Method for operating a temperature calibrator having a cooling unit

Abstract

To simplify a method of operating a temperature calibrator 1 for calibrating a temperature sensor 10, the temperature calibrator having a calibration block 11 for the temperature sensor to be inserted, heating means 12 for heating the calibration block, and a cooling unit 13 for cooling the calibration block.SOLUTION: A temperature calibrator is provided with an actuator 14 configured to bring a cooling unit 13 into thermal conduction contact with a calibration block while cooling and to be spatially separated from the calibration block 11 while heating by forming an air gap 15.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The invention relates to a method for operating a temperature calibrator for calibrating a temperature sensor, the temperature calibrator comprising a calibration block into which a temperature sensor is inserted, heating means for heating the calibration block and a cooling unit for cooling the calibration block. The invention further relates to a temperature calibrator for calibrating a temperature sensor, which can be operated using the method according to the invention. [Background technology]

[0002] From EP 2 074 374 or EP 3 441 709 a temperature calibrator is known, by means of which a temperature sensor can be calibrated, which has a calibration block into which the temperature sensor can be inserted, which has heating means and further has a cooling unit, whereby calibration is carried out both at high temperatures well above 0° C. and at low temperatures below 0° C.

[0003] The cooling unit has a Stirling motor which is usually operated with helium gas. When approaching a calibration temperature, for example above 50° C., it must be ensured that the helium gas is not heated above this temperature, since this could damage the Stirling motor. In order to avoid damage to the Stirling motor and thus to the entire cooling unit, a so-called thermosiphon is used, in which the thermal coupling between the cooling unit and the calibration block is made possible via a cold medium which operates the thermosiphon. The thermosiphon thus extends between the calibration block and the cooling unit, and on the side of the thermosiphon which is located at the cooling unit the cold medium is condensed and on the side of the thermosiphon which is located at the calibration block the cold medium is vaporized again. This allows the calibration block to be brought to the required low temperature, for example down to −60° C. If the calibration block is heated by the heating means, then the cooling unit is stopped, so that the cold medium can escape to the external chamber, so that the thermosiphon can also be kept correspondingly undamaged.

[0004] Thus, for thermal isolation between the heated calibration block and the cooling unit, the thermosiphon forms a coupling member that reliably prevents overheating of the Stirling motor of the cooling unit when the cooling medium is transferred to the external chamber. Unfortunately, however, the use of a thermosiphon is necessary, which complicates the construction of the temperature calibrator and the implementation of the method, especially when changing between high and low temperatures. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] European Patent No. 2074374 [Patent Document 2] European Patent Application Publication No. 3441709 Summary of the Invention [Problem to be solved by the invention]

[0006] The object of the invention is to simplify the method for operating a temperature calibrator according to claim 1, and a further object of the invention is to simplify the design of a temperature calibrator according to claim 7. In particular, it is an object of the invention to avoid the use of a thermosiphon in a heatable and coolable temperature calibrator, and in this respect it is a further object of the invention to avoid the use of an external container for the cooling and heating medium of the thermosiphon. [Means for solving the problem]

[0007] This object is achieved starting from a method according to claim 1 and a temperature calibrator according to claim 7 in conjunction with the respective described features. Advantageous developments of the invention are described in the dependent claims.

[0008] To carry out the method according to the invention, the following: an actuator is provided, the actuator bringing the cooling unit into thermally conductive contact with the calibration block when cooling and spatially separating the cooling unit from the calibration block by forming an air gap when heating; Includes steps.

[0009] When carrying out the method for operating a temperature calibrator according to the invention, it is possible, simply by controlling the actuators, to form an air gap to protect the cooling unit from overheating, and when the temperature of the calibration block is correspondingly high, to enlarge the air gap so that the cooling unit is not heated above a critical temperature. Thus, a thermosiphon for operating the temperature calibrator can be omitted even at low temperatures well below 0° C., which simplifies the operation of the temperature calibrator and in particular its technical construction, which involves fewer components.

