EP4194096B1 - Method for operating a laboratory apparatus cooled by means of a flammable refrigerant - Google Patents

Description

The invention relates to a method for operating a laboratory device cooled by means of a flammable refrigerant and a laboratory device which is cooled by means of a flammable refrigerant.

Refrigerated laboratory equipment must meet various safety requirements. For example, the DIN EN 61010-2-011 standard specifies safety regulations for electrical measuring, control, regulation and laboratory devices. In particular, it should be ensured that the design and construction of cooling devices provides sufficient protection against certain hazards for users, bystanders, trained service personnel and the surrounding areas from the specific hazards that can arise from cooled systems.

The DIN EN 378 standard considers the life cycle of refrigeration systems, particularly with regard to system/equipment safety, but also, for example, with regard to installation areas of the systems, limit values for refrigerants or the protection of people in cold rooms. The standard specifically addresses the flammability classes 1 (no flame spread), 2L (low flammability), 2 (flammable), 3 (highly flammable) for refrigerants, which are defined in the ISO 817 standard. Examples of refrigerants include: E.g.: propane, (iso-)butane (flammability class 3); R152a (flammability class 2); R1234yf (flammability class 2L); R410A, R22 (flammability class 1).

However, highly flammable hydrocarbons, especially propane and (iso)butane, have favorable environmental properties. For example, the value of the ozone depletion potential ("ODP") for the refrigerants mentioned is 0, while the global warming potential ("GWP") or CO2 equivalent is 0 only 3.

It is desirable to use refrigerants that have favorable environmental properties in today's refrigerated laboratory equipment. With regard to the mentioned refrigerants propane and (iso)butane, extended safety precautions are necessary. In particular, a safe environment within the machine is necessary. In particular, the environment must remain safe even if a flammable refrigerant escapes, for example in the event of a leak, damage or malfunction.

WO 2019/238891 A1 describes a centrifuge and methods for preventing ignition of flammable temperature control media in centrifuges, especially after a crash of the centrifuge rotor. Monitoring is carried out to determine whether the pressure in the evaporator is below a predetermined minimum pressure and/or above a predetermined maximum pressure.

Out of DE 10 2012 103 211 A1 a centrifuge with a cooling device is known, which is designed to cool a chamber of the centrifuge. The cooling device contains a compressor. A controller of the compressor motor performs intermittent control to switch ON-OFF the cooling function of the compressor when the speed of the compressor motor is less than a predetermined speed.

According to US 5,261,252 A The noise emission of a centrifuge cooling system and in particular the condenser fan therein is minimized by monitoring the period of time in which the refrigeration compressor is activated and the speed of the condenser fan is controlled according to the period of time that the compressor is activated.

The present invention is based on the technical problem of improving the operational safety of cooled laboratory equipment that is cooled using a flammable refrigerant. Another technical problem on which the present invention is based is to implement a particularly fail-safe and reliable fan control and to detect defects in a fan particularly early and reliably.

According to a basic idea of the present invention, it is proposed to first ventilate an interior area of a cooled laboratory device with a fan after switching it on, controlled using a first control device, which can in particular be a hardware-based control device. Such a ventilation process can in particular have a defined minimum duration. A first test operation (by means of which, for example, proper functionality of the fan can be checked) and/or a first safety operation (by means of which, for example, refrigerant can be removed from the interior by the fan) of the fan can/can be carried out in this way. The first control device and/or the fan can have a power supply that can be independent of other power supplies of other components or devices of the cooled laboratory device and/or can be activated independently of the other power supplies and/or can be designed separately. The power supply can in particular, for example, have a separate cable harness.

The first control device can in particular have a particularly simple structure. “Hardware-based” can mean in particular that all control commands are specified, defined and/or implemented on the hardware side in the first control device - for example by using electrical or electronic components. “Hardware-based” can alternatively or additionally mean in particular that a function of the first control device can be achieved by a discretely constructed circuit and/or that a function of the first control device can be achieved by using standard components (in particular these can be standard electrical or electronic components). can. In particular, the first control device can be a control device without a data interface and/or without a data memory. The first control device can also, for example, only have a ROM memory. “Hardware-based” in relation to the first control device can alternatively or additionally mean that the first control device has no software or no firmware. “Hardware-based” in relation to the first control device can alternatively or additionally mean that the first control device does not have a chip or memory on which software or firmware is stored. “Hardware based” can be in Reference to the first control device alternatively or additionally means that the first control device does not have any control algorithms or control commands that are stored on a chip or in a memory.

The first control device can in particular have an on/off switch or, in a particularly simple embodiment, consist of an on/off switch which can be coupled to an on/off switch of the laboratory device. For example, if the on/off switch of the laboratory device is switched on, the first control device can also be switched on automatically in such a way that the fan ventilates the interior area.

Venting can serve as a test run for the fan and also remove refrigerant from the interior. Other (or all other) devices of the laboratory device that are to be supplied with electrical power can remain switched off at least - until it is automatically determined that the ventilation was successful and / or - until control of the fan has been handed over to a second control device and is automatically determined that the control of the fan by the second control device is successful.

This can in particular avoid the risk of sparks forming in the interior of the cooled laboratory device, which could cause the refrigerant to ignite if the flammable refrigerant is present in the interior.

The second control device can in particular be a control device that is a software and/or firmware-based control device. It can, for example, have a memory (e.g. a rewritable memory chip or a hard drive), for example with stored program commands and/or a measuring sensor system (e.g. a temperature sensor or a measuring probe for a concentration of the refrigerant) and/or a enable variable-speed control of the fan, for example by means of pulse width modulation, with the help of appropriate devices, for example with the help of stored characteristic curves, which can, for example, connect values of the temperature sensor or measuring probe with speeds. If the second control device is firmware-based, program commands can in particular be stored in a ROM memory. If the second control device is software-based, program commands can in particular be stored in a read-write memory. The second control device can be designed to also activate the fan during normal operation of the cooled laboratory device steer. Normal operation of the cooled laboratory device can follow or follow the method according to the invention.

“Software-based” in relation to the second control device can alternatively or additionally mean that the second control device has software. “Software-based” in relation to the second control device can alternatively or additionally mean that the second control device has a chip or a memory on which software "Software-based" can alternatively or additionally mean in relation to the second control device that the second control device has control algorithms or control commands that are stored on a chip or in a memory (in particular on a read-write memory). .

“Firmware-based” in relation to the second control device can alternatively or additionally mean that the second control device has firmware. In relation to the second control device, “firmware-based” can alternatively or additionally mean that the second control device has a chip or a memory on which firmware is stored. “Firmware-based” in relation to the second control device can alternatively or additionally mean that the second control device has control algorithms or control commands that are stored on a chip or in a memory (in particular on a read-only memory).

The second control device can be a control device in which the safety and/or reliability and/or correct function must first be proven through an approval process or certification process. Such a process can be very time-consuming and expensive. In addition, even small subsequent changes can therefore involve a lot of effort. For example, even small subsequent changes may require their own approval process or certification process.

The second control device can generally be connected to a device-side control device which controls the cooled laboratory device (and in particular a fan of the cooled laboratory device) during operation. The second control device can be this device-side control device or a part of this device-side control device or can be connected to it or integrated into it. However, it is not excluded that the second control device can be a control device that is separate from the device-side control device.

In particular, one is proposed

• Belüften eines Innenbereichs des gekühlten Laborgeräts mithilfe eines Lüfters, wobei ein Steuern des Lüfters über einen ersten Zeitraum durch eine erste Steuereinrichtung ausgeführt wird;
• Überprüfen mithilfe eines ersten vordefinierten Kriteriums, ob das Belüften erfolgreich war;
• Übergeben des Steuerns des Lüfters an eine zweite Steuereinrichtung, wenn das Belüften über den ersten Zeitraum erfolgreich war;
• Überprüfen mithilfe eines zweiten vordefinierten Kriteriums, ob der Lüfter durch die zweite Steuereinrichtung erfolgreich gesteuert wird;
• Aktivieren einer Stromversorgung für mindestens eine weitere mit elektrischem Strom zu versorgende Einrichtung des gekühlten Laborgeräts, wenn der Lüfter durch die zweite Steuereinrichtung erfolgreich gesteuert wird.

