using a self-lubricating material is the fact that, j ` ~
~63~
becau~e of the high temperatures of about 180C to 200C to be measured, only very few plastic materials can be used for the anti-friction layer~ Such layers are subjected to strong wear, which leads to their rapid destruction, for they must be very thin in order not to impede the heat transfer too much.
In Figure 1, horizontal kores 13 in the kody 2 are shown which in part are located in the border area between the body 2 of self-lubricating material and the cast body 5.
In those cases where the self-lubricating material chosen for the body 2 is graphite, reinforcing sleeves 3 are inserted into these bores 13. As shown in Figure 3, the metal sleeves 3 receive the ends of a bracket 14 which is installed in a support pipe 15. Bores 18, 18' and 19, 19' are provided in the support pipe 15l through which the arms of the bracket 14 are led.
The ends of the support pipe 15 are fastened to the frame of the apparatus where the temperature device 1 is installed. This apparatus,such as a photocopy machine, i8 not shown in any further detail.
As can be seen from Figure 4, the support pipe 15 runs parallel to the surface 17 whose tempera-ture is to be measured, which may be a metal, a sintered material or a plastic-coated surface.
The support pipe 15 is connected with an angular spring 16 which near its free end is pressed against a pin 20. The spring 16 exerts a torque onto the support pipe 15, whereby it is ensured that the bracket 14 and thus the temperature sensing device 1 fastened to it is pressed against the surface 17.
By lifting the spring 16 off the pin 20, the tem-perature sensing device 1 can easily be removed from the surface 17, so that the temperature sensing device 1 -can be pivoted a~ound the support pipe 15, as indicated by the double arrow B in Figure 4~
Embedded in the cast body 5 are circuit ele-ments 8(Figure l~, which are wired parallel to the sensing element 6 and connected to the connecting wires ll and 12. These circuit elements may be com-posed of one or of several resistors ensuring that, even when there is a high sensor resistance due to an insufficient temperature of the surface 17, the circuit (not shown) processing the signals coming from the temperature sensing device 1 is not switched off.
On the other hand, this resistor or these resistors also ensure that surface 17 is not overheated because, independent from the surface temperature to be measured, at least some current flow takes place through this resistor or these resistors, as long as the line is not inter-rupted, ~ithout this resistor or these resistors, the circuit could not differentiate between a high sensor resistance and a line interruption, i,e., an infinite aensor re8istance, so that, in case of a line interruption, there would be the danger of surface 17 overheating, and thus of a fire caused due to this overheating.
Compared with known, non-contiguous methods of temperature measurement by means of temperature sensing devices requiring a high technical expense, the contact temperature measuring device according to the present invention shows little wear and delay.
..
The temperature sensing elements are arranged in the interior of the cylindrical probe shoe made of a non-magnetic material. The probe shoe is fastened to a free end of a support arm which is also made of a non-magnetic material, such as, e~g., aluminum, plastic or the like. The other end of the support arm is fastened to the frame of the apparatus. In the back side of the support arm, i~e., opposed to the fixing roll, a cut out is provided in which a circular magnet is installed which is divided into two halv~s along a vertical centerline. Each half of the magnet comprises a number ~f north and south pole pieces, with opposite pole pieces belng located adjacent to each other.
There is no direct contact between the sur-face to be measured of the fixing roll and the probe shoe containing the temperature sensing elements.
The toner fixing device known from German Offenlegungsschrift No 2,420,161 comprises a temperature measurin~ device for measuring the surface temperature of a roll and for controlling the heating of the roll.
This temperature measuring device is composed of a photosensitive cell with fiber optics which is arranged close to the fixing roll, and of a light source illumi-nating a fluorescent strip on the circumferential surface of the fixing roll. The intensity of the light emitted by the fluorescent strip is in indirect proportional ratio to the temperature of the strip, i.e., to the temperature of the surface of the fixing roll. The light is led to the photosensitive cell via the fiber optics. The output signal of the cell is amplified and led to a control unit controlling the current supply of a quartz lamp whichproduces the fusing of the toner on 1~6~8Zi a fusing roll of the fixing device.
