EP3555474B1 - Control device and method for operating a refrigerant compressor - Google Patents

Description

FIELD OF THE INVENTION

The present invention relates to an electronic control device for a refrigerant compressor, which has at least one drive unit and a compression mechanism in operative connection with the drive unit with at least one moving back and forth in a cylinder of a cylinder block of the refrigerant compressor in an operating state of the refrigerant compressor for the operational compression of refrigerant comprises pistons driven via a crankshaft of the drive unit, the electronic control device of the refrigerant compressor being set up at least to detect at least one physical process parameter, preferably the rotational speed of the crankshaft or the power consumption of the refrigerant compressor, to detect a switch-off signal directed to the refrigerant compressor, which switch-off signal an operating phase of the refrigerant compressor ended, in which operating phase the refrigerant k ompressor is operated as intended with a positive operating torque, and is set up to regulate a torque applied by the drive unit to the crankshaft to adjust its rotational speed.

The present invention further relates to a refrigerant compressor for use in a cooling device, preferably in a refrigerator or freezer, the refrigerant compressor comprising an electronic control device according to the invention.

The present invention also relates to a cooling device, preferably a refrigerator or freezer, with a refrigerant compressor according to the invention.

The present invention also relates to a method for operating a refrigerant compressor suitable for use in a refrigerator, preferably in a refrigerator or freezer, which comprises a compression mechanism for compressing refrigerant and a drive unit, the compression mechanism by means of a crankshaft to which a torque is applied Drive unit is driven.

STATE OF THE ART

Such electronic control devices are used in refrigerant compressors with variable rotational speed. Variable speed refrigerant compressors have the advantage that they can be tailored more specifically to the cooling requirements of the object to be cooled, for example in that they can be operated at a lower rotational speed in the case of lower cooling requirements and at a correspondingly increased rotational speed in the case of an increased cooling requirement.

The structure of refrigerant compressors is well known. They essentially consist of a drive unit and a compression mechanism in the form of a piston moving back and forth in a cylinder housing between a first and a second dead center, which is connected via a connecting rod to a crankshaft, which in turn is rotatably coupled to a rotor of the drive unit .

A brushless DC motor is typically used as the drive unit. It is possible to determine the relative position of the rotor of the DC motor and thus also the speed of rotation of the motor or the compression mechanism on the basis of the counter-voltage (induced counter-voltage) induced in the motor winding. This method manages without separate sensors and is therefore particularly easy to implement and less prone to failure.

In the case of refrigerant compressors according to the state of the art, noise-related problems arise in particular during the stopping process, which immediately follows a phase in which the refrigerant compressor was operated as intended with a positive operating torque the refrigerant pressure conditions in the system) and frictional forces (both together are referred to as the load torque) on the compression mechanism, which on closer inspection results in a non-uniform speed of the crankshaft over the crankshaft because it varies. In the present application, a fundamental distinction is made between the terms rotational speed and rotational speed. The term speed is used when the actual, instantaneous angular speed of the crankshaft is meant, whereas the term rotational speed is used when the average number of revolutions per minute of the crankshaft is meant, i.e. the value that is commonly meant when one thinks of the Speed of a refrigerant compressor speaks.

Specifically, an increased load torque acts on the compression mechanism during the compression phase compared to the suction phase, which must be overcome by the operating torque of the drive unit in order to keep the compression process going. This increased load torque leads to a reduction in the speed of the crankshaft during the compression phase.

During the suction phase, on the other hand, the gas forces cause a lower load torque than in the compression phase. This leads to an increase in the speed of the crankshaft during the suction phase.

Overall, a load torque that varies over the entire crank angle acts on the compression mechanism and thus on the crankshaft, with the fluctuation range of the load torque primarily depending on the pressure ratio in the refrigerant circuit and on different angular accelerations and thus on a crankshaft speed during one crankshaft rotation that is non-uniform over the crank angle leads.

In order to compensate for oscillations and vibrations of the compression mechanism during operation, it and the drive unit are mounted in a housing via spring elements. The natural frequencies of this vibration system are between 5 Hz and 16 Hz, depending on the type of compressor.

Thus, the increased load torque that recurs during each crankshaft revolution during the compression phase, especially when the refrigerant compressor is operating at rotational speeds below a range between 1000 rpm and 700 rpm, leads to impacts on the compression mechanism, which presses the compression mechanism and drive unit into the spring elements and deflects them, the shock frequency being in the range of the natural frequency of the vibration system, so that the deflections of the spring elements increase with each crankshaft rotation in such a way that the compression mechanism and / or the drive unit can hit the housing, which can lead to undesirable noise emissions. This fact is also a reason why known refrigerant compressors are not operated in the normal, regulated operating phase below a range between 1000 rpm and 700 rpm, i.e. not in the rotational speed range that is critical with regard to noise emissions.

The described, undesirable noise emissions of a refrigerant compressor at low rotational speeds do not only occur in normal, regulated operation, but above all during the stopping process, where these low rotational speeds have to be passed. The stopping process usually proceeds as follows:

If, after a normal, regulated operating phase of the refrigerant compressor, during which the refrigerant compressor was operated as intended with a positive operating torque, the target temperature of the object to be cooled, for example a refrigerator compartment of a refrigerator, is reached, the electronic control device of the refrigerator sends a signal (switch-off signal) to the electronic Control device of the refrigerant compressor, with which this is communicated that no more cooling capacity is required because the target temperature has been reached. It is known from the prior art that the electronic control device of the refrigerant compressor then switches off the drive or the positive operating torque with which the refrigerant compressor was operated as intended during the regulated operating phase (switch-off time). The stopping process therefore begins immediately after the switch-off signal is detected, with the positive operating torque being switched off.

