CN108700051B

CN108700051B - Method for detecting valve locking of coolant compressor and control system of coolant compressor

Info

Publication number: CN108700051B
Application number: CN201780007006.3A
Authority: CN
Inventors: R·卡尔普; H·威格
Original assignee: De Tech Global Equipment Germany Ltd
Current assignee: Danfoss Deutschland GmbH
Priority date: 2016-01-18
Filing date: 2017-01-16
Publication date: 2019-12-31
Anticipated expiration: 2037-01-16
Also published as: WO2017125334A1; US20190010939A1; AT518199B1; CN108700051A; AT518199A1; EP3405673A1; EP3405673B1

Abstract

The invention relates to a method for detecting a valve blockage of a coolant compressor (1), the coolant compressor (1) having a drive unit (4) and a piston-cylinder unit for the circulating compression of a coolant, wherein the drive unit (4) has an electric motor for driving the piston-cylinder unit, wherein the rotational speed (omega) of the electric motor is monitored. According to the invention, the maximum rotational speed (omega) of the electric machine is first detected_max) And if the rotational speed (ω) of the electric machine substantially corresponds to said maximum rotational speed (ω)_max) Executing the following steps: determining a maximum value X of a monitored parameter (I, T) of a refrigerant compressor (1)_max(ii) a In determining the maximum value X_maxDetermining a value X of the monitoring parameter (I, T) after a first period of time (t1) thereafter_t1(ii) a When X is present_t1Less than X_maxAnd satisfies (X)_max‑X_t1)/X_max≥Δ_XWhen valve lockout is detected, Δ X is predetermined.

Description

Method for detecting valve locking of coolant compressor and control system of coolant compressor

Technical Field

The invention relates to a method for detecting a valve blockage of a coolant compressor having a drive unit and a piston-cylinder unit for circulating a compressed coolant, wherein the drive unit has an electric motor for driving the piston-cylinder unit, wherein the rotational speed of the electric motor is monitored.

The invention further relates to a control system for the compression of a coolant, which comprises a drive unit and a piston-cylinder unit for circulating a compressed coolant, wherein the drive unit has an electric motor for driving the piston-cylinder unit, and wherein the control system has control electronics.

Background

In a coolant compressor having a drive unit and a piston-cylinder unit for circulating a compressed coolant, the drive unit has an electric motor for driving the piston-cylinder unit, and the rotational speed of the electric motor is controlled, a possible fault state being present in a blocked valve. The fault state can be, in particular, the locking of a suction or pressure valve. In practice, however, it may also be the case, for example, that a solenoid valve in the cooling circuit, which is not necessarily part of the coolant compressor, fails.

In any case, the blocked valve causes that the coolant is no longer fed to the cooling circuit to the extent required for cooling or is no longer fed at all, and therefore cooling is no longer possible. In order to keep the temperature from dropping, the application device, for example a refrigerator, which controls the coolant compressor, and then usually adjusts the coolant compressor to a maximum cooling capacity, the electric motor is operated at maximum rotational speed — certainly not successfully, since the coolant may no longer be conveyed further in the cooling circuit.

Even when the reason for the blocking of the cooling circuit is not, in any case, the blocking of the valves of the coolant compressor, ultimately, this now leads to the blocking of the valves, in particular of the pressure valves of the coolant compressor. This is so because, as the compressor continues to operate at the highest power level, the back pressure of the cooling medium continues to increase in the pressure interval, so that the pressure valve no longer opens, since the pressure built up by the coolant compressor is no longer sufficient. Generally, when the back pressure is sufficiently high (independent of how it is reached or generated), it always results in at least a blocking of the pressure valve.

In order to prevent the coolant compressor from continuing to operate permanently at the maximum rotational speed due to a fault state, it is known from the prior art to define an interruption condition, for example by raising the temperature of the compressor to, for example, above a certain limit temperature. That is to say, the temperature is continuously monitored and the electric machine is switched off when the limit temperature is exceeded and the electric machine is preferably operated at the maximum rotational speed.

A disadvantage of the known method is that it does not work properly for all coolant compressors. That is, it has been shown that depending on the design or type of the refrigerant compressor, the temperature sometimes does not rise sufficiently to enable a reasonable determination of the limit temperature.

