Constant pressure spraying apparatus, constant pressure spraying method, and monitor

Abstract

The present application provides a constant pressure spraying device, a constant pressure spraying method and a monitor. The constant pressure spraying device comprises a liquid storage cylinder, a spraying pipe, a pump, a filter and a controller. The controller is adapted to adjust the frequency of the pump to adjust the spraying pressure of the liquid, determine the filter element coefficient of the filter element of the filter, the filter element coefficient being related to the frequency of the pump and the spraying pressure of the liquid, and issue a prompt message according to the filter element coefficient of the filter element. The constant pressure spraying method comprises the steps of adjusting the frequency of the pump to adjust the spraying pressure of the liquid, determining the filter element coefficient of the filter element of the filter, the filter element coefficient being related to the frequency of the pump and the spraying pressure of the liquid, and issuing a prompt message according to the filter element coefficient of the filter element. The monitor comprises an acquirer, a controller and a prompter.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of wet process, in particular to a constant pressure spraying device, a constant pressure spraying method and a monitor. BACKGROUND

[0002] Chemical spraying is a common treatment method of wet process equipment. The chemical liquid is sprayed to the treatment surface of the workpiece to be treated through the nozzle to achieve the purpose of cleaning, etching, oil removal, rust removal, etc. The liquid is usually stored in a liquid storage tank and delivered to the spraying pipe by a pump. After spraying, it flows back to the liquid storage tank.

[0003] In order to improve the uniformity of spraying, it is necessary to maintain the constant spraying pressure of the liquid. In the existing constant pressure spraying device, a filter is usually installed to filter the liquid to ensure that the spraying liquid is clean and free of foreign matter, which may cause the nozzle to be blocked. However, the spraying pressure of the liquid changes with the degree of blockage of the filter element, affecting the uniformity of spraying. SUMMARY

[0004] In order to solve the technical problems existing in the prior art, the embodiments of the present application provide a constant pressure spraying device, a constant pressure spraying method and a monitor. By determining the blockage of the filter element, the filter element can be replaced in time, thereby achieving the purpose of maintaining constant spraying pressure and improving the uniformity of spraying.

[0005] According to one aspect of the present application, a constant pressure spraying device is provided. The constant pressure spraying device comprises a liquid storage tank for storing liquid; a spraying pipe for spraying the liquid to the surface of a workpiece to be treated; a pump for pumping the liquid from the liquid storage tank to the spraying pipe; a filter between the pump and the spraying pipe, the filter having a filter element for filtering the liquid; and a controller adapted to: adjust the frequency of the pump to adjust the spraying pressure of the liquid; determine a filter element coefficient of the filter element, the filter element coefficient being related to the frequency of the pump and the spraying pressure of the liquid; and issue a prompt message according to the filter element coefficient of the filter element.

[0006] Optionally, the filter element coefficient of the filter element of the filter is determined based on the following formula:

[0007]

[0008] Wherein, α represents the filter element coefficient of the filter element, f represents the frequency of the pump, and P represents the spraying pressure of the liquid.

[0009] Optionally, the controller comprises a prompter, and the prompt message is issued through the prompter when the filter element coefficient of the filter element reaches a predetermined filter element coefficient.

[0010] Optionally, the controller further comprises a frequency converter through which the frequency of the pump is determined.

[0011] Optionally, the controller further comprises a pressure gauge through which the spraying pressure of the liquid is determined.

[0012] Optionally, the controller further comprises a memory adapted to store a predetermined filter coefficient of the filter element.

[0013] Optionally, the predetermined filter coefficient is related to a filter coefficient of a predetermined time before the filter element is completely clogged.

[0014] Optionally, the controller further comprises a comparator adapted to compare the filter coefficient of the filter element with the predetermined filter coefficient of the filter element.

[0015] According to another aspect of the present application, there is provided a constant pressure spraying method. The constant pressure spraying method comprises the steps of adjusting a frequency of a pump to adjust a spraying pressure of a liquid; determining a filter coefficient of a filter element of a filter, the filter coefficient being related to the frequency of the pump and the spraying pressure of the liquid; and issuing a prompt message according to the filter coefficient of the filter element.

[0016] Optionally, the filter coefficient of the filter element of the filter is determined based on the following equation:

[0017]

[0018] wherein a represents the filter coefficient of the filter element, f represents the frequency of the pump, and P represents the spraying pressure of the liquid.

