A method, device and unit for determining liquid in suction of a compressor

Abstract

The present invention discloses a method, device and unit for judging whether the compressor is inhaled with liquid. The method comprises: real-time monitoring of the suction temperature and the condensing temperature; calculating the exhaust superheat setting value according to the suction temperature and the condensing temperature; and determining that the compressor is in operation with liquid when the exhaust superheat is less than the exhaust superheat setting value. The present invention calculates the exhaust superheat setting value according to the actual operation of the unit as a basis for judging whether the compressor is inhaled with liquid, rather than using a fixed exhaust superheat setting value. This can more accurately judge whether the compressor is inhaled with liquid, avoid the problem of being unable to quickly enter the liquid protection mode under high pressure difference and wide operating range, and avoid the problem of frequently entering the liquid protection mode under the condition of slight liquid and affecting the normal operation of the unit.

Description

Technical Field

[0001] The present invention relates to the technical field of compressors, and in particular to a method, a device and a unit for determining liquid in suction of a compressor. Background Art

[0002] During the operation of the unit, when the internal valve fails or there is too much refrigerant in the system, the refrigerant on the suction side of the compressor will be in a gas-liquid two-phase state, causing a liquid hammer risk to the compressor. Therefore, when the suction liquid state is detected, it should be switched to protection mode to prevent damage to the compressor.

[0003] There are two ways to detect the state of liquid in the air:

[0004] (1) When the suction superheat remains at a low level, the unit is judged to be in a state of liquid-carrying operation. This method cannot determine the degree of liquid-carrying. When the degree of liquid-carrying is low, it has no obvious impact on the normal operation of the compressor. At this time, if the unit enters the liquid-carrying protection mode, it will have a negative effect on the unit.

[0005] (2) When the exhaust superheat is lower than the set value, the system enters the liquid protection mode. When the exhaust superheat is higher than the set value, the system exits the liquid protection mode. There is a normal operating range for the exhaust superheat. Usually, a fixed value lower than the lower limit of the range is taken as the exhaust superheat setting value. This method has a large deviation under high pressure difference and wide operating conditions. For example, in a small cold storage unit, the system will enter the liquid protection mode only when the liquid is seriously carried, which will have an adverse effect on the normal operation of the compressor.

[0006] With regard to the problem that the method for determining whether the compressor is running with liquid in the prior art is not accurate enough, no effective solution has been proposed so far. Summary of the invention

[0007] The embodiments of the present invention provide a method, device and unit for determining whether a compressor is inhaling liquid, so as to at least solve the problem that the determination method of the compressor inhaling liquid in the prior art is not accurate enough.

[0008] In order to solve the above technical problems, an embodiment of the present invention provides a method for determining liquid in suction of a compressor, comprising:

[0009] Real-time monitoring of suction temperature and condensation temperature;

[0010] Calculating an exhaust superheat setting value according to the suction temperature and the condensation temperature;

[0011] When the exhaust gas superheat is less than the exhaust gas superheat setting value, it is determined that the compressor is running with liquid.

[0012] Optionally, calculating the exhaust superheat setting value according to the suction temperature and the condensation temperature includes:

[0013] Calculating a first difference between a suction air temperature setting value and the suction air temperature;

[0014] calculating a second difference between the condensing temperature and a condensing temperature setting value;

[0015] The exhaust superheat setting value is calculated according to the exhaust superheat initial setting value, the first difference and the second difference.

[0016] Optionally, the exhaust superheat setting value is calculated using the following formula:

[0017] △T d_OFF =△T d +A×(T s -T sn )+B×(T cn -T c )+C,

[0018] Among them, △T d_OFF Indicates the exhaust superheat setting value, △T d Indicates the initial setting value of exhaust superheat, T s Indicates the suction temperature setting value, T sn Indicates the real-time monitored suction temperature, T c Indicates the condensing temperature set point, T cn It represents the real-time monitored condensing temperature, A represents the suction temperature deviation correction coefficient, B represents the condensing temperature deviation correction coefficient, and C represents the exhaust superheat set value deviation correction coefficient.

[0019] Optionally, the method further includes: if the exhaust superheat is greater than or equal to the exhaust superheat setting value, determining that the compressor is not operating with liquid, and controlling the compressor to maintain the current operating state.

[0020] Optionally, after determining that the compressor is running with liquid, it also includes: if the state in which the exhaust superheat is less than the exhaust superheat setting value continues for a first preset time, controlling the compressor to enter a liquid protection mode.

[0021] Optionally, after controlling the compressor to enter the liquid protection mode, it also includes: when the time of executing the liquid protection mode reaches a second preset time, exiting the liquid protection mode, and controlling the compressor to continue operating according to the operating state before entering the liquid protection mode.