[0010] Advantageously, the cooling unit comprises a cooling device with a cooling head, in which case the cooling device in particular comprises a Stirling motor, in which case the cooling head can be cooled by the cooling device, in which case the cooling head alone or together with the cooling device is movable by an actuator relative to the calibration block, so that an air gap is created or the size of the air gap is changed or a heat-conducting contact is established between the calibration block and the cooling unit.

[0011] The method is in particular executed by a control unit, which controls the actuator, thereby controlling the gap between the cooling unit and the calibration block, whereby the actuator can also provide information about the size of the gap to the control unit, so that the control unit receives information about how large the gap currently is or whether a thermally conductive contact has been established between the calibration block and the cooling unit.

[0012] It is furthermore advantageous if a temperature measuring sensor is provided, which is arranged in particular in, on or in the region of the cooling head, with the temperature measuring sensor recording temperature values ​​and outputting them, in particular to a control unit, in which case the gap can be controlled exclusively via the temperature information of the temperature measuring sensor, or the control unit additionally takes into account information about the size of the gap, which is output, for example, by an actuator, as described above.

[0013] The method according to the invention can be further improved by setting a critical temperature of the cooling head, above which an air gap is created or enlarged, below which the heat-conducting contact between the cooling unit and the calibration block is re-established. The critical temperature can correspond to the temperature at which the cooling unit and in particular the cooling equipment in the form of a Stirling engine may be maximally heated. In particular, a Stirling engine with helium as cooling medium should not be heated above 50° C., so that this temperature exemplarily forms the critical temperature.

[0014] The actuator may be configured such that an air gap is generated, whereby it has a fixed value or the air gap is eliminated, in particular such that a thermally conductive contact is created between the cooling unit and the calibration block by indirect or direct solid contact. Moreover, in this case, it is also conceivable that the control unit uses the actuator to adaptively control the air gap between the cooling unit and the calibration block, such that the cooling unit and in particular the cooling head are maintained at a critical temperature or at a temperature slightly below the critical temperature before, during and / or after heating of the calibration block. The smaller the temperature difference between the calibration block and the cooling unit, the smaller the air gap can be selected and in particular adaptively controlled.

[0015] The invention further relates to a temperature calibrator for calibrating a temperature sensor, comprising a calibration block into which a temperature sensor can be inserted, heating means capable of heating the calibration block, and a cooling unit capable of cooling the calibration block, in which an actuator is provided by means of which an air gap between the calibration block and the cooling unit can be created and / or set.

[0016] The actuator may be configured as a structural unit together with and / or comprising the cooling unit, or the actuator has a connection to the cooling unit for spatially displacing the cooling unit. The actuator and the cooling unit may be configured in the same structure, or the actuator forms a movable coupling between the cooling unit and the calibration block. In this respect, it is also conceivable that the actuator is arranged in contact with or within the temperature calibrator, and that the cooling unit together with the actuator is movable relative to the calibration block. In this respect, it is also conceivable that the calibration block is displaced or moved relative to the cooling unit.

[0017] In this case, the gap can be set such that the cooling unit can be in thermally conductive contact with the calibration block when cooling, and the gap can be created or enlarged by spatially separating the cooling unit from the calibration block when heating. To set or control the gap, the temperature calibrator and / or the cooling unit have a control unit, which can control, inter alia, the actuator.

[0018] The cooling unit preferably has a cooling head, which can be in thermally conductive contact with the calibration block, on which a clamping ring and / or an insulating ring are arranged and / or the thermally conductive contact is formed via the clamping ring. The cooling head can thus be in direct solid contact with the cooling unit, or the thermally conductive contact can be formed at least indirectly via a further element, for example a clamping ring. The insulating ring can surround the clamping ring radially around the outside, the insulating ring preferably having a circumferential pot or collar which penetrates into an annular gap in the calibration block or surrounds the calibration block, so that the cooling head of the cooling unit remains essentially insulated despite the presence of an air gap.