[0019] Optionally, the prompt message is issued when the filter coefficient of the filter element reaches a predetermined filter coefficient.

[0020] Optionally, the frequency of the pump is determined through a frequency converter.

[0021] Optionally, the spraying pressure of the liquid is determined through a pressure gauge.

[0022] Optionally, the predetermined filter coefficient of the filter element is stored through a memory.

[0023] Optionally, the predetermined filter coefficient is related to a filter coefficient of a predetermined time before the filter element is completely clogged.

[0024] Optionally, the filter coefficient of the filter element is compared with the predetermined filter coefficient of the filter element through a comparator.

[0025] According to another aspect of the present application, a monitor is provided. The monitor comprises: an obtainer adapted to obtain a frequency of a pump and a spray pressure of a liquid, the pump being used to draw the liquid; a controller adapted to: adjust the frequency of the pump to adjust the spray pressure of the liquid; determine a filter factor of a filter element of the filter element, the filter factor being related to the frequency of the pump and the spray pressure of the liquid; and issue a prompt message according to the filter factor of the filter element; and a prompter adapted to issue the prompt message.

[0026] Optionally, the filter factor of the filter element of the filter is determined based on the following formula:

[0027]

[0028] wherein a represents the filter factor of the filter element, f represents the frequency of the pump, and P represents the spray pressure of the liquid.

[0029] Compared with the prior art, the technical scheme of the embodiment of the present application has the following beneficial effects:

[0030] In the embodiment of the present application, the controller is adapted to: adjust the frequency of the pump to adjust the spray pressure of the liquid; determine the filter factor of the filter element of the filter, the filter factor being related to the frequency of the pump and the spray pressure of the liquid; and issue a prompt message according to the filter factor of the filter element, to determine whether the filter element needs to be replaced. By predicting the clogging condition of the filter element of the filter, the filter element of the filter can be replaced in time, so as to maintain a constant spray pressure and improve the uniformity of the spray.

[0031] Further, the filter factor of the filter element of the filter is determined based on the following formula:

[0032]

[0033] wherein a represents the filter factor of the filter element, f represents the frequency of the pump, and P represents the spray pressure of the liquid. Thus, the filter factor of the filter element is calculated in real time by the frequency of the pump and the spray pressure of the liquid, and the calculation is simple and the prediction accuracy is high.

[0034] Further, the controller comprises a prompter, and when the filter factor of the filter element reaches a predetermined filter factor, the prompter issues a prompt message. Thus, by setting an upper limit of the filter factor to alarm to replace the filter element, the loss caused by the clogging of the filter element can be effectively prevented, the waste of the filter element can be reduced, and each filter element can be used up. BRIEF DESCRIPTION OF DRAWINGS

[0035] Other features and advantages of the present application will be better understood from the following detailed description taken in conjunction with the accompanying drawings, in which like reference numerals designate identical or similar elements in which:

[0036] Figure 1 A structural diagram of a constant pressure spraying device according to an embodiment of the present application is shown;

[0037] Figure 2 A flow chart of a constant pressure spraying method according to an embodiment of the present application is shown; and

[0038] Figure 3 A structural block diagram of a monitor according to an embodiment of the present application is shown. DETAILED DESCRIPTION

[0039] The implementation and use of the embodiments will now be discussed in detail with reference to the figures. It should be appreciated that the specific embodiments discussed are merely illustrative of specific ways to implement and use the application and do not limit the scope of the application. In describing the various components of the figures, directional references such as upper, lower, top, bottom, etc. are not absolute but are relative. These directional references are appropriate when the various components are arranged as shown in the figures, but change when the position of the various components in the figures is changed.

[0040] In order to improve the uniformity of the spraying, it is necessary to maintain a constant spraying pressure of the liquid. The spraying pressure and flow rate are the main parameters to control the spraying effect, and the pressure and flow rate can be changed by adjusting the ball valve. Processes that require precise control can use a frequency converter to change the output pressure of the pump to change the spraying pressure and flow rate. However, as the filter element of the filter increases in blocking foreign matter, the output pressure of the pump will decrease. To maintain a constant pressure, a digital pressure gauge needs to be installed behind the filter to return to the control system. The control system (such as a PLC) can dynamically adjust the frequency of the frequency converter to achieve a stable spraying pressure.

[0041] The constant pressure control method can ensure that the spraying pressure does not change with the degree of filter clogging during the production process. When the spraying pressure decreases, the spraying pressure is maintained by increasing the frequency of the pump. However, as the degree of filter clogging becomes severe, the frequency of the pump reaches the upper limit of the working frequency, and the spraying pressure will decrease, at which time the filter element needs to be replaced immediately to prevent the spraying pressure from decreasing to cause the product to be out of specification and scrapped. When the frequency of the pump reaches the upper limit of the working frequency, it can also cause the current to be too high and stop working. If not discovered in time, it can cause a large amount of product to be scrapped.

[0042] Existing methods mainly include: 1. Replacing filter elements at fixed intervals in advance, which can prevent problems during production, but it results in some filter element waste. Sometimes the filter elements can still be used, and replacing them in advance increases the number of filter elements used, increasing costs; 2. Replacing filter elements according to the pump frequency, setting an upper limit for frequency. The problem is that the pump frequency varies when the set pressure value is different, making it difficult to accurately predict the replacement time. Similarly, replacing too early can lead to waste, or replacing too late can fail to prevent problems from occurring.

[0043] Therefore, embodiments of the present invention provide a constant pressure spraying device and a constant pressure spraying method. The constant pressure spraying device includes: a storage tank for storing liquid; a spray pipe for spraying the liquid onto the surface of a workpiece to be treated; a pump for drawing the liquid from the storage tank into the spray pipe; a filter located between the pump and the spray pipe, the filter having a filter element for filtering the liquid; and a controller adapted to: adjust the frequency of the pump to adjust the spraying pressure of the liquid; determine the filter element coefficient of the filter, the filter element coefficient being related to the pump frequency and the spraying pressure of the liquid; and issue a prompt message based on the filter element coefficient to determine whether the filter element needs to be replaced.

[0044] By predicting the clogging status of the filter element, the filter element can be replaced in a timely manner, thereby maintaining a constant spray pressure and improving the uniformity of the spray.

[0045] Figure 1 A schematic diagram of a constant pressure spraying device 100 according to an embodiment of the present invention is shown. Specifically, as... Figure 1 As shown, the constant pressure spraying device 100 includes: a liquid storage tank 10, a pump 20, a filter 30, a spray pipe 40, and a controller. The liquid storage tank 10 is used to store liquids, such as pharmaceutical solutions, and the pump 20 is used to draw liquids from the liquid storage tank 10 into the spray pipe 40. The filter 30 is located between the pump 20 and the spray pipe 40, and the filter 30 has a filter element 31 for filtering the liquid. The spray pipe 40 is used to spray liquids onto the surface of the workpiece to be treated. The spray pipe 40 may include an upper spray pipe 41 and a lower spray pipe 42. The workpiece to be treated can be placed between the upper spray pipe 41 and the lower spray pipe 42. The upper spray pipe 41 and the lower spray pipe 42 are each provided with multiple nozzles. Liquid is sprayed onto the upper and lower surfaces of the workpiece to be treated through the nozzles for cleaning, etching, degreasing, or rust removal.

[0046] The controller is configured to adjust the frequency of the pump 20 to adjust the spraying pressure of the liquid. The controller is further configured to determine a filter core coefficient of the filter core 31 of the filter 30, the filter core coefficient being related to the frequency of the pump 20 and the spraying pressure of the liquid, and to issue a prompt message according to the filter core coefficient of the filter core 31 to determine whether the filter core 31 needs to be replaced.

[0047] In some embodiments, the filter core coefficient of the filter core 31 of the filter 30 is determined based on the following formula:

[0048]

[0049] wherein a represents the filter core coefficient of the filter core 31, f represents the frequency of the pump 20, and P represents the spraying pressure of the liquid.

[0050] In some embodiments, the controller comprises a prompter, and when the filter core coefficient of the filter core 31 reaches a predetermined filter core coefficient, the prompter issues a prompt message. The prompt message can be in the form of sound, text, video, or a combination of sound, text, and video to prompt the user.

[0051] In some embodiments, the controller further comprises a frequency converter installed on the pump 20, and the frequency of the pump 20 is determined by the frequency converter.

[0052] In some embodiments, the controller further comprises a pressure gauge, and the spraying pressure of the liquid is determined by the pressure gauge.

[0053] In some embodiments, the controller further comprises a memory adapted to store a predetermined filter core coefficient of the filter core 30. The predetermined filter core coefficient is related to the filter core coefficient at a predetermined time before the filter core is completely blocked.

[0054] In some embodiments, the controller further comprises a comparator adapted to compare the filter core coefficient of the filter core 31 with the predetermined filter core coefficient of the filter core 31.

[0055] In some embodiments, a pressure gauge 50 is provided between the filter 30 and the spraying pipe 40 at the outlet of the filter 30 to measure the spraying pressure of the liquid. The pressure gauge 50 is connected to the controller, and the measured value of the spraying pressure of the liquid is transmitted to the controller to monitor the spraying pressure of the liquid in real time.

[0056] In some embodiments, a ball valve 60 is provided between the filter 30 and the spraying pipe 40 at the inlet of the spraying pipe 40 to adjust the spraying pressure and flow of the liquid.

[0057] The filter core coefficient of the filter core is calculated in real time by the controller, an upper limit of the filter core coefficient is set to replace the filter core, and accurate prediction can be achieved. For example, it takes about 4 hours to produce a batch, and it is assumed that the filter core is predicted to be blocked 5 hours in advance, and the filter core is replaced before the production of a batch to prevent pump stoppage during production and cause scrap. By recording the filter core coefficient of the filter core, the filter core coefficient of the filter core 5 hours before the filter core is completely blocked is found, and the filter core coefficient is used as a predetermined filter core coefficient. When the calculated filter core coefficient reaches the predetermined filter core coefficient, a prompt message is sent. In this way, the success rate of prediction is more than 90%, and the filter core consumption is reduced by 20%.

[0058] According to another aspect of the present application, a constant pressure spraying method is provided, including the steps of: adjusting the frequency of a pump to adjust the spraying pressure of a liquid; determining a filter core coefficient of a filter core of a filter, the filter core coefficient being related to the frequency of the pump and the spraying pressure of the liquid; and sending a prompt message according to the filter core coefficient of the filter core to determine whether the filter core needs to be replaced.

[0059] In some embodiments, the constant pressure spraying method further includes the steps of: pumping the liquid by the pump; and spraying the liquid to the surface of a workpiece to be processed.

[0060] In some embodiments, the filter core coefficient of the filter core of the filter is determined based on the following formula:

[0061]

[0062] wherein a represents the filter core coefficient of the filter core, f represents the frequency of the pump, and P represents the spraying pressure of the liquid.

[0063] In some embodiments, the prompt message is sent when the filter core coefficient of the filter core reaches a predetermined filter core coefficient.

[0064] In some embodiments, the frequency of the pump is determined by a frequency converter.

[0065] In some embodiments, the spraying pressure of the liquid is determined by a pressure gauge.

[0066] In some embodiments, the predetermined filter core coefficient of the filter core is stored by a memory.

[0067] In some embodiments, the predetermined filter core coefficient is related to the filter core coefficient at a predetermined time before the filter core is completely blocked.

[0068] In some embodiments, the filter core coefficient of the filter core is compared with the predetermined filter core coefficient of the filter core by a comparator.

[0069] In some embodiments, as Figure 2As shown, the constant pressure spraying method comprises the steps of:

[0070] S11, obtaining the frequency of the pump through the frequency converter;

[0071] S13, obtaining the spraying pressure of the liquid through the pressure gauge;

[0072] S15, calculating the filter element coefficient of the filter element through the controller; and

[0073] S17, issuing a prompt message according to the filter element coefficient of the filter element.

[0074] In actual process, to accurately predict the service life of the filter element, different upper limits under different spraying pressure settings should be ensured, and a fixed pressure or frequency cannot be used for prediction. Under the same output pressure, a new filter element needs a lower frequency to achieve the set spraying pressure. As long as the relationship between the spraying pressure of the liquid and the frequency of the pump is found, the service condition of the filter element can be predicted.

[0075] The output pressure of the pump is proportional to the square of the rotating speed, that is, P2 / P1=(N2 / N1) 2 , wherein P1 and P2 represent the output pressure of the pump, and N1 and N2 represent the rotating speed of the pump. Since the rotating speed of the pump is proportional to the frequency, the output pressure of the pump is proportional to the square of the frequency.

[0076] If there is no filter, the ratio of the output pressure of the pump to the square of the frequency is a constant; here, because there is a filter, the constant becomes a variable, which is defined as the filter element coefficient of the filter element.