[0022] The embodiment of the present invention further provides a compressor suction liquid carrying determination device, comprising:

[0023] Monitoring module, used to monitor the suction temperature and condensation temperature in real time;

[0024] A calculation module, used for calculating an exhaust superheat setting value according to the suction temperature and the condensation temperature;

[0025] The determination module is used to determine that the compressor is running with liquid when the exhaust superheat is less than the exhaust superheat setting value.

[0026] The embodiment of the present invention further provides a unit, comprising: the compressor suction liquid carrying determination device according to the embodiment of the present invention.

[0027] An embodiment of the present invention further provides a computer device, comprising: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the steps of the method described in the embodiment of the present invention when executing the computer program.

[0028] The embodiment of the present invention further provides a non-volatile computer-readable storage medium on which a computer program is stored. When the computer program is executed by a processor, the steps of the method described in the embodiment of the present invention are implemented.

[0029] By applying the technical solution of the present invention, during the operation of the unit, the exhaust superheat setting value is calculated according to the real-time monitored suction temperature and condensing temperature, and when the exhaust superheat is less than the exhaust superheat setting value, it is determined that the compressor is running with liquid. The exhaust superheat setting value is calculated according to the actual operation of the unit as a basis for determining whether the compressor is carrying liquid in the suction, rather than using a fixed exhaust superheat setting value, so that the compressor can be more accurately determined to carry out liquid in the suction, avoiding the problem of being unable to quickly enter the liquid protection mode under high pressure difference and wide operating range, and also avoiding the problem of frequently entering the liquid protection mode under the condition of slight liquid carrying and affecting the normal operation of the unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 is a schematic diagram of an external unit of a unit provided by an embodiment of the present invention;

[0031] Figure 2 is a flow chart of a method for determining liquid in suction of a compressor provided by an embodiment of the present invention;

[0032] Figure 3 It is a schematic diagram of the compressor liquid protection process provided by an embodiment of the present invention;

[0033] Figure 4 is a schematic diagram of a pressure-enthalpy diagram provided in an embodiment of the present invention;

[0034] Figure 5 It is a structural block diagram of a compressor suction liquid carrying determination device provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0035] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0036] It should be noted that the terms "first", "second", etc. in the specification, claims and drawings of the present invention are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0037] The optional embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0038] like Figure 1 As shown, the external unit of the unit includes: compressor 1, condenser 2, condensing fan 3, liquid storage tank 4, liquid supply stop valve 5, air intake stop valve 6, exhaust temperature sensing package 7, high pressure switch 8, air intake temperature sensing package 9, low pressure switch 10, condensation temperature sensing package 11, filter drying 12, filter 13 and unloading solenoid valve 14. After the refrigerant discharged from the compressor 1 enters the condenser 2, it enters the internal unit through the liquid supply stop valve 5. The refrigerant coming out of the internal unit returns to the air intake end of the compressor 1 through the air intake stop valve 6, completing a cycle. The exhaust temperature sensing package 7 is used to monitor the exhaust temperature, the air intake temperature sensing package 9 is used to monitor the air intake temperature, and the condensation temperature sensing package 11 is used to monitor the condensation temperature.

[0039] The embodiment of the present invention provides a method for determining whether a compressor has liquid in the air. Figure 2 : is a flow chart of a method for determining liquid in suction of a compressor provided by an embodiment of the present invention. Figure 2 As shown, the method comprises the following steps:

[0040] S201, monitor the suction temperature and condensation temperature in real time.

[0041] S202, calculating the exhaust superheat setting value according to the suction temperature and the condensation temperature.

[0042] S203: When the exhaust gas superheat is less than the exhaust gas superheat setting value, it is determined that the compressor is running with liquid.

[0043] Specifically, the exhaust temperature may also be monitored in real time, and the real-time exhaust superheat degree may be obtained by calculating the difference between the exhaust temperature and the condensation temperature.

[0044] In this embodiment, during the operation of the unit, the exhaust superheat setting value is calculated according to the real-time monitored suction temperature and condensing temperature. When the exhaust superheat is less than the exhaust superheat setting value, it is determined that the compressor suction is entrained with liquid, that is, the compressor is operating with liquid. The exhaust superheat setting value is calculated according to the actual operation of the unit as a basis for determining whether the compressor suction is entrained with liquid, rather than using a fixed exhaust superheat setting value, so that the compressor suction is entrained with liquid can be determined more accurately, avoiding the problem of being unable to quickly enter the entrainment protection mode under high pressure difference and wide operating range, and also avoiding the problem of frequently entering the entrainment protection mode under the condition of slight entrainment and affecting the normal operation of the unit.