Method for operating a laboratory device cooled using a flammable refrigerant, comprising:

• Ventilating an interior area of the cooled laboratory device using a fan, controlling the fan over a first period of time by a first control device;
• Checking whether ventilation was successful using a first predefined criterion;
• transferring control of the fan to a second control device if ventilation was successful over the first period of time;
• Checking whether the fan is successfully controlled by the second control device using a second predefined criterion;
• Activating a power supply for at least one further device of the cooled laboratory device to be supplied with electrical power when the fan is successfully controlled by the second control device.

The flammable refrigerant can in particular be a refrigerant of flammability class 2L, 2 or 3. The flammable refrigerant can in particular be, for example, propane or butane or isobutane (flammability class 3). Other refrigerants, including refrigerants with flammability classes 2L and 2, are not excluded.

The cooled laboratory device can be a device that has a cooling function during operation, for example for samples. The cooled laboratory device can in particular have a refrigeration circuit in which the refrigerant is used. The refrigeration circuit can in particular have an evaporator, a compressor (e.g. a compressor), a condenser (e.g. a condenser) and/or a throttle element. Furthermore, the refrigeration circuit can in particular have connecting elements, seals and/or pipes. The further device to be supplied with electrical power can be, for example, a component of the refrigeration circuit, for example the compressor, which can be designed as an electrically operated compressor, or for example a motor (e.g. of a centrifuge rotor). The cooled laboratory device can in particular, for example, one Be a laboratory centrifuge or a laboratory freezer. Other devices and device types are not excluded.

Ventilating the interior area can in particular be ventilating the interior area, in particular so that any flammable refrigerant that may be present is completely or largely removed from the interior area. Flammable refrigerant could be present in the interior area in situations in which, for example, a leak or a leak in the refrigeration circuit or a component of the refrigeration circuit occurs and as a result the flammable refrigerant has partially reached the interior area.

The interior area can be, for example, an interior area of a housing or a housing part or an interior area under, on, near or within a cover or an inner wall or an outer wall of the cooled laboratory device. The interior region can, for example, contain at least one component or all components of the refrigeration circuit and/or be adjacent to at least one component or all components of the refrigeration circuit and/or be arranged close to at least one component of the refrigeration circuit. The interior can also contain other components of the cooled laboratory device, for example electronics or a motor. The interior area can, for example, have at least one opening to the outside, preferably several openings, to ensure air exchange with a space outside the interior area, in particular an outdoor area and/or an environment.

The fan can in particular be a fan or have a fan. The fan can, for example, be an axial fan or an axial blower or have an axial fan or an axial blower. The speed of the fan can in particular be controllable, so that different fan speeds are possible, for example by means of pulse width modulation (the term pulse width modulation can be understood as a synonym for the term pulse duration modulation). The fan can be located, for example, at the opening to the outside. The fan can preferably be integrated in particular into the cooled laboratory device. It is not excluded that the fan is designed as an external unit.

Controlling the fan over the first period can, in a simple implementation, mean that the fan turns on and stays on for the first period. The fan can, for example, be controlled in such a way that it should reach and/or not fall below a first predefined fan speed over the first period of time. The fan can have a speed determining device (e.g. a Hall sensor) for determining a tachometer signal and/or a number of revolutions per unit of time or can be connected to such a speed determining device.

The first period can, for example, be a predefined time period, for example 3-20 seconds, preferably 5-15 seconds, particularly preferably 8-10 seconds. The first period can be dependent in particular on an interior volume and a volume flow of a fan used. A count or measurement of the first period can be done automatically using a timing device that includes a timer. The counting or measurement of the first period can alternatively or additionally be implemented using an analog or digital timer. In a simple embodiment, a count or measurement of the first period can begin as soon as the fan is switched on or running. Alternatively or additionally, a count or measurement - in particular the start of a count or measurement - can be linked to a condition. For example, the first period or a time measurement can begin as soon as the fan is turned on and has reached a certain fan speed.

The first control device can, for example, have an on/off switch. The on/off switch can be activated, for example, when the laboratory device is switched on. The on/off switch can be coupled to an on/off switch of the laboratory device or can be the on/off switch of the laboratory device. Carrying out the ventilation can be part of the switching on process of the laboratory device. The ventilation can be carried out in particular before the further device of the cooled laboratory device to be supplied with electrical power (or several or all other devices of the cooled laboratory device to be supplied with electric power) are switched on or supplied with power. The ventilation can in particular be carried out automatically. This can mean in particular that the intervention of a human user is not required to carry out the ventilation. If desired, a human user can initiate a switch-on process of the cooled laboratory device, for example by pressing the on/off switch of the laboratory device.

The first control device can in particular have a particularly simple structure. In particular, it can be hardware-based. Reference is made to the above explanations in this regard. The first control device can in particular have a simple, hardware-implemented control logic that enables the fan to be operated at a specific fan speed, which can be a maximum speed of the fan or a specific fan speed. More complex versions of the first Control devices are not excluded. The first control device and/or the fan can have a power supply device/devices (for example, this can be a cable, a connection, and/or a power supply unit), which are separate and/or independent and/or spatially separated from other power supply devices other facilities of the cooled laboratory device is/are. The power supply device/s can, for example, have a separate line/separate lines and/or a separate external connection/separate external connections on the cooled laboratory device or a separate cable harness or connection/separate cable harnesses or connections within the cooled laboratory device. The power supply device(s) can be connected independently of the other power supply devices.

If only the first control device and / or the fan is initially switched on when the cooled laboratory device is switched on during the ventilation process and other devices of the cooled laboratory device are not (yet) supplied with electrical power, there is a risk of sparks forming, especially in the interior of the cooled laboratory device. Flammable refrigerant, if present, can first be removed through the venting process. Other devices that could potentially generate sparks during a power supply will only be switched on later when there is no longer any flammable refrigerant present.

The first predefined criterion can be checked in particular using a checking device. In a simple embodiment, the checking device can have a threshold switch, for example. Such a threshold switch may include an electrical capacitor that is charged as soon as a certain fan speed is reached) and/or an alternative timer or time counter. As soon as, for example after the first period of time, a certain charge value of the electrical capacitor is reached and thus a certain voltage value on the electrical capacitor, the presence of the voltage value can be used as a signal that the checking using the first predefined criterion is successful. However, if the fan speed falls below a certain level, the electrical capacitor can be discharged again. Only when the specific fan speed is reached over a specific period of time (for example the first period of time) can the voltage value be so high that the first predefined criterion is considered to have been successfully met. In a more complex embodiment, the checking device can alternatively or additionally have checking logic, for example implemented using a computing device (e.g. a processor). and corresponding commands, control rules and/or characteristics. The checking device can also have a timer.

The checking device can alternatively or additionally, for example, have an AC voltage amplifier which charges energy into the electrical capacitor when the edges of a tachometer signal (corresponding to a fan speed signal) change. If a frequency of the edge changes (and thus the fan speed) is sufficiently high (e.g. equal to or above the specific fan speed), a higher electrical power enters the electrical capacitor than is withdrawn from it. The checking device can also alternatively or additionally, for example, have an integrated circuit such as a retriggerable, monostable multivibrator or a monoflop.

The checking device can also alternatively or additionally z. B. have a counter or counter that defines a minimum time for ventilation (which can be the first period) in the form of a defined cycle duration. If the fan speed falls below the specified speed, the counter or counter can be reset, so that the counting process of the counter or counter must begin again.

As already mentioned, the fan can have a speed measuring device for measuring a tachometer signal and/or a number of revolutions per unit of time or can be connected to such a speed measuring device. Embodiments for speed measuring devices are known in the prior art; for example, speed measurement using a Hall sensor is possible. The checking device can be part of the first control device or connected to it. A power supply of the checking device can be connected to a power supply of the first control device. The power supply of the checking device can be carried out using a power supply device that is separate and/or independent and/or spatially separated from other power supply devices of other devices of the cooled laboratory device.