[0077] When the device is normally working, the set spraying pressure of the constant pressure spraying device is changed, and the value of the frequency of the pump after the spraying pressure reaches the set value is recorded. Through the curve fitting method, it can be found that:

[0078] P=(f / α) 2

[0079] That is,

[0080] , wherein α represents the filter element coefficient of the filter element, f represents the frequency of the pump, and P represents the spraying pressure of the liquid.

[0081] The filter core coefficients of new and old filter cores are different. By collecting data of new and old filter cores, it can be found that the change of filter core coefficient can represent the clogging condition of the filter core. For example, by calculating the filter core coefficient of a new filter core as 1, the filter core is slowly clogged in use. In order to ensure constant pressure spraying, ensure that the spraying pressure of the liquid is constant, and improve the frequency of the pump, the filter core coefficient is gradually increased, and the filter core coefficient of the filter core is calculated in real time by the controller. When the filter core is completely clogged, the filter core coefficient is 2, at which time the filter core fails. From this time, go back to a predetermined time before, for example, 7 hours ago, and record the filter core coefficient, such as 1.4. Then use 1.4 as the predetermined filter core coefficient. When the filter core coefficient of the filter core in use reaches the predetermined filter core coefficient 1.4, a prompt information is sent to prompt the staff to replace the filter core.

[0082] According to still another aspect of the present application, a monitor is provided for the constant pressure spraying device and the constant pressure spraying method as described above. As shown in Figure 3 the monitor 200 comprises: an obtainer 210 adapted to obtain the frequency of a pump for pumping the liquid and the spraying pressure of the liquid; a controller 220 adapted to: adjust the frequency of the pump to adjust the spraying pressure of the liquid; determine a filter core coefficient of the filter core of the filter, the filter core coefficient being related to the frequency of the pump and the spraying pressure of the liquid; and send a prompt information according to the filter core coefficient of the filter core to determine whether the filter core needs to be replaced; and a prompter 230 adapted to send the prompt information based on the instruction of the controller 220.

[0083] In some embodiments, the filter core coefficient of the filter core of the filter is determined based on the following formula:

[0084]

[0085] wherein a represents the filter core coefficient of the filter core, f represents the frequency of the pump, and P represents the spraying pressure of the liquid.

[0086] In some embodiments, the monitor 200 further comprises a frequency converter 240 through which the frequency of the pump is determined.

[0087] In some embodiments, the monitor 200 further comprises a pressure gauge 250 through which the spraying pressure of the liquid is determined, and the pressure gauge 250 can adopt the pressure gauge 50 in Figure 1

[0088] In some embodiments, the monitor 200 further comprises a memory 260 adapted to store a predetermined filter core coefficient of the filter core.

[0089] ​In some embodiments, the monitor 200 further comprises a comparator 270 adapted to compare a filter coefficient of the filter cartridge with a predetermined filter coefficient of the filter cartridge.

[0090] In embodiments of the present application, the controller is adapted to: adjust the frequency of the pump to adjust the spray pressure of the liquid; determine a filter coefficient of the filter cartridge of the filter, the filter coefficient being related to the frequency of the pump and the spray pressure of the liquid; and issue a prompt according to the filter coefficient of the filter cartridge to determine whether the filter cartridge needs to be replaced. By predicting the clogging of the filter cartridge of the filter, the filter cartridge of the filter can be replaced in time, so as to maintain a constant spray pressure and improve the uniformity of the spray.

[0091] Further, the filter coefficient of the filter cartridge of the filter is determined based on the following formula:

[0092]

[0093] wherein a represents the filter coefficient of the filter cartridge, f represents the frequency of the pump, and P represents the spray pressure of the liquid. Thus, the filter coefficient of the filter cartridge is calculated in real time by the frequency of the pump and the spray pressure of the liquid, which is simple to calculate and has high prediction accuracy.

[0094] Further, the controller comprises a prompter, and when the filter coefficient of the filter cartridge reaches a predetermined filter coefficient, a prompt is issued by the prompter. Thus, by setting an upper limit of the coefficient to alarm to replace the filter cartridge, the loss caused by the clogging of the filter cartridge can be effectively prevented, the waste of the filter cartridge can be reduced, and each filter cartridge can be used up.

[0095] The technical content and technical features of the present application have been disclosed above, but it can be understood that, under the creative idea of the present application, those skilled in the art can make various changes and improvements to the disclosed concepts, but all of them belong to the protection scope of the present application. The above description of the embodiments is illustrative rather than restrictive, and the protection scope of the present application is determined by the claims.

Claims

1. A constant pressure shower apparatus, characterised in that, The method comprises the steps of: adjusting the frequency of a pump to adjust the spraying pressure of a liquid; determining a filter coefficient of a filter core of the filter, the filter coefficient being related to the frequency of the pump and the spraying pressure of the liquid; determining a predetermined filter coefficient of the filter core of the filter, the predetermined filter coefficient being related to a filter coefficient at a predetermined time before the filter core is completely blocked; comparing the filter coefficient of the filter core with the predetermined filter coefficient of the filter core, and issuing a prompt information when the filter coefficient of the filter core reaches the predetermined filter coefficient. The filter coefficient of the filter core of the filter is determined based on the following formula: wherein a represents the filter coefficient of the filter core, f represents the frequency of the pump, and P represents the spraying pressure of the liquid. The controller comprises a prompter, and the prompt information is issued through the prompter when the filter coefficient of the filter core reaches the predetermined filter coefficient. The controller further comprises a frequency converter through which the frequency of the pump is determined. The controller further comprises a pressure gauge through which the spraying pressure of the liquid is determined. The controller further comprises a memory adapted to store the predetermined filter coefficient of the filter core. The controller further comprises a comparator adapted to compare the filter coefficient of the filter core with the predetermined filter coefficient of the filter core. The method comprises the steps of:

2. The constant pressure shower apparatus of claim 1, wherein, adjusting the frequency of a pump to adjust the spraying pressure of a liquid; 3. The constant pressure shower apparatus of claim 2, wherein, determining a filter coefficient of a filter core of the filter, the filter coefficient being related to the frequency of the pump and the spraying pressure of the liquid; 4. The constant pressure shower apparatus of claim 2, wherein, and 5. A constant pressure shower apparatus as claimed in any one of claims 2 to 4, wherein, determining a predetermined filter coefficient of the filter core of the filter, the predetermined filter coefficient being related to a filter coefficient at a predetermined time before the filter core is completely blocked; 6. The constant pressure shower apparatus of any one of claims 2 to 4, wherein, comparing the filter coefficient of the filter core with the predetermined filter coefficient of the filter core, and issuing a prompt information when the filter coefficient of the filter core reaches the predetermined filter coefficient.

7. A constant pressure showering method characterised in that, The filter coefficient of the filter core of the filter is determined based on the following formula: wherein a represents the filter coefficient of the filter core, f represents the frequency of the pump, and P represents the spraying pressure of the liquid. The prompt information is issued through a prompter when the filter coefficient of the filter core reaches the predetermined filter coefficient. The frequency of the pump is determined through a frequency converter. The spraying pressure of the liquid is determined through a pressure gauge. The predetermined filter coefficient of the filter core is stored through a memory. The filter coefficient of the filter core is compared with the predetermined filter coefficient of the filter core through a comparator. The method comprises the steps of:

8. The constant pressure showering method of claim 7, wherein, obtaining the frequency of a pump and the spraying pressure of a liquid when the pump is running, the pump being used to extract the liquid; 9. The constant pressure showering method of claim 8, wherein, adjusting the frequency of the pump to adjust the spraying pressure of the liquid; 10. The constant pressure showering method of claim 8, wherein, ​ 11. The constant pressure showering method of any of claims 8-10, wherein, ​ 12. The constant pressure shower method of any one of claims 8 to 10, wherein, ​ 13. A monitor, characterized in that ​ ​ ​ ​ determining a filter core coefficient of a filter core of the filter, the filter core coefficient being related to a frequency of the pump and a spray pressure of the liquid; determining a predetermined filter core coefficient of the filter core of the filter, the predetermined filter core coefficient being related to a filter core coefficient at a predetermined time before the filter core is completely clogged; comparing the filter core coefficient of the filter core with the predetermined filter core coefficient of the filter core, and issuing a prompt information when the filter core coefficient of the filter core reaches the predetermined filter core coefficient; and a prompter adapted to issue the prompt information; wherein the filter core coefficient of the filter core of the filter is determined based on the following formula: wherein a represents the filter core coefficient of the filter core, f represents the frequency of the pump, and P represents the spray pressure of the liquid.

Images