Disclosure of Invention

It is therefore an object of the present invention to provide a method which enables a reliable detection of the blocking state of the compressor, specifically the blocking of the valve. Accordingly, it is a further object of the present invention to provide a control system for a coolant compressor which enables a blocking state of the compressor, specifically a blocking of the valve, to be reliably detected in order to be able to take countermeasures.

A complex series of tests with different types of coolant compressors each having a drive unit and a piston-cylinder unit for circulating a compressed coolant, wherein the drive unit has an electric motor for driving the piston-cylinder unit and wherein the rotational speed of the electric motor is monitored, have shown that a significantly reduced or even completely stopped mass flow occurring in the blocked state, specifically when the valve is blocked, can lead to certain monitoring parameters, although initially increasing in their value and reaching a maximum value, then decreasing again in a certain, preferably predetermined, time period, while the electric motor continues to run at the highest rotational speed.

In this and in the following text, "maximum rotational speed" is always understood to mean the maximum rotational speed that the coolant compressor, or the electric machine, actually reaches in the current cooling circuit. For different reasons, the maximum rotational speed may differ from the theoretically possible maximum rotational speed of the electric machine, for example because the application device is not used or requires, for example, 4000min for noise reasons^-1But a lower rotational speed, for example 3600min-1, is predetermined as the "theoretical maximum rotational speed". Furthermore, various external conditions, such as, for example, too low supply voltages, may result in the theoretical maximum rotational speed (of course also the maximum rotational speed of theoretically possible electric motors) not being reached, so that the maximum rotational speed is actually lower than idealThe maximum rotational speed (of course also below the maximum rotational speed of the theoretically possible electric machine) is considered.

A typical monitoring parameter is the current consumption of the electric motor, which, after rising to a maximum value of, for example, 0.85A, falls back to a certain value (for example, 0.425A) within a certain period of time, while the electric motor is always running at the maximum rotational speed.

As an important criterion for the occurrence of a valve blockage, it is therefore possible to use the situation that a monitoring parameter drops "sufficiently" within a certain period of time, wherein this parameter is associated with the respective type of coolant compressor and can be determined by means of laboratory tests and can be predetermined accordingly.

Accordingly, in a method for detecting a valve lock of a coolant compressor having a drive unit and a piston-cylinder unit for circulating a compressed coolant, wherein the drive unit has an electric motor for driving the piston-cylinder unit, wherein the rotational speed of the electric motor is monitored, it is provided according to the invention that the maximum rotational speed of the electric motor is first detected, and if the rotational speed of the electric motor substantially corresponds to the maximum rotational speed, the following steps are carried out:

-determining a maximum value X of a monitored parameter of the coolant compressor_max；

-determining the maximum value X_maxDetermining the value X of the monitored parameter after a first period of time thereafter_t1；

When X is_t1Less than X_maxAnd satisfies (X)_max-X_t1)/X_max≥Δ_XWhen valve closure is detected, wherein_XIs predetermined.

The valve closure can be in particular a suction or pressure valve closure. In practice, however, it is also possible to trigger the blocking state by other failed elements in the cooling circuit, for example solenoid valves, which do not necessarily have to be part of the coolant compressor. However, as already explained above, in the blocked state, the usual result is a blocking of the valves of the coolant compressor, in particular of the pressure valves of the coolant compressor, wherein the blocked valves largely, preferably completely, block the mass flow of the coolant.

In the case of an application, the motor continues to operate at the maximum rotational speed as a result of the application device controlling the coolant compressor, for example, by means of a refrigerator, since the application device finds that the desired cooling has not occurred and therefore continues to require the maximum cooling capacity. A typical value for the maximum rotational speed is 3000min^-1To 4000min^-1. It should be noted here that coolant compressors with variable rotational speed are obviously involved, but otherwise only a single rotational speed is provided during operation of the coolant compressor, which at the same time also represents the maximum rotational speed.

In practice, certain minimum rotational speed fluctuations are unavoidable. It is therefore reasonable to start with a maximum rotational speed tolerance range of typically ± 2% at the maximum. If the rotational speed is changed in such a way that it is very different from the maximum rotational speed, in particular more than 2% less than the maximum rotational speed value, the method is stopped. In the case of an increase in the rotational speed, the actual maximum rotational speed value is not yet reached, wherein the method is generally restarted when the actual maximum rotational speed value is reached. In the case of a drop in the rotational speed, the blocking situation, to be precise the blocking of the valve, typically no longer occurs, as a result of which the desired cooling is achieved and the application requires less cooling capacity. The method is thereby interrupted and only restarted when the maximum rotational speed is reached again.

As already determined, the extent to which the monitored parameter decreases with time is related to the respective type of coolant compressor. In a preferred embodiment of the method according to the invention, Δ is provided in this case_X≧ 0.2, preferably Δ_XNot less than 0.4, particularly preferably Δ_XNot less than 0.5. That is, the percentage decrease in the value of the monitored parameter must be at least 20%, preferably at least 40%, particularly preferably at least 50%.

As already stated, the current consumed by the electric motor can be used as a monitoring parameter with the stated temporal behavior in the blocking state. Similarly, the motor winding temperature and the temperature of the control electronics of the motor or of the coolant compressor also have the same temperature behavior, so that this temperature is also ideally suited as a monitoring parameter. Therefore, the advantages in the method according to the inventionIn an alternative embodiment, it is provided that the monitoring parameter is the current consumed by the electric motor or the temperature of the control electronics of the coolant compressor, in particular of the electric motor or the motor windings of the electric motor. Obviously, this temperature is always given with respect to the ambient temperature of the coolant compressor. If the ambient temperature is, for example, 20 ℃ (room temperature) and 90 ℃ is measured as the maximum value of the temperature, then X_maxThe temperature was 70 ℃.

As already obtained in complex tests, it is recommended that the maximum value X is not determined directly after the detection of the maximum rotational speed of the electric machine_maxBut waits for a certain predetermined time for this purpose. This allows a certain pressure relationship balance to be adjusted for which the monitored parameter may first have its maximum value Xmax. Otherwise, there is the risk that the value of the monitoring parameter continues to increase until the pressure relationship is balanced. In a preferred embodiment of the method according to the invention, it is therefore provided that the maximum value X is determined only after an initial period of time after the detection of the maximum rotational speed of the electric machine_max. In other words, detecting the highest rotational speed defines the starting time or starting moment for the method. In the preferred embodiment, the maximum value X of the monitored variable is determined directly at the start time or after the start time_maxBefore, an initial period of time is waited.

An optimal initial period of time can be obtained in experiments for different coolant compressor types and then predetermined accordingly, wherein the initial period of time is typically a few minutes. In a preferred embodiment of the method according to the invention, it is therefore provided that the initial period of time is at least 5 minutes, preferably at least 10 minutes, particularly preferably at least 15 minutes.

In order to ensure as far as possible that the conditions for the blocking state, in particular for the valve closure, are actually met, the monitoring parameter can be determined again quickly after the last determination of the monitoring parameter and can be compared with the maximum value X_maxAnd comparing and checking. If the comparison also indicates a blocking state, it can be assumed with very high reliability that a blocking state, to be precise a valve lock, is actually present. Therefore, the advantages in the method according to the inventionIn an alternative embodiment, it is provided that after a check period following the detection of a valve closure, the value X of the monitoring parameter is determined_t2And when X is_t2Less than X_maxIs and (X)_max-X_t2)/X_max≥Δ_XWhen valve lockout is detected, it is verified. In this case, the waiting of the verification time period should take into account possible fluctuations in the monitoring parameter, i.e. when the value of the monitoring parameter is also correspondingly low after the verification time period, it can be assumed with a high probability that the reduction is not caused by accidental fluctuations.

Obviously, a particularly preferred embodiment variant is also conceivable in which the condition (X) is checked for verification purposes_max-X_t2)/X_max≥Δ_X', wherein, Δ_X‘≠Δ_XPreferably Δ_X‘＞Δ_X. That is, for verification, it is checked whether the monitored parameters of the coolant compressor are developing over time as predicted by model calculations and/or laboratory experiments, wherein the time development is typically continuing to decrease.

An optimal check time period can be obtained and accordingly determined in tests for different coolant compressor types, wherein the check time period is typically up to several minutes. In a preferred embodiment of the method according to the invention, it is therefore provided that the checking period is 15 seconds to 5 minutes, preferably 30 seconds to 3 minutes, particularly preferably 45 seconds to 1 minute 30 seconds.