In this temperature measuring unit, too, there is no direct contact between the temperature sensing element and the surface to be measured. This device is quite complicated, however, since a photosensitive cell with fiber optics and a light source for illuminating the fluorescent strip on the surface of the fixing roll to be measured are required, and it is rather accident-sensitive, because the fiber optics is easily contam-inated by toner which then causes failure of the temperature measuring device.
SUMMAR~ OF THE INVENTION
It is therefore an object of the present invention to provide an improved temperature sensing device.
Another object of the invention resides in providing an improved temperature sensing device which over a longer period of time is maintenance-free and makes possible a rapid measurement of the temperature of a moving surface.
It is also an object of the invention to provide such a temperature sensing device which is technically uncomplicated, can be inexpensively built and is relatively free of wear.
In accomplishing the foregoing objects, there has been provided in accordance with the present invention a temperature sensing element for sensing the temperature of a moving external surface, comprising: a contact body of a self-lubricating material having an exterior contact surface shaped to conform to the surface whose temperature is to be sensed, said contact body having an internal recess therein; a temperature sensing element positioned in the internal recess of said contact body;
B
a cast body of a high-temperature resistant casting material, said cast body being firmly bonded to said contact body of self-lubricating material; a contact area between said contact body and said cast body having at least one blind bore into which a reinforcing metal sleeve is inserted; a supportin~ bracket having at least one end inserted into said metal sleeve; a supporting member running parallel to the surface to be measured, said bracket being attached to said supporting member; and biasing means cooperating with a pin and connected to said supporting member for exerting a torque on said supporti.ng member for pressing the contact surface against the surface to be measured. In one preferred embodiment, the contact body is comprised of graphite, the temperature sensing element is sealed in a glass pearl which is inserted into the internal recess of the contact body, and the internal recess is lined with a heat-conductive paste to ensure a good thermal contact between the contact body and the glass pearl containing the temperature sensing element, Further objects, features and advantages of the present invention will become apparent from the detailed description of preferred embodiments which follows.
'- ix~
'BRIEF DESCRIPTION OF THE;D~A~XNGS
In the drawings:
Figure 1 is a sectional view of the temperatu,re sensing device according to the present invention;
Figure 2 is a side view of the temperature sensing device, seen in the direction of the arrow A
in Figure l;
Figure 3 is a schematic view, partly in section,-illustrating the mounting of the temperature sensing de-vice of the invention by means o~ a bracket and a support pipe; and Figure 4 is a schematic view of the arrangement of the temperature sensing device contacting the surface whose temperature is to be measured.
DETAILED DESCRIPTION OF PREFE~RED EMBODIMENTS
The invention pertains to a temperature sensing device of the type described in the introduction of the application, which is composed of a body of a self-lubricati,ng material having an outward surface which serves as the contact surface, and of a cast body of a high-temperature resistant casting material, which after casting and setting is firmly bonded to the body of self-lubricating material. The body of self-lubri-cating material serves as the fixture for the sensing element.
In one embodiment of the invention, the sensing element is sealed in a glass pearl which has been in-serted into a bore of the body of a self-lubricating material. This bore contains a heat-conductive paste ensuring a good thermal contact between the body of self-lubricating material and the glass pearl in which the sensing element is sealed~ Thus a rapid temperature measurement is made possible, since the temperature present at the contact surface of the body of self-lubricating material is led, via the heat-conductive paste, through the body of self-lubricating material and to the sensing element in the glass pearl with practically no delay. It is advisable to connect the sensing ele-ment to connecting wires which are embedded in the cast body. Via these connecting wires, the ends of which project from the cast body, the sensing element is connected to an electrical circuit containing, inter alia, an amplifier for amplifying the output signal of the sensing element to the strength required.
