阅读说明：本技术 压缩机回油方法、制冷系统及空调 (compressor oil return method, refrigeration system and air conditioner ) 是由 卓明胜 刘思源 黄凯亮 覃业星 于 2019-09-06 设计创作，主要内容包括：本发明涉及一种压缩机回油方法、制冷系统及空调。其中,压缩机回油方法包括：检测压缩机的油位；在压缩机的油位低于预设油位值时,控制压缩机关机；判断压缩机的油位是第几次低于预设油位值；如果判断压缩机的油位第一次低于预设油位值,则控制压缩机开机,进入回油调节步骤,完成第一次回油；所述回油调节步骤包括：调节增大电子膨胀阀的开度；在调节增大电子膨胀阀的开度后,使压缩机保持运行达到第一预设时间；调节减小电子膨胀阀的开度。本发明有效缓解了环境温度较高时,压缩机容易缺油保护的问题,且减小冷冻油对换热的影响,有利于压缩机长期可靠的运行。(The invention relates to an oil return method for a compressor, a refrigeration system and an air conditioner. The oil return method of the compressor comprises the following steps: detecting an oil level of a compressor; when the oil level of the compressor is lower than a preset oil level value, controlling the compressor to shut down; judging that the oil level of the compressor is lower than the preset oil level value for the second time; if the oil level of the compressor is judged to be lower than the preset oil level value for the first time, the compressor is controlled to start, an oil return adjusting step is carried out, and the first oil return is completed; the oil return adjusting step comprises the following steps: adjusting and increasing the opening degree of the electronic expansion valve; after the opening degree of the electronic expansion valve is adjusted and increased, the compressor is kept running for a first preset time; and regulating and reducing the opening degree of the electronic expansion valve. The invention effectively relieves the problem that the compressor is easy to be protected from oil shortage when the environmental temperature is higher, reduces the influence of the refrigeration oil on heat exchange, and is beneficial to the long-term reliable operation of the compressor.)

1. A compressor oil return method is characterized by comprising the following steps:

Detecting an oil level of a compressor;

When the oil level of the compressor is lower than a preset oil level value, controlling the compressor to shut down;

judging that the oil level of the compressor is lower than the preset oil level value for the second time;

if the oil level of the compressor is judged to be lower than the preset oil level value for the first time, the compressor is controlled to start, an oil return adjusting step is carried out, and the first oil return is completed;

The oil return adjusting step comprises the following steps:

Adjusting and increasing the opening degree of the electronic expansion valve;

After the opening degree of the electronic expansion valve is adjusted and increased, the compressor is kept running for a first preset time;

and regulating and reducing the opening degree of the electronic expansion valve.

2. The compressor oil return method of claim 1, wherein the oil return adjusting step, adjusting increasing the opening degree of the electronic expansion valve, comprises: and after the compressor is controlled to be started, the compressor runs for a second preset time, and the opening degree of the electronic expansion valve is adjusted and increased.

3. The compressor oil return method of claim 1, further comprising: and if the oil level of the compressor is judged to be lower than the preset oil level value for the second time, whether the running time of the compressor after the first oil return is finished reaches a third preset time or not is continuously judged, and if the running time does not reach the third preset time, an alarm is given out.

4. The compressor oil return method of claim 1, further comprising: and if the oil level of the compressor is judged to be lower than the preset oil level value for the second time, continuously judging whether the running time of the compressor after the first oil return is finished reaches a third preset time, if so, controlling the compressor to start, entering an oil return adjusting step, and finishing the second oil return.

5. The compressor oil return method of claim 4, wherein in the oil return adjusting step, adjusting increasing the opening degree of the electronic expansion valve comprises: the opening degree of the electronic expansion valve is increased by first adjustment and the opening degree of the electronic expansion valve is increased by second adjustment;

After the opening degree of the electronic expansion valve is adjusted and increased for the first time, the compressor is kept running for a first preset time;

Then, adjusting and increasing the opening degree of the electronic expansion valve for the second time;

After the opening degree of the electronic expansion valve is adjusted and increased for the second time, the compressor is kept running for a first preset time;

And regulating and reducing the opening degree of the electronic expansion valve.

6. The compressor oil return method of claim 1, further comprising: and if the oil level of the compressor is judged to be lower than the preset oil level value for the third time, giving an alarm.