The crankshaft of the compression mechanism also runs through complete revolutions after the switch-off time, starting at the first dead center (crank angle 0 °), whereby a suction phase (correct: suction and re-expansion phase) is carried out, during which refrigerant is sucked into the cylinder. This suction phase ends theoretically when the cylinder has reached the second dead center (crank angle 180 °). Then the compression phase begins (correct: compression and expulsion phase), during which the refrigerant in the cylinder is compressed and expelled from the cylinder. Theoretically, the compression phase ends when the piston has reached the first dead center (crank angle 360 °) again. In practice, however, the actual compression of the refrigerant only begins at a crank angle of around 210 ° (depending on the refrigerant compressor, the pressure conditions, the valve design, etc.) but at least after 180 ° and the suction phase at around 30 °, in any case after the first dead center.

Switching off the drive unit of the refrigerant compressor at a switch-off time, which switch-off time in reality does not coincide with the detection of the switch-off signal by the electronic control device but is slightly backwards in time, initiates the stopping process and results in the crankshaft in a non-powered state (without positive operating torque) and only continues to rotate due to its inertia until it has come to a complete standstill, ie its rotational speed is 0. Colloquially, one could also say that the refrigerant compressor is "running out".

During the non-powered state, the crankshaft rotates exclusively due to the kinetic energy it has at the time of switch-off and the inertia. It rotates in an uncontrolled manner, so to speak, and its rotational speed behavior is dependent on the load torque acting on the compression mechanism. The load torque leads to a constant reduction in the rotational speed of the crankshaft of the non-driven refrigerant compressor, so that the kinetic energy of the crankshaft decreases until, depending on the pressure conditions in the refrigerant circuit, it is no longer sufficient to overcome the load torque (limit rotational speed).

It must be taken into account that when the drive unit is switched off, unlike during the normal regulated operating phase, there is no positive operating torque which counteracts the load torque, in particular the increased load torque in the compression phase, so that when the drive unit is switched off, the increased load torque in the compression phase occurs The impacts acting on the compression mechanism penetrate unbraked, so to speak, and therefore the effects on the deflection of the spring elements are even more serious than is the case in the normal regulated operating phase, where the positive operating torque counteracts the impacts and thus dampens them somewhat.

This in turn means that the deflection of the spring elements at low speeds during the stopping process is even greater than during normal regulated operation of the refrigerant compressor at the same low speeds and thus the likelihood of contact between the compression mechanism / drive unit and the housing is also higher, which means that overall one higher noise emissions.

In addition, in the event that the piston is currently in a compression phase, when the kinetic energy of the crankshaft is no longer sufficient to overcome the load torque, the situation can arise that the piston of the compression mechanism is again in the direction of the second Dead center is pushed back, the direction of rotation of the compression mechanism is reversed.

The reversal of the direction of rotation is associated with an additional stopping jerk acting on the compression mechanism, which leads to an additional deflection of the spring elements.

Especially during the stopping process, where, as already described above, no positive operating torque counteracts the load torque and the increased load torque acting in the compression phase already stimulates the oscillation system abruptly in the range of its natural frequency anyway Stopping jerk due to the reversal of the direction of rotation contributes even more to the deflection of the spring elements, so that the probability that the compression mechanism / drive unit will strike the housing wall is increased again and thus cause undesirable noise emissions.

It is known from the prior art to end the non-drive phase by applying a braking torque and thereby at least avoid kickback of the refrigerant compressor and thus the jerk. It is provided that the crankshaft, which rotates without drive after the switch-off time, is actively braked and brought to a standstill by applying a braking torque when the rotational speed falls below a certain level. To do this, it is necessary to constantly monitor the rotational speed of the non-driven crankshaft after the switch-off time and to monitor the crankshaft at a defined rotational speed, which in any case must be sufficiently high to be able to overcome the load torque by then, i.e. must be above the limit rotational speed by means of actively braking the braking torque that is applied to the crankshaft at the end of the stopping process.

For reasons of energy efficiency, the braking torque that causes the crankshaft to come to a standstill can sensibly only be applied after the crankshaft has fallen below a certain rotational speed, since the energy consumption of a braking torque that causes a crankshaft rotating at a higher than this specific rotational speed would be disproportionately high. In order to achieve this specific rotational speed, the prior art provides for the said braking process to be preceded by a comparatively long period of time, which period extends between the switch-off signal and the application of the braking torque and in which the crankshaft coasts down without a positive operating torque or to be exposed to a braking torque running in the opposite direction. In electronic control devices according to the prior art, the stopping process that begins at the time of switch-off is thus made up of the period in which the crankshaft coasts down in an uncontrolled manner and the final braking process, which is intended to bring the crankshaft to a standstill.