In a further embodiment of this invention, wired parallel to the sensing elements are circuit ele-ments which are connected to the connecting wires and embedded in the cast body~ In the area of the contact surface between the cast body and the body of self-lubricating material, bores are provided in the body of self-lubricating material which are reinforced by means of metal sleeves. Into these bores, the ends of a bracket are introduced which is supported in a pipe, parallel to the surface whose temperature is to be measured. This embodiment makes it possible to pivot the temperature sensing device around the bracket, in order to bring the contact surface of the temperature sensing device into the correct position with respect to the surface to be measured. The sensing element preferably is a negative-temperature coefficient re-sistor. The casting material used may, e.g., be sili-cone rubber.
The present invention will be explained in more detail by way of an exemplary embodiment in the attached figures of drawing.
1~6385~J
The temperature sensing device 1 which is schematically shown in Figure 1 is composed o~ a body 2 of a self-lubricating material and of a cast body 5.
Graphite is preferably used as the self-lubricating material for the body 2, but it is also possible to use a sintered material containing finely divided graphite particles, intercalated polytetrafluoro-ethylene or an alloy of soft metals, such as, e.g., bronze. In the body 2 of self-lubricating material, a bore 9 is provided into which a glass pearl 7 is inserted having its upper end extending into the cast body 5~ A sensing element 6, e.g., a negative-temperature coefficient resistor, is sealed in the glass pearl 7. Any sensing element causing either a current change or a voltage change as a reaction to temperature variations detected by the temperature sensing device 1 can be used as the sensing element in the present invention.
The outward surface of the body 2 forms a contact surface 10, the shape of which is adapted to the surface whose te~perature is to be measured, as shown in Figures 2 and 4.
The body 2 of a self-lubricating material serves as the fixture for the sensing element 6. In the bore 9, a heat-conductive paste 4 is contained which ensures a good thermal contact between the body 2 and the glass pearl 7 in which the sensing element 6 i5 included. Connecting wires 11 and 12, which are embedded in the cast body 5, lead from the sensing element 6 to the outside. It is advisable to form the ends of these connecting wires 11 and 12 as plug wires. Thus a simple plug-and-socket connection can be created between the temperature sensing device 1 and an electronic circuit for the further processing -` ~16;~827 , of the electric output signals of the sensing element 6.
This electronîc circuit is conventional and is not shown in the figures of drawing.
T~e cast body 5 is made of a high-temperature resistant casting mass, such as, e.g., a silicone rubber or a similar material having a thermal conductivity of less than a.5 W m l K l.
The thermal conductivity of the casting mass for the body 5 is low compared with the thermal con-ductivity of the materials used for producing the body 2,the thermal conductivity of the latter varying between about 4 and 250 W m l K l Due to the fact that the body 2 possesses a large contact surface lO and a small massl an excellent thermal contact is made possible between the temperature sensing device l and the moving surface 17 (Figure 4) whose temperature is to be measured, i.e., the tempera-ture chan~es of the moving surface 17 are registered with practically no delay. Since the thermal conducti-vity of the cast body 5, or respectively of the castingmass used for its production, is low, the cast body S
hardly contributes to the undesired, detrimental total thermal capacitance of the temperature sensing device l, and thus its influence on the temperature measurement is kept very small.
Due to the self-lubricating properties of the body 2, and, in the preferred embodiment, especially to the anti-friction proQerties of graphite, it is not necessary to apply a special anti-friction layer onto this body 2, which would be necessary if a conventional metal body was used as the fixture for the sensing ele-ment 6. Another disadvantage which can be avoided by using a self-lubricating material is the fact that, j ` ~
~63~
becau~e of the high temperatures of about 180C to 200C to be measured, only very few plastic materials can be used for the anti-friction layer~ Such layers are subjected to strong wear, which leads to their rapid destruction, for they must be very thin in order not to impede the heat transfer too much.
In Figure 1, horizontal kores 13 in the kody 2 are shown which in part are located in the border area between the body 2 of self-lubricating material and the cast body 5.
In those cases where the self-lubricating material chosen for the body 2 is graphite, reinforcing sleeves 3 are inserted into these bores 13. As shown in Figure 3, the metal sleeves 3 receive the ends of a bracket 14 which is installed in a support pipe 15. Bores 18, 18' and 19, 19' are provided in the support pipe 15l through which the arms of the bracket 14 are led.