7. the compressor oil return method of claim 1, wherein in the oil return adjusting step, adjusting increasing the opening degree of the electronic expansion valve comprises: the opening degree of the electronic expansion valve is increased by 5 to 15 percent on the basis of the original opening degree.

8. the compressor oil return method of claim 1, wherein in the oil return adjusting step, adjusting to reduce the opening degree of the electronic expansion valve comprises: and adjusting the opening degree of the electronic expansion valve to be the opening degree when the opening degree is not increased, or determining the opening degree of the electronic expansion valve according to the unit operation parameters.

9. the compressor oil return method according to claim 1, wherein the first preset time is 10 seconds to 100 seconds.

10. the compressor oil return method according to claim 2, wherein the second preset time is 1 minute to 3 minutes.

11. the compressor oil return method according to claim 3 or 4, wherein the third preset time is 3 to 10 minutes.

12. The oil return method for the compressor according to claim 1, wherein when the oil level of the compressor is lower than the predetermined oil level value, the compressor is controlled to be shut down and the electronic expansion valve is closed, and before the compressor is controlled to be started, the electronic expansion valve is opened at an original opening degree and waits for a fourth predetermined time to be reached, so that the compressor is controlled to be started.

13. The compressor oil return method of claim 12, wherein the fourth predetermined time is 10 seconds to 60 seconds.

14. A refrigeration system comprising a compressor (1), a condenser (2), an electronic expansion valve (3) and an evaporator (4) connected in sequence, wherein the refrigeration system controls oil return of the compressor (1) by using the oil return method of the compressor (1) according to claim 1;

The refrigeration system further comprises a sensor and a controller; the controller is electrically connected with the sensor, the compressor (1) and the electronic expansion valve (3);

the sensor is used for detecting the oil level of the compressor (1) and sending a signal to the controller;

The controller is used for receiving the signals sent by the sensors; the controller is configured to control the start and stop of the compressor (1) and to control the opening degree of the electronic expansion valve (3).

15. The refrigeration system according to claim 14, wherein the sensor comprises a proximity switch configured to send a signal to the controller when the oil level of the compressor (1) is lower than the preset oil level value.

16. An air conditioner characterized by comprising a refrigeration system as claimed in claim 14 or 15.

Technical Field

the invention relates to the field of compressors, in particular to an oil return method for a compressor, a refrigeration system and an air conditioner.

Background

air-cooled screw unit receives ambient temperature to influence great, and leads to exhaust temperature and exhaust superheat degree great easily, and then makes the oil return effect of compressor refrigeration oil in the compressor casing bad, and refrigeration oil is discharged the condenser along with the refrigerant and is participated in the heat transfer, appears the oil temperature on the high side easily when long-term ambient temperature is higher, and the oil level descends gradually, the phenomenon that the refrigerating output reduces.

disclosure of Invention

One of the objectives of the present invention is to provide an oil return method for a compressor, a refrigeration system and an air conditioner, which are used to alleviate the problem of poor oil return effect.

some embodiments of the present invention provide a compressor oil return method, including:

Detecting an oil level of a compressor;

When the oil level of the compressor is lower than a preset oil level value, controlling the compressor to shut down;

Judging that the oil level of the compressor is lower than the preset oil level value for the second time;

if the oil level of the compressor is judged to be lower than the preset oil level value for the first time, the compressor is controlled to start, an oil return adjusting step is carried out, and the first oil return is completed;

The oil return adjusting step comprises the following steps:

adjusting and increasing the opening degree of the electronic expansion valve;

After the opening degree of the electronic expansion valve is adjusted and increased, the compressor is kept running for a first preset time;

And regulating and reducing the opening degree of the electronic expansion valve.

in some embodiments, in the oil return adjusting step, adjusting to increase the opening degree of the electronic expansion valve includes: and after the compressor is controlled to be started, the compressor runs for a second preset time, and the opening degree of the electronic expansion valve is adjusted and increased.

in some embodiments, the compressor oil return method further comprises: and if the oil level of the compressor is judged to be lower than the preset oil level value for the second time, whether the running time of the compressor after the first oil return is finished reaches a third preset time or not is continuously judged, and if the running time does not reach the third preset time, an alarm is given out.