[0019] It is furthermore advantageous if a temperature measuring sensor is arranged in or on the cooling head, in particular the temperature measuring sensor can be accommodated in a clamping ring. In this case, the temperature measuring sensor can transmit a temperature value to the control, so that the gap between the cooling unit or the cooling head and the calibration block can be controlled via the temperature value. Furthermore, the actuator can have a distance measuring unit, by means of which the value of the gap can be transmitted to the control.

[0020] The calibration block may further advantageously have or form a calibration sleeve, so that a contact between the cooling unit, in particular the cooling head, and the calibration sleeve, preferably directly, takes place. In this case, the heating means may for example surround the calibration sleeve or the calibration volume and form a receiving area for receiving the calibration sleeve in the calibration block, so that when the calibration block, in particular the calibration sleeve of the calibration block, is heated, heat can be introduced directly into the sleeve.

[0021] The actuator may form the lifting device in various ways: for example, the actuator may comprise a lifting magnet, a spindle nut unit, a stepping motor, a piezo motor, a motor transmission unit or a pneumatic or hydraulic unit.

[0022] Further means for improving the present invention will now be described in detail with reference to the drawings, together with a description of preferred embodiments of the present invention. [Brief description of the drawings]

[0023] [Figure 1] 1 shows a temperature calibrator having a calibration block, a cooling unit and an actuator, where thermally conductive contact is made between the calibration block and the cooling unit. [Diagram 2] FIG. 2 shows a temperature calibrator according to FIG. 1, where an air gap is created between the cooling unit and the calibrator. [Diagram 3]FIG. 2 shows the temperature profile of the calibration block and the temperature profile of the cooling unit over time, where the heating run, the cooling run and the set gap between the cooling unit and the calibration block over time are also plotted. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] In Figures 1 and 2 a temperature calibrator 1 is shown diagrammatically, which comprises a calibration block 11 with a hollow cylindrical calibration volume and a calibration sleeve 22 inserted in the calibration volume. Outside the calibration block 11 there are located heating means 12, for example in the form of a heating sheet, in which case other forms of heating means may also be used, in particular resistive heating. In this case the calibration block 11 is surrounded, except for the bottom surface, by an insulator 23 with a number of insulating elements.

[0025] On the bottom side, the calibration block 11 has a cooling contact surface 24, with which the cooling unit 13 can be in thermally conductive contact. For this purpose, the cooling unit 13 has a cooling head 17, which can be in contact with the cooling contact surface 24 via a clamping ring 20 mounted on the cooling head 17, as shown in Fig. 1. In contrast, Fig. 2 shows an air gap 15 between the cooling head 17 or the clamping ring 20 and the cooling contact surface 24.

[0026] An actuator 14 is used to create a heat-conducting contact according to Fig. 1 or a gap 15 according to Fig. 2 between the cooling head 17 or the clamping ring 20 of the cooling unit 13 and the cooling contact surface 24 of the calibration block 11. By means of the actuator 14, for example the cooling unit 13 and in this respect also the cooling head 17 together with the clamping ring 20 can be moved up and down, so that the gap 15 is created or a heat-conducting contact is established with the cooling contact surface 24 in the normally stationary calibration block 11. The actuator 14 is only shown diagrammatically and can be configured in various ways, in particular as a reciprocating device which can be controlled by a control 18 of the temperature calibrator 1, in which case in particular the actuator 14 and the control 18 are components of the temperature calibrator 1.

[0027] The cooling unit 13 has a temperature measuring sensor 19. The temperature measuring sensor 19 is shown arranged, for example, in a clamping ring 20, the temperature measuring sensor 19 can also be attached in other ways in or in the area of ​​the cooling head 17. The temperature measuring sensor 19 provides a temperature value which can be recorded by the control 18. Depending on the temperature of the cooling head 17 which can be determined in this way, the control 18 can control the actuator 14 so that the cooling head 17 and thus the cooling unit 13 do not exceed a critical temperature. The higher the temperature of the calibration block 11, the higher the temperature in or at the surface of the cooling head 17 detected by the temperature measuring sensor 19, so that by appropriately controlling the actuator 14, the gap 15 is also set larger via the control 18. The heating of the calibration block 11 is performed in this case by the heating means 12. The heating means 12 can heat the calibration block 11 and thus also the cooling contact surface 24 above a critical temperature. To avoid heating of the cooling head 17 above a critical temperature, e.g. 50°C, the gap 15 can be suitably enlarged by the actuator 14, thereby weakening the heat conduction from the heated calibration block 11 to the cooling head 17 and thus to the cooling unit 13.

