DE102020103862B4 - Method for controlling a heat pump for a motor vehicle, in particular hybrid electric motor vehicle or electric vehicle, and heat pump for a motor vehicle - Google Patents

Abstract

Method (100) for controlling a heat pump (13) for a motor vehicle (10), in particular a hybrid electric vehicle or electric vehicle (12), the heat pump (13) having an evaporator (14) designed as a heat exchanger (18), a compressor (15), a capacitor (16) and a throttle (17), comprising the steps of - determining the value of a pressure parameter of the heat pump (13), - comparing the determined value of the pressure parameter with an upper limit value, and if the determined value of the pressure parameter is greater or is equal to the upper limit value: - carrying out a de-icing process for the evaporator (14), or, if the determined value of the pressure parameter is smaller than the upper limit value: - repeating the process starting with the first process step, characterized in that the pressure parameter is a suction pressure change rate and that the suction pressure change rate is compared with the upper limit, the upper limit being a suction pressure change rate limit.

Description

The present invention relates to a method for controlling a heat pump for a motor vehicle, in particular a hybrid electric vehicle or electric vehicle, wherein the heat pump comprises an evaporator designed as a heat exchanger, a compressor, a capacitor and a throttle. The present invention further relates to a heat pump for a motor vehicle, in particular a hybrid electric motor vehicle or electric vehicle, and a motor vehicle, in particular a hybrid electric motor vehicle or electric vehicle.

Technological background

Heat pumps are used, among other things, to heat passenger compartments in motor vehicles. The motor vehicles can in particular be hybrid electric vehicles or electric vehicles. The heat required to heat the vehicle interior is taken from the outside air using a heat exchanger designed as an evaporator. To do this, the heat exchanger must be cooled below the ambient temperature. If the ambient or outside air falls below its dew point, frost forms on the surface of the heat exchanger, which prevents the air from flowing through the heat exchanger. The efficiency of the heat pump decreases.

The DE 37 06 152 A1 discloses a method for controlling a motor vehicle air conditioning system. The motor vehicle air conditioning system includes a refrigeration circuit with a refrigerant compressor, a condenser, an evaporator and a throttle device arranged upstream of the evaporator. The compressor performance, the condenser performance and the evaporator performance are recorded directly or indirectly by sensor means, and depending on at least two of these performance values and the inclusion of the parameters for the cooling power requirement, the evaporator icing, the compression end temperature and the liquid deflection, output signals are used to influence the compressor performance and the condenser performance and/or the evaporator performance. As a measure of evaporator icing, the suction pressure can be measured using a pressure sensor.

The DE 101 55 457 A1 discloses an air conditioning system with a variable-stroke compressor, wherein the stroke of the compressor is regulated by the inflow of the refrigerant from the outlet pressure chamber into the drive chamber and / or by the outflow of the refrigerant from the drive chamber into the intake pressure chamber, wherein two valves that can be operated independently of one another are connected to a control device, wherein a valve is arranged in the engine room inflow and a valve in the engine room outlet. For air conditioning, the outlet pressure or the suction pressure can be used as a control variable, depending on whether the system is operated as a heat pump or as a refrigeration system. Furthermore, by opening both valves at the same time, the flow of refrigerant moving through the vehicle components can be minimized in order to avoid icing of the evaporator if the system is not intended to deliver any cooling capacity.

The DE 11 2013 005 367 T5 discloses a vehicle air conditioning system with a control device configured to determine ice formation on an outdoor heat exchanger based on a coolant evaporation pressure of the outdoor heat exchanger and a coolant evaporation pressure of the outdoor heat exchanger during non-ice formation.

From the US 2018 / 0 031 289 A1 a method for de-icing a heat exchanger of an air conditioning system is known. The de-icing process can be initiated depending on a measured suction pressure.

From the US 2017 / 0 038 125 A1 Another method for de-icing a heat exchanger of an air conditioning system is known, wherein icing of the heat exchanger is determined based on a measured suction pressure.

The US 2007 / 0 199 335 A1 discloses a method for defrosting an evaporator of an air conditioning system in which the suction pressure is monitored.

In order to counteract icing of the heat exchanger, time-controlled defrosting cycles are known in the prior art, in which the heat exchanger is heated cyclically. The ice on the heat exchanger melts due to the heating and the ambient air can flow through the heat exchanger again. Time-controlled defrost cycles are very inefficient and have a significant impact on the performance of the heat pump.