In some embodiments, the compressor oil return method further comprises: and if the oil level of the compressor is judged to be lower than the preset oil level value for the second time, continuously judging whether the running time of the compressor after the first oil return is finished reaches a third preset time, if so, controlling the compressor to start, entering an oil return adjusting step, and finishing the second oil return.

In some embodiments, in the oil return adjusting step, adjusting to increase the opening degree of the electronic expansion valve includes: the opening degree of the electronic expansion valve is increased by first adjustment and the opening degree of the electronic expansion valve is increased by second adjustment;

after the opening degree of the electronic expansion valve is adjusted and increased for the first time, the compressor is kept running for a first preset time;

Then, adjusting and increasing the opening degree of the electronic expansion valve for the second time;

After the opening degree of the electronic expansion valve is adjusted and increased for the second time, the compressor is kept running for a first preset time;

And regulating and reducing the opening degree of the electronic expansion valve.

In some embodiments, the compressor oil return method further comprises: and if the oil level of the compressor is judged to be lower than the preset oil level value for the third time, giving an alarm.

In some embodiments, in the oil return adjusting step, adjusting to increase the opening degree of the electronic expansion valve includes: the opening degree of the electronic expansion valve is increased by 5 to 15 percent on the basis of the original opening degree.

in some embodiments, in the oil return adjusting step, adjusting to reduce the opening degree of the electronic expansion valve includes: and adjusting the opening degree of the electronic expansion valve to be the opening degree when the opening degree is not increased, or determining the opening degree of the electronic expansion valve according to the unit operation parameters.

In some embodiments, the first predetermined time is 10 seconds to 100 seconds.

In some embodiments, the second predetermined time is 1 minute to 3 minutes.

in some embodiments, the third predetermined time is 3 minutes to 10 minutes.

In some embodiments, when the oil level of the compressor is lower than the preset oil level value, the compressor is controlled to be shut down, the electronic expansion valve is closed, the electronic expansion valve is opened at the original opening degree before the compressor is controlled to be started, and the compressor is controlled to be started after a fourth preset time is reached.

In some embodiments, the fourth predetermined time is 10 seconds to 60 seconds.

Some embodiments of the present invention provide a refrigeration system, including a compressor, a condenser, an electronic expansion valve and an evaporator, which are connected in sequence, wherein the refrigeration system controls oil return of the compressor by using the above-mentioned compressor oil return method;

the refrigeration system further comprises a sensor and a controller; the controller is electrically connected with the sensor, the compressor and the electronic expansion valve;

The sensor is used for detecting the oil level of the compressor and sending a signal to the controller;

The controller is used for receiving the signals sent by the sensors; the controller is configured to control start and stop of the compressor and control an opening degree of the electronic expansion valve.

in some embodiments, the sensor comprises a proximity switch configured to send a signal to the controller when the oil level of the compressor is below the preset oil level value.

some embodiments of the present invention provide an air conditioner including the refrigeration system described above.

Based on the technical scheme, the invention at least has the following beneficial effects:

In some embodiments, the opening degree of the electronic expansion is increased, and the refrigeration oil is pumped into the compressor through the suction action of the compressor, so that the oil return effect is achieved; the problem that the compressor is easy to lack oil for protection when the environmental temperature is high is effectively solved, the influence of the refrigeration oil on heat exchange is reduced, and the long-term reliable operation of the compressor is facilitated.

Drawings

the accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the invention without limiting the invention. In the drawings:

Fig. 1 is a schematic diagram of a refrigeration system provided by some embodiments of the present invention.

Reference numerals in the drawings indicate:

1-a compressor; 2-a condenser; 3-an electronic expansion valve; 4-evaporator.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments. It is to be understood that the described embodiments are merely a few embodiments of the invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments of the present invention without any inventive step, are within the scope of the present invention.

In the description of the present invention, it is to be understood that the terms "center", "longitudinal", "lateral", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate orientations or positional relationships based on those shown in the drawings, and are used merely for convenience in describing the present invention and for simplifying the description, and do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore, should not be taken as limiting the scope of the present invention.

As shown in fig. 1, the refrigeration system includes a compressor 1, a condenser 2, an electronic expansion valve 3, and an evaporator 4, which are connected in this order.

Optionally, the condenser 2 comprises a finned condenser.

optionally, the evaporator 4 comprises a flooded evaporator.