[0028] Around the periphery of the cooling head 17, an insulating ring 21 is shown that is configured in a pot-like manner and can enter into an annular groove 25 machined in the insulator 23 of the calibration block 11. This ensures that the effects of freezing on the cooling head 17 are reduced to a minimum when the temperature falls below the freezing point.

[0029] The calibration block 11 is formed essentially by a calibration volume into which the calibration sleeve 22 is inserted, which can be removed in a known manner from the calibration volume, so that the calibration sleeve can be exchanged, for example, for different configurations. The calibration sleeve 22 is machined in the center with a hole 26 into which the temperature sensor 10 is inserted. In the lower area facing the cooling contact surface 24, the calibration sleeve 22 has a smaller diameter, so that an annular gap 27 is formed, which further transitions into a bottom gap between the calibration sleeve 22 and the inside of the cooling block 11. The bottom gap is formed, for example, by a ring or, for example, by a circumferential projection 28, which ensures the bottom gap on the lower side. Thus, a homogeneous temperature profile can be generated in the calibration block 11, and in particular in the calibration sleeve 22, especially during cooling. In particular, when the calibration block 11 is cooled via the cooling contact surface 24, the area in which the temperature sensor 10 is located is not cooled too strongly, while the remaining area on the upper side of the calibration sleeve 22 still has a higher temperature.

[0030] FIG. 3 shows a schematic diagram of the temperature profile of the cooling head and calibration block over time, where temperature is indicated by T on the vertical axis, whereas time is indicated by t on the horizontal axis.

[0031] The temperature versus time diagram is the temperature of the calibration block T BL and the temperature of the cooling head T KK According to the exemplary profile, the temperature T BL is the ambient temperature T U Starting from the first measured temperature T M1 The temperature is then increased to the measured temperature T M1 is the critical temperature T K exceeds the critical temperature T K The cold head is still in contact with the cold contact surface of the calibration block until the critical temperature T is reached. The contact position is represented in the diagram by a bar at the position I of solid contact between the calibration block and the cold head. KWhen the measured temperature T is reached, the actuator moves the cooling head so that an air gap is created, as shown by the bar at position II, at which point there is an air gap between the calibration block and the cooling head. M1 After the duration of and subsequent cooling of the calibration block, the critical temperature T K The subsequent measured temperature T may again fall below 0° C. and may fall below 0° C. as a cooling temperature. M2 Until position I with solid contact between the cooling head and the calibration block is obtained again.

[0032] The following sequence shows the ambient temperature T U Once again, the critical temperature T K Reaching and Exceeding the Standards of Proofreading Book T BL The temperature rises again to the critical temperature T K is exceeded, finally position II is set again with an air gap between the calibration block and the cooling head.

[0033] Corresponding to the temperature profile and corresponding to the set air gap or the set solid contact, a heating operation H is carried out which is characterized by the bar profile H, and during cooling, in a cooling operation K, the bar profile K in the adjacent diagram is carried out.

[0034] With the illustrated settings of the positions of both the solid contact I and the air gap II, the cooling head reaches a critical temperature T K It becomes clear that the critical temperature cannot be exceeded because whenever the calibration block exceeds a critical temperature, the solid contact is released and an air gap is established.

[0035] Thereby, a thermosiphon between the cooling unit and the calibration block is no longer required, nevertheless effectively avoiding damage to the cooling unit with the Stirling motor.