The applicant's not yet published German patent application "Method for operating an air conditioning system for a vehicle" describes a method for operating an air conditioning system for a vehicle, which provides that overall energy efficiencies are determined for a group of operating strategies for the air conditioning system and an operating strategy with the greatest overall efficiency that covers a determined heating power requirement is selected.

Presentation of the invention: task, solution, advantages

The present invention is based on the object of providing a method for controlling a heat pump for a motor vehicle, in particular a hybrid electric vehicle or electric vehicle, which enables efficient operation of the heat pump and also does not require excessive technical complexity on the part of the heat pump. A further object of the present invention is to provide a heat pump for a motor vehicle, in particular a hybrid electric motor vehicle or electric vehicle, and a motor vehicle, in particular a hybrid electric motor vehicle or electric vehicle, with which the aforementioned advantages are achieved.

• - Ermittlung des Wertes eines Druckparameters der Wärmepumpe,
• - Vergleichen des ermittelten Wertes des Druckparameters mit einem oberen Grenzwert,

und
wenn der ermittelte Wert des Druckparameters größer oder gleich dem oberen Grenzwert ist:

• - Durchführen eines Enteisungsverfahrens für den Verdampfer,

oder
wenn der ermittelte Wert des Druckparameters kleiner als der obere Grenzwert ist:

• - Wiederholen des Verfahrens beginnend mit dem ersten Verfahrensschritt, wobei der Druckparameter eine Saugdruckänderungsrate ist und wobei die Saugdruckänderungsrate mit dem oberen Grenzwert verglichen wird, wobei der obere Grenzwert ein Saugdruckänderungsratengrenzwert ist.

To solve the problem on which the invention is based, a method for controlling a heat pump for a motor vehicle, in particular a hybrid electric vehicle or electric vehicle, is proposed, wherein the heat pump comprises an evaporator designed as a heat exchanger, a compressor, a capacitor and a throttle, comprising the steps

• - Determination of the value of a pressure parameter of the heat pump,
• - Comparing the determined value of the pressure parameter with an upper limit value,

and
if the determined value of the pressure parameter is greater than or equal to the upper limit value:

• - carrying out a de-icing procedure for the evaporator,

or
if the determined value of the pressure parameter is smaller than the upper limit value:

• - Repeating the method starting with the first method step, wherein the pressure parameter is a suction pressure change rate and wherein the suction pressure change rate is compared with the upper limit, the upper limit being a suction pressure change rate limit.

The evaporator is a heat exchanger. In the following, these terms can be used interchangeably.

By carrying out a de-icing method according to the invention depending on whether a determined value of a pressure parameter of the heat pump is less than or equal to a lower limit value and/or greater than or equal to an upper limit value, a method for controlling a heat pump and in particular a de-icing control of a heat pump is provided, according to which, depending on the situation, de-icing is only carried out if the evaporator of the heat pump is actually icing. In particular, since no time-controlled defrost cycles are carried out, the efficiency of the heat pump is improved. Since it is also known in the prior art to record pressure parameters for reasons of protecting the heat pump, in particular the compressor, no additional sensors are required for a heat pump to carry out the method. The method can preferably be used with little effort even in known heat pump concepts by adapting an existing control device.

The method for controlling a heat pump for a motor vehicle can also be referred to as a de-icing control.

In addition to the pressure parameter designed as a suction pressure change rate, it can be provided that the pressure parameter is a suction pressure and that the suction pressure is compared with the lower limit, the lower limit being a suction pressure limit.

Thus, in addition to the suction pressure change rate, the suction pressure can be used as a pressure parameter and the prerequisite for the deicing process to be carried out is that the determined value of the suction pressure reaches or falls below a, in particular predetermined, suction pressure limit value.

If the pressure parameter is the rate of change in suction pressure, the amount of the rate of change in suction pressure is preferably used as the value of the pressure parameter. Particularly preferably, the pressure parameter is the amount of the suction pressure change rate, and the amount of the suction pressure change rate is compared with the upper limit, the upper limit being a suction pressure change rate limit.

The prerequisite for the de-icing process to be carried out is that the determined value of the suction pressure change rate, in particular that the amount of the suction pressure change rate, reaches or exceeds a, in particular predetermined, suction pressure change rate limit value.

To determine the suction pressure, a sensor for determining the suction pressure, in particular a suction pressure sensor, can be provided in the heat pump, in particular in the refrigerant circuit on the suction side of the compressor.

