Self-cleaning method of surface cleaning machine

Abstract

The present invention belongs to the technical field of cleaning equipment, and specifically provides a self-cleaning method of a surface cleaning machine, including a process of cleaning a sewage suction channel: turning on a liquid supply device, spraying cleaning liquid into a cleaning roller or a cleaning tank, turning on a drive motor, driving the cleaning roller to rotate, turning on the sewage suction motor and operating at a first power P1, a control system obtaining an output flow of the liquid supply device, controlling a PWM duty cycle of the sewage suction motor according to the output flow, sucking the cleaning liquid into the sewage suction channel through a sewage suction port, so that the cleaning liquid in the sewage suction channel collides with each other during an up and down fluctuation process to generate a shock wave on the inner wall of the sewage suction channel, wherein the maximum amplitude of the shock wave is no greater than the height of the sewage suction channel, so as to continuously flush the inner wall of the sewage suction channel and the sewage suction port, and the short-term impact force in the small space of the sewage suction channel is large, so that the connection of the sewage suction channel can also be impacted, there is no cleaning dead angle, resources are saved, and the cleaning efficiency is high and the cleaning effect is good.

Description

Technical Field

[0001] The invention belongs to the technical field of cleaning equipment, and specifically provides a self-cleaning method of a surface cleaning machine. Background Art

[0002] As people's living standards improve, a variety of surface cleaning machines have gradually entered their daily lives, providing great convenience for cleaning house floors. An existing surface cleaning machine includes a body and a hinged floor brush assembly, a dirt suction module, and a water supply module. The water supply module includes a water tank and a water spray structure. The dirt suction module includes a dirt suction motor, a dirt suction channel, and a dirt storage bucket. The dirt suction motor, dirt storage bucket, and water tank are all mounted on the body. A dirt suction port and a dirt suction channel connected to the port are provided within the cleaning assembly. The cleaning assembly includes a cleaning roller. With the assistance of the cleaning roller, the dirt suction motor draws dirt from the cleaning roller and the floor through the port and channel into the dirt storage bucket mounted on the body. After the surface cleaning machine cleans the surface to be cleaned, the cleaning roller, dirt storage bucket, dirt suction port, and dirt suction channel become dirty. To facilitate self-cleaning of the surface cleaning machine, an increasing number of surface cleaning machines are also equipped with a cleaning assembly. When the cleaning roller needs to be cleaned, the surface cleaning machine is placed in the cleaning tank of the cleaning assembly, and the rotating cleaning roller performs self-cleaning. Although existing surface cleaning machines can use cleaning components to complete self-cleaning of the cleaning roller, they are still unable to automatically clean the suction port and suction channel. Over time, bacteria will breed and odor will be emitted, giving customers a bad experience.

[0003] The patent application with application number CN202210334684.3 and titled “Self-cleaning method and cleaning device for cleaning equipment” discloses a self-cleaning method, comprising: starting the main motor to work at a first power to suck in the cleaning liquid through the suction nozzle and sucking at least part of the cleaning liquid from the first end to the second end; shutting down the main motor so that the cleaning liquid in the recovery pipe flows back from the second end to the first end, so as to clean the recovery pipe by the reciprocating flow of the cleaning liquid. Although this application can effectively rinse away the dirt attached to the inner wall of the recovery pipe by starting the main motor to make the cleaning liquid flow back and forth in the recovery pipe, thereby improving the self-cleaning effect of the cleaning equipment and reducing the amount of cleaning liquid used. In reality, the dirt bucket of a floor scrubber is usually placed on the machine body. Since the recovery pipe generally includes a suction hose and a suction pipe connected to the suction hose and placed inside the bucket, sewage or dirt must pass through the suction port, suction hose, and suction pipe to enter the dirt bucket. The path is long and difficult to clean. In addition, the dirt bucket is usually detachable and can be washed by hand, while part of the suction hose is connected to the suction pipe in the bucket, and the other part is placed inside the floor brush and cannot be detached, making it difficult to clean. If it is set to be detachable, improper installation by the customer will affect the suction effect. In addition, since soft objects such as dirt or hair can easily stick to the wall, the suction hose must have a certain degree of flexibility so that it can move with the movement of the machine body during the detergent operation. Therefore, during the automatic cleaning process, the main motor is only adjusted to allow the cleaning liquid to flow repeatedly in the sewage suction hose. Under the action of gravity and the lifting of the main motor, the cleaning liquid is likely to form an inertial upward vortex and an inertial downward direct current, which has a poor cleaning effect on the sewage suction hose. In addition, the inertial flow can easily pass over the connection between the sewage suction hose and the sewage suction pipe, which is not conducive to the cleaning of the connection and cannot achieve the purpose of completely and automatically cleaning the sewage suction channel. Summary of the Invention

[0004] In order to solve the above problems in the prior art, the present application provides a self-cleaning method for a surface cleaning machine, which controls the PWM duty cycle of the sewage suction motor according to the output flow, thereby generating an impact flow, which has a better effect on cleaning the sewage suction channel.

[0005] A self-cleaning method for a surface cleaning machine includes a process of cleaning a dirt suction channel:

[0006] The liquid supply device is turned on, and cleaning liquid is sprayed onto the cleaning roller or the cleaning tank. The drive motor is turned on, and the drive motor drives the cleaning roller to rotate. The sewage suction motor is turned on and operates at a first power P1 to suck the cleaning liquid into the sewage suction channel through the sewage suction port, and drives the cleaning liquid to form an up and down flow in the sewage suction channel to continuously flush the inner wall of the sewage suction channel and the sewage suction port; after the liquid supply device is turned on, the control system obtains the output flow of the liquid supply device, and controls the PWM duty cycle of the sewage suction motor according to the output flow, so that the cleaning liquid in the sewage suction channel collides with each other during the up and down fluctuation process to generate a shock wave on the inner wall, and the maximum amplitude of the shock wave is not greater than the height of the sewage suction channel.

[0007] Furthermore, if the output flow rate Q of the liquid supply device is a fixed value within the range of 25ml / min-65ml / min, the sewage suction motor is controlled to operate at a fixed value within the range of 25% to 60% of the PWM duty cycle; or, if the output flow rate Q of the liquid supply device is a fixed value within the range of 25ml / min-65ml / min, the sewage suction motor is controlled to operate at a dynamically changing value within the range of 25% to 60% of the PWM duty cycle.

[0008] Furthermore, if the output flow rate Q of the liquid supply device is a dynamically changing value within the range of 25ml / min-65ml / min, the sewage suction motor is controlled to operate with a fixed value of a PWM duty cycle within the range of 25% to 60%; or, if the output flow rate Q of the liquid supply device is a dynamically changing value within the range of 25ml / min-65ml / min, the sewage suction motor is controlled to operate with a dynamically changing value of a PWM duty cycle within the range of 25% to 60%.

[0009] Furthermore, the driving motor is turned on first to drive the cleaning roller to rotate, and then the sewage suction motor and the liquid supply device are turned on and run according to the preset value. The duration of the sewage suction channel cleaning process is T, 20s≤T≤120s.

[0010] Furthermore, the driving motor is first turned on to drive the cleaning roller to rotate, and then the sewage suction motor and the liquid supply device are turned on and run according to preset values. The process of cleaning the sewage suction channel includes n sub-cycles, where n≥1.

[0011] Furthermore, a dirt detection sensor is provided on the dirt suction channel, and the number n of sub-cycles is determined by the dirt level detected by the dirt sensor; alternatively, the number n of sub-cycles is determined by a predetermined duration set in the control system, and the maximum amplitude of the shock wave in each sub-cycle is not the same.

[0012] Furthermore, the sewage suction channel includes a sewage suction pipe arranged in the sewage bucket and a sewage suction hose arranged between the floor brush and the body. One end of the sewage suction hose is connected to the sewage suction pipe, and the other end of the sewage suction hose is connected and communicated with the sewage suction port in the roller brush chamber. The height between the top of the sewage suction pipe and the air vent of the sewage bucket is H. The automatic cleaning method is also provided with a sewage suction process. During sewage suction, the maximum height to which the sewage suction motor drives the cleaning liquid to rise in the sewage bucket is h, where h≤0.5H.

[0013] Furthermore, the automatic cleaning method also includes a sewage suction process: the driving motor continues to drive the cleaning roller to rotate, the liquid supply device stops supplying liquid, and the sewage suction motor operates at a second power P2 to suck the generated dirt or dirty liquid into the sewage bucket through the sewage suction port and the sewage suction channel. The operation time is t, 20s≤t≤30s, where P1<P2. During the sewage suction process, the maximum height h of the cleaning liquid when it is sprayed out from the sewage suction pipe satisfies 0.2H≤h≤0.5H.