[0045] Specifically, the exhaust superheat setting value is calculated according to the intake temperature and the condensing temperature, including: calculating the first difference between the intake temperature setting value and the intake temperature; calculating the second difference between the condensing temperature and the condensing temperature setting value; and calculating the exhaust superheat setting value according to the exhaust superheat initial setting value, the first difference and the second difference.

[0046] This embodiment calculates the exhaust superheat setting value that meets the current actual operating conditions based on the exhaust superheat initial setting value, the deviation between the real-time suction temperature and the suction temperature setting value, and the deviation between the real-time condensing temperature and the condensing temperature setting value, thereby providing a guarantee for the accurate judgment of the compressor suction liquid.

[0047] Furthermore, the exhaust superheat setting value can be calculated using the following formula:

[0048] △T d_OFF =△T d +A×(T s -T sn )+B×(T cn -T c )+C,

[0049] Among them, △T d_OFF Indicates the exhaust superheat setting value, △T d Indicates the initial setting value of exhaust superheat, T s Indicates the suction temperature setting value, T sn Indicates the real-time monitored suction temperature, T c Indicates the condensing temperature set point, T cn It represents the real-time monitored condensing temperature, A represents the suction temperature deviation correction coefficient, B represents the condensing temperature deviation correction coefficient, and C represents the exhaust superheat set value deviation correction coefficient.

[0050] Among them, the correction coefficients A, B, and C respectively correct the influence of suction temperature deviation, condensing temperature deviation, and set temperature deviation on the exhaust temperature set value. A is used to correct the set value change amplitude caused by suction temperature changes, B is used to correct the set value change amplitude caused by condensing temperature changes, and C is used to correct the deviation of the exhaust superheat set value. For example, the default value of A is 1, the default value of B is 1, and the default value of C is 0, that is, for every 1°C increase in condensing temperature or every 1°C decrease in suction temperature, △T d_OFF Rise 1℃.

[0051] Exhaust superheat initial setting value △T d , Suction temperature setting value T s , condensation temperature setting value T c The setting is as follows: Under the set operating conditions, the initial setting value of exhaust superheat △T d It is related to the type of refrigerant. Through the external low-pressure sensor, the opening of the throttling element connected to the indoor unit is adjusted to simulate the low suction superheat condition. The exhaust superheat, suction temperature and condensing temperature during stable operation are collected, and the control program parameters are set according to the collected values.

[0052] This embodiment can accurately calculate the exhaust superheat setting value that meets the current actual operating conditions based on the above formula.

[0053] In one embodiment, the method may further include: if the exhaust superheat is greater than or equal to the exhaust superheat setting value, determining that the compressor is not running with liquid, controlling the compressor to maintain the current operating state, and the unit continues to operate normally.

[0054] After determining that the compressor is running with liquid, the method may further include: if the exhaust superheat is less than the exhaust superheat setting value for a first preset time, controlling the compressor to enter a liquid protection mode. The first preset time may be preset according to the actual situation of the unit, for example, the first preset time is set to 30 seconds. In this embodiment, the compressor enters the liquid protection mode after the compressor runs with liquid for a certain period of time, which can ensure control accuracy.

[0055] After controlling the compressor to enter the liquid protection mode, the method may further include: when the time of executing the liquid protection mode reaches a second preset time, exiting the liquid protection mode, and controlling the compressor to continue to operate according to the operating state before entering the liquid protection mode. The second preset time can be preset according to the actual situation of the unit, for example, the second preset time is set to 2 minutes. This embodiment can exit the liquid protection mode in time to enable the unit to operate normally.

[0056] The following is a description of the compressor suction liquid determination method in conjunction with a specific embodiment. However, it is worth noting that this specific embodiment is only for better illustrating the present application and does not constitute an improper limitation on the present application. The explanations of terms that are the same or corresponding to the above embodiment will not be repeated in this embodiment.

[0057] like Figure 3 As shown in the figure, the compressor flooding protection includes the following steps:

[0058] S301, start the unit.

[0059] S302, the unit is running, for example, the unit is running in cooling mode.

[0060] S303, during the operation of the unit, the exhaust temperature, condensing temperature and suction temperature are monitored in real time.

[0061] S304, calculate e s =A×(T s -T sn ) and e c =B×(T cn -T c ).

[0062] S305, calculate △T d_OFF =△T d +e s +e c +C.