The first time period can likewise be dependent on the type of coolant compressor and can be predefined accordingly (in particular in accordance with tests already carried out). In a preferred embodiment of the method according to the invention, it is therefore provided that the first period of time is at least 3 hours, preferably at least 5 hours, particularly preferably at least 6 hours.

In a preferred embodiment of the method according to the invention, it is provided that, after the valve closure has been detected, a corresponding fault message is written/recorded in a readable memory provided for it. In a preferred embodiment of the method according to the invention, it is likewise provided that, after the detection of a valve closure is verified, a corresponding fault message is written in a readable memory provided for it. The corresponding writing into the readable memory takes place and the information is supplied to a different control system (for example the control system of the application device) for further processing. Furthermore, this information can also be read at a later time for diagnostic purposes, in particular when the storage is an immutable storage, for example a so-called FLASH-, EPROM-, or NVRAM storage.

In practice, the detection or verification of the blocking state, or rather of the valve blocking, can be used to switch off the compressor, since it is clear that the desired cooling cannot be achieved in this state. Therefore, the continued operation of the motor at the maximum rotational speed means unnecessary load of the compressor and unnecessary energy consumption. Accordingly, according to the invention, an operating method for operating a coolant compressor is provided, which operating method comprises the method according to the invention, wherein the electric motor is stopped after a valve closure is detected. Similarly, according to the invention, an operating method for operating a coolant compressor is provided, which operating method comprises the method according to the invention, wherein the electric motor is stopped after it has been verified that a valve lock has been detected. Preferably, the motor does not consume current in the stopped state, so that unnecessary energy consumption does not occur.

Tests have shown that after restarting the coolant compressor, the cause of the blocking situation is often no longer present. For example, it is possible that the solenoid valve has already activated the blocking state because it is not open and thus blocks the cooling circuit, and that it opens as intended when restarting. In a preferred embodiment of the operating method according to the invention, it is therefore provided that the electric motor is restarted after the second period of time. Here, waiting for the second period of time may be used to cause a certain degree of pressure ratio/pressure condition relief, which may contribute to a latched valve release. Furthermore, the temperature of the compressor can also be moderated or restored during the second time period, which likewise contributes to the release of the blocked valve.

The second waiting time can be relatively short, in particular in the range of seconds, in particular if the blocked valve has an unstable behavior and is accordingly blocked in several runs of the coolant compressor and is not blocked again in the remaining runs. In a preferred embodiment of the operating method according to the invention, it is therefore provided that the second period of time is at least 3 seconds, preferably at least 6 seconds, particularly preferably at least 15 seconds. However, it must generally be noted that the value for the second time period may differ significantly depending on the application.

In practice, it is reasonable that the second time period cannot be arbitrarily long, since it is of course also possible for a fault state to occur in which the blocked valve is no longer relaxed. In a particularly preferred embodiment of the operating method according to the invention, it is therefore provided that the second time period is at most 60 minutes. It is assumed that the locked valve must be released within the maximum duration of the second time period, otherwise a fault state results in which the locked valve is no longer released.

In a control system for a coolant compressor, similar to the above embodiments, the coolant compressor comprises a drive unit and a piston-cylinder unit for circulating a compressed coolant, wherein the drive unit has an electric motor for driving the piston-cylinder unit, and wherein the control system has control electronics, it being provided according to the invention that the control electronics are provided for carrying out the method according to the invention and/or for carrying out the operating method according to the invention.

In order to ultimately be able to provide a coolant compressor which reliably determines the blocking state, in particular the blocking of the valve, and responds thereto, in a coolant compressor having a drive unit and a piston-cylinder unit for circulating compressed coolant, wherein the drive unit has an electric motor for driving the piston-cylinder unit, it is provided according to the invention that the coolant compressor comprises a control system according to the invention.

It should be noted that in all of the above-described embodiments, the coolant compressor is in particular a coolant compressor having a heat-sealed housing, wherein the drive unit and the piston-cylinder unit are arranged in the housing.

Drawings

The present invention will now be explained in detail based on examples. The drawings are exemplary and while illustrating the idea of the invention, they are not in any way limiting or in an absolute way embodying the idea of the invention.

Wherein:

fig. 1 shows a schematic axial view of a coolant compressor according to the invention, with the upper housing half removed,

fig. 2 shows a diagrammatic illustration of the method according to the invention.

