A detection method for outdoor defrosting of a heat pump unit

Abstract

The application discloses a kind of detection methods of heat pump unit outdoor defrosting, belong to the technical field of control method, after the end of rated defrosting mode, based on the ultrasonic ranging unit of pre-fixing in the specified position of the peripheral of heat pump unit's outdoor fin heat exchanger detection obtains its initial distance L1 between heat pump unit's outdoor fin heat exchanger surface, and based on the humidity detection unit of pre-set obtains outdoor environment humidity H;After running rated length, based on the ultrasonic ranging unit detection obtains its dynamic distance L2 between heat pump unit's outdoor fin heat exchanger surface;Based on initial distance L1 and dynamic distance L2, the distance difference ΔL between them is calculated;According to environmental humidity H and distance difference ΔL corresponding adjustment heat pump unit next time switch to defrosting mode time interval T0, based on the above detection method, realize the high efficiency stability operation of heat pump unit, reduce the influence of user experience except defrosting, more stable and reliable.

Description

Technical Field

[0001] This invention relates to the technical field of control methods, and in particular to a detection method for outdoor defrosting of a heat pump unit. Background Technology

[0002] In the field of heat pumps, heat pump units are prone to frost formation during outdoor operation in winter, especially at the outdoor finned heat exchanger. If defrosting is not performed in time, the heat exchanger will reduce the performance of the heat pump, decrease energy efficiency, and in extreme cases, even cause the compressor to fail. Therefore, timely defrosting of heat pump units is of great importance.

[0003] Existing defrost detection methods typically involve measuring the temperature difference between the finned heat exchanger and the ambient temperature during heating to determine and control defrost switching. This method requires installing a temperature sensor on the outdoor finned heat exchanger. However, in practical applications, when the outdoor finned heat exchanger is frosted / iced, the temperature sensor may also be covered by the frost or ice layer, leading to inaccurate temperature readings and misjudgments. This can result in the unit either not defrosting or defrosting frequently, affecting normal unit operation. Secondly, this detection method is mainly for short-term detection. Once an abnormal temperature is detected, it switches to defrost mode without a transition period, often resulting in frequent switching to defrost and causing significant temperature fluctuations at the indoor end, greatly impacting the user experience. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a highly efficient, stable, accurate and reliable detection method for outdoor defrosting of heat pump units.

[0005] To achieve the above objectives, the present invention provides a method for detecting outdoor defrosting of a heat pump unit, comprising the following steps:

[0006] Step S1. The heat pump unit operates in defrost mode;

[0007] Step S2. After the rated defrosting mode ends, the initial distance L1 between the ultrasonic ranging unit and the surface of the outdoor finned heat exchanger of the heat pump unit is obtained based on the ultrasonic ranging unit that is pre-fixed at a designated position on the periphery of the outdoor finned heat exchanger of the heat pump unit, and the outdoor ambient humidity H is obtained based on the preset humidity detection unit.

[0008] Step S3. The heat pump unit is switched to normal mode. After running for the rated time, the dynamic distance L2 between it and the outdoor finned heat exchanger surface of the heat pump unit is obtained based on the ultrasonic ranging unit.

[0009] Step S4. Calculate the distance difference ΔL between the initial distance L1 and the dynamic distance L2;

[0010] Step S5. Adjust the time interval T0 for the next switch of the heat pump unit to defrost mode according to the ambient humidity H and the distance difference △L, wherein the ambient humidity H and / or the distance difference △L are inversely proportional to the time interval T0.

[0011] Furthermore, it also includes three vertically aligned ultrasonic ranging units, which are respectively aligned with the upper, middle, and lower positions of the outdoor finned heat exchanger. The ultrasonic ranging unit located in the middle position detects and obtains the horizontal distance between itself and the surface of the outdoor finned heat exchanger as the initial distance L1. The two ultrasonic ranging units located in the upper and lower positions detect and obtain the average horizontal distance between themselves and the surface of the outdoor finned heat exchanger as the dynamic distance L2.

[0012] Furthermore, based on humidity values, there are four humidity ranges: [0%, 40%], (40%, 60%], (60%, 80%], and (80%, 100%). Based on distance values, there are four distance ranges: [0], (0%, 0.5], and (0.5%, +∞). Each humidity range and distance range corresponds to a time interval T0. The corresponding time interval T0 is determined based on the humidity range corresponding to the ambient humidity H and the distance range corresponding to the distance difference ΔL.

[0013] Furthermore, in step S4, the compressor operating frequency P of the heat pump unit is adjusted before entering the next defrosting mode based on the distance difference ΔL, wherein the distance difference ΔL is inversely proportional to the compressor operating frequency P.