The ends of the support pipe 15 are fastened to the frame of the apparatus where the temperature device 1 is installed. This apparatus,such as a photocopy machine, i8 not shown in any further detail.
As can be seen from Figure 4, the support pipe 15 runs parallel to the surface 17 whose tempera-ture is to be measured, which may be a metal, a sintered material or a plastic-coated surface.
The support pipe 15 is connected with an angular spring 16 which near its free end is pressed against a pin 20. The spring 16 exerts a torque onto the support pipe 15, whereby it is ensured that the bracket 14 and thus the temperature sensing device 1 fastened to it is pressed against the surface 17.
By lifting the spring 16 off the pin 20, the tem-perature sensing device 1 can easily be removed from the surface 17, so that the temperature sensing device 1 -can be pivoted a~ound the support pipe 15, as indicated by the double arrow B in Figure 4~
Embedded in the cast body 5 are circuit ele-ments 8(Figure l~, which are wired parallel to the sensing element 6 and connected to the connecting wires ll and 12. These circuit elements may be com-posed of one or of several resistors ensuring that, even when there is a high sensor resistance due to an insufficient temperature of the surface 17, the circuit (not shown) processing the signals coming from the temperature sensing device 1 is not switched off.
On the other hand, this resistor or these resistors also ensure that surface 17 is not overheated because, independent from the surface temperature to be measured, at least some current flow takes place through this resistor or these resistors, as long as the line is not inter-rupted, ~ithout this resistor or these resistors, the circuit could not differentiate between a high sensor resistance and a line interruption, i,e., an infinite aensor re8istance, so that, in case of a line interruption, there would be the danger of surface 17 overheating, and thus of a fire caused due to this overheating.
Compared with known, non-contiguous methods of temperature measurement by means of temperature sensing devices requiring a high technical expense, the contact temperature measuring device according to the present invention shows little wear and delay.
..
Claims (10)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A temperature sensing element for sensing the tempera-ture of a moving external surface, comprising:
a contact body of self-lubricating material having an exterior contact surface shaped to conform to the surface whose temperature is to be sensed, said contact body having an internal recess therein;
a temperature sensing element positioned in the inter-nal recess of said contact body;
a cast body of a high-temperature resistant casting material, said cast body being firmly bonded to said contact body of self-lubricating material;
a contact area between said contact body and said cast body having at least one blind bore into which a reinforcing metal sleeve is inserted;
a supporting bracket having at least one end inserted into said metal sleeve;
a supporting member running parallel to the surface to be measured, said bracket being attached to said supporting member; and biasing means cooperating with a pin and connected to said supporting member for exerting a torque on said supporting member for pressing the contact surface against the surface to be measured,
a contact body of self-lubricating material having an exterior contact surface shaped to conform to the surface whose temperature is to be sensed, said contact body having an internal recess therein;
a temperature sensing element positioned in the inter-nal recess of said contact body;
a cast body of a high-temperature resistant casting material, said cast body being firmly bonded to said contact body of self-lubricating material;
a contact area between said contact body and said cast body having at least one blind bore into which a reinforcing metal sleeve is inserted;
a supporting bracket having at least one end inserted into said metal sleeve;
a supporting member running parallel to the surface to be measured, said bracket being attached to said supporting member; and biasing means cooperating with a pin and connected to said supporting member for exerting a torque on said supporting member for pressing the contact surface against the surface to be measured,
2. A temperature sensing device as claimed in Claim 1, wherein said contact body is comprised of graphite, said temperature sensing element is sealed in a glass pearl which is inserted into said internal recess of said contact body, and wherein said internal recess is lined with a heat-conductive paste to ensure a good thermal contact between said contact body and said glass pearl containing the temperature sensing element.