The first predefined criterion may, for example, have a condition related to a fan speed and/or related to a period of time in which the fan should operate, for example, at a specific fan speed. The first predefined criterion can - more specifically - be, for example, that a certain fan speed, which can also be referred to as the first predefined fan speed, for example, must be reached and/or not fallen below. Achieving and/or not falling below the first predefined fan speed can occur over a certain period of time, which is the first period of time can be required by the first predefined criterion. The condition that a specific fan speed (which can be the first predefined fan speed) must be achieved over a specific period of time (which can be the first period of time) can be designed in such a way that experience has shown that at the specific fan speed and the specific period of time, that flammable refrigerant located in the interior area is completely or almost completely removed from the interior area. Ventilation can be considered successful in particular if the first predefined criterion has been met.

As already mentioned, the second control device can in particular be a control device that is a software and/or firmware-based control device. Reference is made to the above comments regarding the second control device. For example, the second control device can be designed to implement demand-based control of the fan. For example, the second control device can have a measuring sensor system (e.g. a temperature sensor for determining a temperature value in the indoor area and/or in an outdoor area or a measuring probe for a concentration of the refrigerant), with the help of which a ventilation requirement can be determined - for example using integrated software -/firmware-defined rules and/or characteristics - and a corresponding fan speed can be determined.

Handing over control of the fan can, for example, be handing over control over a power supply of the fan, for example using a transfer device, which can be, for example, a corresponding switch (e.g. an RS flip-flop) or a corresponding switch (e.g. an RS flip-flop) that triggers a corresponding switching process. The switch can be triggered, for example, if a signal or a voltage value is output or is present at the electrical capacitor which indicates that the ventilation was successful. The transfer device can also have an electronic control and/or a computing device (e.g. a processor) and/or a relay.

The handover can be carried out in particular when the first predefined criterion has been successfully met. If the first predefined criterion has not been successfully met or the ventilation was not successful, the particular consequence may be that the transfer is not carried out. In this case, for example, operation of the cooled laboratory device can be stopped or prevented, for example based on a predefined switch-off criterion, for example if after a predefined period of time the first predefined criterion has not been met. If If the ventilation was not successful, the cooled laboratory device can be switched off automatically or not switched on at all.

The second control device can generally have a more complex structure than the first control device, particularly if it is software and/or firmware-based. Since it has a particularly simple structure, the first control device can be particularly reliable or fail-safe, in particular more reliable or fail-safe or less error-prone than the second control device. The first control device is therefore well suited to initially ventilate the interior area in order to particularly reliably remove any flammable refrigerant that may be present from the interior area. In addition, it is advantageous that the risk of sparking is reduced, as explained above.

Whether the second predefined criterion has been met can be checked in particular using a further checking device, for example comprising a computing device (e.g. a processor) and commands, control rules and/or characteristics for checking the tacho signal of the fan and/or a timer . Alternatively or additionally, it is not excluded that the checking device with which the first predefined criterion is checked additionally checks whether the second predefined criterion has been met.

The further checking device can be part of the second control device or connected to it. A power supply of the further checking device can be connected to a power supply of the second control device. The power supply of the further checking device can be carried out using a power supply device that is separate and/or independent and/or spatially separated from further power supply devices of other devices of the cooled laboratory device.

The second predefined criterion may, for example, have a condition related to a fan speed and/or related to a period of time in which the fan should operate, for example, at a specific fan speed. The second predefined criterion can - more concretely - be, for example, that a certain fan speed, which can also be referred to, for example, as a second predefined fan speed, must be reached and/or not fallen below. Reaching and/or not falling below the second predefined fan speed can be required by the second predefined criterion over a certain period of time.

The power supply for the at least one further device to be supplied with electrical power can be activated, for example, using an activation device, for example comprising a computing device (e.g. a processor) and corresponding commands. Activation can take place after a certain delay time, which for security reasons must have passed since the handover. The delay time can be, for example, 5 seconds or 10 seconds. The delay time can also be shorter, for example, e.g. B. 5-1 seconds. The activation device can alternatively or additionally in particular have a switch, for example a relay, for activating a power supply for the at least one further device to be supplied with electrical power, or can be connected to such a switch. Activation can be carried out in particular when the second predefined criterion has been successfully met. The term “further device to be supplied with electrical power” is to be understood in such a way that the fan itself is not included in this term.

The at least one further device to be supplied with electrical power can be any other component of the cooled laboratory device that is supplied with electrical power. In particular, it can be a component of the refrigeration circuit, for example the compressor (which can be designed as a compressor, for example), a drive motor (for example if the cooled laboratory device is a centrifuge), a display or a control device. Activating the power supply for the at least one further device to be supplied with electrical power can also mean that the cooled laboratory device is switched on - for example completely - so that operation of the cooled laboratory device (for example, if it is a centrifuge) is stopped operation) can begin.

The method can be designed in such a way that the activation of the power supply for the at least one component is not carried out or, for example, not in a predefined period of time or not before the cooled laboratory device is switched off and switched on again, if the control is carried out by the second control device or the second Tax procedure is not successful.

All of the steps mentioned in the process can occur or be carried out automatically. The step of ventilating the indoor area can be followed by the step of checking using the first predefined criterion. The step of checking using the first predefined criterion can be followed by passing control. The passing step can be checked using the second predefined criterion consequences. The step of checking using the second predefined criterion can be followed by the step of activating. The method can be designed so that the next step only follows when the previous step has been completed.

The presented method offers a simple and cost-effective way to improve the operational safety of refrigerated laboratory equipment that is cooled using a flammable refrigerant. Before there is a risk of sparking from the flammable refrigerant, venting the interior will remove any flammable refrigerant that may be present. Furthermore, a test run of the fan is carried out in order to detect a malfunction of the fan at an early stage. In addition to the fact of ventilation as such and the increased operational reliability that this brings, it is also advantageous that a particularly fail-safe and independent hardware-based control (if the first control device is designed in this way) controls the ventilation and a defect in the fan (for example a mechanical blockage or a Contact problem) can be detected early and reliably, especially before spark sources within the cooled laboratory device are activated.

It is also advantageous that a problem in the second control device can be recognized separately, with the second control device being able to realize a fan speed that meets requirements, in particular by means of pulse width modulation, provided it is designed accordingly. If necessary, the second control device is only activated in an advantageous manner when a defect in the fan can be ruled out. Since the first control device is fundamentally more reliable than the second control device, a potentially harmful fan malfunction directly after switching on the cooled laboratory device is particularly effectively prevented - through the initial use of the first control device.

Another advantage is that an initial ventilation control, which can in particular be hardware-based, requires little effort in development and approval. Other, more structurally complex and/or more expensive control or protective measures (e.g. pressure sensors) become unnecessary.

The present invention is fundamentally suitable for all devices that contain a refrigeration circuit with flammable refrigerant. The present invention can also be applied to other devices that contain or produce dangerous gases or other fumes that are hazardous to health.

In an advantageous embodiment of the method according to the invention, a power supply for the fan is produced before the interior area is ventilated, in particular immediately before the ventilation.

The power supply can preferably be produced in particular using an on/off switch of the cooled laboratory device. The cooled laboratory device can be designed so that the on/off switch is the only switch that needs to be pressed at the start of operation of the cooled laboratory device. Ventilation of the interior can then begin automatically. Power can also, less preferably, be provided using a separate on/off switch.

“Immediately before ventilating” can mean that ventilating immediately follows the establishment of the power supply - for example using the on/off switch of the cooled laboratory device - for example preferably within 5 seconds, or within 10 seconds or 20 seconds or a minute.

The presented design allows a simple and user-friendly switching process. In particular, if the power supply is established immediately before ventilation, the switch-on process can be particularly safe, as it were, since the period of time in which the fan is supplied with electrical power before the interior is ventilated is very small and so there is a risk of sparks forming on the fan itself is minimized.

In an advantageous embodiment of the method according to the invention, the power supply for the fan is produced by switching on the cooled laboratory device. This can mean in particular that the power supply for the fan is automatically established when the cooled laboratory device is switched on, for example using an on/off switch of the cooled laboratory device. The power-on process may include additional steps after power is supplied to the fan. Further steps of the switch-on process - in particular the transfer of control of the fan and the activation of the power supply for at least one further device of the cooled laboratory device to be supplied with electrical power - can then follow.

The presented embodiment allows a particularly simple and user-friendly switching process.