Detailed Description

Fig. 1 shows a coolant compressor 1 according to the invention, wherein the hermetically sealed housing 2 of the coolant compressor 1 is only partially shown, to be precise the upper half of the housing 2 is removed in order to see into the housing 2. A cylinder housing 3 of the piston-cylinder unit can be seen in the interior of the housing 2. The cylinder housing 3 is mounted at a drive unit 4, the drive unit 4 comprising an electric motor for driving the piston-cylinder unit. In this case, the electric motor drives the pistons of the piston-cylinder units in the cylinders arranged in the cylinder jacket 3 via a crankshaft 10 and connecting rods. Thereby, a cyclic movement of the piston in the cylinder along the cylinder axis is achieved for compressing the coolant.

The coolant is sucked into the cylinder via the suction muffler 9 and the suction valve arranged in the valve plate 6, compressed and guided via the pressure valve arranged in the valve plate 6 into the outwardly guided pressure pipe 8. The coolant is then conducted to a condenser (not shown) in a coolant circuit of the application, for example a refrigerator, into which the coolant compressor 1 is integrated.

The valve plate 6 is mounted in the region of the cylinder head at the cylinder, wherein the cylinder head 5 can be seen in fig. 1, the cylinder head 5 being bolted to the cylinder by means of bolts 7. Here, the valve plate 6 is arranged between the cylinder head 5 and the cylinder.

The coolant compressor 1 is operated at a variable rotational speed ω, i.e. the rotational speed ω of the electric motor is dependent on the cooling power required by the application. At maximum cooling power, the motor rotates at maximum speed ω_maxRun, which is typically at 3000min^-1To 4000min^-1In the meantime.

In the blocked state, the mass flow of the coolant in the cooling circuit is drastically reduced or completely stopped. The blocked state can be caused by or lead to a valve lock of the coolant compressor 1, since the valve, in particular the pressure valve, can open as a result of the pressure ratio no longer being established properly. The latter means that the pressure built up by the piston-cylinder unit is not sufficient to overcome the back pressure built up as a result of the blocking state.

In order to be able to reliably determine the blocking state, specifically the valve blocking, it is provided according to the invention that, in addition to the rotational speed ω, the monitoring parameters of the refrigerant compressor 1 are also continuously monitored in order to obtain a time curve thereof. The current I to which the electric motor is subjected and the temperature T of the control electronics of the coolant compressor 1, specifically the electric motor or the motor windings of the electric motor, are taken into consideration as monitoring parameters. It is clear that said temperature is always given with respect to the ambient temperature of the coolant compressor (typically room temperature, exactly 20 ℃).

According to the invention, when the highest rotational speed ω is detected_maxThen, if the rotational speed ω of the electric machine substantially corresponds to the maximum rotational speed ω_maxExecuting the following steps:

determining the maximum value X of the monitored parameter of the refrigerant compressor 1_max；

-determining the maximum value X_maxDetermining the value X of the monitoring parameter after a first time period t1_t1；

Fig. 2 shows these method steps in terms of a graph of the curves of I and T as a function of time T. The time curve of the rotational speed ω of the electric machine is shown directly in the diagram. In the illustrated embodiment of the method according to the invention, the maximum rotational speed ω is detected for the first time_maxThereafter, first wait for a predetermined initial period of time t0 to determine X_maxA certain pressure ratio/pressure relationship balance may be adjusted previously. Typically, t0 is at least 5 minutes, preferably at least 10 minutes, particularly preferably at least 15 minutes.

In a typical application scenario similar to fig. 2, the current I is increased to X, for example after an initial time period t0_maxEqual to a value of 0.85A. Similarly, in this typical application scenario, after an initial time period T0, the temperature T is increased to, for example, X_max70 ℃ (corresponding to 90 ℃ measured at an ambient temperature of 20 ℃).

In determining X_maxAfter a first time period t1, X is determined_t1Wherein t1 is typically at least 3 hours, preferably at least 5 hours, particularly preferably at least 6 hours. That is, the highest rotation speed ω is detected for the first time_maxAnd determining X_t1The elapsed time between t0+ t 1. In a typical application scenario similar to fig. 2, the current I is dropped to the value X after the first time period t1_t10.425A, specifically, for example, equal to a relative reduction of 20% to 50%. Similarly, in this typical application scenario, after a first period of time T1, the temperature T is lowered to, for example, X_t150 ℃ (corresponding to 70 ℃ at ambient temperature of 20 ℃).

