METHOD FOR OPERATING A TEMPERATURE CALIBRATOR WITH COOLING UNIT

Abstract

A method of operating a temperature calibrator for calibrating a temperature sensor having a calibration block into which the temperature sensor is introduced and having a heating means by which the calibration block is heated and having a cooling unit by which the calibration block is cooled and an actuator by which the cooling unit is brought into thermal conductivity contact with the calibration block during cooling and is spatially separated from the calibration block during heating while forming an air gap. The invention further relates to a temperature calibrator is also disclosed.

Claims

1. A method of operating a temperature calibrator for calibrating a temperature sensor including: a calibration block into which the temperature sensor is introduced; a heating means by which the calibration block is heated; a cooling unit by which the calibration block is cooled; and an actuator, the method comprising bringing the cooling unit into thermal conductivity contact with the calibration block during cooling and bringing the cooling unit to be spatially separated from the calibration block on heating while forming an air gap by the actuator.

2. The method according to claim 1, wherein the cooling unit has a refrigeration unit having a cooling head that Is coolable by the refrigeration unit, the method further comprising moving at least the cooling head or the cooling head together with the refrigeration unit being relative to the calibration block by the actuator.

3. The method according to claim 1, further comprising regulating the air gap between the cooling unit and the calibration block by regulating the actuator with a controller.

4. The method according to claim 1, wherein a temperature sensing element is configured to be disposed in, at, or in the region of the cooling head, the method further comprising recording a temperature value by the temperature sensing element and outputting the temperature value to the controller.

5. The method according to claim 1, further defining a critical temperature of the cooling head, with the air gap being generated or increased in size on an exceeding of the critical temperature and with the thermal conductivity contact being again established between the cooling unit and the calibration block on a falling below of the critical temperature.

6. The method according to claim 5, further comprising tracking by the controller the air gap between the cooling unit and the calibration block by means of the actuator before, during, and/or after a heating of the calibration block such that the cooling unit including the cooling head remains at the critical temperature or slightly below the critical temperature.

7. A temperature calibrator for calibrating a temperature sensor, comprising: a calibration block into which the temperature sensor is introduced; a heating means by which the calibration block is heatable; a cooling unit by which the calibration block is coolable; and an actuator is configured to generate and/or set an air gap between the calibration block and the cooling unit.

8. The temperature calibrator according to claim 7, wherein the air gap can be set such that the cooling unit can be brought into thermal conductivity contact with the calibration block during the cooling and the air gap can be generated or increased in size by means of a spatial separation of the cooling unit from the calibration block during the heating.

9. The temperature calibrator according to claim 7, wherein the cooling unit has a cooling head that can be brought into thermal conductivity contact with the calibration block, with a locking ring and/or an insulating ring being arranged on the cooling head and/or with the thermal conductivity contact being formed via the locking ring.

10. The temperature calibrator according to claim 9, wherein a temperature sensing element is disposed in or at the cooling head and/or the temperature sensing element is disposed in the locking ring.

11. The temperature calibrator according to claim 7, wherein the actuator has a lifting device and/or a lifting solenoid and/or a spindle and nut unit and/or a stepper motor and/or a piezo motor and/or a motor transmission unit and/or a pneumatic or hydraulic unit.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Further measures improving the invention will be shown in more detail below together with the description of a preferred embodiment of the invention with reference to the Figures. There are shown:

[0022] FIG. 1 a temperature calibrator having a calibration block, a cooling unit, and an actuator, with a thermal conductivity contact being present between the calibration block and the cooling unit;

[0023] FIG. 2 a temperature calibrator in accordance with FIG. 1, with there being an air gap between the cooling unit and the calibrator; and

[0024] FIG. 3 the view of a temperature progression of the calibration block and of the temperature progression of the cooling unit, with both a heating operation, a cooling operation, and the set gap between the cooling unit and the calibration block over time furthermore being entered.