[0014] Furthermore, the sewage suction process is interspersed with the process of cleaning the sewage suction channel; or, the sewage suction process is arranged after cleaning the sewage suction channel; or, the sewage suction process is arranged before cleaning the sewage suction channel; or, the sewage suction process is arranged before and after cleaning the sewage suction channel.

[0015] Furthermore, if the output flow rate Q of the liquid supply device is a fixed value of 35ml / min or 50ml / min, the sewage suction motor is controlled to cycle at any two fixed values ​​within the PWM duty cycle range of 25% to 60%; or, if the output flow rate Q of the liquid supply device is a fixed value of 35ml / min or 50ml / min, the sewage suction motor is controlled to cycle at any two dynamically changing values ​​within the PWM duty cycle range of 25% to 60%.

[0016] The self-cleaning method of the surface cleaning machine described above in this application has at least the following beneficial effects:

[0017] 1. After the liquid supply device is turned on, the control system obtains the output flow of the liquid supply device, and controls the PWM duty cycle of the sewage suction motor according to the output flow, so that the cleaning liquid in the sewage suction channel collides with each other during the up and down fluctuation process to generate a shock wave on the inner wall. The maximum amplitude of the shock wave is not greater than the height of the sewage suction channel. This control method changes the flow rate or direction of the cleaning liquid in the sewage suction channel, so that the cleaning liquid in the sewage suction channel no longer flows along the inner wall, but is sprayed toward the inner wall of the sewage suction channel, thereby flushing the inner wall of the sewage suction channel. In particular, the impact force of this shock wave is large, which can easily wash away dirt or hair stuck on the inner wall, causing it to flow with the cleaning liquid and then enter the sewage suction channel. Moreover, the maximum amplitude of the shock wave of the cleaning liquid is controlled to be no greater than the height of the sewage suction channel. Since the liquid flow formed by the cleaning liquid is non-directional and the short-term impact force in a small space is large, and the cleaning liquid can be concentrated in the sewage suction channel to repeatedly hit the inner wall to flush it, it can also produce impact on the connection of the sewage suction channel, leaving no dead corners for cleaning, saving resources, and having a good flushing effect. Therefore, this method of automatically cleaning the sewage suction channel is energy-saving, efficient, and has a good cleaning effect.

[0018] 2. The sewage suction channel includes a sewage suction pipe arranged in the sewage bucket and a sewage suction hose arranged between the floor brush and the body, one end of the sewage suction hose is connected to the sewage suction pipe, and the other end of the sewage suction hose is connected and connected to the sewage suction port in the roller brush chamber. The height between the top of the sewage suction pipe and the vent of the sewage bucket is H, and the maximum height of the cleaning liquid when the sewage suction motor drives the cleaning liquid to be sprayed out of the sewage suction pipe is h, where h≤0.5H. After the surface cleaning machine performs automatic cleaning, the dirty liquid can be driven by the sewage suction motor to enter the storage barrel from the sewage suction port and the sewage suction channel. In the process of entering, even if the dirty liquid in the sewage storage barrel is close to the highest water level line, the cleaning liquid will not impact the vent under the action of the sewage suction motor, thereby avoiding abnormalities of the sewage suction motor due to water ingress. At the same time, it can be ensured that during automatic cleaning, under the action of the sewage suction motor, not only the sewage suction pipe and the sewage suction hose can be cleaned, but the sewage suction pipe in the sewage suction barrel can also be cleaned in place. At the same time, the cleaning liquid can be controlled to form a shock wave to clean the sewage suction pipe separately and clean it, thereby realizing semi-automatic cleaning of the sewage storage barrel. During the cleaning process, it is also ensured that the sewage suction motor is not contaminated and can work normally.

[0019] 3. The automatic cleaning method also includes a sewage suction process: the drive motor continues to drive the cleaning roller to rotate, the liquid supply device stops supplying liquid, and the sewage suction motor operates at a second power P2 to suck the generated sewage or dirty liquid into the sewage tank through the sewage suction port and the sewage suction channel. The operation time is t, 20s≤t≤30s, where P1<P2. During the sewage suction process, the maximum height h of the cleaning liquid rising from the sewage suction pipe satisfies 0.2H≤h≤0.5H. This ensures that the surface cleaning machine can suck all dirty cleaning liquid or sewage into the sewage tank after cleaning the surface to be cleaned, and that no cleaning liquid enters the vent of the sewage tank during the sewage suction process, thereby preventing the sewage suction motor from being contaminated and ensuring its normal operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Some embodiments of the present application are described below with reference to the accompanying drawings, in which:

[0021] Figure 1 is a schematic diagram of the surface cleaning device of the present invention placed on a cleaning seat;

[0022] Figure 2 is a schematic diagram of the cleaning seat of the present invention;

[0023] Figure 3 It is a schematic diagram of the upward movement of cleaning liquid in the sewage suction channel when the sewage suction motor of the present invention is operating at a power lower than the rated power;

[0024] Figure 4 It is a schematic diagram of the upward movement of cleaning liquid in the sewage suction channel when the sewage suction motor of the present invention is operating at a power lower than the rated power;

[0025] Figure 5 It is a schematic diagram of the shock wave formed by the cleaning fluid when the PWM duty cycle of the sewage suction motor is adjusted according to the flow rate;

[0026] Figure 6 is a schematic diagram of the sewage tank of the present invention;

[0027] Figure 7 This is a schematic diagram of a square wave in which the PWM duty cycle of the sewage suction motor is controlled at a fixed value in Example 1;

[0028] Figure 8 Schematic diagram of a waveform in which the PWM duty cycle of the sewage suction motor is controlled to alternate between two arbitrary fixed values ​​in the second embodiment;

[0029] Figure 9 This is a schematic diagram of the shock wave formed by adjusting the water volume when the duty cycle of the sewage suction motor is fixed at 0.31;

[0030] Figure 10 This is a schematic diagram of the shock wave formed by adjusting the water volume when the duty cycle of the sewage suction motor is fixed at 0.41;

[0031] Figure 11 This is a schematic diagram of the shock wave formed by adjusting the duty cycle of the sewage suction motor while the water volume is fixed at 25ml / min.

[0032] Figure 12 This is a schematic diagram of the shock wave formed by adjusting the duty cycle of the sewage suction motor while the water volume is fixed at 45ml / min.

[0033] Figure 13 This is a schematic diagram of the shock wave formed by fixing the water volume at 65ml / min and adjusting the duty cycle of the sewage suction motor.

[0034] Description of reference numerals:

[0035] 1. Main body; 11. Water tank; 12. Sewage container; 121. Sewage suction pipe; 122. Vent; 123. Maximum water level; 13. Sewage suction motor; 14. Sewage suction channel; 141. Sewage suction hose; 15. Sewage suction port; 2. Cleaning assembly; 21. Floor brush; 22. Cover; 23. Liquid spray port; 25. Roller brush chamber; 26. Scraper; 3. Cleaning roller; 4. Cleaning seat; 41. Cleaning tank. DETAILED DESCRIPTION

[0036] It should be understood by those skilled in the art that the embodiments described below are only part of the embodiments of the present application, rather than all the embodiments of the present application, and that these embodiments are intended to explain the technical principles of the present application and are not intended to limit the scope of protection of the present application. Based on the embodiments provided in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort should still fall within the scope of protection of the present application.

[0037] It should be noted that in the description of this application, terms such as "center," "upper," "lower," "top," "bottom," "left," "right," "vertical," "horizontal," "inner," and "outer" that indicate directions or positional relationships are based on the directions or positional relationships shown in the accompanying drawings. This is merely for the convenience of description and does not indicate or imply that the device or element must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, it should not be understood as a limitation on this application. In addition, the terms "first," "second," and "third" are used for descriptive purposes only and should not be understood as indicating or implying relative importance.

[0038] Furthermore, it should be noted that, in the description of this application, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; mechanical connections, electrical connections; direct connections, indirect connections through an intermediate medium, or internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on the specific circumstances.

[0039] The cleaning liquid in the present invention can be clean water, or a mixture of clean water and detergent or other chemical cleaning agents.

[0040] The present invention provides a surface cleaning machine and a cleaning seat 4, such as Figure 1 As shown, the surface cleaning machine includes a body 1, a control system arranged in the body (not shown in the figure) and a cleaning component 2 hinged to the body 1, a liquid supply device is provided on the body 1, and the cleaning component 2 in the present invention includes a floor brush 21, a driving motor (not shown in the figure) arranged on the floor brush, a scraper 26, and a cleaning roller 3 arranged at the bottom of the floor brush 21, the floor brush 21 is provided with a roller brush cavity 25 with a front opening, and the floor brush 21 is also provided with a cover body 22 covering the roller brush cavity 25, the cleaning roller 3 is located in the roller brush cavity 25 and is covered by the cover body 22, and the cavity wall of the roller brush cavity 25 is provided with a cleaning roller 3. The surface cleaning machine is provided with a scraping bar 26, a sewage suction port 15, and a liquid spray port 23. The liquid supply device includes a water tank 11, a liquid supply pipeline, and a liquid spray port 23 provided on the floor brush 21. The sewage suction system includes a sewage suction motor 13, a sewage storage bucket 12, and a sewage suction channel 14 for connecting the sewage suction port 15 and the sewage storage bucket 12. The liquid spray port 23 is provided above the scraping bar, and the sewage suction port 15 is provided below the scraping bar 26. The cleaning roller 3 is driven to rotate by a drive motor. During automatic cleaning, the surface cleaning machine is placed on a cleaning seat 4, which is provided with a cleaning tank 41, and the cleaning roller 3 is correspondingly placed in the cleaning tank 41. In this embodiment, the sewage suction channel includes a sewage suction pipe 121 provided in the storage bucket and a sewage suction hose 141 connected and communicated with the sewage suction pipe 121 at one end. The other end of the sewage suction hose 141 is communicated with the sewage suction port 15. In the present invention, the sewage suction channel 14 includes a sewage suction pipe 121 arranged in the sewage bucket 12 and a sewage suction hose 141 arranged between the floor brush 21 and the body 1. One end of the sewage suction hose 141 is connected to the sewage suction pipe 121, and the other end of the sewage suction hose 141 is connected and connected to the sewage suction port 15 in the roller brush chamber 25. A vent 122 is provided at the top of the sewage bucket 12. A HEPA for gas-liquid separation is generally placed at the vent 122. The height between the top of the sewage suction pipe 121 and the vent 122 of the sewage bucket 12 is H. The maximum height when the sewage suction motor drives the cleaning liquid to be sprayed out of the sewage suction pipe is h, wherein h / ≤0.5H.

[0041] The self-cleaning process of the sewage suction channel of the floor scrubber of the present invention is as follows: first, the liquid supply device is turned on to spray cleaning liquid into the cleaning roller 3 or the cleaning tank 41, and the drive motor is turned on to drive the cleaning roller 3 to rotate. After the liquid supply device is turned on, the sewage suction motor 13 is turned on and operates at a first power P1. The control system (not shown in the figure) obtains the output flow of the liquid supply device, controls the PWM duty cycle of the sewage suction motor 13 according to the output flow, and sucks the cleaning liquid into the sewage suction channel 14 through the sewage suction port 15, and drives the cleaning liquid to form an up and down flow in the sewage suction channel 14, so that the cleaning liquid in the sewage suction channel 14 collides with each other during the up and down fluctuation process to generate shock waves on the inner wall, thereby continuously flushing the inner wall of the sewage suction channel and the sewage suction port 15; wherein the maximum amplitude of the shock wave is not greater than the height of the sewage suction channel 14. In the present invention, the control system controls the PWM duty cycle of the sewage suction motor so that the maximum amplitude of the generated shock wave does not exceed the height of the sewage suction pipe in the storage bucket.

[0042] Below we explain this control process in detail in the form of a comparative example. From the experimental verification results, when the ripple state of the shock wave is relatively large and large, the cleaning effect is good. If the amplitude of the shock wave is greater than the height of the upper sewage suction channel, the shock wave has entered the storage barrel, and the sewage suction channel cannot be cleaned. We set the amplitude of the shock wave to be no greater than the height of the sewage suction channel, but because it collides with the inner wall, especially the cleaning liquid that rises to the mouth of the sewage suction channel, some droplets or a very small amount of droplets will pass through the highest point of the sewage suction channel and enter the sewage storage barrel. This situation is a bit of a waste of resources, and this situation is also what we should try to avoid. Therefore, we evaluate the cleaning effect of the floor scrubber according to the correlation between the cleaning effect and the size of the ripples, as well as whether the cleaning liquid drips into the sewage storage barrel. The evaluation table is as follows:

[0043] Table 1: Cleaning fluid status effects and corresponding scoring values.

[0044] Cleaning fluid status Ⅰ Assignment of points Cleaning fluid status II Negative score Large ripples 10 No dripping 0 Large ripples 8 Very little dripping -1 Small ripples 6 Little dripping -2 Small ripple 4 More dripping -3 No obvious ripples 2 More dripping -4 No ripples (large water drop effect) 1 Heavy dripping -5 Not reached the highest point 0

[0045] Table 2: Comparison of the switching between operating at a fixed value lower than its rated power and stopping the operation without adjusting the flow rate and the duty cycle of the sewage suction motor.

[0046]

[0047] It can be seen from Table 2 that although the sewage suction motor runs intermittently at a constant power lower than the rated power, the flow rate is selected to a certain fixed value, that is, the sewage suction motor is energized, and then its power is reduced by half, for example, the sewage suction motor still continues to run, and then the cleaning liquid enters the sewage suction channel under the drive of the sewage suction motor and is not sucked into the sewage tank. Then the sewage suction motor stops working, and the stopping time is longer than the working time, for example, working for 5 seconds and stopping for 6 seconds, then the cleaning liquid rises to a certain height in the sewage suction channel, and then falls down and returns to the sewage suction port or the cleaning tank. Therefore, the cleaning liquid only moves up and down in the sewage suction channel, such as Figure 3 and Figure 4 As shown, no shock wave is generated, and the cleaning effect on the sewage suction channel is average. After multiple cycles, the cleaning effect is still average, especially for the dust, mud and hair adhering to the sewage suction channel. There is no cleaning effect on the connection between the sewage suction pipe and the sewage suction hose in the sewage suction channel.

[0048] Table 3: The duty cycle of the sewage suction motor is fixed, the flow rate is adjusted, the state change of the cleaning fluid and the assigned score.

[0049]

[0050] Table 4: Fixed flow value, adjustment of the duty cycle of the sewage suction motor, cleaning fluid state change and assigned value.

[0051]

[0052] From Table 3 and Table 4, it can be seen that when the sewage suction motor is operated at a fixed PWM duty cycle and the flow rate is adjusted, the direction of the cleaning fluid can be changed, such as Figure 5 As shown, the cleaning fluids collide with each other to generate shock waves. Figure 5 This is just a schematic diagram of the shock wave generation. In reality, there are many shock waves that fill the entire sewage suction channel. Figures 7 to 11As shown, when the PWM duty cycle of the sewage suction motor meets 25% or more, a shock wave can be generated. The flow rate has little effect on the size of the shock wave ripples and the maximum amplitude of the shock wave. The flow rate only affects whether the cleaning liquid will overflow from the top of the sewage suction pipe into the storage bucket. Moreover, when the flow rate is large, the cleaning liquid rises slowly and the time of the shock wave is longer. Therefore, the impact force of the shock wave is relatively weaker. When the shock wave ripples are large and the impact force is also large, due to the impact of the shock wave, a better cleaning effect is achieved, especially for the wet dust and hair adhering to the inner wall of the sewage suction channel. When the amplitude of the shock wave reaches the maximum and the flow rate is appropriate and the impact force is also large, please wash the connection between the sewage suction pipe and the sewage suction hose more thoroughly. In order to save resources, it is more appropriate to control the flow rate of the water supply device within the range of 25ml / min to 65ml / min. Otherwise, although the cleaning liquid can generate larger ripples, that is, amplitude, the shock wave generation time is long, resulting in the weakening of the impact force of the shock wave, and more cleaning liquid drips into the storage barrel, resulting in a waste of cleaning liquid, and too much shock wave enters the storage barrel. If there is waste water in the storage barrel that has not been poured out, the cleaning liquid that enters collides with the cleaning liquid in the storage barrel, which will generate a larger shock wave, which may splash to the vent of the sewage storage barrel, causing the HEPA at the vent to be wetted, and seriously enter the sewage suction motor, polluting the sewage suction motor, and also causing harm to the operation of the sewage suction motor.

[0053] From Table 4 and Figures 7 to 11 It can be seen that when the flow rate of the water supply device is controlled within the range of 25ml / min to 65ml / min, and the duty cycle of the sewage suction motor is within the range of 25% to 60%, a shock wave with a large amplitude and appropriate impact force can be obtained. At the same time, such a shock wave has a better cleaning effect on the inner wall of the sewage suction channel and the channel connection. In particular, when the sewage suction motor works alternately at any two fixed values ​​within the range of 25% to 60%, or works at any two dynamically changing values ​​within the range of 25% to 60%, the cleaning effect is better, but the impact force is large. Even if the flow rate is small, there is a risk that the cleaning liquid will rush out of the sewage suction pipe into the sewage tank, resulting in a slight waste of resources.