In an advantageous embodiment of the method according to the invention, the first control device is a hardware-based control device.

Reference is made to the above comments regarding the hardware-based controller and the term “hardware-based”. The hardware-based control device can have a particularly simple structure and can be independent of other devices of the cooled laboratory device and can therefore be particularly reliable and fail-safe. A defect in the fan, for example a blockage or a contact problem, can be detected before other components of the cooled laboratory device can be damaged. If the fan is defective, operation of the cooled laboratory device may still be impossible. A determination of such a defect can advantageously be made before there is a risk of the refrigerant being ignited by other, potentially spark-generating devices of the cooled laboratory device, the switching of which would be pointless and possibly harmful in the event of a defective fan.

In an advantageous embodiment of the method according to the invention, the second control device is a software-based or a firmware-based control device.

Reference is made to the above comments regarding the software-based or firmware-based controller and the terms "software-based" and "firmware-based". The software-based or firmware-based control device is advantageous because it can enable, in particular, needs-based control of the fan, in particular needs-based control of the fan speed. If the ventilation requirement is low, for example due to an already low temperature indoors, a low fan speed may be sufficient. Only when there is a high need for ventilation, for example when there is an increased temperature indoors, can a high fan speed be set. Implementation can be done, for example, using characteristic curves or maps. This configuration allows low energy consumption by the fan, low wear and a long service life of the fan, lower maintenance requirements, low contamination, for example from dust in the interior, and lower noise.

In an advantageous embodiment of the method according to the invention, the first criterion is or includes not falling below or reaching a first predefined fan speed.

Not falling below the limit can in particular mean not falling below the limit over a certain period of time. The specific period can in particular be, for example, the first period. The specific period of time may be a period of time which, in conjunction with the first predefined fan speed, enables ventilation such that flammable refrigerant is completely or approximately completely removed from the interior. The first predefined fan speed may be selected to enable ventilation such that flammable refrigerant is completely or approximately completely removed from the interior within the specific period of time.

How long the specific period of time must be and what fan speed must be required can, for example, be determined experimentally and/or with the help of simulations. The first predefined fan speed can alternatively be a (e.g. predefined) maximum speed at a specific voltage (e.g. 12 V) or a nominal speed of the fan.

Reaching a first predefined fan speed is also conceivable as a first criterion. Achievement can, for example, be required within a certain period of time. For example, it can be measured whether the first predefined fan speed is reached properly and/or whether it is reached within a period of time. The time period can be, for example, a typical acceleration time of the fan, for example in the interval of 0.1 to 3 seconds. If the acceleration is too slow, i.e. the first predefined fan speed is not reached within the time period, this may indicate a defect in the fan.

The first predefined fan speed can itself be a variable value. For example, the first predefined fan speed may depend on a temperature, for example an indoor temperature or an outdoor temperature, or on a period of time during which the cooled laboratory device was not in operation.

The presented embodiment makes it possible to carry out a reliable assessment of the functionality of the fan in a simple and easy-to-implement manner with little control and testing effort. In particular, it is easy to test whether the fan itself is functioning properly. If, for example, proper control by the second control device fails, it can be ruled out that there is an error in the fan itself (e.g. blockage, mechanical defect, contact problems, etc.).

In an advantageous embodiment of the method according to the invention, the second criterion is or includes not falling below a second predefined fan speed.

Not falling below the limit can in particular mean not falling below the limit over a further specific period of time. The further specific period of time can, for example, be a period of the order of seconds (e.g. located in the interval of 2-20 seconds).

The second predefined fan speed can be a fan speed at which safe ventilation is guaranteed during (normal) operation of the cooled laboratory device. "Safe" here can refer, for example, to a temperature, for example a temperature in the interior, that should be maintained for safety reasons, or for example to a refrigerant leak, for example in the event of a leak. Here, “safe” can mean, for example, that the refrigerant leakage at the fan speed can be safely compensated for by transporting it away using ventilation. The second predefined fan speed can also be above a minimum fan speed (which can also be referred to as forced ventilation speed) at which safe ventilation is just guaranteed in (normal) operation of the cooled laboratory device.

The second predefined fan speed can itself be a variable value. For example, the second predefined fan speed may depend on a temperature, for example an indoor temperature or an outdoor temperature.

The presented embodiment allows a reliable assessment of the functionality of the second control device (and also of the fan) to be implemented in a simple and easy-to-implement manner with little control and testing effort. This can prevent damage to other equipment in the cooled laboratory device. A simulation of typical ventilation situations of the cooled laboratory device - as they occur in normal operation of the cooled laboratory device - can be carried out before the actual start of normal operation.

In an advantageous embodiment of the method according to the invention, if the fan speed falls below the second predefined speed, the fan speed is briefly increased by the first control device.

The short-term increase in speed can also be referred to as a “boost”. The short-term increase in speed can be carried out in particular if the second predefined fan speed is slightly below the speed limit. In such cases, it can be assumed, for example, that there is a mechanical problem with the fan, which can possibly be solved with a short boost. This could be, for example, dust deposits on the fan. The short-term increase in speed can, for example, be in an interval of 0.5 to 5 seconds, preferably 1 to 2 seconds. The short-term speed increase can be carried out several times in a row if the fan speed falls below the second predefined speed several times in a row.

The short-term increase in speed can also lead to a possible malfunction of the second control device, which causes a drop in speed of the fan, being eliminated.

The presented embodiment makes it possible to easily eliminate an underlying cause if the fan speed is too low. The cause can in particular be of a mechanical nature or have its origin in the second control device. In particular, the design is user-friendly, since a possible deactivation of a main switch of the cooled laboratory device and/or switching the cooled laboratory device off and on again and/or even repairs of the cooled laboratory device can be avoided.

In an advantageous embodiment of the method according to the invention, the power supply for the at least one further device to be supplied with electrical power is permanently or temporarily deactivated if a third predefined criterion is violated.

The third predefined criterion can in particular be not falling below a third predefined fan speed. The third predefined fan speed can be a minimum fan speed (which can also be referred to as forced ventilation speed) at which safe ventilation is just guaranteed in (normal) operation of the cooled laboratory device. The third predefined fan speed may be below the second predefined fan speed (if provided).

The permanent deactivation can in particular deactivate a switch, for example a relay, for the power supply of the at least one further device to be supplied with electrical power. The switch or relay may involve a main power supply to the refrigerated laboratory equipment being deactivated. The deactivation can, for example, be maintained until the cooled laboratory device is switched on again or over a predefined period of time.

The presented embodiment increases operational reliability because operation of the cooled laboratory device can be avoided in advance in the event of a malfunction of the second control device and/or the fan. In particular, the malfunction is detected before operation begins, so that damage to other equipment of the cooled laboratory device or dangerous situations in which refrigerant is not removed or is not removed sufficiently can be avoided.

In an advantageous embodiment of the method according to the invention, the power supply for the at least one further device to be supplied with electrical current is activated only after a second period of time has elapsed, which begins with or after the fan control is transferred to the second control device.

The second period can, for example, be understood as the minimum period during which checking using the second predefined criterion must always take place. This further increases the informative value and quality of the checking using the second predefined criterion and thus the operational reliability of the cooled laboratory device.

In an advantageous embodiment of the method according to the invention, before ventilating the interior of the cooled laboratory device, it is checked whether the power supply for the at least one further device to be supplied with electrical power is deactivated and/or whether a fan speed detection is functioning properly.

The measures mentioned prevent the at least one further device to be supplied with electrical power, e.g. B. is supplied with electrical power due to a malfunction and therefore represents a source of danger due to the possible formation of sparks. For example, if the further device to be supplied with electrical power can be supplied with power by means of a relay, it can be checked whether the relay is properly deactivated.

A proper function of the fan speed detection can, for example, be designed in such a way that it is checked whether the fan, which is still stationary, properly outputs a signal that its speed is at zero before the interior area is ventilated.

If a check as to whether the power supply is deactivated and/or whether a fan speed detection is functioning properly is not successful, carrying out further steps of the method according to the invention, in particular ventilation, can be prevented. This further increases operational safety. In particular, correct fan speed detection further increases the probability that further method steps can be carried out properly and correctly, in particular if the first predefined criterion and / or the second predefined criterion (and possibly the third predefined criterion) each depend on fan speeds.