Alternatively, the compressor 1 comprises an air-cooled screw compressor.

The refrigeration cycle mode of the refrigeration system is as follows: the refrigerant is compressed by the compressor 1, enters the condenser 2 to exchange heat with the surrounding environment, is throttled by the electronic expansion valve 3, enters the evaporator 4 to exchange heat with water, and finally returns to the compressor 1 through the air suction pipeline.

When the ambient temperature is higher, the inside oil return effect of compressor is bad, leads to easily that the refrigeration oil to participate in the condensation heat transfer along with the refrigerant gets into the condenser through the blast pipe, and the oil level descends thereupon, and the compressor produces the phenomenon of lack of oil easily, and the phenomenon of lack of oil aggravates the rise of motor temperature and exhaust temperature more.

Based on the above, some embodiments of the present disclosure provide a compressor oil return method, which is suitable for oil return of a compressor in a refrigeration system.

in some embodiments, a compressor oil return method includes:

Detecting an oil level of a compressor;

When the oil level of the compressor is lower than a preset oil level value, controlling the compressor to shut down;

Judging that the oil level of the compressor is lower than the preset oil level value for the second time;

And if the oil level of the compressor is judged to be lower than the preset oil level value for the first time, controlling the compressor to start, entering an oil return adjusting step, and finishing the first oil return.

The oil return adjusting step comprises:

Adjusting and increasing the opening degree of the electronic expansion valve;

After the opening degree of the electronic expansion valve is adjusted and increased, the compressor is kept running for a first preset time;

And regulating and reducing the opening degree of the electronic expansion valve.

After the refrigerant oil is discharged from the compressor, the refrigerant oil is condensed from a gas state to a liquid state in the condenser and flows along with the refrigerant in the pipeline, and finally the refrigerant oil flows into the evaporator.

according to the oil return method for the compressor, the opening degree of electronic expansion is increased, and the refrigeration oil is pumped into the compressor through the air suction effect of the compressor, so that the oil return effect is achieved; the problem that the compressor is easy to lack oil for protection when the environmental temperature is high is effectively solved, the influence of the refrigeration oil on heat exchange is reduced, and the long-term reliable operation of the compressor is facilitated.

Based on some embodiments of the present disclosure, when the oil level of the compressor is lower than the preset oil level value for the first time, the alarm is not performed, but the compressor is restarted, the opening degree of the electronic expansion valve is increased, and after the opening degree of the electronic expansion valve is adjusted and increased, the compressor keeps running for the first preset time, the opening degree of the electronic expansion valve is adjusted and decreased, and then the refrigeration system continues to work normally.

In some embodiments, the first predetermined time is 10 seconds to 100 seconds. Preferably, the compressor is kept in operation for 60 seconds after the opening degree of the electronic expansion valve is adjusted to be increased.

the setting of the first preset time is too long, other protections may be caused, the setting of the first preset time is too short, the oil return effect may not be good, and the specific setting value of the first preset time can be set according to the refrigerant quantity and the refrigerating oil quantity of each refrigerating system.

In some embodiments, when the oil level of the compressor is lower than the preset oil level value, the compressor is controlled to be shut down, the electronic expansion valve is closed, the electronic expansion valve is opened at the original opening degree before the compressor is controlled to be started, and the compressor is controlled to be started after a fourth preset time is reached.

Firstly, the electronic expansion valve is opened at the original opening degree, and the starting of the compressor is controlled because the fourth preset time is reached: the refrigerant in the whole system is circulated, and the fault caused during starting is prevented.

that is, the electronic expansion valve is opened at the original opening degree for a fourth preset time before the compressor is started.

for example: and opening the electronic expansion valve at the original opening degree 30 seconds before the compressor is started.

The setting of the fourth preset time can be adjusted according to the size of the refrigeration system. Optionally, the fourth preset time is 10 seconds to 60 seconds, and preferably 30 seconds.

In some embodiments, controlling the compressor to start further comprises detecting a parameter related to the operation of the compressor, determining whether the compressor can be started under the parameter, and starting the compressor if a compressor starting condition is met.

optionally, the parameters related to the operation of the compressor include water temperature, ambient temperature, compressor off time, whether there is a fault, etc.

That is, the compressor is started in case that other parameters satisfy the start of the compressor except that the oil level of the compressor is lower than the preset oil level value.

In some embodiments, in the oil return adjusting step, adjusting to increase the opening degree of the electronic expansion valve includes: and after the compressor is controlled to be started, the compressor runs for a second preset time, and the opening degree of the electronic expansion valve is adjusted and increased.

In some embodiments, the second predetermined time is 1 minute to 3 minutes.

Preferably, after the compressor is controlled to start, the compressor is controlled to run for 2 minutes, and the opening degree of the electronic expansion valve is adjusted and increased.

In some embodiments, the compressor oil return method further comprises: and if the oil level of the compressor is judged to be lower than the preset oil level value for the second time, whether the running time of the compressor after the first oil return is finished reaches a third preset time or not is continuously judged, and if the running time does not reach the third preset time, an alarm is given out. And performing oil supplementation on the compressor according to the alarm.

In some embodiments, the compressor oil return method further comprises: and if the oil level of the compressor is judged to be lower than the preset oil level value for the second time, continuously judging whether the running time of the compressor after the first oil return is finished reaches a third preset time, if so, controlling the compressor to start, entering an oil return adjusting step, and finishing the second oil return.

Wherein, the oil return regulation step includes:

adjusting and increasing the opening degree of the electronic expansion valve;

after the opening degree of the electronic expansion valve is adjusted and increased, the compressor is kept running for a first preset time;

and regulating and reducing the opening degree of the electronic expansion valve.

In some embodiments, in the oil return adjusting step, adjusting to increase the opening degree of the electronic expansion valve includes: the opening degree of the electronic expansion valve is increased by first adjustment and the opening degree of the electronic expansion valve is increased by second adjustment;

After the opening degree of the electronic expansion valve is adjusted and increased for the first time, the compressor is kept running for a first preset time;

Then, adjusting and increasing the opening degree of the electronic expansion valve for the second time;

After the opening degree of the electronic expansion valve is adjusted and increased for the second time, the compressor is kept running for a first preset time;

And regulating and reducing the opening degree of the electronic expansion valve.

That is, when the oil level of the compressor is lower than the preset oil level value for the first time, the compressor is forced to start; and entering an oil return step, finishing first oil return, and after the first oil return is finished, if the continuous operation time of the compressor reaches or exceeds a third preset time, determining that the large electronic expansion valve has an oil return effect. If the oil level of the compressor is lower than the preset oil level value for the second time after the running time of the compressor reaches or exceeds the third preset time, the fault still does not give an alarm, the compressor is forcibly started again, the oil return for the second time is carried out, and the oil return strength can be further increased.

For example: when the running time of the compressor after the first oil return reaches or exceeds a third preset time (for example, 6 minutes), controlling the compressor to start, and entering an oil return adjusting step, wherein the oil return adjusting step comprises the following steps:

The opening degree of the electronic expansion valve is adjusted and increased by 5 percent; and after the compressor keeps running for 60 seconds, the opening degree of the electronic expansion valve is adjusted and increased by 5 percent again, and after the compressor keeps running for 60 seconds, the opening degree of the electronic expansion valve is adjusted and reduced again, and the compressor enters automatic running.

If the oil level is reported again to be too low for protection after the compressor returns oil for the second time, no matter how long the compressor runs, the fault needs to be reported, the fault is not recovered, and the compressor cannot be started again.

in some embodiments, the third predetermined time is 3 minutes to 10 minutes. Preferably 6 minutes.

In some embodiments, the compressor oil return method further comprises: and if the oil level of the compressor is judged to be lower than the preset oil level value for the third time, giving an alarm. The compressor performs oil supplement and other operations.

in some embodiments, in the oil return adjusting step, adjusting to increase the opening degree of the electronic expansion valve includes: the opening degree of the electronic expansion valve is increased by 5 to 15 percent on the basis of the original opening degree.

of course, the increase of the opening of the electronic expansion valve can be adjusted according to the actual oil return condition, which is related to the refrigerant state of the whole refrigeration system and the amount of refrigerant, so as to achieve the purpose of quick oil return without other protection.

Preferably, the opening degree is increased by 5% from the original opening degree of the electronic expansion valve. For example: the original opening degree is 40%, and the adjusted opening degree is 45%.