[0014] Furthermore, in step S4, the fan speed S of the heat pump unit is adjusted before entering the next defrosting mode based on the distance difference △L, wherein the distance difference △L is proportional to the fan speed S.

[0015] Furthermore, the rated duration in step S3 is 45 minutes.

[0016] The present invention adopts the above-mentioned solution, and its beneficial effects are as follows: by mapping the detected ambient humidity H and distance difference ΔL with the corresponding humidity range and distance range to determine the corresponding time interval T0, the heat pump unit switches to the defrost mode after running in normal mode at time interval T0, thereby achieving efficient and stable operation of the heat pump unit, reducing the impact of defrosting on user experience, and making it more stable and reliable. Attached Figure Description

[0017] Figure 1 Flowchart of the outdoor defrosting test method for heat pump units.

[0018] Figure 2 This is a schematic diagram of the ultrasonic ranging unit in a heat pump unit.

[0019] Among them, 1-ultrasonic ranging unit, 2-outdoor finned heat exchanger. Detailed Implementation

[0020] To facilitate understanding of the present invention, a more complete description is given below with reference to the accompanying drawings. Preferred embodiments of the invention are shown in the drawings. However, the invention can be implemented in many different forms and is not limited to the embodiments described herein. These embodiments are provided to provide a thorough and complete understanding of the disclosure of the invention.

[0021] See appendix Figure 1-2 As shown in this embodiment, a method for detecting outdoor defrosting of a heat pump unit is applicable to heat pump units operating in low-temperature outdoor environments, thereby solving the problem of frosting on the outdoor finned heat exchanger 2 of the heat pump unit. Specifically, it includes the following steps:

[0022] Step S1. The heat pump unit is operated in defrost mode.

[0023] Step S2. After the defrosting mode ends, the initial distance L1 between the ultrasonic ranging unit 1, which is pre-fixed at a designated position on the periphery of the outdoor finned heat exchanger 2 of the heat pump unit, is obtained, as is the outdoor ambient humidity H, which is obtained based on the preset humidity detection unit.

[0024] In step S2, after the defrosting mode ends, the surface of the outdoor finned heat exchanger 2 of the heat pump unit should be frost-free / ice-free. At this time, the initial distance L1 detected by the ultrasonic ranging unit 1 is equivalent to the maximum distance between the ultrasonic ranging unit 1 and the surface of the outdoor finned heat exchanger 2. If frost / ice forms on the surface of the outdoor finned heat exchanger 2, it is equivalent to reducing the distance between the ultrasonic ranging unit 1 and the surface of the outdoor finned heat exchanger 2.

[0025] Step S3. The heat pump unit is switched to normal mode. After running for the rated time, the dynamic distance L2 between the heat pump unit and the surface of the outdoor finned heat exchanger 2 of the heat pump unit is obtained based on the ultrasonic ranging unit 1.

[0026] In step S3, when the heat pump unit operates in normal mode under low temperature or high humidity conditions, frost / ice formation is likely to occur on the surface of the outdoor finned heat exchanger 2. Therefore, based on the frost / ice formation during the rated operating time of the heat pump unit, the future frost / ice formation is predicted in a shorter time period and adaptive adjustments are made in advance to avoid affecting the normal operation of the heat pump unit and to avoid frequent switching of defrosting mode, which would affect the user experience. Specifically, the dynamic distance L2 detected by the ultrasonic ranging unit 1 indirectly reflects the frost / ice formation of the outdoor finned heat exchanger 2.

[0027] Step S4. Calculate the distance difference ΔL between the initial distance L1 and the dynamic distance L2.

[0028] In step S4, the calculated distance difference ΔL directly reflects the frosting / icing condition of the outdoor finned heat exchanger 2. That is, the thicker the frosting / icing on the outdoor finned heat exchanger 2, the larger the distance difference ΔL; conversely, if the outdoor finned heat exchanger 2 is in a frost-free / ice-free state, the distance difference ΔL is 0.

[0029] Step S5. Adjust the time interval T0 for the next switch of the heat pump unit to defrost mode according to the ambient humidity H and the distance difference △L, wherein the ambient humidity H and / or the distance difference △L are inversely proportional to the time interval T0.

[0030] In step S5, the time interval T0 of the next defrosting mode is adjusted based on the ambient humidity H and the distance difference ΔL, so as to ensure the duration of normal operation of the heat pump unit as much as possible and reduce the impact of defrosting on the user's comfort.

[0031] In this embodiment, an ultrasonic ranging unit 1 is used as the detection method to obtain the initial distance L1 and dynamic distance L2. This method is unique and effectively solves the problems of large errors and misjudgments that exist in traditional temperature sensor temperature measurement and optical ranging sensor judgment. The main reason is that the outdoor finned heat exchanger 2 of the heat pump unit is in the outdoor environment. When frost / ice layer accumulates on the surface, it either directly covers the temperature sensor or affects the judgment of the optical ranging sensor, and cannot be used as an effective judgment basis. This causes the heat pump unit to be unable to switch or to switch to defrost mode frequently, which in turn affects the normal operation of the heat pump unit.

