Automatic oil return system of air conditioning unit
Through the dual level sensor control system, the opening and closing of the oil return valve is automatically adjusted, which solves the problem of bypass in the oil return system of the water (ground) source heat pump unit, and achieves stable operation and energy efficiency improvement of the unit.
Patent Information
- Application Number
- CN202421388282.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-06-18
- Publication Date
- 2025-05-30
- Estimated Expiration
- 2034-06-18
AI Technical Summary
Under different operating conditions, the amount of lubricant oil separated by the oil separator is different, resulting in the valve of the return pipeline that needs to be opened large, and some refrigerant gas returns to the compressor with the lubricant oil, causing bypass and affecting the energy efficiency of the unit.
The dual level sensor control system is adopted to detect the oil level in the oil collecting tank through high and low level sensors. The solenoid valve automatically opens or closes according to the oil level changes to ensure that only the lubricant oil returns to the compressor and avoids bypass.
It realizes an automatic oil return system with a simple structure, stable operation and avoids bypass, ensuring the stable operation and energy efficiency of the unit.
Smart Images
Figure CN222925643U_ABST
Abstract
Description
Technical Field
[0001] The utility model belongs to the technical field of full liquid or falling film type water (ground) source heat pump systems for central air conditioners, and particularly relates to an automatic oil return system for an air conditioner unit. Background Technique
[0002] The water (ground) source heat pump unit is the most core component in the central air conditioning system. Whether the system can smoothly and stably return oil in the water (ground) source heat pump unit is the key to the normal operation of the entire unit.
[0003] Each unit is equipped with an oil return system. In the oil return system of full liquid or falling film type units, an oil separator is set. The separated lubricating oil accumulates at the bottom of the oil separator. The bottom of the oil separator is connected to the suction end of the compressor in the unit through a pipeline. Due to the pressure of the oil separator being much higher than the pressure at the suction end of the compressor, the separated lubricating oil automatically flows back to the suction end of the compressor by using the pressure difference on both sides and enters the compressor to ensure the oil return of the unit. However, under different operating conditions of the unit and the influence of liquid carrying, the amount of oil separated by the oil separator is different. To ensure sufficient oil in the compressor of the unit, the valves of the oil return pipeline from the oil separator to the suction end of the compressor are all opened to the maximum state; when the unit operates under relatively stable conditions, the amount of separated lubricating oil is less at this time. In the state where the opening degree of the oil return pipeline valve is relatively large, some refrigerant gases will return to the suction end of the compressor together with the lubricating oil, which we call bypass. The bypassed refrigerant does not go through the subsequent heat exchange process of the system, resulting in a decrease in the cooling capacity of the unit and affecting the energy efficiency of the unit.
[0004] Currently, in the existing technology, there is a method of using a pressure gauge to achieve automatic oil return. For example, patent CN207050284U discloses an automatic oil return device for an air conditioning system, including: a pressure gauge for detecting the pressure above the liquid level in the oil separator or the pressure at the bottom of the oil separator; an oil return pipeline connected to the oil outlet of the oil separator and the suction port of the compressor respectively, and an oil return valve is provided on the oil return pipeline; a controller connected to the pressure gauge and the oil return valve respectively. When the pressure is greater than the preset high pressure threshold or the pressure is less than the preset low pressure threshold, the oil return valve is controlled to open, and when the pressure is lower than the preset low pressure threshold or the pressure is greater than the preset low pressure threshold, the oil return valve is controlled to close. When the oil return valve is closed, the oil separator or the compressor should be replenished with oil in time to avoid equipment damage. Therefore, its control process is simple and effective, and problems such as untimely oil return, overly frequent oil return, or oil return when the liquid level is low can be avoided.
[0005] The above system may have the following disadvantages:
[0006] Disadvantage 1: The process is too complex and the calculation program is too cumbersome.
[0007] Difficult to control: The oil level inside the oil separator cannot be too high itself because it must return to the compressor in a timely manner. Taking the oil level of 100 mm inside the oil separator as an example, assuming that the density of the lubricating oil is the same as that of water, 1 atmospheric pressure, i.e., 101325 Pa, is equivalent to the pressure generated by a 10-meter water column, and the pressure generated by 100 mm of water is 100 Pa. Therefore, to control the liquid level using a pressure sensor, a high-precision sensor must be used to achieve the effect. High-precision sensors are costly. Moreover, regardless of the influence of the pressure corresponding to the oil level inside the oil separator, during the operation of the unit, the high pressure of the unit, i.e., the pressure inside the oil separator, is not constant and continuously adjusts and changes with the external environment. Affected by this, the oil return valve of the unit may be in a continuous on-off state.
[0008] Unstable control: During the operation of the unit, under different operating conditions, the high-pressure value of the unit, i.e., the pressure inside the oil separator, is different and varies greatly. If a pressure sensor is used to control the liquid level, the value of only one pressure sensor cannot correctly reflect the liquid level inside the oil separator. Utility Model Content
[0009] The utility model provides an automatic oil return system for an air-conditioning unit, which can solve the problems pointed out in the background technology.
[0010] An automatic oil return system for an air-conditioning unit includes a compressor, an intake pipeline, an exhaust pipeline, an oil separator, and an oil return pipeline. A return valve is provided on the oil return pipeline; a collecting tank is connected below the oil separator, and a high-level liquid level sensor and a low-level liquid level sensor are provided in the collecting tank. One end of the oil return pipeline is connected to the collecting tank, and the other end is connected to the intake pipeline. The high-level liquid level sensor, the low-level liquid level sensor, and the return valve are all connected to a control system.