For the reasons discussed above, however, it is problematic that the stopping process is drastically lengthened, in particular by allowing the crankshaft to coast down to reach the specific rotational speed from which the braking torque can sensibly be applied. In addition to the associated noise emissions caused by the - at first very slowly - passing through the critical Rotational speed range are caused, the further problem arises that the electronic control device must be supplied with power for the purpose of constant monitoring of the rotational speed during the entire period in which the crankshaft coasts down in an uncontrolled manner. Switching off the power supply of the electronic control device, which is usually done by the electronics of the cooling device in which the refrigerant compressor is used, can therefore only take place in electronic control devices according to the prior art when the crankshaft has been brought to a standstill. For the reasons mentioned, it can thus be stated in summary that the operation of known variable-speed refrigerant compressors at low speeds causes an excitation of the vibration system in the range of its natural frequencies and therefore leads to undesirable noise emissions. Since this effect can be observed particularly strongly during the stopping process, in which the crankshaft of the refrigerant compressor has to pass through a rotational speed range that is critical in terms of noise generation, a stopping process that is as short as possible is generally desirable. In electronic control devices as they are known from the prior art, however, this endeavor is opposed by the need to first reduce the rotational speed of the crankshaft below a certain value of the rotational speed before the braking torque causing the crankshaft to come to a standstill with a reasonable expenditure of energy and without danger any electronic components of the control device can be applied. DE20 2012 013046 shows a generic control device for compressors. As described above, the braking torque is only applied there after the speed has fallen below a certain level.

OBJECT OF THE INVENTION

It is therefore an object of the present invention to provide an electronic control device for a refrigerant compressor which enables the refrigerant compressor, in particular the crankshaft of the refrigerant compressor, to be stopped quickly and energy-efficiently, and which enables the refrigerant compressor to be operated at low speeds - i.e. in particular during the stopping process - keeps the noise generated as low as possible.

In addition, it is an object of the invention to provide a refrigerant compressor and a cooling device which offer the advantages just mentioned. In addition, it is an object of the invention to provide a method for operating a refrigerant compressor which is quick and easy enables cost-effective stopping of the refrigerant compressor and keeps the noise development associated with braking and stopping as low as possible.

DISCLOSURE OF THE INVENTION

• eine Antriebseinheit sowie
• einen mit der Antriebseinheit in Wirkverbindung stehenden Kompressionsmechanismus mit zumindest einem sich in einem Zylinder eines Zylinderblocks des Kältemittelkompressors in einem Betriebszustand des Kältemittelkompressors zur betriebsgemäßen Verdichtung von Kältemittel hin- und herbewegenden und über eine Kurbelwelle der Antriebseinheit angetriebenen Kolben umfasst,

wobei die elektronische Steuerungseinrichtung des Kältemittelkompressors zumindest dazu eingerichtet ist,

• zumindest einen physikalischen Prozessparameter, vorzugsweise die Drehgeschwindigkeit der Kurbelwelle oder die Leistungsaufnahme des Kältemittelkompressors, zu detektieren,
• ein an den Kältemittelkompressor gerichtetes Abschaltsignal zu detektieren, welches Abschaltsignal eine Betriebsphase des Kältemittelkompressors beendet, in welcher Betriebsphase der Kältemittelkompressor mit einem positiven Betriebsdrehmoment bestimmungsgemäß betrieben wird, sowie dazu eingerichtet ist,
• ein von der Antriebseinheit an die Kurbelwelle zur Einstellung deren Drehgeschwindigkeit angelegtes Drehmoment zu regeln,

dadurch gelöst, dass die elektronische Steuerungseinrichtung weiters dazu eingerichtet ist, unmittelbar nach Detektieren des Abschaltsignals ein Bremsmoment an die Kurbelwelle anzulegen, wobei das Bremsmoment dem während der Betriebsphase vorherrschenden positiven Drehmoment entgegengerichtet ist und der Betrag dieses Bremsmomentes eine Funktion des detektierten physikalischen Prozessparameters, vorzugsweise der Drehgeschwindigkeit der Kurbelwelle oder der Leistungsaufnahme des Kältemittelkompressors, ist.One of the above-mentioned objects is achieved in an electronic control device according to the invention for a refrigerant compressor, which at least

• a drive unit as well
• comprises a compression mechanism which is in operative connection with the drive unit and has at least one piston that moves back and forth in a cylinder of a cylinder block of the refrigerant compressor in an operating state of the refrigerant compressor for the operational compression of refrigerant and is driven via a crankshaft of the drive unit,

wherein the electronic control device of the refrigerant compressor is set up at least to

• to detect at least one physical process parameter, preferably the rotational speed of the crankshaft or the power consumption of the refrigerant compressor,
• to detect a switch-off signal directed to the refrigerant compressor, which switch-off signal ends an operating phase of the refrigerant compressor, in which operating phase the refrigerant compressor is operated as intended with a positive operating torque, and is set up to do so,
• regulate a torque applied by the drive unit to the crankshaft to adjust its rotational speed,

solved in that the electronic control device is further set up to apply a braking torque to the crankshaft immediately after detecting the switch-off signal, the braking torque being opposed to the positive torque prevailing during the operating phase and the amount of this braking torque being a function of the detected physical process parameter, preferably the Rotational speed of the crankshaft or the power consumption of the refrigerant compressor.

The application of the braking torque to the crankshaft according to the invention leads to the braking process being carried out directly to the operating phase in which the refrigerant compressor was operated with positive operating torque, and thus starts at the same time as the stopping process. A prolongation of the stopping process known from the prior art by letting the crankshaft run down in order to reduce its rotational speed before the actual braking process, which is initiated by applying the braking torque, is thus avoided. Instead, the braking process begins at the moment immediately following the detection of the switch-off signal and generally extends until the crankshaft comes to a standstill. Overall, this results in a significantly shortened stopping process compared to the prior art, which is due to the avoidance of the crankshaft running out on the one hand and faster braking of the crankshaft due to the earlier braking process on the other.

In addition, the inventive selection of the amount of braking torque as a function of the detected process parameter of the refrigerant compressor enables particularly energy-efficient braking of the crankshaft, since different braking torques can be applied to the crankshaft at different process times during the braking process.

The selection of the braking torque as a function of the rotational speed of the crankshaft of the refrigerant compressor has proven to be particularly advantageous, since high braking torques in particular at the beginning of the braking process - i.e. when the rotational speed is still high - are associated with increased energy loss. In addition, the crankshaft can be stopped quickly and at the same time in an energy-efficient manner by varying the braking torque applied over the entire braking process as a function of the respective rotational speed of the crankshaft.

It is therefore provided in a preferred embodiment of the electronic control device according to the invention that the physical process parameter is the rotational speed of the crankshaft.

Since an energetically favorable braking of the crankshaft can be achieved in particular at low rotational speeds, it is provided in a further preferred embodiment of the electronic control device according to the invention that the amount of the braking torque applied to the crankshaft is indirectly proportional to the rotational speed of the crankshaft immediately after the switch-off signal is detected, which the crankshaft has at the moment of the detection of the switch-off signal.

As a result, the braking torque applied to the crankshaft at the beginning of the braking process - i.e. immediately after the switch-off signal has been detected - in the case of high or low rotational speeds during the Switch-off signal for the previous operating phase selected lower or higher. At low rotational speeds, a corresponding selection of the braking torque leads to a further shortening of the stopping process, since the crankshaft is already exposed to a high braking torque at the beginning of the stopping process. At high rotational speeds of the crankshaft at the moment the switch-off signal is detected, however, the selection of the braking torque according to the invention leads to a lower energy requirement over long stretches of the stopping process, while the stopping process according to the invention compared to stopping processes with a phase of the crankshaft coasting according to the prior art by the Braking torque already applied at the beginning of the stopping process is nevertheless shortened.

In order to further shorten the duration of the stopping process and to keep the noise development associated with the operation of the refrigerant compressor at low speeds as low as possible, it is advantageous to maintain the braking torque applied at the beginning of the stopping process over the entire stopping process. Therefore, in a further preferred embodiment of the electronic control device according to the invention, it is provided that the braking torque is maintained until the crankshaft comes to a standstill.

In a particularly preferred embodiment of the electronic control device according to the invention, it is provided that the braking torque applied to the crankshaft forms a braking profile, a function determining the course of the braking profile being stored by the electronic control device and preferably a linear dependence on the current rotational speed of the crankshaft and / or the time that has elapsed since the detection of the switch-off signal.

The implementation of the braking torque as a braking profile, which braking profile represents the time curve of the braking torque, enables the amount of the braking torque to be optimally adapted to the rotational speed of the crankshaft, which decreases during the stopping process. Based on the value of the braking torque at the beginning of the stopping process - i.e. immediately after the switch-off signal has been detected - it is possible, for example, to increase the amount of the applied braking torque during the stopping process in order to gradually increase the braking effect. This can take place as a function of the actual rotational speed of the crankshaft, which in turn depends on the applied braking torque and is further reduced as the stopping process continues. Alternatively, measurement and / or evaluation of the current rotational speed during the stopping process can be dispensed with and the prefabricated braking profile can be determined as a function of the time that has elapsed since the switch-off signal was detected. In both cases, it is necessary that a function that defines the specific braking profile - with functional parameters, the current rotational speed of the crankshaft and / or the time that has elapsed since the switch-off signal was detected - is stored by the electronic control device. Overall, this allows a particularly advantageous braking profile to be selected, which means that the crankshaft is only braked slightly at the beginning of the stopping process and the braking effect becomes higher and higher as the speed of rotation continues to decrease. As a result, the stopping process can be shortened further and the energy requirement of the refrigerant compressor can be reduced during the stopping process.

In a further preferred embodiment of the electronic control device according to the invention, it is provided that the electronic control device is set up to set the rotational speed of the crankshaft, preferably several times, particularly preferably continuously, at a predetermined rate in a braking period extending between the detection of the switch-off signal and the standstill of the crankshaft Compare rotational speed values.

This makes it possible to determine in which of several rotational speed regimes determined by the specific choice of the specified rotational speed values the crankshaft is in each case during the braking period. In this context, it has proven to be particularly advantageous to compare the current rotational speed several times or as often as technically possible, that is to say continuously, with the predefined rotational speed values during the braking period. It is provided according to the invention that the function determining the braking profile, which is stored by the electronic control device, has a different value or a different curve for each rotational speed regime, i.e. for all values of the current rotational speed of the crankshaft between two of the specified rotational speed values (e.g. slope, curvature) of the applied braking profile.

In a particularly preferred embodiment of the electronic control device according to the invention, it is therefore provided that the course of the braking profile essentially follows a piece-wise linear function, each of the predetermined rotational speed values being assigned a section of the braking period within which this piece-wise linear function has an essentially constant gradient having.

As a result, the electronic control device according to the invention enables the braking period to be divided into any number of sections subdivide, with the braking profile in each of these sections following the course of a linear function with a specific slope assigned to the respective area. As a result, the braking profile can be applied to the crankshaft in a particularly simple, stable and easily implemented manner and, at the same time, an optimal adaptation of the respective braking torque to the instantaneous speed of the crankshaft can be ensured. In contrast to the strictly mathematical sense of a (piece-wise) linear function, the term piece-wise linearity in the present document is to be interpreted in such a way that the value of the slope can assume any real number, in particular zero. In this sense, it can be provided that the function determining the course of the braking profile is constant within a section of the braking period, the said gradient - in accordance with the above diction - being zero in this section.

In another particularly preferred embodiment of the electronic control device according to the invention, it is provided that the amount of the braking torque resulting from the course of the braking profile is a function of the time that has elapsed since the detection of the switch-off signal, which increases monotonically from the time of the detection of the switch-off signal to the time of the standstill of the crankshaft follows.

Since in this embodiment of the control device the amount of the braking torque increases monotonically (increases or remains the same), preferably increases strictly monotonically (always increases) from the time of the detection of the switch-off signal to the time of the standstill of the crankshaft, it is a function of the time elapsed since the detection of the switch-off signal follows, it is ensured that the braking effect to which the crankshaft is exposed immediately after the detection of the switch-off signal increases or at least does not decrease during the entire stopping process. As a result, the crankshaft can be stopped quickly and in an energy-efficient manner - initially independently of the respective instantaneous value of the rotational speed and its specific course during the entire braking period.

An object of the present invention is also achieved by a refrigerant compressor for use in a cooling device, preferably in a refrigerator or freezer, the refrigerant compressor comprising an electronic control device according to the invention.

As a result, all of the above-described advantages of the electronic control device according to the invention can be used in conjunction with a refrigerant compressor suitable for use in a cooling device. In particular, it becomes possible for the one that occurs during the stopping process To keep the development of noise as low as possible and to ensure a rapid and energy-efficient stopping of the compressor in response to the detection of the switch-off signal sent to the refrigerant compressor by a control device of the cooling device.

An object of the invention is also achieved in a cooling device, preferably a refrigerator or freezer, with a refrigerant compressor having an electronic control device according to the invention. As a result, all of the advantages discussed above can also be used in the cooling device according to the invention.

• Detektieren eines eine Betriebsphase, in der der Kältemittelkompressor mit einem positiven Betriebsdrehmoment bestimmungsgemäß betrieben wird, beendenden Abschaltsignals;
• Detektieren eines physikalischen Prozessparameters, vorzugsweise einer Drehgeschwindigkeit der Kurbelwelle oder einer Leistungsaufnahme des Kältemittelkompressors;
• Anlegen eines Bremsmomentes an die Kurbelwelle unmittelbar nach dem Detektieren des Abschaltsignals, wobei das Bremsmoment dem positiven Betriebsdrehmoment in seiner Wirkrichtung entgegengesetzt und der Betrag des Bremsmomentes eine Funktion des detektierten physikalischen Prozessparameters, vorzugsweise der Drehgeschwindigkeit der Kurbelwelle oder der Leistungsaufnahme des Kältemittelkompressors, ist.

An object of the invention is a method for operating a refrigerant compressor suitable for use in a refrigerator, preferably in a refrigerator or freezer, which comprises a compression mechanism for compressing refrigerant and a drive unit, the compression mechanism by means of a crankshaft to which a torque is applied Drive unit is driven, achieved in that it comprises the following steps:

• Detecting a shutdown signal ending an operating phase in which the refrigerant compressor is operated as intended with a positive operating torque;
• Detecting a physical process parameter, preferably a rotational speed of the crankshaft or a power consumption of the refrigerant compressor;
• Applying a braking torque to the crankshaft immediately after detecting the switch-off signal, the braking torque being the opposite of the positive operating torque in its effective direction and the amount of the braking torque being a function of the detected physical process parameter, preferably the rotational speed of the crankshaft or the power consumption of the refrigerant compressor.

The method according to the invention enables the braking process to begin immediately after the switch-off signal has been detected and thus at the same time as the stopping process. It also makes it possible to adapt the braking process, in particular the amount of braking torque applied immediately after detection of the switch-off signal, ie the amount of a torque opposing the operating torque, to that operating phase which was ended by the switch-off signal. As a result, the stopping process of the crankshaft is significantly shortened overall, as a result of which both the development of noise and the energy consumption associated with the braking torque causing the crankshaft to come to a standstill can be reduced during the stopping process.

In a preferred embodiment of the method according to the invention, it is provided that the physical process parameter is the rotational speed of the crankshaft.

Since the rotational speed that the crankshaft has at the beginning of the stopping process, i.e. immediately after the detection of the switch-off signal, is decisive for the braking torque required to stop the crankshaft, this embodiment enables the crankshaft to be stopped particularly efficiently and quickly.

Since the braking torque necessary for a specified reduction in the rotational speed in a specified time interval in the case of a high rotational speed of the crankshaft is much higher than the braking torque necessary for the same reduction in the rotational speed in the same time interval in the case of a low rotational speed of the crankshaft, it is at a Particularly preferred embodiment of the method according to the invention provides that the amount of the braking torque applied to the crankshaft immediately after detection of the switch-off signal is essentially indirectly proportional to the rotational speed of the crankshaft that the crankshaft is at the moment the switch-off signal is detected.

As a result, the stopping process can be shortened and the total energy consumption required to stop the crankshaft can be reduced considerably.

In order to further shorten the stopping process, a further preferred embodiment of the method according to the invention provides that the braking torque is maintained at least in sections within a braking period, but preferably until the crankshaft comes to a standstill, the braking period being that period between the detection of the switch-off signal and the crankshaft is at a standstill.

In another particularly preferred embodiment of the method according to the invention, it is provided that the braking torque is applied to the crankshaft in the form of a braking profile, a function determining the course of the braking profile being stored by the electronic control device, and preferably a linear dependence on the current one Speed of rotation of the crankshaft and / or the time that has elapsed since the detection of the shutdown signal.

By using such a braking profile, the braking torque required to stop the crankshaft can be varied over the entire braking process, which can be used to further shorten the stopping process.

It is particularly preferably provided that the amount of the braking torque resulting from the course of the braking profile increases monotonically from the point in time of the detection of the switch-off signal to the point in time when the crankshaft comes to a standstill.

This ensures that the braking effect to which the crankshaft is exposed increases steadily in the course of the stopping process and the crankshaft can be stopped quickly.

In order to determine in which of several rotational speed regimes determined by the specific choice of the specified rotational speed values the crankshaft is in each case during the braking period, it is provided in a preferred embodiment of the method according to the invention that the rotational speed of the crankshaft, preferably several times, during the braking period , particularly preferably constantly, is compared with predetermined rotational speed values and the braking period is at least partially, preferably the entire braking period, subdivided into process time segments, the rotational speed of the crankshaft in each of these process time segments being in a value range that is assigned to one of the predetermined rotational speed values.

In order to obtain a particularly easy to implement and efficient braking profile, a further particularly preferred embodiment of the method according to the invention provides that the course of the braking profile essentially follows a piece-wise linear function of the process time, this function having a section with a constant gradient in each process time segment having.

BRIEF DESCRIPTION OF THE FIGURES

The invention will now be explained in more detail using an exemplary embodiment. The drawing is exemplary and is intended to explain the idea of the invention, but in no way restrict it or reproduce it conclusively.

FIG. 1

zwei einander korrespondierende Diagramme, welche einen mittels einer erfindungsgemäßen Steuerungseinrichtung geregelten Anhalteprozess darstellen.

It shows:

FIG. 1

two diagrams corresponding to one another, which represent a stopping process regulated by means of a control device according to the invention.

WAYS OF CARRYING OUT THE INVENTION

FIG. 1 shows two diagrams corresponding to one another, which show the rotational speed n of a crankshaft of a refrigerant compressor and the torque M applied to the crankshaft during an operating phase II in which the refrigerant compressor is operated as intended, as well as during a stopping process III following this operating phase, each as a function of Process time t.

At time t ₀ , which coincides with the origin of the abscissa, an electronic control device according to the invention detects a start signal directed to the refrigerant compressor. In response to the start signal, a drive unit of the refrigerant compressor sets the crankshaft of the refrigerant compressor in motion. After the crankshaft has first been moved into a predetermined position in the course of a corresponding starting process I of the refrigerant compressor, the crankshaft is accelerated _{from this position to a predetermined rotational speed n start.} As soon as the rotational speed of the crankshaft has reached the value n _Start , the starting process I is completed and the refrigerant compressor is ready for use in order to provide the cooling power required by a cooling device in which the refrigerant compressor is used. As long as such a need does not exist or a further control device of the cooling device in which the refrigerant compressor is used has not been communicated to the inventive electronic control device of the refrigerant compressor, the crankshaft maintains the rotational speed n _start . According to the invention, the starting speed n _start can be reached and maintained by means of an open control loop.

As soon as the electronic control device according to the invention is informed of a specific need for cooling power, which cooling power can be automatically determined by the other control electronics of the cooling device or manually determined by a user of the cooling device and which cooling power corresponds to a certain desired temperature within the cooling device, the rotational speed n of the crankshaft by means of a closed control loop from the starting speed n _start (hereinafter abbreviated rpm) on a in a range between about 700 rpm and 4000 rpm lying and corresponding to the predetermined cooling demand rotational velocity command value regulated n _target. For this purpose, a certain, positive operating torque M is applied to the crankshaft, which in coordination with a measured value of the current rotational speed n the crankshaft is varied until the rotational speed setpoint n _{setpoint is} reached. This rotational speed setpoint n _setpoint is maintained until the required cooling capacity has been made available to the refrigerator and the result is the desired temperature in the refrigerator or in an area of the refrigerator, such as the freezer compartment of a refrigerator.

• Unmittelbar nach Detektieren des Abschaltsignals legt die elektronische Steuerungseinrichtung ein dem in der Betriebsphase II vorherrschenden Drehmoment (seiner Richtung nach) entgegen gerichtetes Drehmoment, also ein Bremsmoment, an die Kurbelwelle an und leitet somit gleichzeitig den Bremsprozess ein. Der Anhalteprozess III weist somit keinen aus dem Stand der Technik bekannten, dem Bremsprozess vorhergehenden Zeitraum auf, in welchem die Kurbelwelle unkontrolliert ausläuft, um die Drehgeschwindigkeit der Kurbelwelle vor Anlegen des Bremsmomentes unter einen bestimmten,
• ausreichend geringen Wert zu reduzieren. Dadurch wird der Anhalteprozess insgesamt deutlich verkürzt, womit eine Verkürzung jener Zeit einhergeht,
• innerhalb welcher der Kältemittelkompressor einen hinsichtlich der Lärmerzeugung kritischen Drehgeschwindigkeitsbereich, also den Bereich zwischen etwa 700 rpm und 0 rpm, durchläuft.

As a result of reaching the desired temperature, the electronic control device is informed of this in the form of a switch-off signal directed to the refrigerant compressor. The stopping process III, which begins following the detection of this shutdown signal and at the end of which the crankshaft comes to a complete standstill, is structured according to the invention as follows:

• Immediately after detecting the switch-off signal, the electronic control device applies a torque to the crankshaft that is opposite to the torque prevailing in operating phase II (in its direction), i.e. a braking torque, and thus simultaneously initiates the braking process. The stopping process III thus does not have a period of time known from the prior art, prior to the braking process, in which the crankshaft coasts down in an uncontrolled manner in order to keep the rotational speed of the crankshaft below a certain,
• to reduce sufficiently low value. As a result, the stopping process is significantly shortened overall, which is accompanied by a shortening of the time
• within which the refrigerant compressor runs through a rotational speed range that is critical in terms of noise generation, that is to say the range between approximately 700 rpm and 0 rpm.

However, since the braking torque, which would be necessary to _{completely brake the crankshaft, which was at a high rotational speed n setpoint} at the time the switch-off signal was detected, would be much too high and more, both from the point of view of energy efficiency and for noise reasons In addition, there would also be the risk that components of the control device and / or the refrigerant compressor would be damaged during this violent braking, it is provided according to the invention that the braking torque applied to the crankshaft immediately after the detection of the switch-off signal is a function of the rotational speed that the crankshaft at Time of the detection of the shutdown signal.

Specifically, it is planned and off Fig. 1 It can be clearly seen that the braking torque applied to the crankshaft immediately after the shutdown signal is detected _{is lower in the case of a high setpoint value of the rotational speed n setpoint of} the crankshaft at the time the shutdown signal is detected than in the case of a low one Rotational speed n _{setpoint of} the crankshaft at the time of the detection of the switch-off signal. The amount of the braking torque applied to the crankshaft immediately after the switch-off signal is detected is thus indirectly proportional to the rotational speed n _setpoint that the crankshaft has at the time the switch-off signal is detected. Alternatively, it can also be provided that when determining the amount of the braking torque, another detected, physical process parameter, for example the power consumption of the refrigerant compressor, takes the place of the rotational speed of the crankshaft - the braking torque is the function of another process parameter is.

If the crankshaft has a high rotational speed n _Soll at the time the switch-off signal is detected, the braking torque applied at the beginning of the stopping process initially leads to a comparatively weak braking of the crankshaft, whereas the braking effect is comparatively high when the crankshaft has a low rotational speed n _Soll at the time of the detection of the shutdown signal.

Due to the braking process that begins at the same time as the start of the stopping process, the rotational speed of the crankshaft decreases faster than with refrigerant compressors according to the state of the art, in which the crankshaft initially coasts down in an uncontrolled manner for the purpose of speed reduction before the braking torque, which ultimately brings about the complete standstill of the crankshaft and to prevent a reversal of the direction of rotation at the last moment of the stopping process, is applied to the crankshaft.

In order to achieve an ever stronger braking effect as the process time t progresses since the switch-off signal was detected, the braking torque applied to the crankshaft forms a braking profile that extends over an entire braking period between the detection of the switch-off signal and the standstill of the crankshaft. This means that the crankshaft is exposed to a braking torque during the entire braking period. The amount of this braking torque, which results from the course of the braking profile, increases monotonically from the point in time at which the switch-off signal is detected until the crankshaft comes to a standstill. The course of the braking profile itself can in turn contain a function of the current rotational speed of the crankshaft and / or the process time t (for example that has elapsed since the start of the stopping process), a function determining this course being stored by the control device according to the invention.

In the exemplary embodiment shown, the braking period is divided into four (scenario 1) or two (scenario 2) process time segments (T ₁ , T ₂ , T ₃ , T ₄ or T ₁₁ , T ₂₂ ) without affecting the general public. Within each of these process time segments lies the respective rotational speed of the crankshaft, which is monitored by the electronic control device with a high frequency, for example with a frequency higher than 10 Hz, and with predefined values (n ₁ , n ₂ , n ₃ , n ₀ or n ₃ , n ₀ ) of the rotational speed is compared, in each case in a range which is assigned to a predefined value of the rotational speed. The braking profile extending over the entire braking period and thus over all process time segments (T ₁ , T ₂ , T ₃ , T ₄ or T ₁₁ , T ₂₂ ) can be designed in such a way that it follows the course of a piecewise linear function of the process time t , the slope of this function in each of the process time segments (T ₁ , T ₂ , T ₃ , T ₄ or T ₁₁ T ₂₂ ) each having a different, constant value.

Below the last non-vanishing, predefined value of the rotational speed (in both scenarios this is the rotational speed n ₃ ), the said slope of the said piecewise linear function of the process time t assumes the value zero - the braking profile applied to the crankshaft, more precisely its amount, is therefore constant in the last process time segment (T ₄ in the case of scenario 1; T ₂₂ in the case of scenario 2) of the braking period. Thus, the braking behavior caused by the electronic control device according to the invention during the final process time segment immediately preceding the standstill of the crankshaft differs from that of the remaining process time segments within which the amount of the braking torque increases or rises monotonically.

REFERENCE LIST

M.

Torque

n

Speed of rotation of the crankshaft

nα, nβ, ...

specified rotational speed values

nStart

specified speed of rotation

nSoll

Target value of the rotation speed

t

Process time

t0

Time of detection of a start signal

Ti, Tii

Process time segments of the braking period (i = 1,2, ..., 11,22, ...)

Claims (18)

1. Electronic control device for a refrigerant compressor, which comprises at least

   • a drive unit and

   • a compression mechanism that is in operative connection with the drive unit and that has at least one piston that moves back-and-forth in a cylinder of a cylinder block of the refrigerant compressor in an operating state of the refrigerant compressor for compression of refrigerant as intended and is driven via a crankshaft of the drive unit

   wherein the electronic control device of the refrigerant compressor is configured at least

   • to detect at least one physical process parameter, preferably the rotary speed (n) of the crankshaft or the power consumption of the refrigerant compressor,

   • to detect a shutoff signal directed to the refrigerant compressor, which shutoff signal ends an operating phase of the refrigerant compressor, in which operating phase the refrigerant compressor is operated as intended with a positive operating torque, and

   • to control a torque applied by the drive unit to the crankshaft in order to set its rotary speed (n),

   characterized in that the electronic control device is further configured to apply a braking torque to the crankshaft immediately after detection of the shutoff signal, where the braking torque is directed opposite to the positive torque that existed during the operating phase and the magnitude of said braking torque is a function of the detected physical process parameter, preferably the rotary speed (n) of the crankshaft or the power consumption of the refrigerant compressor.
2. Electronic control device as in Claim 1, characterized in that the physical process parameter is the rotary speed (n) of the crankshaft.
3. Electronic control device as in Claim 1 or 2, characterized in that the magnitude of the braking torque applied to the crankshaft immediately after detection of the shutoff signal is inversely proportional to the rotary speed (n) of the crankshaft that the crankshaft has at the moment of the detection of the shutoff signal.
4. Electronic control device as in one of Claims 1 to 3, characterized in that the braking torque is maintained up to a complete stop of the crankshaft.
5. Electronic control device as in one of Claims 1 to 4, characterized in that the braking torque applied to the crankshaft forms a braking profile, where a function defining the course of the braking profile is stored by the electronic control device and preferably comprises a linear dependency on the current rotary speed (n) of the crankshaft and/or the time elapsed since detection of the shutoff signal.
6. Electronic control device as in one of Claims 1 to 5, characterized in that the electronic control device is configured to compare, during a braking period extending between the detection of the shutoff signal and the complete stop of the crankshaft, the rotary speed (n) of the crankshaft, preferably a number of times, especially preferably continuously, with preset rotary speed values (n_α, n_β,...).
7. Electronic control device as in Claim 6, characterized in that the course of the braking profile essentially follows a piecewise linear function, where a segment of the braking period is associated with each of the preset rotary speed values (n_α, n_β,...), within which segment said piecewise linear function exhibits an essentially constant slope.
8. Electronic control device as in one of Claims 5 to 7, characterized in that the magnitude of the braking torque resulting from the course of the braking profile increases monotonously from the time of the detection of the shutoff signal to the time of the complete stop of the crankshaft.
9. Refrigerant compressor for use in a refrigeration unit, preferably in a refrigerator or freezer, where the refrigerant compressor comprises an electronic control device as in one of the preceding claims.
10. Refrigeration unit, preferably a refrigerator or freezer, with a refrigerant compressor as in Claim 9.
11. Method for operating a refrigerant compressor suitable for use in a refrigeration unit, preferably in a refrigerator or freezer, which comprises a compression mechanism for compression of refrigerant and a drive unit, where the compression mechanism is driven by means of a crankshaft of the drive unit that is supplied with a torque, characterized in that it comprises the following steps:

    • detecting a shutoff signal ending an operating phase in which the refrigerant compressor is operated as intended with a positive operating torque;

    • detecting a physical process parameter, preferably a rotary speed (n) of the crankshaft or a power consumption of the refrigerant compressor;

    • applying a braking torque to the crankshaft immediately after the detection of the shutoff signal, where the braking torque opposes the positive operating torque in its direction of action and the magnitude of the braking torque is a function of the detected physical process parameter, preferably the rotary speed (n) of the crankshaft or the power consumption of the refrigerant compressor.
12. Method as in Claim 11, characterized in that the physical process parameter is the rotary speed (n) of the crankshaft.
13. Method as in Claim 11 or 12, characterized in that the magnitude of the braking torque applied to the crankshaft immediately after detection of the shutoff signal is essentially inversely proportional to the rotary speed (n) of the crankshaft that the crankshaft has at the moment of the detection of the shutoff signal.
14. Method as in one of Claims 11 to 13, characterized in that the braking torque is maintained at least in a segment within a braking period, but preferably up to the complete stop of the crankshaft, where the braking period is the time between the detection of the shutoff signal and the complete stop of the crankshaft.
15. Method as in Claim 14, characterized in that the braking torque is applied to the crankshaft in the form of a braking profile, where a function defining the course of the braking profile is stored by the electronic control device, and preferably comprises a linear dependency on the current rotary speed (n) of the crankshaft and/or of the elapsed time since detection of the shutoff signal.
16. Method as in Claim 15, characterized in that the magnitude of the braking torque resulting from the course of the braking profile increases monotonously from the time of the detection of the shutoff signal to the time of the complete stop of the crankshaft.
17. Method as in one of Claims 14 to 16, characterized in that during the braking period the rotary speed (n) of the crankshaft is compared, preferably a number of times, especially preferably continuously, with preset rotary speed values (n_α, n_β,... ) and the braking period is divided at least partially, preferably the entire braking time is divided, into process time segments (T_α, T_β,...), where in each of said process time segments (T_α, T_β,...) the rotary speed (n) of the crankshaft lies in a value range with which one of the preset speed values (n_α, n_β,...) is associated.
18. Method as in Claim 17, characterized in that the course of the braking profile essentially follows a piecewise linear function of the process time, where said function exhibits a segment with constant slope in each process time segment (T_α, T_β,...).

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