• einen Lüfter, ausgestaltet zur Lüftung eines Innenbereichs des gekühlten Laborgeräts;
• eine erste Steuereinrichtung, ausgestaltet, ein Steuern des Lüfters derart auszuführen, dass ein Belüften des Innenbereichs über einen ersten Zeitraum durchgeführt wird;
• eine Überprüfungseinrichtung, ausgestaltet zur Überprüfung mithilfe eines ersten vordefinierten Kriteriums, ob das Belüften über den ersten Zeitraum erfolgreich war;
• eine zweite Steuereinrichtung, die ausgestaltet ist, den Lüfter zu steuern;
• eine Übergabeeinrichtung, ausgestaltet zum Übergeben des Steuerns des Lüfters an die zweite Steuereinrichtung, wenn das Belüften über den ersten Zeitraum erfolgreich war;
• eine Aktivierungseinrichtung, ausgestaltet, eine Stromversorgung für mindestens eine weitere mit elektrischem Strom zu versorgende Einrichtung des gekühlten Laborgeräts zu aktivieren, wenn der Lüfter durch die zweite Steuereinrichtung erfolgreich gesteuert wird;

wobei die Überprüfungseinrichtung zusätzlich ausgestaltet ist, mithilfe eines zweiten vordefinierten Kriteriums zu überprüfen, ob der Lüfter durch die zweite Steuereinrichtung erfolgreich gesteuert wird, oder das gekühlte Laborgerät eine weitere Überprüfungseinrichtung aufweist, die ausgestaltet ist, mithilfe eines zweiten vordefinierten Kriteriums zu überprüfen, ob der Lüfter durch die zweite Steuereinrichtung erfolgreich gesteuert wird.Furthermore, a laboratory device cooled by means of a flammable refrigerant is proposed, comprising:

• a fan designed to ventilate an interior area of the cooled laboratory device;
• a first control device, designed to control the fan in such a way that the interior area is ventilated over a first period of time;
• a checking device designed to check using a first predefined criterion whether the ventilation was successful over the first period of time;
• a second control device configured to control the fan;
• a transfer device designed to transfer control of the fan to the second control device if ventilation was successful over the first period of time;
• an activation device, designed to activate a power supply for at least one further device of the cooled laboratory device to be supplied with electrical power when the fan is successfully controlled by the second control device;

wherein the checking device is additionally designed to use a second predefined criterion to check whether the fan is successfully controlled by the second control device, or the cooled laboratory device has a further checking device that is designed to use a second predefined one Criterion to check whether the fan is successfully controlled by the second control device.

The cooled laboratory device can in particular be designed to carry out the method according to the invention in at least one of the embodiments set out, in particular to carry it out automatically. With regard to the cooled laboratory device and configurations of the cooled laboratory device, reference is made in full to explanations of the method according to the invention and to the configurations of the method according to the invention. In particular (but not exclusively) reference is made here to explanations on the cooled laboratory device, on the flammable refrigerant, on the fan, on the interior, on the first control device, on the first period of time, on the checking device, on the first predefined criterion, on the second predefined criterion, on ventilation, to the second control device, to the transfer device, for controlling the fan and for transferring the control, to the activation device, to the further device to be supplied with electrical power and to the further checking device.

In particular, the first control device, the checking device, the second control device, the transfer device, the activation device and/or the further transfer device can be units integrated into the cooled laboratory device. The devices mentioned can each, at least partially or all, comprise at least one electronic component and/or a programmable computing device and/or use or share a programmable computing device. Preferably, the first control device does not have a programmable computing device and/or is not or only indirectly connected to a programmable computing unit.

In one embodiment, the cooled laboratory device can in particular be a laboratory freezer or a centrifuge.

• Fig. 1: Eine schematisch dargestellte Ausgestaltung eines erfindungsgemäßen gekühlten Laborgeräts;
• Fig. 2: Eine schematisch dargestellte weitere Ausgestaltung eines erfindungsgemäßen gekühlten Laborgeräts;
• Fig. 3: Eine schematisch dargestellte Ausgestaltung des erfindungsgemäßen Verfahrens.

Embodiments of the invention will now be described with reference to the accompanying drawings. The individual figures in the drawing show:

• Fig. 1 : A schematically illustrated embodiment of a cooled laboratory device according to the invention;
• Fig. 2 : A schematically illustrated further embodiment of a cooled laboratory device according to the invention;
• Fig. 3 : A schematically illustrated embodiment of the method according to the invention.

In various exemplary embodiments, the same reference numbers are used for functionally identical devices, steps, instances and elements. However, this does not necessarily mean that the exemplary embodiments are the same exemplary embodiment or parts of the same exemplary embodiment.

In Fig. 1 A cooled laboratory device 1 according to the invention is shown, which is designed as a laboratory centrifuge. However, the invention is not limited to laboratory centrifuges. For example, the cooled laboratory device 1 could also be a laboratory freezer. The cooled laboratory device 1 has a fan 2. A speed sensor 22 and a fan motor 21 are provided on the fan 2, more precisely on a fan shaft. The speed sensor 22 and the fan motor 21 can be understood as parts of the fan 2. The fan 2 is located at a first opening OE1 of a housing 11 of the cooled laboratory device 1. The housing 11 may have a cover that can be opened (not shown) to provide access to a centrifuge rotor 4. The centrifuge rotor 4 can be set in rotation via a drive motor 5 integrated in the housing. The centrifuge rotor 4 is also rotatably mounted via rotor bearings 52 integrated in the housing, which can be designed as roller bearings, for example. A second opening OE2 is provided on the side of the housing 11 opposite the first opening OE1 in order to enable ventilation through the interior region 3. Additional openings (not shown) may be provided.

The cooled laboratory device 1 has an interior area 3. The interior area 3 extends essentially below the centrifuge rotor 4, that is, facing away from the top of the centrifuge rotor with oblique insertion areas for sample tubes, and extends to the underside of the cooled laboratory device 1. Inside the interior area 3 is the cooled laboratory device 1 in the state shown a small amount of refrigerant KM - for example due to a small leak in the refrigeration circuit KM and a long downtime of the cooled laboratory device without use. The refrigerant KM is a flammable refrigerant, for example propane.

The cooled laboratory device 1 has a KAE refrigeration circuit. The KAE refrigeration circuit has several evaporators 6 (i.e. cold generators). They serve in particular to cool the centrifuge rotor 4, the surroundings of the centrifuge rotor 4, the drive motor 5 and the rotor bearings 52. The refrigeration circuit KAE also has a compressor 7 (e.g. a compressor), a capacitor 8 located outside the housing 11 (the can be a condenser), and a throttle 9. The compressor 7 is with a power line 73 connected, which is used to power the compressor 7. The drive motor 5 is connected to a power line 53, which serves to power the drive motor 5. In the light of the general description, the compressor 7 and the drive motor 5 can be understood as further devices of the cooled laboratory device 1 to be supplied with electrical power.

The cooled laboratory device 1 is supplied with electrical power via an external power supply EX (which can have a power plug and possibly a power supply unit) and a power cable EXN. The EXN power cable docks into an on/off switch 10 of the cooled laboratory device. The on/off switch 10 has a push button (indicated here) for switching on/off. The on/off switch 10 allows electric current to flow when turned on through a power line 103, a power line ST13, a power line UEP3, and a power line ST23. The power lines through which circuits can be created are explained in more detail below.

The power line ST13 runs from the on/off switch 10 to a first control device ST1. The power line ST23 runs from the on/off switch 10 to a second control device ST2. The power line 103 runs from the on/off switch 10 to an activation device AKE. The power line UEP3 runs from the on/off switch 10 to a checking device UEP.

The first control device ST1 is designed to enable ventilation of the interior area 3 of the fan 2 over a first period of time, which can last, for example, 8-10 seconds. Here, a voltage can be present on the fan 2, which causes the fan 2 to be operated at a maximum speed, for example at least 2500 revolutions per minute.