[0036] The invention is not limited in its implementation to the preferred embodiment described above, but rather can be implemented in several ways using the means shown, even if in principle in other types of configurations. All features and / or advantages, including structural details or spatial arrangements, which are evident from the claims, the description or the drawings, may be important to the invention, either alone or in various combinations. This application relates to the invention described in the claims, but also includes the following as other aspects. 1. A method of operating a temperature calibrator (1) for calibrating a temperature sensor (10), comprising the steps of: A temperature calibrator (1) comprising a calibration block (11) in which a temperature sensor (10) is introduced, a heating means (12) for heating the calibration block (11), and a cooling unit (13) for cooling the calibration block (11), An actuator (14) is provided, and the actuator (14) controls the cooling unit (13) to When cooled, it is placed in thermally conductive contact with the calibration block (11); Upon heating, a gap (15) is formed to spatially separate the calibration block (11). A method comprising: 2. 2. The method according to claim 1, wherein the cooling unit (13) comprises a cold equipment (16) having a cooling head (17), the cooling head (17) being coolable by the cold equipment (16), and wherein at least the cooling head (17), or the cooling head (17) together with the cold equipment (16), is moved relative to the calibration block (11) by an actuator (14). 3. 3. The method according to claim 1 or 2, characterized in that a control unit (18) is provided, and the control unit (18) controls the actuator (14) to thereby control the gap (15) between the cooling unit (13) and the calibration block (11). 4. 4. The method according to any one of claims 1 to 3, characterized in that a temperature measuring sensor (19) is provided, in particular in or in contact with or in the region of the cooling head (17), by means of which temperature values ​​are recorded and output, in particular to the control unit (18). 5. The critical temperature (T K ) is set, and when the critical temperature is exceeded, voids (15) are generated or expanded, and the critical temperature (T K ), re-establishing heat-conducting contact between the cooling unit (13) and the calibration block (11). 6. 10. The method according to claim 9, wherein the controller (18) is adapted to use the actuator (14) to adjust the gap (15) between the cooling unit (13) and the calibration block (11) such that the cooling unit (13), in particular the cooling head (17), is maintained at or just below a critical temperature before, during and / or after heating of the calibration block (11). 7. A temperature calibrator (1) for calibrating a temperature sensor (10), comprising: A temperature calibrator (1) comprising: a calibration block (11) into which a temperature sensor (10) can be inserted; a heating means (12) capable of heating the calibration block (11); and a cooling unit (13) capable of cooling the calibration block (11); A temperature calibrator (1), characterized in that an actuator (14) is provided, by means of which a gap (15) can be created and / or set between the calibration block (11) and the cooling unit (13). 8. A temperature calibrator (1) as described in any one of the above, characterized in that the gap (15) can be set so that the cooling unit (13) can be in thermally conductive contact with the calibration block (11) during cooling, and the gap (15) can be created or enlarged by spatially separating the cooling unit (13) from the calibration block (11) during heating. 9. The temperature calibrator (1) according to any one of the above claims, characterized in that the cooling unit (13) has a cooling head (17), which can be brought into thermally conductive contact with the calibration block (11), and a clamping ring (20) and / or an insulating ring (21) are arranged on the cooling head (17), and / or the thermally conductive contact is formed via the clamping ring (20). 10. A temperature calibrator (1) according to any one of the above claims, characterized in that a temperature measuring sensor (19) is arranged in or in contact with the cooling head (17) and / or that the temperature measuring sensor (19) is arranged in the clamping ring (20). 11. The temperature calibrator (1) according to any one of the above claims, characterized in that the actuator (14) comprises a lifting device and / or a lifting magnet and / or a spindle nut unit and / or a stepping motor and / or a piezo motor and / or a motor transmission unit and / or a pneumatic unit or a hydraulic unit. [Explanation of symbols]

[0037] 1 Temperature calibrator 10 Temperature Sensor 11 Calibration Block 12 Heating means 13 Cooling unit 14 Actuator 15 void 16 Cooling equipment 17 Cooling Head 18 Control Unit 19 Temperature measurement sensor 20 Fastening ring 21 Insulation ring 22 Calibration Sleeve 23 Insulators 24 Cooling contact surface 25 Annular groove 26 holes 27 Annular gap 28 Protrusion T temperature T K critical temperature T BL Calibration Block Temperature T KK Cooling head temperature T U Ambient temperature T M1 Measurement temperature T M2 Measurement temperature t time I Solid contact position II Location of the gap H Heating operation K Cooling operation