[0032] In this embodiment, three ultrasonic ranging units 1 are also included, which are vertically aligned and respectively aligned with the upper, middle and lower positions of the outdoor finned heat exchanger 2. The ultrasonic ranging unit 1 located in the middle position detects and obtains the horizontal distance between itself and the surface of the outdoor finned heat exchanger 2 as the initial distance L1. The two ultrasonic ranging units 1 located in the upper and lower positions detect and obtain the average horizontal distance between themselves and the surface of the outdoor finned heat exchanger 2 as the dynamic distance L2. Specifically, when frost / ice forms on the surface of the outdoor finned heat exchanger 2, it is not evenly distributed on the surface, but mainly concentrated at the refrigerant inlet or outlet position of the outdoor finned heat exchanger 2 (corresponding to the upper and lower positions of the outdoor finned heat exchanger 2). There will be instances where frost / ice forms at one of the upper or lower positions of the outdoor finned heat exchanger 2, while the other positions have not yet formed frost. Therefore, the average horizontal distance monitored by the two ultrasonic ranging units 1 at the upper and lower positions is used as the dynamic distance L2, which can more accurately predict and judge the future frost / ice formation of the outdoor finned heat exchanger 2.

[0033] For ease of understanding, the following explanation is based on the initial distance L1 and the dynamic distance L2, combined with the specific frosting / icing conditions.

[0034] Scenario 1: When the initial distance L1 and the dynamic distance L2 are equal, it means that the outdoor finned heat exchanger 2 has not yet frosted / iced, and it is predicted that the risk of frosting / icing during the subsequent normal operation is small, so it can operate normally, and the time interval T0 is relatively longer.

[0035] Scenario 2: When the distance difference △L between the initial distance L1 and the dynamic distance L2 is within the rated distance range, it means that although the outdoor finned heat exchanger 2 has experienced a small amount of frost / ice formation, and the risk of frost / ice formation during subsequent normal operation is predicted to be moderate, although the frost / ice layer formed has a certain impact on the performance of the heat pump unit, it can still operate in normal mode relatively stably, and extend the normal mode operation time as much as possible. The time interval T0 is relatively moderate.

[0036] Scenario 3: When the distance difference △L between the initial distance L1 and the dynamic distance L2 is greater than the rated distance range, it means that although a large amount of frost / ice has occurred in the outdoor finned heat exchanger 2, and the risk of frost / ice will occur during the subsequent normal operation is predicted to be high, the frost / ice layer formed will not only have a certain impact on the performance of the heat pump unit, but also affect the normal operation mode. It is necessary to switch to the defrosting mode as soon as possible, and the time interval T0 is relatively shorter.

[0037] In this embodiment, in step S4, the compressor operating frequency P of the heat pump unit is adjusted before entering the next defrosting mode based on the distance difference ΔL, wherein the distance difference ΔL is inversely proportional to the compressor operating frequency P. This method of adjusting the compressor operating frequency P is mainly used to slow down the frosting / icing rate of the outdoor finned heat exchanger 2. For ease of understanding, the following explanation is provided in conjunction with the three scenarios mentioned above: For scenario one, the risk of frosting / icing is low, and the compressor operating frequency P operates at 100%; for scenario two, the risk of frosting / icing is moderate, and the compressor operating frequency P operates at 80% to appropriately reduce frosting; for scenario three, the risk of frosting / icing is high, and the compressor operating frequency P operates at 60% to minimize frosting.

[0038] In this embodiment, in step S4, the fan speed S of the heat pump unit is adjusted before entering the next defrosting mode based on the distance difference ΔL, wherein the distance difference ΔL is proportional to the fan speed S. This method of adjusting the fan speed S is mainly used to slow down the frosting / icing rate of the outdoor finned heat exchanger 2. For ease of understanding, the following explanation is provided in conjunction with the three scenarios mentioned above: For scenario one, the risk of frosting / icing is low, and the fan speed S operates at 100%; for scenario two, the risk of frosting / icing is moderate, and the fan speed S operates at 120%, appropriately increasing the airflow rate to improve the heat exchange rate; for scenario three, the risk of frosting / icing is high, and the fan speed S operates at 140%, significantly increasing the airflow rate to improve the heat exchange rate, especially preventing moisture in the air from lingering on the outdoor finned heat exchanger 2.

[0039] In summary, adjusting the compressor operating frequency P and / or fan speed S are both aimed at slowing down the frosting / icing rate of the outdoor finned heat exchanger 2, thereby ensuring that the heat pump unit can maintain normal operation as much as possible when the risk of frosting / icing occurs, and thus guaranteeing the user experience.