The suction pressure sensor determines, preferably cyclically, the suction pressure in the refrigerant circuit and can transmit the determined value of the suction pressure, or a corresponding electrical signal, to a control device.

It can preferably be provided that the control device compares the determined value of the suction pressure with a predetermined suction pressure limit value, and/or that the control device compares the determined value of the suction pressure change rate limit with a predetermined suction pressure change rate limit value.

If the pressure parameter is the rate of change in suction pressure, the control device can also be designed to determine a rate of change in suction pressure from at least two values of the suction pressure determined at a time interval. The rate of change in suction pressure can also be referred to as a gradient, a time gradient or a time derivative of the suction pressure.

The design of the method using the suction pressure or the rate of change in suction pressure as a pressure parameter is based on the knowledge that the change in the suction pressure occurs under known operating conditions of the heat pump, for example the ambient temperature, the air humidity, the speed of a fan of the compressor and/or the one designed as a heat exchanger The amount of air flowing through the compressor provides an indication of the efficiency of the heat pump.

The thermal insulation effect of frost depositing on the evaporator designed as a heat exchanger in the event of icing and the resulting reduced air flow through the evaporator designed as a heat exchanger due to the blocking result in a lower temperature of the refrigerant of the heat pump and thus also a lower suction pressure Achieving the required heating output is necessary.

If the suction pressure of the, preferably output-controlled, heat pump falls below a predetermined suction pressure limit, this can be seen as an indication of icing or the precipitation of frost on the evaporator. Since the suction pressure initially changes only slowly at the start of icing and drops more and more quickly as the icing progresses, the suction pressure change rate offers a good indicator for detecting icing of the evaporator.

If the heat pump includes, for example, R-744 as a refrigerant, it can be provided that if the suction pressure falls below 15 bar, for example, a de-icing process is carried out for the evaporator of the heat pump, which is designed as a heat exchanger.

It can preferably be provided that the de-icing process includes heating the evaporator designed as a heat exchanger.

To heat the evaporator, the heat pump can be operated in reverse mode so that heat is released via the evaporator. Furthermore, it can be provided that the evaporator designed as a heat exchanger includes an electric heater, which is activated to carry out the deicing process. It is also possible for waste engine heat to be passed through the evaporator to de-ice the evaporator.

It can preferably be provided that the suction pressure limit value and/or the suction pressure change rate limit value are determined as a function of environmental parameters and/or operating parameters of the heat pump.

Since the suction pressure during operation and when the heat exchanger is not icy depends on the environmental parameters and/or operating parameters, an invariably set suction pressure limit value or an invariably set suction pressure change rate limit value can lead to defrosts that are too early or too late in time.

It is therefore particularly advantageous if the suction pressure limit or the suction pressure change rate limit is determined as a function of the environmental parameters and/or the operating parameters of the heat pump. The determination of the suction pressure limit value and/or the suction pressure change rate limit value is preferably carried out at regular time intervals, so that the suction pressure limit value and/or the suction pressure change rate limit value correlates as optimally as possible with the currently existing environmental parameters or operating parameters.

Particularly preferably, the determination of the suction pressure limit value or the suction pressure change rate limit value is carried out as the first step of the method, particularly preferably immediately before determining the value of the pressure parameter of the heat pump.

It can preferably be provided that the environmental parameters and/or the operating parameters include at least one of the parameters from the group comprising an ambient temperature, an amount of air flowing through the evaporator designed as a heat exchanger and an amount of air taken from the evaporator and/or the condenser a quantity of heat, a humidity and a compressor speed.

Furthermore, it is possible that the environmental parameters and/or the operating parameters also include other parameters.

The amount of heat taken from the evaporator preferably corresponds to the amount of heat absorbed by the evaporator from the environment.

At very low ambient temperatures, small amounts of air flowing through the evaporator designed as a heat exchanger and/or large amounts of heat taken from the evaporator, de-icing processes can occur that are carried out too early if a fixed suction pressure limit or a fixed suction pressure change rate limit is assumed. Accordingly, at high ambient temperatures, high amounts of air flowing through the evaporator designed as a heat exchanger and/or small amounts of heat taken from the evaporator, deicing processes that are carried out too late can occur if a fixed suction pressure limit or a fixed suction pressure change rate limit is assumed.