DETAILED DESCRIPTION OF THE INVENTION

[0025] A temperature calibrator 1 is shown in a schematic manner in FIGS. 1 and 2 and the temperature calibrator 1 has a calibration block 11 comprising a hollow cylindrical calibration volume and a calibration sleeve 22 inserted therein. A heating means 12, for example in the form of a heating film, with other forms of heating means, in particular resistance heaters, in particular also being able to be used, is located at the outer side at the calibration block 11. The calibration block 11 is here surrounded, except at a bottom side, by an insulation 23 comprising a plurality of insulating elements.

[0026] At the base side, the calibration block 11 has a cooling contact surface 24 and the cooling unit 13 can be brought into thermal conductivity contact with the cooling contact surface 24. The cooling unit 13 has a cooling head 17 for this purpose that can be brought into contact with the cooling contact surface 24 by means of a locking ring 20 attached to the cooling head 17, as shown in FIG. 1. FIG. 2, in contrast, shows an air gap 15 between the cooling head 17 or the locking ring 20 and the cooling contact surface 24.

[0027] An actuator 14 serves to establish either the thermal conductivity contact in accordance with FIG. 1 or the air gap 15 in accordance with FIG. 2 between the cooling head 17 or the locking ring 20 of the cooling unit 13 and the cooling contact surface 24 of the calibration block 11, by which actuator 14 by way of example the cooling unit 13 and to this extent also the cooling head 17 with the locking ring 20 can be traveled up and down to form the gap or to establish the thermal conductivity contact with the cooling contact surface 24 with an otherwise stationary calibration block 11. The actuator 14 is only shown schematically and it can be designed in a different manner, in particular as a lifting device that can be controlled by a controller 18 of the temperature calibrator 1, with the actuator 14 and the controller 18 in particular being components of the temperature calibrator 1.

[0028] The cooling unit 13 has a temperature sensing element 19 that is shown by way of example arranged in the locking ring 20 and the temperature sensing element 19 can also be attached in another manner in or in the region of the cooling head 17. The temperature sensing element 19 provides a temperature value that can be received by the controller 18. Depending on the temperature of the cooling head 17 that can be determined in this manner, the actuator 14 can be controlled by means of the controller 18 such that the cooling head 17 and thus the cooling unit 13 do not exceed a critical temperature. The greater the temperature of the calibration block 11 is, the greater the temperature in or at the cooling head 17 also becomes that is sensed by the temperature sensing element 19 and the greater the air gap 15 is set by the controller 18 as a consequence thereof in that the actuator 14 is correspondingly controlled. The heating of the calibration block 11 takes place by means of the heating means 12 here that can heat the calibration block 11 and thus also the cooling contact surface 24 above a critical temperature. To avoid a heating of the cooing head 17 above the critical temperature, for example 50° C., the air gap 15 can be correspondingly increased in size by means of the actuator 14 to weaken the heat transfer from the heated calibration block 11 into the cooling head 17 and thus into the cooling unit 13.

[0029] An approximately pot-shaped insulating ring 21 is shown around the cooling head 17 and can dip into an annular groove 25 that is introduced into an insulation 23 of the calibration block 11. The effect of ice formation at the cooling head 17 is thus minimized if it adopts temperatures below freezing point.

[0030] The calibration block 11 is substantially formed by a calibration volume into which the calibration sleeve 22 is inserted, with the calibration sleeve being able to be removed from the calibration volume in a manner known per se to swap it, for example, with different embodiments. A bore 26 into which the temperature sensor 10 is introduced is inserted centrally in the calibration sleeve 22. The calibration sleeve 22 has a smaller diameter in the lower region facing in the direction toward the cooling contact surface 24, whereby an annular gap 27 is formed that moreover merges into a base gap between the calibration sleeve 22 and the inner side of the cooling block 11. The base gap is generated, for example, by a ring or by a, for example, peripheral projection 28, that secures the base gap at the lower side. A uniform temperature profile can thus be generated in particular on a cooling in the calibration block 11 and in particular in the calibration sleeve 22. The region in which the temperature sensor 10 is arranged in particular does not cool down excessively on the cooling of the calibration block 11 over the cooling contact surface 24, whereas the upper, remaining region of the calibration sleeve 22 still has a higher temperature.