Depending on the type of the refrigerant compressor 1, Δ may be used_XA predetermined special value, wherein typically Δ is satisfied_X≧ 0.2, preferably Δ_XNot less than 0.4, particularly preferably Δ_XNot less than 0.5. Values matching the respective type are preferably obtainable in laboratory tests. In the illustrated embodiment of FIG. 2, (X)_max-X_t1)/X_max0.56. I.e. at a predetermined delta_XAt 0.5, a valve lockout or blocking condition is detected.

In the embodiment of FIG. 2, to ensure, by determining X_t1Thereafter a relatively short check time period t2 is waited for in order to thereby determine again the current value X of the monitored parameter_t2And checking the condition (X)_max-X_t2)/X_max≥Δ_XConfirming detection of valve lockout. Typically, the verification time period t2 is 15 seconds to 5 minutes, preferably 30 seconds to 3 minutes, particularly preferably 45 seconds to 1 minute 30 seconds.

In a typical application scenario similar to that of FIG. 2, in the verificationAfter a time period t2, the current I is reduced to, for example, X_t2A value of 0.23A. Similarly, in this typical application scenario, after a verification time period T2, the temperature T is dropped to, for example, X_t2A value of 18.9 ℃ (corresponding to 38.9 ℃ measured at an ambient temperature of 20 ℃).

In the illustrated embodiment of FIG. 2, (X)_max-X_t2)/X_max0.73. That is, at Δ_XA predetermined time of 0.5 proves or confirms that the valve closure was successfully detected before.

For the purpose of the method described, the coolant compressor 1 has a control system with control electronics, which are provided for carrying out the method. Preferably, the control electronics also form the above-mentioned control electronics of the motor.

In the exemplary embodiment of fig. 2, the control electronics are furthermore provided for carrying out the operating method according to the invention, according to which the electric motor is stopped after the valve lockout, specifically the blocking state of the electric motor, has been verified. Accordingly, in the lower graph of fig. 2, the rotation speed ω is shifted from the maximum rotation speed ω_maxAnd drops to 0.

After the stop, the motor no longer consumes current I, but rather the control electronics, specifically the temperature T of the motor winding, continues to slowly decrease (up to ambient temperature), so that the curve of T in the region after T2 is indicated by a dashed line in fig. 2.

Since after restarting the coolant compressor 1 there is often no longer the cause of the blocking situation, the control electronics can be arranged to restart the motor after a relatively short second time period t 3. Typically, the second time period t3 is only a few seconds, for example at least 3 seconds, preferably at least 6 seconds, particularly preferably at least 15 seconds. In practice, the second time period t3 is typically limited to a maximum of 60 minutes.

In the lower diagram of fig. 2, the different situation after the motor is switched on again is indicated by means of a dashed line. One of these cases is that the electric machine is again at the highest rotational speed ω_maxThis may be the case in operation, particularly when there is a blocking condition as before. In this situationIn the situation by detecting the maximum rotation speed omega_maxThe described method according to the invention for detecting valve blocking is immediately started again.

In particular, if the blocking situation no longer exists, a situation can also occur in which the rotational speed ω of the electric machine is at a maximum rotational speed ω_maxThe following is a description. In this case, the described method according to the invention for detecting valve closure is not started again, but rather as soon as the maximum rotational speed ω is subsequently detected_maxThe method is started again.

It should be noted that the control system may have a memory in which the corresponding fault information is written after the blocking state has been detected or verified, which fault information can then be read again from the memory, in particular for diagnostic purposes. Furthermore, the storage device can be used to store values, in particular for Δ, which are set during the method or operating method according to the invention for the particular refrigerant compressor 1 present_XT0, t1, t2 and t 3.