It is therefore particularly advantageous if the suction pressure limit value and/or the suction pressure change rate limit value is determined or determined as a function of the ambient temperature, an amount of air flowing through the evaporator designed as a heat exchanger, and an amount of heat taken from the evaporator and/or the condenser. The suction pressure limit and/or the suction pressure change rate limit can be determined or set in any combinations depending on one or more of these parameters.

Provision can preferably be made for the suction pressure limit to be increased when the ambient temperature increases.

The suction pressure limit is thus adjusted depending on the ambient temperature, in such a way that the suction pressure limit is reduced at low ambient temperatures and that the suction pressure limit is increased at higher ambient temperatures. For example, it can be provided that the suction pressure limit is 25 bar at an ambient temperature of 0 ° C and that the suction pressure limit is 15 bar at an ambient temperature of -10 ° C.

It can preferably be provided that the amount of air flowing through the evaporator designed as a heat exchanger is estimated using at least one of the parameters speed of a fan, a degree of opening of a radiator blind or a radiator blind or the driving speed of a motor vehicle, and / or that the amount of air flowing through the evaporator designed as a heat exchanger Air quantity is measured.

It can preferably be provided that the suction pressure limit value is increased when the amount of air flowing through the evaporator designed as a heat exchanger increases. A large amount of air flowing through the evaporator designed as a heat exchanger thus leads to an increase in the suction pressure limit value, and a small amount of air flowing through the evaporator designed as a heat exchanger leads to a reduction in the suction pressure limit value.

For example, it can be provided that with an amount of air flowing through the evaporator designed as a heat exchanger of 0.2 kg/s, the suction pressure limit is set to 15 bar, while with an amount of air flowing through the evaporator designed as a heat exchanger of 0.8 kg/s, the suction pressure limit is set 30 bar is set.

Furthermore, it can preferably be provided that the amount of heat taken from the evaporator and/or the condenser is estimated taking into account the operating parameters of the heat pump, and/or that the amount of heat taken from the evaporator and/or the condenser is measured.

The method and procedure for estimating the amount of heat taken from the evaporator and/or the condenser based on the operating parameters of the heat pump are known to those skilled in the art. An estimate is preferred because the corresponding measurement technology required to measure the amount of heat removed from the evaporator is complex and complex. In principle, however, it is also possible to measure the amount of heat taken from the evaporator directly.

Furthermore, it can be provided that the suction pressure limit is increased when the amount of heat removed from the evaporator and/or the condenser increases.

With high amounts of heat removed from the evaporator, the suction pressure limit is increased, and with small amounts of heat taken from the evaporator, the suction pressure limit is reduced.

Particularly preferably, the suction pressure limit value can depend on a combination of the parameters ter the ambient temperature, the amount of air flowing through the evaporator designed as a heat exchanger and the amount of heat removed from the evaporator and / or the condenser.

In a further embodiment, it can also be provided that the suction pressure change rate limit value is also determined depending on the ambient temperature, the amount of air flowing through the evaporator designed as a heat exchanger or the amount of heat removed from the heat exchanger.

The adjustments to the suction pressure change rate limit can be made in accordance with the adjustments to the suction pressure limit, that is, if the ambient temperature increases, and/or an increase in the amount of air flowing through the heat exchanger and/or if the amount of heat removed from the heat exchanger increases, the suction pressure change rate limit is also increased.

It is also possible for the suction pressure change rate limit value to be adjusted in the opposite direction, so that, for example, when the ambient temperature is reduced, and/or when the amount of air flowing through the evaporator designed as a heat exchanger is reduced, and/or when the amount of air flowing through the evaporator designed as a heat exchanger is reduced The amount of heat removed increases the suction pressure change rate limit.

Preferably, however, the suction pressure change rate limit value is at least not dependent on the amount of air flowing through the evaporator designed as a heat exchanger, since the suction pressure change rate is preferably an indicator of the amount of air flowing through the evaporator designed as a heat exchanger.

A further solution to the problem on which the invention is based is to provide a heat pump for a motor vehicle, in particular a hybrid electric vehicle or electric vehicle, comprising an evaporator designed as a heat exchanger, a compressor, a capacitor and a throttle, the heat pump further having a sensor for measuring a suction pressure , and wherein the heat pump has a control device, wherein the control device is designed to receive signals from the sensor, wherein the control device is designed to carry out a previously described method.

The method step of carrying out a de-icing process for the evaporator designed as a heat exchanger can be implemented by the control device sending a control or regulation signal to a de-icing device.