[0063] S306, determine whether the exhaust superheat T<△T d_OFF And the continuous operation time with liquid is t1≥t OFF If yes, go to S307, if no, return to S302 to maintain refrigeration operation. Wherein, t1 represents the duration of the state that the exhaust gas superheat is less than the exhaust gas superheat setting value, t OFF Indicates the first preset time mentioned above.

[0064] S307, entering the liquid protection mode.

[0065] S308, determine whether t2≥ts is satisfied, if yes, return to S302 to re-enter the cooling mode, if no, return to S307 to continue to execute the liquid protection mode. Wherein, t2 represents the liquid protection time, that is, the actual time of executing the liquid protection mode; ts represents the recovery time, that is, the second preset time mentioned above.

[0066] This embodiment provides a compressor suction liquid determination solution for existing units, which can be applied to units with high pressure difference and wide operating range, for example, it can be applied to integrated refrigeration systems or split refrigeration systems.

[0067] like Figure 4As shown in the figure, it is a pressure-enthalpy diagram showing the refrigeration cycle of the compressor. The ordinate represents the pressure and the abscissa represents the enthalpy value. cn Indicates the condensation temperature, T e It indicates the evaporation temperature. Figure 4 The four state points 3, 4, 5, and 7 are on the isotherm. In actual operation, when the suction temperature and condensing temperature are constant, the typical operating states include: liquid-carrying operation state, i.e., cycle 5-0-8-7-5; low suction superheat operation state, i.e., cycle 4-1-8-7-4; normal operation state, i.e., cycle 3-2-8-6-3. When in low suction superheat or liquid-carrying operation state, the suction temperature is approximately the evaporation temperature. At this time, the exhaust superheat decreases as the degree of liquid-carrying increases (the dryness of the refrigerant at the suction end decreases). Figure 4 The temperature corresponding to the middle state point 1 is the exhaust temperature T1 corresponding to the cycle. When the exhaust temperature is lower than T1, the compressor is in the state of carrying liquid. That is to say, when the exhaust superheat is lower than (T1-T cn ), the compressor is in the state of running with liquid. When the pressure difference increases, the exhaust superheat increases accordingly. For example, compared with the cycle 4-1-8-7-4, the pressure difference of the cycle 3-2-8-6-3 is increased, and the exhaust superheat of the cycle 3-2-8-6-3 is greater than the exhaust superheat of the cycle 4-1-8-7-4 (i.e. T1-T cn ).

[0068] It should be noted that the steps shown in the flowcharts of the accompanying drawings can be executed in a computer system such as a set of computer executable instructions, and that, although a logical order is shown in the flowcharts, in some cases, the steps shown or described can be executed in an order different from that shown here.

[0069] Based on the same inventive concept, an embodiment of the present invention further provides a compressor suction liquid determination device, which can be used to implement the compressor suction liquid determination method described in the above embodiment. The device can be implemented by software and / or hardware, and the device can generally be integrated into the controller of the unit.

[0070] Figure 5 : is a structural block diagram of a compressor suction liquid carrying determination device provided by an embodiment of the present invention, such as Figure 5 As shown, the device comprises:

[0071] Monitoring module 51, used for real-time monitoring of suction temperature and condensation temperature;

[0072] A calculation module 52, for calculating an exhaust superheat setting value according to the suction temperature and the condensation temperature;

[0073] The determination module 53 is used to determine that the compressor is running with liquid when the exhaust gas superheat is less than the exhaust gas superheat setting value.

[0074] Optionally, the calculation module 52 includes:

[0075] A first calculation unit, used for calculating a first difference between a suction air temperature setting value and the suction air temperature;

[0076] A second calculation unit, used for calculating a second difference between the condensing temperature and a set value of the condensing temperature;

[0077] The third calculation unit is used to calculate the exhaust superheat setting value according to the exhaust superheat initial setting value, the first difference and the second difference.

[0078] Optionally, the third calculation unit calculates the exhaust superheat setting value using the following formula:

[0079] △T d_OFF =△T d +A×(T s -T sn )+B×(T cn -T c )+C,

[0080] Among them, △T d_OFF Indicates the exhaust superheat setting value, △T d Indicates the initial setting value of exhaust superheat, T s Indicates the suction temperature setting value, T sn Indicates the real-time monitored suction temperature, T c Indicates the condensing temperature set point, T cn It represents the real-time monitored condensing temperature, A represents the suction temperature deviation correction coefficient, B represents the condensing temperature deviation correction coefficient, and C represents the exhaust superheat set value deviation correction coefficient.

[0081] Optionally, the determination module 53 is further used to: if the exhaust superheat is greater than or equal to the exhaust superheat setting value, determine that the compressor is not running with liquid, and control the compressor to maintain the current operating state.