List of reference numerals

1 refrigerant compressor

2 cover of refrigerant compressor

3 cylinder cover shell

4 drive unit

5 Cylinder cover

6 valve plate

7 bolt

8 outwardly directed pressure pipe

9 suction muffler

10 crankshaft

I current carried by the motor

Control electronics for a T-machine or the temperature of a machine winding of a machine

time t

t0 initial time period

t1 first time period

t2 verification period

t3 second time period

Rotational speed of omega motor

ω_maxMaximum rotational speed of an electric machine

Claims

1. Method for detecting valve blocking of a coolant compressor (1), which coolant compressor (1) has a drive unit (4) and a piston-cylinder unit for circulating a compressed coolant, which drive unit (4) has an electric motor for driving the piston-cylinder unit, wherein the rotational speed (ω) of the electric motor is monitored, characterized in that first the highest rotational speed (ω) of the electric motor is detected_max) If the rotational speed (ω) of the motor corresponds to the maximum rotational speed (ω)_max) Executing the following steps:

-determining a maximum value X of a monitored parameter (I, T) of the refrigerant compressor (1)_max；

-determining said maximum value X_maxDetermining a value X of the monitoring parameter (I, T) after a first period of time (t1) thereafter_t1；

2. The method of claim 1, wherein Δ is_X≥0.2。

3. Method according to claim 1 or 2, characterized in that the monitored parameter is the current (I) consumed by the motor or the temperature (T) of the control electronics of the coolant compressor (1) or the motor windings of the motor.

4. Method according to claim 1 or 2, characterized in that the highest rotational speed (ω) of the electrical machine is detected_max) The maximum value X is determined only after a subsequent initial period of time (t0)_max。

5. The method according to claim 4, wherein the initial period of time (t0) is at least 5 minutes.

6. Method according to claim 1 or 2, characterized in that after a verification time period (t2) after valve lockout is detected, the value X of the monitoring parameter (I, T) is determined_t2And when X is_t2Less than X_maxIs and (X)_max-X_t2)/X_max≥Δ_XWhen valve lockout is detected, it is verified.

7. Method according to claim 6, characterized in that said verification time period (t2) is comprised between 15 seconds and 5 minutes.

8. The method according to claim 1 or 2, characterized in that the first period of time (t1) is at least 3 hours.

9. Method according to claim 1 or 2, characterized in that after the valve blocking has been detected, the corresponding fault information is written down in a readable memory provided for it.

10. Method according to claim 6, characterized in that after the detection of a valve closure is verified, a corresponding fault message is written in a readable memory provided for it.

11. The method of claim 2, wherein Δ is_X≥0.4。

12. The method of claim 11, wherein Δ is_X≥0.5。

13. Method according to claim 3, characterized in that the monitored parameter is the temperature (T) of the control electronics of the electric machine.

14. The method according to claim 5, wherein the initial period of time (t0) is at least 10 minutes.

15. The method according to claim 14, wherein the initial period of time (t0) is at least 15 minutes.

16. The method according to claim 7, characterized in that the verification time period (t2) is 30 seconds to 3 minutes.

17. Method according to claim 16, characterized in that said verification time period (t2) is 45 seconds to 1 minute 30 seconds.

18. The method according to claim 8, wherein the first period of time (t1) is at least 5 hours.

19. The method according to claim 18, wherein the first period of time (t1) is at least 6 hours.

20. An operating method for operating a coolant compressor (1), comprising a method according to one of claims 1 to 19, wherein the electric motor is stopped after a valve lockout is detected.

21. An operating method for operating a coolant compressor (1), comprising a method according to claim 6, wherein the electric motor is stopped after it is verified that a valve lock is detected.

22. Operating method according to any one of claims 20 to 21, characterised in that the electric machine is restarted after a second period of time (t 3).

23. Operating method according to claim 22, characterized in that the second period of time (t3) is at least 3 seconds.

24. Operating method according to claim 22, characterized in that the second time period (t3) is a maximum of 60 minutes.

25. Operating method according to claim 23, characterised in that the second period of time (t3) is at least 6 seconds.

26. Operating method according to claim 25, characterised in that the second period of time (t3) is at least 15 seconds.

27. A control system for a coolant compressor (1), which coolant compressor (1) comprises a drive unit (4) and a piston-cylinder unit for circulating a compressed coolant, wherein the drive unit (4) has an electric motor for driving the piston-cylinder unit, the control system having control electronics, characterized in that the control electronics are provided for carrying out the method according to any one of claims 1 to 19 and/or for carrying out the operating method according to any one of claims 20 to 26.

28. A coolant compressor (1) having a drive unit (4) and a piston-cylinder unit for circulating a compressed coolant, wherein the drive unit (4) has an electric motor for driving the piston-cylinder unit, characterized in that the coolant compressor (1) comprises a control system according to claim 27.