In some embodiments, in the oil return adjusting step, adjusting to decrease the opening degree of the electronic expansion valve includes: the opening degree of the electronic expansion valve is adjusted to the opening degree when not increased.

in some embodiments, in the oil return adjusting step, adjusting to decrease the opening degree of the electronic expansion valve includes: and determining the opening degree of the electronic expansion valve according to the unit operation parameters.

the unit operation parameters are unit operation parameters related to the compressor, and the unit operation parameters comprise target water temperature, compressor load and the like. The opening degree of the electronic expansion valve is adjusted to enable the unit to be in a safe and stable state capable of guaranteeing capacity.

As shown in fig. 1, some embodiments of the present disclosure provide a refrigeration system including a compressor 1, a condenser 2, an electronic expansion valve 3, and an evaporator 4, which are connected in series. The refrigeration system adopts the compressor oil return method in the above embodiment to control the oil return of the compressor 1.

the refrigeration system further includes a sensor and a controller; the controller is electrically connected with the sensor, the compressor 1 and the electronic expansion valve 3.

The sensor is used to detect the oil level of the compressor 1 and to send a signal to the controller.

The controller is used for receiving signals sent by the sensor, and the controller is configured to control the start and stop of the compressor 1 and control the opening degree of the electronic expansion valve 3.

in some embodiments, the compressor is preset with a first preset time, a second preset time, a third preset time, a fourth preset time, and/or the like.

In some embodiments, a preset oil level value is preset in the controller, the sensor sends an oil level signal of the compressor to the controller in real time, the controller compares the oil level signal with the preset oil level value, whether the oil level of the compressor is lower than the preset oil level value is judged, and the oil level of the compressor is judged to be lower than the preset oil level value for the second time.

in some embodiments, the sensor comprises a proximity switch configured to send a signal to the controller when the oil level of the compressor 1 is below a preset oil level value.

Optionally, the proximity switch is an oil level alarm, and when the oil level drops to the protection height, the proximity switch is turned off and feeds back a signal to the controller, and the controller controls the compressor to shut down.

in some embodiments, a compressor oil return method employed in a refrigeration system, comprising:

The controller detects the oil level of the compressor through the sensor and judges whether the compressor is lack of oil or not.

And when the controller judges that the oil level of the compressor is lower than the preset oil level value, controlling the compressor to shut down.

If the controller judges that the oil level of the compressor is under protection for the first time, the fault is not reported, and the compressor is forced to start.

the controller regulates to increase the opening degree of the electronic expansion valve, for example: the original opening degree of the electronic expansion valve is increased by 5 percent.

And after the controller adjusts and increases the opening degree of the electronic expansion valve, the time for the compressor to keep running reaches a first preset time, and then the controller adjusts and decreases the opening degree of the electronic expansion valve.

The first preset interval may be selected to be 60 seconds. I.e. the compressor is kept running for 60 seconds, the opening degree of the electronic expansion valve is adjusted to be reduced.

The opening degree of the electronic expansion valve can be restored to the original opening degree by adjusting and reducing the opening degree of the electronic expansion valve, or the opening degree of the electronic expansion valve can be automatically adjusted according to related parameters of the refrigeration system.

In some embodiments, the controller controls the electronic expansion valve to close when the compressor is shut down, so that before starting the compressor, the electronic expansion valve is opened at an original opening degree, the electronic expansion valve is stopped for a fourth preset time, optionally, the compressor is started after the fourth preset time is 30 seconds, the compressor is operated for a second preset time, optionally, the second preset time is 2 minutes, and then the opening degree of the electronic expansion valve is increased by adjusting.

Some embodiments provide an air conditioner including the refrigeration system described above.

in the description of the present invention, it should be understood that the terms "first", "second", "third", etc. are used to define the components, and are used only for the convenience of distinguishing the components, and if not otherwise stated, the terms have no special meaning, and thus, should not be construed as limiting the scope of the present invention.

furthermore, the technical features of one embodiment may be combined with one or more other embodiments advantageously without explicit negatives.

finally, it should be noted that the above examples are only used to illustrate the technical solutions of the present invention and not to limit the same; although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art will understand that: modifications to the specific embodiments of the invention or equivalent substitutions for parts of the technical features may be made; without departing from the spirit of the present invention, it is intended to cover all aspects of the invention as defined by the appended claims.