[0082] Optionally, the above-mentioned device also includes: a first control module, which is used to control the compressor to enter a liquid-carrying protection mode after determining that the compressor is running with liquid, if the exhaust superheat is less than the exhaust superheat setting value for a first preset time.

[0083] Optionally, the above-mentioned device also includes: a second control module, which is used to exit the liquid protection mode after controlling the compressor to enter the liquid protection mode when the execution time of the liquid protection mode reaches a second preset time, and control the compressor to continue operating according to the operating state before entering the liquid protection mode.

[0084] The above device can execute the compressor suction liquid determination method provided by the embodiment of the present invention, and has the corresponding functional modules and beneficial effects of the execution method. For technical details not described in detail in this embodiment, please refer to the compressor suction liquid determination method provided by the embodiment of the present invention.

[0085] The embodiment of the present invention further provides a unit, comprising: the compressor suction liquid determination device described in the above embodiment. The unit of this embodiment comprises a compressor, for example, the unit may be an air conditioner or a refrigerator.

[0086] An embodiment of the present invention further provides a computer device, comprising: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the steps of the method described in the above embodiment when executing the computer program.

[0087] An embodiment of the present invention further provides a non-volatile computer-readable storage medium on which a computer program is stored. When the computer program is executed by a processor, the steps of the method described in the above embodiment are implemented.

[0088] The device embodiments described above are merely illustrative, wherein the units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0089] Through the description of the above implementation methods, those skilled in the art can clearly understand that each implementation method can be implemented by means of software plus a necessary general hardware platform, and of course, it can also be implemented by hardware. Based on this understanding, the above technical solution is essentially or the part that contributes to the prior art can be embodied in the form of a software product, and the computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, a disk, an optical disk, etc., including a number of instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in each embodiment or some parts of the embodiments.

[0090] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for determining liquid in suction of a compressor, characterized in that: include: Real-time monitoring of suction temperature and condensation temperature; Calculating an exhaust superheat setting value according to the suction temperature and the condensation temperature; When the exhaust gas superheat is less than the exhaust gas superheat setting value, it is determined that the compressor is running with liquid.

2. The method according to claim 1, characterized in that Calculating an exhaust superheat setting value according to the suction temperature and the condensation temperature includes: Calculating a first difference between a suction air temperature setting value and the suction air temperature; calculating a second difference between the condensing temperature and a condensing temperature setting value; The exhaust superheat setting value is calculated according to the exhaust superheat initial setting value, the first difference and the second difference.

3. The method according to claim 2, characterized in that The exhaust superheat setting value is calculated using the following formula: △T d_OFF =△T d +A×(T s -T sn )+B×(T cn -T c )+C, Among them, △T d_OFF Indicates the exhaust superheat setting value, △T d Indicates the initial setting value of exhaust superheat, T s Indicates the suction temperature setting value, T sn Indicates the real-time monitored suction temperature, T c Indicates the condensing temperature set point, T cn It represents the real-time monitored condensing temperature, A represents the suction temperature deviation correction coefficient, B represents the condensing temperature deviation correction coefficient, and C represents the exhaust superheat set value deviation correction coefficient.

4. The method according to claim 1, characterized in that: Also includes: If the exhaust gas superheat is greater than or equal to the exhaust gas superheat setting value, it is determined that the compressor is operating without liquid, and the compressor is controlled to maintain the current operating state.

5. The method according to any one of claims 1 to 4, characterized in that After determining that the compressor is running with liquid, the method further includes: If the state in which the exhaust gas superheat is less than the exhaust gas superheat setting value continues for a first preset time, the compressor is controlled to enter a liquid-carrying protection mode.

6. The method according to claim 5, characterized in that After controlling the compressor to enter the liquid-carrying protection mode, the method further includes: When the time for executing the liquid-carrying protection mode reaches a second preset time, the liquid-carrying protection mode is exited, and the compressor is controlled to continue to operate according to the operating state before entering the liquid-carrying protection mode.

7. A compressor suction liquid determination device, characterized in that: include: Monitoring module, used to monitor the suction temperature and condensation temperature in real time; A calculation module, used for calculating an exhaust superheat setting value according to the suction temperature and the condensation temperature; The determination module is used to determine that the compressor is running with liquid when the exhaust superheat is less than the exhaust superheat setting value.

8. A unit, characterized in that: include: The compressor suction liquid carrying determination device as claimed in claim 7.

9. A computer device comprising: A memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the steps of the method according to any one of claims 1 to 6 when executing the computer program.

10. A non-volatile computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 6 are implemented.

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