The sensor for determining the suction pressure is preferably arranged on the suction pressure side of the compressor in the refrigerant circuit.

In addition, further sensors can be provided.

A further solution to the problem on which the invention is based is to provide a motor vehicle, in particular a hybrid electric motor vehicle or electric vehicle, comprising a heat pump as described above.

A yet further solution to the problem on which the invention is based consists in providing an air conditioning system comprising a heat pump as described above and in providing a motor vehicle, in particular a hybrid electric vehicle or electric vehicle, comprising such an air conditioning system.

Short description of the characters

The invention is explained in more detail below with reference to the attached figures.

• 1 ein Kraftfahrzeug mit einer Wärmepumpe,
• 2 ein Ablaufdiagramm eines Verfahrens zur Regelung einer Wärmepumpe,
• 3 ein Ablaufdiagramm eines weiteren Verfahrens zur Regelung einer Wärmepumpe, und
• 4 einen Graphen mit dem zeitlichen Verlauf eines Saugdrucks und einer einen Wärmeübertrager durchströmenden Luftmenge.

Show it

• 1 a motor vehicle with a heat pump,
• 2 a flowchart of a method for controlling a heat pump,
• 3 a flowchart of a further method for controlling a heat pump, and
• 4 a graph with the time course of a suction pressure and a quantity of air flowing through a heat exchanger.

Detailed description of the characters

1 shows a motor vehicle 10 with an air conditioning system 11 comprising a heat pump 13. The heat pump 13 is designed to carry out a process based on a flow chart in 2 method 100 shown for controlling a heat pump 13 for a motor vehicle 10. This in 1 Motor vehicle 10 shown can be designed as a hybrid electric vehicle or electric vehicle 12. The heat pump 13 includes an evaporator 14, a compressor 15, a condenser 16 and a throttle 17. The evaporator 14 is designed to absorb ambient heat Heat exchanger 18 is formed. A sensor 20 for measuring the suction pressure is arranged in the refrigerant circuit 19 of the heat pump 13. The heat pump 13 also includes a control device 21, which is designed to receive signals from the sensor 20 and to carry out a method 100 described below.

According to 2 In a first step S1 of the method, a value of a pressure parameter of the heat pump 13 is determined. The pressure parameter can be the suction pressure or the suction pressure change rate. In a second method step S2, the determined value of the pressure parameter is compared with a lower limit value and/or an upper limit value. In the case of suction pressure as a pressure parameter, this is compared with a lower limit, the lower limit being a suction pressure limit. If, on the other hand, the pressure parameter is a suction pressure change rate, the suction pressure change rate, preferably the amount of the suction pressure change rate, is compared with an upper limit, the upper limit being a suction pressure change rate limit.

If the determined value of the suction pressure falls below the suction pressure limit and/or if the determined value of the suction pressure change rate, in particular the determined value of the amount of the suction pressure change rate, exceeds the suction pressure change rate limit, then in a next method step S3 a de-icing process is carried out for the evaporator 14 designed as a heat exchanger 18. After carrying out the de-icing process, the method 100 for controlling a heat pump 13 is carried out again, starting with the first method step S1.

However, if the determined value of the suction pressure is greater than the suction pressure limit value or if the determined value of the suction pressure change rate, in particular the determined value of the amount of the suction pressure change rate, is smaller than the suction pressure change rate limit, then the method 100 according to step S4 is repeated starting with the first method step S1.

3 shows an expanded embodiment of the method 100 according to the invention.

The method 100 begins in a first step S0 by calculating a suction pressure limit and/or a suction pressure change rate limit depending on environmental parameters and/or operating parameters of the heat pump 13. The environmental parameters or the operating parameters can in particular include an ambient temperature, an amount of air flowing through the evaporator 14 designed as a heat exchanger 18 or an amount of heat taken from the evaporator 14. In a next method step S1 of the method 100, a value of the suction pressure or the rate of change in suction pressure is determined.