The first control device ST1 is hardware-based. It has a switch that can produce a power supply to the fan 2 (more precisely: to the fan motor 21), coming from the power line ST13, which can ultimately supply both the fan 2 and the first control device ST1 itself with electrical power. The switch can basically be switched on at the start of operation of the cooled laboratory device 1 or can be designed to be switched on automatically or to be switched on automatically for the first period of time. With regard to the term “hardware-based” reference is also made to the explanations in the general part of the description.

In principle, it is not excluded within the scope of the present invention that the first control device ST1 alternatively or additionally has a control by a chip or processor, and has control commands that control the fan 2 (the fan motor 21) or a power supply for the fan 2 (the fan motor 21) can control. It is not excluded that the first control device ST1 is designed to be able to adjust a speed of the fan 2 (of the fan motor 21), for example by means of pulse width modulation. In principle, however, it is preferred that the first control device ST1 has a simple structure and, for example, achieves its functionality using the switch mentioned (which can be an on/off switch).

An interface ST1-UEG is used to control and/or supply energy to the fan 2 (the fan motor 21). The interface ST1-UEG can be designed to transmit or route electrical energy (and/or alternatively or additionally control commands) from the first control device ST1 to a transfer device UEG. The ST1-UEG interface can therefore have a power line that can create a power circuit, and possibly also a data line. The transfer device UEG is designed to transfer the control of the fan 2 (of the fan motor 21) from the first control device ST1 to the second control device ST2 or, conversely, from the second control device ST2 to the first control device ST1. For this purpose, the transfer device UEG can have a switch which, in particular, can carry out a change in the power supply of the fan motor 21 between the first control device ST1 and the second control device ST2. An interface UEG-2, which has a power line (which can create a circuit), leads from the transfer device to the fan 2 (to the fan motor 21) in order to enable the fan motor 21 to be supplied with power. It is not excluded that the UEG-2 interface also has a data line if, for example, the fan 2 is designed accordingly (if, for example, it has its own additional control device).

The UEP checking device is also provided. It is designed to use a first predefined criterion to check whether the ventilation of the interior area was successful over the first period of time. The first predefined criterion can be that a first predefined fan speed (e.g. 2500 revolutions per minute) is reached and maintained over a minimum period of time (corresponding to the first period of time, it can be 8 seconds long, for example) for safe ventilation. Other configurations of the first predefined criterion are not excluded.

In the presented embodiment of the cooled laboratory device 1 according to the invention, the checking device UEP is designed in such a way that it has a computing device (e.g. a processor) and corresponding commands. It cannot be ruled out that the checking device UEP is constructed differently, in particular more simply, for example as an electrical capacitor which is charged as soon as a certain fan speed is reached and which reaches a certain voltage value (at the earliest) after the first period of time has elapsed ( Threshold switch) has been reached, which triggers a switchover at the transfer device UEG.

Alternatively or additionally, it is also not excluded that the checking device UEP has a device for time counting, which begins a time measuring process as soon as the first predefined fan speed is reached and, as soon as the first period of time has expired, triggers the switchover at the transfer device UEG.

The checking device UEP is connected to the speed sensor 22 via an interface 22-UEP and can therefore receive a fan speed signal for the purpose of checking whether the first predefined criterion is met. The interface 22-UEP is designed to transmit the fan speed signal from the speed sensor 22 (which can be designed, for example, as a Hall sensor), so that it is received and used to check whether the ventilation of the interior area was successful over the first period of time , can be interpreted. Receiving and interpreting is carried out by the checking device UEP. All interfaces mentioned, including the 22-UEP interface, can e.g. B. have a power cable and / or a data cable.

Furthermore, the checking device UEP is connected to the first control device ST1 via an optional interface UEP-ST1. Via the optional interface UEP-ST1, the checking device UEP can, for example, check whether the switch of the first control device ST1 was switched correctly during the first period of time as part of checking whether the ventilation was successful.

Furthermore, the checking device UEP is connected to the transfer device UEG via an interface UEP-UEG. If the first predefined criterion was met, i.e. the ventilation of the interior area 3 was successful, a signal is sent to the transfer device UEG via the UEP-UEG interface, which is sent from the first control device ST1 (and from the ST1-UEG interface) to the second Control device ST2 (and the interface ST2-UEG) can be switched, for example switching the Switch of the transfer device UEG can be done. The switch of the transfer device UEG can be designed to be switchable based on this signal.

The second control device ST2 is designed to enable the fan 2 to be controlled, for example by means of pulse width modulation (PWM). The second control device ST2 is firmware-based. This can mean in particular that it has a memory, for example a ROM memory, which contains control commands, for example functional relationships or (predetermined) characteristics that enable the fan 2 (the fan motor 21) to be controlled as required, for example based on Temperature values that a temperature sensor (not shown) in the interior 3 and / or a temperature sensor outside the interior 3 can measure. It is not excluded that the second control device ST2 is alternatively or additionally software-based, for example having a read-write memory that contains control commands that can be adapted. The second control device ST2 also contains a computing device, e.g. B. a processor for implementing and interpreting the control commands.

The second control device ST2 can be designed to control the fan 2 even during normal operation of the cooled laboratory device.

An interface ST2-UEG is used to control and/or power the fan 2 (the fan motor 21). The interface ST2-UEG can be designed to transmit or route electrical energy and/or control commands from the second control device ST2 to the transfer device UEG. The ST2-UEG interface can have a power line that can create a power circuit, and possibly also a data line. The transfer device UEG is designed to transfer the control of the fan 2 (the fan motor 21) to the second control device ST2. When the transfer has taken place, the fan 2 (the fan motor 21) is supplied with electrical power via the interface ST2-UEG and the further interface UEG-2.

In the presented embodiment of the cooled laboratory device 1, the checking device UEP is designed to use a second predefined criterion to check whether the fan 2 is successfully controlled by the second control device ST2. The second predefined criterion that must be met is that the fan speed must not fall below a specified minimum speed for safe basic ventilation (second predefined fan speed) over a second period of time. The second period can be, for example, 5 seconds long. The second predefined fan speed can be, for example, 1100 revolutions per minute.

The checking device UEP is connected to the speed sensor 22 via an interface 22-UEP and can therefore receive a fan speed signal for the purpose of checking whether the second predefined criterion is met. The checking device UEP can also have a time measuring device.

The interface 22-UEP is configured to transmit the fan speed signal from the speed sensor 22 so that it can be received and interpreted to check whether control over the second period was successful. Receiving and interpreting is carried out by the checking device UEP.

Furthermore, the checking device UEP is connected to the second control device ST2 via an optional interface UEP-ST2. Via the optional interface UEP-ST2, the checking device UEP can, for example, additionally check whether the control of the fan 2 by the second control device ST2 is carried out properly during the second period of time as part of checking whether the control over the second period of time was successful is.

If the control over the second period of time was successful, i.e. the second predefined criterion is met, then a signal is sent via an interface UEP-AKE to the activation device AKE that power supplies for the compressor 7 (via the power line 73) and the drive motor 5 ( can be activated via the power line 53). The activation device 103 in particular has a switch, for example a relay, which can produce the power supplies when a corresponding signal is present.

The cooled laboratory device 1 is shown in a state in which refrigerant KM is located in the interior 3. Already the control by the first control device ST1 - the ventilation of the interior area 3 over the first period of time - removes the refrigerant KM completely from the interior area 3, so that when potentially sparking further devices of the cooled laboratory device 1 (compressor 7 and Drive motor 5) is no longer present and no longer poses a danger. At the time of activation, the control of the fan 2 is also checked for proper function using the second control device ST2. The second control device ST2 also controls the fan during normal operation of the cooled laboratory device 1, which can be connected.

The checking device UEP can optionally be additionally designed to initiate a short-term speed increase by the first control device ST1 if the fan speed falls below the second predefined fan speed (minimum speed for safe basic ventilation during operation) within the second predefined period of time. The checking device UEP can be designed (in particular, it can have corresponding control commands), in this case to instruct the transfer device UEG to carry out a switching process to the first control device ST1. The short-term increase in speed can, for example, take place over a short period of time (e.g. 1 second) until a switch is made. The checking device UEP can be designed in such a way that the second period of time is started again after the short-term increase in speed in order to check whether the control by the second control device ST2 is successful.