[0011] Preferably, the return valve is a solenoid valve.
[0012] Preferably, a filter is provided on the oil return pipeline.
[0013] Preferably, shut-off valves are provided at both ends of the oil return pipeline.
[0014] Beneficial effects: The utility model provides an automatic oil return system for an air-conditioning unit, which has a simple structure, stable operation, is easy to implement, and does not have the phenomenon of bypassing refrigerant, ensuring the stable operation of the unit and improving the energy efficiency of the unit.
[0015] Advantages of using two liquid level sensors:
[0016] 1. Simple structure, simple controller programming, and simple control.
[0017] 2. Avoid frequent opening of the oil return solenoid valve. If only one liquid level sensor is used, when the oil level is just above the position of the sensor, the solenoid valve opens for oil return; at this time, when the oil level drops just below the sensor position, the solenoid valve closes and stops oil return. When the oil level rises, the above process is repeated, resulting in the solenoid valve being frequently in the open and closed states, which affects the service life of the solenoid valve.
[0018] 3. Ensure that when the solenoid valve opens, only oil is returned and there is no phenomenon of bypass gas.
[0019] Description of the oil return process: When the unit starts, the oil in the oil collection tank gradually increases. When the oil level is higher than the low liquid level sensor, the solenoid valve does not open. When the oil level is higher than the high liquid level sensor, the solenoid valve opens and starts oil return; the oil in the oil collection tank decreases and the oil level begins to drop. When the oil level is lower than the high liquid level sensor, the solenoid valve is still open and the oil return state continues; when the oil level is lower than the low liquid level sensor, the solenoid valve closes and the oil return state ends and oil return stops. When the oil level rises again, the above oil return process is repeated. Description of the drawings
[0020] Figure 1 is a system schematic diagram of the present invention.
[0021] Description of the reference numerals in the drawings:
[0022] Reference numerals in the figure: compressor 1; suction pipeline 2; discharge pipeline 3; oil separator 4; oil return pipeline 5; oil return valve 6; oil collection tank 7; high liquid level sensor 8; low liquid level sensor 9; control system 10; filter 11; shut-off valve 12. Specific embodiments
[0023] The following combines the drawings to describe in detail a specific embodiment of the present invention, but it should be understood that the protection scope of the present invention is not limited by the specific embodiment. Embodiment
[0024] As Figure 1 shown, an automatic oil return system for an air-conditioning unit provided by an embodiment of the present invention includes a compressor 1, a suction pipeline 2, a discharge pipeline 3, an oil separator 4, and an oil return pipeline 5. An oil return valve 6 is provided on the oil return pipeline 5; specifically, the oil return valve 6 is a solenoid valve. The oil separator 4 is located after the compressor 1 and before the condenser; a oil collection tank 7 is connected below the oil separator 4. A high liquid level sensor 8 and a low liquid level sensor 9 are provided in the oil collection tank 7. One end of the oil return pipeline 5 is connected to the oil collection tank 7, and the other end is connected to the suction pipeline 2. The high liquid level sensor 8, the low liquid level sensor 9, and the oil return valve 6 are all connected to the control system 10. Specifically, the oil return valve 6 is a solenoid valve.
[0025] In some embodiments, a filter 11 is provided on the oil return pipeline 5 to filter the oil return. The filter 11 is installed before the solenoid valve.
[0026] In some embodiments, shut-off valves 12 are provided at both ends of the oil return pipeline 5 to facilitate the maintenance and repair of the pipeline filter 11.
[0027] The utility model uses the pressure difference of the unit as the power for oil return. The control system 10 controls the opening and closing of the solenoid valve according to the oil level detected by the liquid level sensor, ensuring that only lubricating oil passes through the oil return pipeline and preventing bypass phenomena. The specific control method is as follows: when the low-level liquid level sensor 9 and the high-level liquid level sensor 8 simultaneously detect the oil level, the solenoid valve opens and oil return begins. When the low-level liquid level sensor 9 and the high-level liquid level sensor 8 simultaneously do not detect the oil level, the solenoid valve closes and there is no oil return.
[0028] The above discloses only several specific embodiments of the utility model. However, the embodiments of the utility model are not limited thereto, and any changes that can be conceived by those skilled in the art should fall within the protection scope of the utility model.
Claims
1. An automatic oil return system for an air conditioning unit, comprising a compressor (1), an air intake pipeline (2), an air discharge pipeline (3), an oil separator (4) and an oil return pipeline (5), wherein the oil return pipeline (5) is provided with an oil return valve (6); the characteristics are: The oil separator (4) is connected to an oil collecting tank (7) below, and a high-level liquid level sensor (8) and a low-level liquid level sensor (9) are provided in the oil collecting tank (7). One end of the oil return pipeline (5) is connected to the oil collecting tank (7), and the other end is connected to the air intake pipeline (2). The high-level liquid level sensor (8), the low-level liquid level sensor (9) and the oil return valve (6) are all connected to a control system (10).
2. The automatic oil return system for an air conditioning unit according to claim 1, characterized in that: The oil return valve (6) is a solenoid valve.
3. The automatic oil return system for an air conditioning unit according to claim 1, characterized in that: The oil return pipeline (5) is provided with a filter (11).
4. The automatic oil return system for an air conditioning unit according to claim 1, characterized in that: Both ends of the oil return pipeline (5) are provided with shut-off valves (12).