3. A temperature sensing device as claimed in Claim 1, further comprising connecting wires for the sensing element embedded into said cast body, wherein the ends of said wires project from said cast body,
4. A temperature sensing device as claimed in Claim 3, further comprising at least one circuit element wired parallel to said temperature sensing element, said circuit element being connected to said connecting wires and embedded in said cast body.
5. A temperature sensing device as claimed in Claim 1, wherein said temperature sensing element comprises a negative-temperature coefficient resistor.
6. A temperature sensing device as claimed in Claim 1, wherein said casting material comprises a silicone rubber.
7. A temperature sensing device as claimed in Claim 1, wherein said contact body of a self-lubricating material comprises a sintered material containing finely divided graphite particles,
8. A temperature sensing device as claimed in Claim 1, wherein said contact body of a self-lubricating material comprises an alloy of soft metals,
9. A temperature sensing device as claimed in Claim 4, wherein the ends of the connecting wires include wire plugs.
10. A temperature sensing device as claimed in Claim 1, wherein said contact body of a self-lubricating material comprises a metallic material containing intercalated polytetrafluoroethyl-ene.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19803009108 DE3009108A1 (en) | 1980-03-10 | 1980-03-10 | TEMPERATURE PROBE |
| DEP3009108.8 | 1980-03-10 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1163827A true CA1163827A (en) | 1984-03-20 |
Family
ID=6096735
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000371540A Expired CA1163827A (en) | 1980-03-10 | 1981-02-23 | Temperature sensing device |
Country Status (5)
| Country | Link |
|---|---|
| EP (1) | EP0036957A3 (en) |
| JP (1) | JPS56140223A (en) |
| CA (1) | CA1163827A (en) |
| DE (1) | DE3009108A1 (en) |
| ES (1) | ES8202147A1 (en) |
Families Citing this family (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3220541A1 (en) * | 1982-06-01 | 1983-12-01 | Siemens AG, 1000 Berlin und 8000 München | Holder for an electric temperature sensor |
| DE9012823U1 (en) * | 1990-09-06 | 1990-11-08 | Siemens Ag, 8000 Muenchen, De | |
| US5123752A (en) * | 1991-04-15 | 1992-06-23 | Eastman Kodak Company | Wear resistant temperature sensing device |
| JP2002124305A (en) * | 2000-10-13 | 2002-04-26 | Matsushita Electric Ind Co Ltd | Battery pack |
| FI126956B (en) | 2010-10-14 | 2017-08-31 | Janesko Oy | Method and gauge for measuring temperature |
| FI125815B (en) | 2010-10-14 | 2016-02-29 | Janesko Oy | Measurement detector for temperature measurement |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3175178A (en) * | 1963-01-08 | 1965-03-23 | King Seeley Thermos Co | Electric temperature probe |
| US3357249A (en) * | 1966-01-03 | 1967-12-12 | Xerox Corp | Temperature sensor |
| US3968343A (en) * | 1974-10-29 | 1976-07-06 | Xerox Corporation | Fuser roll temperature regulator probe |
| US4000394A (en) * | 1975-08-28 | 1976-12-28 | Xerox Corporation | Fuser thermal detector |
| CH607722A5 (en) * | 1976-12-13 | 1978-10-13 | Zellweger Uster Ag | Device for continuous measurement of the temperature of moving and heated material webs |
-
1980
- 1980-03-10 DE DE19803009108 patent/DE3009108A1/en not_active Withdrawn
-
1981
- 1981-02-23 CA CA000371540A patent/CA1163827A/en not_active Expired
- 1981-03-02 EP EP81101488A patent/EP0036957A3/en not_active Withdrawn
- 1981-03-06 ES ES500188A patent/ES8202147A1/en not_active Expired
- 1981-03-10 JP JP3325881A patent/JPS56140223A/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| ES500188A0 (en) | 1982-01-16 |
| ES8202147A1 (en) | 1982-01-16 |
| EP0036957A2 (en) | 1981-10-07 |
| JPS56140223A (en) | 1981-11-02 |
| DE3009108A1 (en) | 1981-09-24 |
| EP0036957A3 (en) | 1983-09-07 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |