METHOD AND APPARATUS FOR EXTRACTING A REFRIGERANT AND STATE UNIT

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority from German Patent Application No. 10 2024 119 795.1, filed Jul. 11, 2024, which is incorporated herein by reference as if fully set forth.

TECHNICAL FIELD

The invention relates to a method for extracting a refrigerant with a suction pump.

BACKGROUND

Refrigeration systems, for example air conditioning systems and heat pumps, use a refrigerant in a refrigerant circuit in order to achieve the appropriate heating and/or cooling effect.

Situations arise in which the refrigerant has to be removed from the refrigerant circuit, for instance if a refrigeration system needs repairing.

In order to remove the refrigerant from a refrigerant circuit, it is known in the prior art to use a suction station. Such a suction station has a suction valve on the input side, which suction valve is connected to the refrigerant circuit to be evacuated, for instance to a service connection of the refrigeration system. The suction station furthermore has a suction pump, which is connected to an empty refrigerant pressure cylinder on the output side. The suction pump compresses the gaseous refrigerant and pumps it into the refrigerant pressure cylinder. During the extraction process, it is therefore necessary for the refrigerant to be gaseous.

Depending on the ambient conditions, it may occur that, instead of being fully gaseous, the refrigerant in the refrigerant circuit is at least partially liquid. Since a liquid is not compressible, the suction pump is unable to generate full power in this situation or it may even become damaged. This is manifested, for instance, by a knocking or jumping/bouncing of the suction station.

It has hitherto been the case that, during the extraction process, the engineer hears unusual noises from the suction pump and may then reduce the supply of liquid to the suction pump by reducing the opening of the suction valve. In order to avoid such undesired states of the suction pump, it is also usual in the prior art to operate the valve permanently with the smallest opening or to reduce the cross section of the lines in order to avoid damage to the suction pump. However, the extraction procedure consequently takes an unnecessarily long time.

SUMMARY

The object of the invention, therefore, is to improve the extraction procedure.

This object is achieved according by a method according to the invention that includes one or more of the features disclosed herein, as well as by an apparatus and a state unit according to the invention that have one or more of the features disclosed herein.

The method according to the invention is characterized in that the refrigerant used is ascertained before the extraction process, in that the pressure and temperature of the refrigerant are ascertained repeatedly during the extraction process, in that a phase state of the refrigerant is determined from the pressure and the temperature and in that a suction valve of the suction pump is controlled on the basis of the phase state of the refrigerant.

The phase state of the refrigerant, i.e. whether the refrigerant contains liquid components, may thus be identified objectively. As a result, the suction valve can be controlled such that the opening of the suction valve is as large as possible without the suction pump entering a critical or undesired state, which occurs if the refrigerant is at least partially liquid. It is therefore no longer necessary to “hear” the state of the pump in order to possibly control the suction valve.

The phase state of the refrigerant may change over the distance between the refrigeration system and the suction station, which means that it may be advantageous if the pressure and/or the temperature is ascertained at the inlet or in the vicinity of the inlet of the suction station.

In one embodiment, the suction valve of the suction pump is controlled in an automated manner depending on the phase state of the refrigerant. Intervention from a user is therefore unnecessary and the opening of the suction valve may be controlled optimally in an automated manner.

In an alternative embodiment, to control the suction valve, information about the position of the suction valve is output, according to which a user of the suction pump may adjust the valve. The method according to the invention may therefore also be used with suction stations which do not enable automatic control of the suction valve, for example.

In one embodiment, the information about the position of the control valve may comprise an absolute valve position. To this end, the information may include, for example, a graphical representation of an operating element of the suction valve.

Additionally or alternatively, the information may comprise directional information for moving an operating element of the suction valve. For example, this may include whether the opening of the suction valve should be reduced or increased. It may also include whether an operating element of the suction valve should be moved upwards, downwards, to the right or to the left.

In one embodiment, the information also includes a representation of the phase state of the refrigerant. A user may thus identify the phase state directly. A manual correction of the valve position may possibly also take place on the basis of this representation, even when the suction valve is controlled automatically.

In order to determine the phase state of the refrigerant, it is necessary to firstly ascertain the refrigerant. This is conveniently realized manually, for instance on the basis of a table or database.

Alternatively, it may also be provided that the refrigerant is ascertained in an automated manner by a refrigerant sensor. Fully automatic extraction may thus take place, for example.

In one embodiment, the pressure is ascertained in an automated manner by a pressure sensor.

In one embodiment, the temperature is ascertained in an automated manner by a temperature sensor.

As a result of the automated ascertainment of the parameters of the refrigerant, repeated determination of the phase state is possible.

In one embodiment, a phase diagram is assigned to a refrigerant. The phase state of the refrigerant is ascertained according to the ascertained pressure and the ascertained temperature on the basis of the assigned phase diagram.

In one embodiment, the opening of the suction valve is reduced if a liquid phase state of the refrigerant is determined and the opening of the suction valve is increased if a gaseous phase state of the refrigerant is determined. Liquid refrigerant may thus be prevented from making its way into the suction pump.

The invention furthermore comprises an apparatus for extracting a refrigerant, having a suction pump and a controllable suction valve, wherein the apparatus furthermore has a state unit, the apparatus having a pressure sensor and a temperature sensor and the state unit being designed to determine a phase state of the refrigerant, and wherein the suction valve can be controlled depending on the phase state. With such an apparatus, it is possible to carry out an extraction procedure in a quick and reliable manner. Damage to the suction pump, which may be caused by extracting liquid refrigerant, is thus prevented.

In one embodiment, the suction valve is controlled in an automated manner depending on the phase state. Fully automated extraction is thus enabled, the extraction procedure taking place as quickly as possible, without damage to the suction pump.

In one embodiment, the apparatus additionally or alternatively has an information unit, which is designed to output information for adjusting the suction valve manually on the basis of the phase state of the refrigerant. Manual control of the suction valve is thus possible, it being possible for the control to take place according to objective criteria rather than by ear, as was previously the case.

In one embodiment, the information unit is designed to display the information visually. To this end, the information unit may have, for instance, a screen or individual optical elements, such as light-emitting diodes.

Such an apparatus may be, for example, a suction station. The suction station preferably comprises the suction valve and the suction pump. The state unit may be a separate device, which is separate from the suction station.

In one embodiment, the pressure sensor is arranged in the suction station. The pressure may therefore be ascertained directly at the inlet of the suction pump. It is advantageous here if a connection for communicating the pressure values to the state unit is present. This connection may preferably be realized via a radio link.

In one embodiment, the pressure sensor is arranged in the state unit. The pressure may therefore also be ascertained if, for example, the suction station does not have a pressure sensor or a connection for communicating the pressure value.

In one embodiment, the temperature sensor is an external temperature sensor. By way of example, in order to ascertain the temperature value near to the suction station, such a temperature sensor may be arranged on a refrigerant line in the vicinity of the suction station via a clip.

The temperature sensor may also be arranged in the state unit.

In one embodiment, the apparatus is designed to carry out a method according to the invention.

The invention also comprises a state unit having at least one refrigerant input, having a refrigerant output, having a pressure sensor and having a temperature sensor, the state unit being designed to determine a phase state of the refrigerant, and the state unit being designed to control the suction valve depending on the phase state. This state unit is preferably designed as a separate device. The extraction method according to the invention may thus be carried out with any conventional suction station.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is explained in more detail below on the basis of exemplary embodiments with reference to the accompanying drawings, in which:

FIG. 1 shows a flow chart of a method for extracting refrigerant,

FIG. 2 shows a block diagram of a first embodiment of an apparatus for extracting refrigerant,

FIG. 3 shows a block diagram of a first embodiment of an apparatus for extracting refrigerant,

FIG. 4 shows a block diagram of a first embodiment of an apparatus for extracting refrigerant,

FIG. 5 shows a block diagram of a first embodiment of an apparatus for extracting refrigerant, and

FIG. 6 shows a schematic representation of an information unit.

DETAILED DESCRIPTION

FIG. 1 shows a flow chart of a method 1 according to the invention for extracting a refrigerant from a refrigeration system.

In a first step 2, the refrigerant used or to be extracted is ascertained. This step generally takes place before an extraction procedure is started. The ascertainment of the refrigerant takes place manually, for instance via a selection list, or in an automated manner, for example with the aid of a sensor.

In a second step 3, the pressure and the temperature of the refrigerant are ascertained. Both parameters are preferably ascertained in an automated manner via sensors.

In a third step 4, a phase state of the refrigerant is determined on the basis of the pressure and the temperature. To this end, a phase diagram may be assigned to each refrigerant and stored, for instance, in a database. The phase state may be determined from the pressure and the temperature on the basis of this phase diagram.

In a fourth step 5, it is now checked on the basis of the phase state whether the refrigerant is purely gaseous or comprises at least a liquid fraction.

If the refrigerant contains a liquid fraction or the fraction of liquid is greater than in the most recent measurement, the opening of a suction valve is reduced in a fifth step 6. This may be performed manually by a user. To this end, information may be output to the user, which may include, for example, the position of the suction valve and/or the direction in which the suction valve has to be moved. The information may also comprise the current phase state.

Alternatively, the reduction in the opening of the suction valve may also take place automatically.

If the refrigerant does not contain any liquid or contains less liquid than in the most recent measurement, the opening of the suction valve is increased in an alternative sixth step 7. If a wider opening is no longer possible, i.e. the maximum opening has already been achieved, this opening is maintained.

The increase in the opening of the suction valve may also take place manually and/or in an automated manner here, analogously to the reduction in the opening.

It is thus always possible to carry out the extraction procedure at the maximum possible speed, since the suction valve is always opened as wide as possible without damage occurring to the suction pump.

The reduction or increase in the opening of the suction valve, whether automated or manual, may correlate with the fraction of liquid. This means that, the greater the liquid fraction, the greater the reduction/increase, i.e. the further the suction valve is closed/opened. Liquid is thus prevented from making its way into the suction pump and the maximum possible opening is always set. A phase state may therefore correlate directly, i.e. absolutely, with an opening of the suction valve so that a relative consideration with respect to the previous phase state is not required.

In a subsequent seventh step 8, it is established whether the system to be evacuated is already empty.

If this is the case, the extraction procedure is terminated in step 9.

If the system is not yet empty, the process continues with step 3 and the pressure and the temperature are ascertained again.

FIG. 2 shows a block diagram of a first apparatus 10 for extracting a refrigerant from a refrigeration or climate control system 11. Such a refrigeration or climate control system 11 may be, for instance, an air conditioning system or a heat pump.

The apparatus 10 has a state unit 12 and a suction station 13, which, in this example, are designed as separate devices.

The suction station 13 has a suction valve 14 and a suction pump 15. Internally, the suction valve 14 is connected to the suction pump 15. This means that the suction valve 14 determines the quantity of refrigerant that makes its way to the suction pump 15. The suction station 13 is connected to a refrigerant pressure cylinder 16. The extracted refrigerant is compressed into the refrigerant pressure cylinder 16 by the suction pump 15.

The state unit 12 has a high pressure input 17 and a low pressure input 18. These are connected respectively to the high pressure circuit 19 and the low pressure circuit 20 of the system 12 for extraction purposes.

The state unit 12 has an output 29, which is or will be connected to the suction valve 14 of the suction station.

In the example shown, the state unit 12 has a pressure sensor (not shown) at the high pressure input 17 and at the low pressure input 18 in each case and at least one temperature sensor, each of which is integrated in the state unit 12. Moreover, the state unit 12 has a memory, for instance, in which a respective phase diagram for various refrigerants is stored. The state unit 12 is designed to determine a phase state from a pressure and a temperature of the refrigerant. This phase state reveals the fraction of liquid that may be contained in the refrigerant.

In this example, the state unit 12 has a control connection 21 to the suction station 13, via which the suction valve 14 may be controlled. To this end, the suction valve 14 has, for instance, an electromotive actuator. Additionally, the suction valve 14 may have a manual operating element.

According to the method of FIG. 1, the opening of the suction valve 14 is therefore reduced if the refrigerant has a liquid fraction or increased if less liquid is present. Automatic and continuous control of the suction valve 14 is thus enabled so that an extraction procedure takes place at maximum speed.

Before an automatic extraction procedure can be started, the refrigerant firstly has to be selected. To this end, the state unit 12 may have a screen, for instance a touch-screen, on which a selection list of various refrigerants is firstly presented and in which the refrigerant used is selected. The state unit 12 may additionally or alternatively have an interface to an external control, for instance an app, via which the refrigerant can be selected so that the state unit does not need its own screen.

FIG. 3 shows a further embodiment of an apparatus 10 for extracting refrigerant. Functionally equivalent features to those in FIG. 1 are denoted by the same reference signs.

The suction station 13 has only a manually controllable valve 14 here. This means that there is no control connection to the state unit 12. To this end, the suction valve 14 has an operating element (not shown), via which the opening of the suction valve 14 can be adjusted.

To this end, the state unit 12 has an information unit 22, for instance a screen for graphically representing information for controlling the suction valve 14. A valve position, which is represented graphically, is derived from the phase state of the refrigerant here. A user may then adjust the suction valve 14 at the suction station 13 accordingly via the operating element. The advantage of this is that the user receives an objective indication for controlling the suction valve and no longer has to proceed by ear.

FIG. 4 shows a further embodiment of the apparatus 1, which is of a similar to design to that in FIG. 2. The suction station 13 has a pressure sensor here, for instance at the input of the suction valve 14, which is connected to the state unit 12 via a control connection 23. Pressure values may thus be communicated to the state unit 12.

Moreover, an external temperature sensor 24 is present, which is arranged on a refrigerant line in the vicinity of the suction valve 14. The temperature sensor 24 likewise has a control connection 25 to the state unit 12 for communicating the temperature values. In this embodiment, the state unit 12 may additionally also have internal pressure and/or temperature sensors. However, to determine the phase state, the externally ascertained pressure and temperature values are preferably used, since these may be ascertained nearer to the suction valve 14. The suction valve 14 is controlled automatically by the state unit 12 via the control connection 21.

In all embodiments, the control connections 21, 23 and/or 25 may be designed as wired or wireless connections, for instance as a wireless link such as Bluetooth.

FIG. 5 shows a further alternative embodiment of an apparatus 10 for extracting refrigerant. In contrast to the previous embodiments, the state unit 12 here is integrated in the suction station 13. The suction station 13 and state unit 12 are therefore combined in one device. The state unit 12 has an internal control connection 21 here for controlling the suction valve 14 automatically.

In addition to the embodiments shown here, it is, of course, possible to combine the individual components of the individual embodiments in any desired manner. In this regard, for instance, an external temperature sensor may also be used in FIG. 5, which can be connected to the internal state unit 12.

It is also possible that the state unit 12 of FIGS. 2 to 4 and also the suction station 13 of FIG. 5 has only one input for connection to a refrigerant circuit. In this case, the high pressure circuit and the low pressure circuit must be evacuated separately in succession, in which case the connection has to be changed. In any case, the invention is not restricted to the embodiments shown.

FIG. 6 shows, by way of example, an information unit 22 for representing information visually. The example shows a representation 26 of an operating element of a suction valve 14, which indicates an absolute position. With such information, the suction valve 14 may be controlled quickly and in a relatively precise manner.

Additionally or alternatively, the information unit 22 has direction indicators 27, which indicate, for example, the direction in which an operating element of the suction valve 14 should be moved.

Furthermore additionally, the information unit 22 may feature a representation 28 of the phase state, which represents the fraction of liquid graphically.

LIST OF REFERENCE SIGNS

• • 1 Method
  • 2 First step
  • 3 Second step
  • 4 Third step
  • 5 Fourth step
  • 6 Fifth step
  • 7 Sixth step
  • 8 Seventh step
  • 9 Eighth step
  • 10 Apparatus for extracting a refrigerant
  • 11 Refrigeration or climate control system
  • 12 State unit
  • 13 Suction station
  • 14 Suction valve
  • 15 Suction pump
  • 16 Refrigerant pressure cylinder
  • 17 High pressure input
  • 18 Low pressure input
  • 19 High pressure circuit
  • 20 Low pressure circuit
  • 21 Control connection
  • 22 Screen
  • 23 Control connection P
  • 24 External temperature sensor
  • 25 Control connection T
  • 26 Representation of an operating element
  • 27 Direction indicator
  • 28 Representation of the phase state
  • 29 Output of the state unit