The checking device UEP can optionally be additionally designed to include the switch (which can be a relay, for example) of the activation device AKE, which can enable power supplies for the compressor 7 (via the power line 73) and the drive motor 5 (via the power line 53). , for a certain period of time or permanently (e.g. until the cooled laboratory device 1 is switched on again) to deactivate or block if a third predefined (critical) fan speed is undershot, which no longer guarantees safe operation in the event of a leak would. The third predefined fan speed can e.g. B. be at 500 revolutions per minute.

The checking device UEP can optionally be additionally designed to check a signal from the speed sensor 22 and/or the correct state of the activation device AKE before the first period of time, i.e. before the start of ventilation of the interior area 3. For this purpose, the checking device UEP can have corresponding control commands. The signal from the speed sensor (which can also be called a tachometer signal) should initially correspond to a fan speed of zero. The AKE activation device switch should be deactivated. If at least one of these criteria is not met, the checking device UEP can be designed to include the switch (which can be a relay, for example) of the activation device AKE, the power supplies for the compressor 7 (via the power line 73) and the drive motor 5 ( via the power line 53) can enable deactivation or blocking for a certain period of time or permanently (e.g. until the cooled laboratory device 1 is switched on again).

In Fig. 2 a further embodiment of the cooled laboratory device 101 according to the invention is shown. However, the cooled laboratory device 101 now shown has, in contrast to cooled laboratory device 101 has a first checking device UEP1 and a second checking device UEP2. The (joint) verification facility UEP does not exist.

The comments on the first presented embodiment of the cooled laboratory device 1 apply accordingly, apart from the following comments, which include the first checking device UPE1 and the second checking device UEP2 as well as the interfaces 22-UEP1, 22-UEP2, UEP2-ST2, UEP2-AKE and UEP2 -UEG and the UEP23 power line. The power line UEP23 runs from the on/off switch 10 to the second checking device UEP2.

The first checking device UEP1 is designed to use a first predefined criterion to check whether the ventilation of the interior area was successful over the first period of time. The first predefined criterion is that the first predefined fan speed (e.g. 2500 revolutions per minute) is reached and maintained over a minimum period of time (corresponding to the first period, it can be 8 seconds long, for example) for safe ventilation. In this way, any potentially dangerous mixture within the cooled laboratory device can be neutralized. Other configurations of the first predefined criterion are not excluded.

The first checking device UEP1 has a threshold switch (e.g. an electrical capacitor that is charged as soon as the first predefined fan speed is reached). Alternatively or additionally, it can have a time counting device that begins a time measurement process as soon as the first predefined fan speed is reached.

The first checking device UEP1 is connected to the speed sensor 22 via the interface 22-UEP1 and can therefore receive a fan speed signal for the purpose of checking whether the first predefined criterion is met.

The information is transmitted to the transfer device UEG via the UEP1-UEG interface that the specific voltage value of the electrical capacitor has been reached or that the time measurement process has reached the minimum period. This information may mean that ventilation of the refrigerated laboratory equipment was successful.

This triggers a switchover at the transfer device UEG, which can be switched from the first control device ST1 (and from the interface ST1-UEG) to the second control device ST2 (and the interface ST2-UEG), i.e. a Switching the switch of the transfer device UEG can take place. The switch of the transfer device UEG is designed to be switchable based on the information.

The interface 22-UEP1 is designed to transmit the fan speed signal from the speed sensor 22 (which can be designed, for example, as a Hall sensor), so that the threshold switch (e.g. an electrical capacitor that is being charged) or a alternative timer/counter of the first checking device UEP1 can be used to check whether the first predefined criterion is met.

In the presented embodiment of the cooled laboratory device 101, the second checking device UEP2 is designed to use a second predefined criterion to check whether the fan 2 is successfully controlled by the second control device ST2. The second predefined criterion that must be met is that the fan speed must not fall below a second predefined fan speed (this can be a predefined minimum speed for safe basic ventilation) over a second period of time. The second period can be, for example, 5 seconds long. The second predefined fan speed can be, for example, 1100 revolutions per minute.

The second checking device UEP2 is connected to the speed sensor 22 via an interface 22-UEP2 and can therefore receive a fan speed signal for the purpose of checking whether the second predefined criterion is met.

The interface 22-UEP2 is configured to transmit the fan speed signal from the speed sensor 22 so that it can be received and interpreted to check whether control over the second period was successful. The reception and interpretation is carried out by the second checking device UEP2.

Furthermore, the second checking device UEP2 is connected to the second control device ST2 via an optional interface UEP-ST2. Via the optional interface UEP-ST2, the second checking device UEP2 can, for example, check whether the control of the fan 2 was carried out properly by the second control device ST2 as part of checking whether the control over the second period of time was successful. It is not excluded that the second checking device UEP and the second control device ST2 are designed as a common unit.

If the control over the second period of time was successful, i.e. the second predefined criterion is met, then a signal is sent via an interface UEP2-AKE to the activation device AKE that power supplies for the compressor 7 (via the power line 73) and the drive motor 5 ( can be activated via the power line 53). The activation device 103 in particular has a switch, for example a relay, which can produce the power supplies when a corresponding signal is present.

The second checking device UEP2 can exchange information with the transfer device UEG via the UEP2-UEG interface. For example, the second checking device UEP2 can optionally be additionally designed to initiate a short-term speed increase by the first control device ST1 when the fan speed falls below the second predefined fan speed (predetermined minimum speed for safe basic ventilation during operation). The second checking device UEP2 can be designed (in particular, it can have corresponding control commands), in this case to instruct the transfer device UEG to carry out a switching process to the first control device ST1. The short-term increase in speed can occur briefly (for example over a period of 1 second) until switching back (brief boost of fan 2 to avoid a critical lower speed). The second checking device UEP2 can be designed in such a way that the second period of time is started again after the short-term increase in speed in order to check again whether the control by the second control device ST2 is successful.

The second checking device UEP2 can optionally be additionally designed to enable the switch (which can be a relay, for example) of the activation device AKE, which enables power supplies for the compressor 7 (via the power line 73) and the drive motor 5 (via the power line 53). can be deactivated or blocked for a certain period of time or permanently (e.g. until the cooled laboratory device 101 is switched on again) if a third predefined fan speed is undershot, which would no longer ensure safe operation in the event of a leak. The third predefined fan speed can e.g. B. be at 500 revolutions per minute.

The second checking device UEP2 can optionally be additionally designed to check a signal from the speed sensor 22 and/or the correct state of the activation device AKE before the first period of time, i.e. before the start of ventilation of the interior area 3. For this purpose, the second checking device UEP2 can do the corresponding Have control commands. The signal from the speed sensor (which can also be called a tachometer signal) should initially correspond to a fan speed of zero, the switch of the activation device AKE should be deactivated.

If at least one of these criteria is not met, the second checking device UEP2 can be designed to include the switch (which can be a relay, for example) of the activation device AKE, the power supplies for the compressor 7 (via the power line 73) and the drive motor 5 (via the power line 53) can enable deactivation or blocking for a certain period of time or permanently (e.g. until the cooled laboratory device 101 is switched on again).

In Fig. 3 an embodiment of the method according to the invention for operating a laboratory device cooled by means of a flammable refrigerant (for example a laboratory centrifuge or a laboratory freezer) is shown. The cooled laboratory device can be, for example, the cooled laboratory device 1 or the cooled laboratory device 101. Reference is made in full to the above explanations of embodiments of the cooled laboratory device according to the invention, where applicable, with reference being made to the relevant comments. The cooled laboratory device 1 and the cooled laboratory device 101 can each be designed to carry out the method according to the invention, in particular to carry it out automatically.

In an optional upstream control step SCK, it is checked whether a power supply for further devices to be supplied with electrical power is properly deactivated. The other facilities to be supplied with electrical power can be e.g. B. be a drive motor 5 and / or a compressor 7 or a display or an electrical opening mechanism of a lid of the cooled laboratory device.

In addition, within the control step SCK it can be checked whether a fan speed detection is functioning properly, for example by checking whether a fan speed signal is initially equal to zero.

In a preliminary step SC0, it is checked whether the fan reaches a predefined minimum speed for safe ventilation or whether this predefined minimum speed is exceeded. If this is not the case, the cooled laboratory device can be aborted and switched off automatically.