In a subsequent method step S2, the determined value of the suction pressure is compared with a suction pressure limit and/or the suction pressure change rate, preferably the amount of the suction pressure change rate, is compared with a suction pressure change rate limit. If the determined value of the suction pressure falls below the suction pressure limit and/or if the determined value of the suction pressure change rate, in particular the determined value of the amount of the suction pressure change rate, exceeds the suction pressure change rate limit, then in a next method step S3, a de-icing process for the heat exchanger 18 is carried out. After carrying out the de-icing process, the method 100 for controlling a heat pump 13 is carried out again, starting with the first method step S0. On the other hand, if the determined value of the suction pressure is greater than the suction pressure limit value or if the determined value of the suction pressure change rate, in particular the determined value of the amount of the suction pressure change rate, is smaller than the suction pressure change rate limit value, then the method 100 after step S2 according to step S4 starts again with the first method step Go through S0.

4 shows the change in the suction pressure as the icing of the heat exchanger 18 of the heat pump 13 increases over time. The time t is plotted on the x-axis of the coordinate system. The first graph 22 shows the time course of the suction pressure as the icing of the heat exchanger 18 increases over time. The second graph 23 shows the time course of the air-side pressure loss on the heat exchanger 18. When the heat exchanger 18 begins to ice up, the suction pressure is high and the air-side pressure loss is small amount. As icing increases, the suction pressure decreases, while at the same time the air-side pressure loss on the heat exchanger 18 increases. In particular, the first graph 22 for the suction pressure shows that the decrease in the suction pressure is an indicator of icing of the heat exchanger 18. Since the amount of the rate of change of the suction pressure, that is to say the amount of the rate of change of suction pressure, increases with increasing icing of the heat exchanger 18, the rate of change of suction pressure is also an indicator of icing of the heat exchanger 18.

List of reference symbols

100

Proceedings

50

Procedural step

S1

Procedural step

S2

Procedural step

S3

Procedural step

S4

Procedural step

10

motor vehicle

11

air conditioner

12

Electric vehicle

13

Heat pump

14

Evaporator

15

compressor

16

capacitor

17

throttle

18

Heat exchanger

19

Refrigerant circulation

20

sensor

21

Control device

22

First graph

23

Second graph

Claims (8)

Method (100) for controlling a heat pump (13) for a motor vehicle (10), in particular a hybrid electric vehicle or electric vehicle (12), the heat pump (13) having an evaporator (14) designed as a heat exchanger (18), a compressor (15), a capacitor (16) and a throttle (17), comprising the steps - determining the value of a pressure parameter of the heat pump (13), - comparing the determined value of the pressure parameter with an upper limit value, and if the determined value of the pressure parameter is greater or is equal to the upper limit value: - carrying out a de-icing process for the evaporator (14), or, if the determined value of the pressure parameter is smaller than the upper limit value: - repeating the process starting with the first process step, characterized in that the pressure parameter is a suction pressure change rate and that the suction pressure change rate is compared with the upper limit, the upper limit being a suction pressure change rate limit. Procedure (100) according to Claim 1 , wherein the de-icing process includes heating the evaporator (14) designed as a heat exchanger (18). Procedure (100) according to Claim 1 or 2 , wherein the suction pressure change rate limit value is determined depending on environmental parameters and / or operating parameters of the heat pump (13). Procedure (100) according to Claim 3 , wherein the environmental parameters and / or operating parameters include at least one of the parameters from the group comprising an ambient temperature, an amount of air flowing through the evaporator (14) designed as a heat exchanger (18) and an amount of heat removed from the evaporator (14) and / or the condenser (16). include. Procedure (100) according to Claim 4 , wherein the amount of air flowing through the evaporator (14) designed as a heat exchanger (18) is estimated using at least one of the parameters speed of a fan, a degree of opening of a radiator blind or a radiator blind or the driving speed of a motor vehicle (10), and / or where the The amount of air flowing through the evaporator (14) designed as a heat exchanger (18) is measured. Method (100) according to one of Claims 4 or 5 , wherein the amount of heat taken from the evaporator (14) and/or the condenser (16) is estimated taking into account the operating parameters of the heat pump (13), and/or wherein the amount of heat taken from the evaporator (14) and/or the condenser (16). is measured. Heat pump (13) for a motor vehicle (10), in particular hybrid electric vehicle or electric vehicle (12), comprising an evaporator (14) designed as a heat exchanger (18), a compressor (15), a capacitor (16) and a throttle (17), further comprising a sensor (20) for measuring a suction pressure, and a control device (21), wherein the control device (21) is designed to receive signals from the sensor (20), characterized in that the control device (21) is designed, to carry out a method (100) according to one of the preceding claims. Motor vehicle (10), in particular hybrid electric vehicle or electric vehicle (12), comprising a heat pump (13). Claim 7 .

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