Claims

1. A method of operating a temperature calibrator (1) for calibrating a temperature sensor (10), comprising the steps of: A method, comprising: a temperature calibrator (1) comprising a calibration block (11) in which a temperature sensor (10) is introduced, heating means (12) for heating the calibration block (11), and a cooling unit (13) for cooling the calibration block (11), The calibration block (11) is formed with a cooling contact surface (24), An actuator (14) is provided, and the actuator (14) controls the cooling unit (13) to during cooling, in thermally conductive contact with the cooling contact surface (24) of the calibration block (11); Upon heating, a gap (15) is formed to spatially separate the calibration block (11) from the cooling contact surface (24). A method comprising:

2. 2. The method according to claim 1, characterized in that the cooling unit (13) has a cold equipment (16) with a cooling head (17), the cooling head (17) being coolable by the cold equipment (16), and at least the cooling head (17), or the cooling head (17) together with the cold equipment (16), is moved relative to the calibration block (11) by an actuator (14).

3. 2. The method according to claim 1, further comprising providing a control unit (18) by which the actuator (14) is controlled to thereby control the gap (15) between the cooling unit (13) and the calibration block (11).

4. 3. The method according to claim 1 or 2, characterized in that a temperature measuring sensor (19) is provided in or on or in the area of ​​the cooling head (17), by means of which temperature values ​​are recorded and output to the control unit (18).

5. The critical temperature (T Ｋ ) is set, and when the critical temperature is exceeded, voids (15) are generated or expanded, and the critical temperature (T Ｋ 3. The method according to claim 1, further comprising re-establishing heat-conducting contact between the cooling unit (13) and the calibration block (11) when the temperature drops below the reference temperature (Tc) of the calibration block (11).

6. 4. The method according to claim 1 or 3, characterized in that the control unit (18) uses the actuator (14) to track the gap (15) between the cooling unit (13) and the calibration block (11) such that the cooling unit (13) or the cooling head (17) is maintained at a critical temperature or at a temperature just below the critical temperature before, during and / or after heating of the calibration block (11).

7. A temperature calibrator (1) for calibrating a temperature sensor (10), comprising: A temperature calibrator (1) comprising: a calibration block (11) into which a temperature sensor (10) can be inserted; a heating means (12) capable of heating the calibration block (11); and a cooling unit (13) capable of cooling the calibration block (11), The calibration block (11) has a cooling contact surface (24); A temperature calibrator (1), characterized in that an actuator (14) is provided, by means of which a gap (15) can be generated and / or set between a cooling contact surface (24) of the calibration block (11) and a cooling unit (13).

8. 8. The temperature calibrator (1) of claim 7, characterized in that the gap (15) can be set such that the cooling unit (13) can be in thermally conductive contact with the calibration block (11) during cooling, and the gap (15) can be created or enlarged by spatially separating the cooling unit (13) from the calibration block (11) during heating.

9. 8. The temperature calibrator (1) according to claim 7, characterized in that the cooling unit (13) has a cooling head (17), which can be brought into thermally conductive contact with the calibration block (11), and a clamping ring (20) and / or an insulating ring (21) are arranged on the cooling head (17), and the thermally conductive contact is formed via the clamping ring (20).

10. 10. A temperature calibrator (1) according to claim 7 or 9, characterized in that a temperature measuring sensor (19) is arranged in or in contact with the cooling head (17) and / or that the temperature measuring sensor (19) is arranged in the clamping ring (20).

11. 9. The temperature calibrator (1) according to claim 7 or 8, characterized in that the actuator (14) comprises a lifting device and / or a lifting magnet and / or a spindle nut unit and / or a stepping motor and / or a piezo motor and / or a motor transmission unit and / or a pneumatic or hydraulic unit.

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