After carrying out the preliminary step, in a first step SC1, an interior area (for example the interior area 3) of the cooled laboratory device is ventilated over a first period of time. The fan is controlled via a first control device (e.g. the first control device ST1), which can in particular be hardware-based. The first period is selected such that at a first predefined fan speed, the interior of the cooled laboratory device is completely or almost completely freed of any refrigerant that may be present.

After the ventilation has been carried out, a second step SC2 checks whether a first predefined criterion (e.g. reaching a fan speed of at least 2500 revolutions per minute over 8 seconds, this fan speed can be referred to as the first predefined speed) has been met is, for example using a simply constructed checking device, for example the first checking device UEP1. As mentioned, successful ventilation can alternatively or additionally be carried out using a more complex checking device, for example the UEP checking device.

Any refrigerant that may be present inside is now completely or almost completely removed, so that other devices of the laboratory device that are to be supplied with electrical power do not pose a danger due to spark formation, before they are supplied with electrical power.

In a third step SC3, if the control of the fan was successful (indicated by a check mark), the control of the fan is transferred to a second control device, for example using the transfer device UEG. The second control device can in particular be a software or firmware-based control device and have stored control commands and/or characteristics.

If controlling the fan was not successful (indicated by an “x”), the procedure can be terminated. In particular, the cooled laboratory device can be switched off automatically, as indicated by the symbol "O".

In a fourth step SC4, using a second predefined criterion (e.g. the fan must not fall below a predefined minimum speed for long-term safe ventilation, this speed can be referred to as the second predefined fan speed) it is checked whether the control of the fan is successful is.

If this is not the case, but a third predefined criterion is not violated (e.g. the fan speed drops below a predefined critical speed, which can be referred to as the third predefined fan speed, whereby this speed no longer ensures safe operation in the presence of a leak ensured), in an optional additional step SC4B, the control can be briefly transferred to the first control device, which causes a brief fan speed increase (boost) towards the maximum speed of the fan. The fourth step SC4 can then be carried out again. The optional additional step SC4b can be carried out a limited number of times. If the second predefined criterion is still not met, an abort can occur, e.g. B. switching off the cooled laboratory device (not shown).

Checking whether the control of the fan is successful can be done using a checking device (e.g. checking device UPE or second checking device UEP2).

If the ventilation is successful (indicated by a check mark), the further devices to be supplied with electrical power are activated, possibly with a time delay (indicated by a clock symbol), in a fifth step SC5, for example with the help of an activation device - that This means that normal operation of the cooled laboratory device can begin.

List of reference symbols:

• 1: refrigerated laboratory device
• 10: On/Off switch
• 101: refrigerated laboratory equipment
• 103: Power line
• 11: Housing
• 2: Fan
• 21: Fan motor
• 22: Speed sensor
• 22-UEP: Interface between speed sensor and checking device
• 22-UEP1: Interface between speed sensor and first checking device
• 22-UEP2: Interface between speed sensor and second checking device
• 3: Indoor area
• 4: Centrifuge rotor
• 5: Drive motor
• 51: Rotor shaft
• 52: Rotor bearing
• 53: Power line for the drive motor
• 6: Evaporator (refrigerator)
• 7: Compressor (e.g. compressor)
• 73: Power line for the compressor
• 8: Condenser (Condenser)
• 9: Throttle
• AKE: Activation facility
• EX: external power supply
• EXN: Power cord
• KAE: refrigeration cycle
• KM: Refrigerant
• OE1: first opening
• OE2: second opening
• ST1: first control device
• SC1: first step
• ST13: Power line for the first control device
• ST1-UEG: Interface between the first control device and the transfer device
• ST2: second control device
• SC2: second step
• ST23: Power line for the second control device
• ST2-UEG: Interface between second control device and transfer device
• SC3: third step
• SC4: fourth step
• SC4B: additional step
• SC5: fifth step
• SCK: control step
• UEG: transfer facility
• UEG-2: Interface between transfer device and fan
• UEP: verification facility
• UEP1: first verification facility
• UEP2: second verification facility
• UEP23: Power line for the second verification device
• UEP2-AKE: Interface between second verification device and
• Activation facility
• UEP2-ST2 Interface between second checking device and second control device
• UEP2-UEG: Interface between second verification device and transfer device
• UEP3: Power line for the verification facility
• UEP-AKE: Interface between verification facility and activation facility
• UEP-ST1: Interface between checking device and first control device
• UEP-ST2: Interface between checking device and second control device
• UEP-UEG: Interface between verification facility and transfer facility

Claims (13)

1. A method for operating a laboratory apparatus (1; 101) that is cooled by means of a flammable refrigerant (KM), comprising:

   - Ventilating an internal area (3) of the cooled laboratory apparatus (1; 101) with the aid of a fan (2), wherein control of the fan (2) is carried out over a first period of time by a first control device (ST1);

   - checking by means of a first predefined criterion whether the ventilation was successful;

   - transferring control of the fan (2) to a second control device (ST2) if the ventilation was successful over the first time period;

   - checking by means of a second predefined criterion whether the fan (2) is successfully controlled by the second control device (ST2);

   - activating a power supply for at least one further device (5, 7) of the cooled laboratory apparatus (1; 101) to be supplied with electric current if the fan (2) is successfully controlled by the second control device (ST2).
2. Method according to claim 1, characterized in that a power supply for the fan (2) is established before ventilating the inner area (3), in particular immediately before ventilating.
3. Method according to claim 2, characterized in that the power supply for the fan (2) is established by a switch-on process of the cooled laboratory apparatus (1; 101).
4. Method according to any one of claims 1-3, characterized in that the first control device (ST1) is a hardware-based control device.
5. Method according to any one of claims 1-4, characterized in that the second control device (ST2) is a software-based or a firmware-based control device.
6. Method according to any one of claims 1-5, characterized in that the first criterion is or comprises not falling below or reaching a first predefined fan speed.
7. Method according to any one of claims 1-6, characterized in that the second criterion is or comprises not falling below a second predefined fan speed.
8. Method according to claim 7, characterized in that, if the second predefined fan speed is undershot, a brief speed increase of the fan (2) is effected by the first control device (ST1).
9. Method according to one of claims 1-8, characterized in that a permanent or temporary deactivation of the power supply for the at least one further device (5, 7) to be supplied with electric current takes place if a third predefined criterion is violated.
10. Method according to one of the claims 1-9, characterized in that the activation of the power supply for the at least one further device (5, 7) to be supplied with electrical current takes place only after the expiry of a second time period which begins with or after the transfer of the fan control to the second control device (ST2).
11. Method according to one of the claims 1-10, characterized in that, before ventilating the inner area (3) of the cooled laboratory apparatus (1; 101), it is checked whether the power supply for the at least one further device (5, 7) to be supplied with electric current is deactivated and/or whether a fan speed detection is functioning properly.
12. Laboratory apparatus (1; 101) cooled by means of a flammable refrigerant (KM), comprising:

    - a fan (2) configured to ventilate an interior region (3) of the cooled laboratory apparatus (1; 101);

    - a first control device (ST1) configured to perform control of the fan (2) such that ventilation of the interior region (3) is performed over a first period of time;

    - a verification means (UEP; UEP1) configured to verify, by means of a first predefined criterion, whether the ventilation has been successful over the first period of time;

    - second control means (ST2) adapted to control the fan (2);

    - a transfer device (UEG) adapted to transfer control of the fan (2) to the second control device (ST2) to the second control means (ST2) when the ventilation has been successful over the first period of time;

    - an activating means (AKE) adapted to activate a power supply for at least one further device (5, 7) of the cooled laboratory apparatus (1; 101) to be supplied with electric current when the fan (2) is successfully controlled by the second control means (ST2);

    wherein the checking device (UEP) is additionally designed to check with the aid of a second predefined criterion whether the fan (2) is successfully controlled by the second control device ST2, or the cooled laboratory apparatus (1; 101) has a further checking device (UEP2) which is designed to check with the aid of a second predefined criterion whether the fan (2) is successfully controlled by the second control device (ST2).
13. Laboratory apparatus (1; 101) according to claim 12, characterized in that the laboratory apparatus (1; 101) is a laboratory freezer or a centrifuge.

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