[0031] FIG. 3 shows the progression of temperatures of the cooling head and of the calibration block over time in a schematic manner, with the temperature on the ordinate being called T while the time on the abscissa is called t.

[0032] The diagram of the temperature over time shows two temperature progressions that are formed by the temperature T.sub.BL of the calibration block and the temperature T.sub.KK of the cooling head. If the temperature T.sub.BL of the cooling block is heated in accordance with the exemplary progression to a first measurement temperature T.sub.M1, starting from an environmental temperature T.sub.U, the measurement temperature T.sub.M1 exceeds the critical temperature T.sub.K. Until the critical temperature T.sub.K is reached, the cooling head is still in a contact position with the cooling contact surface of the calibration block that is shown in the diagram by bars at a position I in solid state contact between the calibration block and the cooling head. On the reaching of the critical temperature T.sub.K, the actuator travels the cooling head such that the air gap is produced, shown by bars at the position II and to this extent with an air gap between the calibration block and the cooling head. After a holding period of the measurement temperature T.sub.M1 and a further cooling of the calibration bock, the critical temperature T.sub.K is again fallen below and the position I with a solid state contact between the cooling head and the calibration block is again reached up to a further measurement temperature T.sub.M2 that can be below 0° C. as the cooling temperature.

[0033] The further progression again shows an increase in the temperature of the calibration block T.sub.BL that again reaches and exceeds the critical temperature T.sub.K, beyond the environmental temperature T.sub.U, at which finally the position II is again adopted with the air gap between the calibration block and the cooling head.

[0034] A heating operation H, marked by the bar progression at H takes place corresponding to the temperature progression and corresponding to the set air gap or to the set solid state contact and a bar progression at K takes place in cooling operation K in a secondary diagram.

[0035] It becomes clear by the shown setting of the two positions of solid state contact I and air gap II that the cooling head cannot exceed the critical temperature T.sub.K since whenever the calibration block exceeds the critical temperature, the solid state contact is released and the air gap is set.

[0036] Damage to the cooling unit, comprising a Sterling engine, is thus effectively avoided even though a thermosiphon between the cooling unit and the calibration block is no longer required.

[0037] The invention is not restricted in its design to the preferred embodiment specified above. A number of variants is rather conceivable that also makes use of the solution shown with generally differently designed embodiments. All the features and/or advantages, including any construction details or spatial arrangements, originating from the claims, the description, or the drawings can be essential to the invention both per se and in the most varied combinations.

REFERENCE NUMERAL LIST

[0038] 1 temperature calibrator [0039] 10 temperature sensor [0040] 11 calibration block [0041] 12 heating means [0042] 13 cooling unit [0043] 14 actuator [0044] 15 air gap [0045] 16 refrigeration unit [0046] 17 cooling head [0047] 18 controller [0048] 19 temperature sensing element [0049] 20 locking ring [0050] 21 insulating ring [0051] 22 calibration sleeve [0052] 23 insulation [0053] 24 cooling contact surface [0054] 25 annular groove [0055] 26 bore [0056] 27 annular gap [0057] 28 projection: [0058] T temperature [0059] T.sub.K critical temperature [0060] T.sub.BL temperature of the calibration block [0061] T.sub.KK temperature of the cooling head [0062] T.sub.U environmental temperature [0063] T.sub.M1 measurement temperature [0064] T.sub.M2 measurement temperature [0065] t time [0066] I position of the solid state contact [0067] II position for the air gap [0068] H heating operation [0069] K cooling operation