[0040] In this embodiment, the rated duration in step S3 is preferably 45 minutes. Those skilled in the art can adjust the rated duration according to the actual working conditions, and no specific limitation is made here.

[0041] In this embodiment, humidity ranges are divided into four levels: a first humidity range [0%, 40%], a second humidity range, a third humidity range, and a fourth humidity range [40%, 60%], a sixth humidity range [60%, 80%], and a seventh humidity range [80%, 100%]. Distance ranges are also divided into four levels: a first distance range [0], a second distance range [0%, 0.5], and a third distance range [0.5%, +∞]. Each level of humidity range and each level of distance range maps to a corresponding time interval T0. The corresponding time interval T0 is determined based on the humidity range corresponding to the ambient humidity H and the distance range corresponding to the distance difference ΔL.

[0042] Specifically, based on the mapping relationship between each humidity range and each distance range, the corresponding time interval T0 is determined. The larger the ambient humidity H and / or the distance difference ΔL, the shorter the time interval T0. Thus, by mapping the detected ambient humidity H and distance difference ΔL to the corresponding humidity range and distance range, the corresponding time interval T0 is determined. After the heat pump unit operates in normal mode at time interval T0, it switches to defrost mode for defrosting.

[0043] In summary, after the heat pump unit has been operating in normal mode for the rated duration, the dynamic distance L2 is detected and obtained by the ultrasonic ranging unit 1. Combined with the initial distance L1 detected at the end of defrosting, the distance difference ΔL is calculated and confirmed to reflect the risk of frost / ice formation. This makes it easier to make accurate predictions and adjust the time interval T0, especially solving the problems of inaccurate traditional defrosting detection methods and the impact of frequent defrosting switching on user experience.

[0044] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the present invention in any way. Any modifications or variations made by those skilled in the art, without departing from the scope of the present invention, using the disclosed technical content, are equivalent embodiments of the present invention. Therefore, all equivalent changes made based on the concept of the present invention without departing from the scope of the present invention should be covered within the protection scope of the present invention.

Claims

1. A method for detecting outdoor defrosting of a heat pump unit, characterized in that: It includes the following steps: Step S1. The heat pump unit operates in defrost mode; Step S2. After the rated defrosting mode ends, the initial distance L1 between the ultrasonic ranging unit and the surface of the outdoor finned heat exchanger of the heat pump unit is obtained based on the ultrasonic ranging unit that is pre-fixed at a designated position on the periphery of the outdoor finned heat exchanger of the heat pump unit, and the outdoor ambient humidity H is obtained based on the preset humidity detection unit. Step S3. The heat pump unit is switched to normal mode. After running for the rated time, the dynamic distance L2 between it and the outdoor finned heat exchanger surface of the heat pump unit is obtained based on the ultrasonic ranging unit. Step S4. Calculate the distance difference ΔL between the initial distance L1 and the dynamic distance L2; Step S5. Adjust the time interval T0 for the next switch of the heat pump unit to defrost mode according to the ambient humidity H and the distance difference △L, wherein the ambient humidity H and / or the distance difference △L are inversely proportional to the time interval T0; It also includes three vertically aligned ultrasonic ranging units, which are respectively aligned with the upper, middle and lower positions of the outdoor finned heat exchanger. The ultrasonic ranging unit located in the middle position detects and obtains the horizontal distance between itself and the surface of the outdoor finned heat exchanger as the initial distance L1. The two ultrasonic ranging units located in the upper and lower positions detect and obtain the average horizontal distance between themselves and the surface of the outdoor finned heat exchanger as the dynamic distance L2. In step S4, the compressor operating frequency P of the heat pump unit is adjusted before entering the next defrosting mode based on the distance difference ΔL, wherein the distance difference ΔL is inversely proportional to the compressor operating frequency P; In step S4, the fan speed S of the heat pump unit is adjusted before entering the next defrosting mode based on the distance difference ΔL, wherein the distance difference ΔL is proportional to the fan speed S.

2. The method for detecting outdoor defrosting of a heat pump unit according to claim 1, characterized in that: Humidity intervals are divided into four levels based on humidity values: [0%, 40%], (40%, 60%], (60%, 80%], and (80%, 100%). Distance intervals are divided into four levels based on distance values: [0%, (0%, 0.5%), (0.5%, +∞). Each level of humidity interval and distance interval corresponds to a time interval T0. The time interval T0 is determined based on the humidity interval corresponding to the ambient humidity H and the distance interval corresponding to the distance difference ΔL.

3. The detection method for outdoor defrosting of a heat pump unit according to claim 2, characterized in that: The rated duration in step S3 is 45 minutes.

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