[0054] The control process of the automatic cleaning and suction channel of the present invention is described in detail below with specific implementation methods.

[0055] Example 1

[0056] In this embodiment, the rated power P of the sewage suction motor is 100W, the height H between the top of the sewage suction pipe 121 and the vent 122 of the sewage bucket 12 is 50cm, the actual working power of the sewage suction motor during sewage suction is 90W, the height of the sewage suction pipe 121 is 180cm, the highest water level 123 of the sewage bucket 12 is 120cm, and the ratio of h / H is 0.3. By controlling the power of the sewage suction motor 13, the maximum height h to which the cleaning liquid rises when it is ejected from the sewage suction pipe in the sewage bucket driven by the sewage suction motor is 15cm. Therefore, when the cleaning liquid rushes out of the sewage suction pipe into the sewage bucket, the maximum height to which the cleaning liquid can rise is 195cm. The surge or There is still a safe space of 35cm for splashing. In this way, during the sewage suction process, even if the cleaning liquid has approached the highest water level line 123 of the sewage bucket 12, when the remaining cleaning liquid enters the sewage bucket through the sewage suction pipe, even if the cleaning liquid collides with the cleaning liquid in the storage bucket, the cleaning liquid will not splash to the vent. Every time the cleaning liquid enters the storage bucket, the safety space for the cleaning liquid to rise under the action of the sewage suction motor is much greater than its rising height. Whether it is during the sewage suction process of the cleaning work or the automatic cleaning process, the cleaning liquid will not spray into the vent in the storage bucket. Not only will HEPA not be contaminated, but the working environment of the sewage suction motor will also be safer, ensuring the normal cleaning and automatic cleaning.

[0057] When the surface cleaning machine needs to be cleaned, the surface cleaning machine is placed on the cleaning seat and the automatic cleaning function is started. The automatic cleaning working process of the surface cleaning machine is as follows:

[0058] 1) Enter step A - cleaning roller cleaning stage: At this time, first turn on the liquid supply device. In this embodiment, the liquid supply device includes a water tank and a liquid spray port. The cleaning liquid in the water tank is sent to the liquid spray port through the water supply channel and sprayed onto the cleaning roller or the cleaning tank; then turn on the drive motor, and the drive motor drives the cleaning roller to rotate to clean the roller brush on the cleaning roller.

[0059] 2) After the cleaning roller is cleaned, step B - the sewage suction stage is entered: the sewage suction motor is turned on. In this step, the liquid supply device is turned off, the drive motor continues to work, and the cleaning roller is driven to rotate continuously. The sewage suction motor sucks the cleaning liquid on the roller brush of the cleaning roller through the sewage suction port and the sewage suction channel to the sewage storage bucket. The working power of the sewage suction motor is 100w. At this time, the sewage suction motor drives the cleaning liquid from the sewage suction pipe into the storage bucket. When the cleaning liquid is sprayed out from the sewage suction pipe, the maximum height h at the pipe mouth of the sewage suction pipe is 25cm, so it will not impact the vent and can smoothly enter the storage bucket.

[0060] 3) After the sewage suction stage is over, the process enters step C-cleaning the sewage suction channel: the liquid supply device is started again, and the liquid supply device supplies water to the cleaning roller or the cleaning tank at a fixed flow rate Q of 50 ml / min. The sewage suction motor 13 and the drive motor continue to move. The sewage suction motor 13 is turned on, and the control system obtains the output flow rate Q of the liquid supply device. The PWM duty cycle of the sewage suction motor is controlled according to the output flow rate Q. The sewage suction motor works at the first power P1. Under the action of the sewage suction motor and the cleaning roller, the cleaning liquid in the cleaning tank is sucked into the sewage suction channel through the sewage suction port, and drives the cleaning liquid to fluctuate up and down in the sewage suction channel. Continuously flush the inner wall of the sewage suction channel and the sewage suction port; in this embodiment, the waveform of the sewage suction motor controlled by the control system is a square wave with a waveform duration of 500us, and the sewage suction motor is controlled to work continuously at a fixed value of 35% of the PWM duty cycle, then the actual working power P1 of the sewage suction motor is 40w, and the working duration is 120s, so that the cleaning liquid in the sewage suction channel collides with each other during the up and down fluctuation process to generate shock waves on the inner wall, and the maximum amplitude of the shock wave is not greater than the height of the sewage suction channel, so the cleaning liquid is always moving up and down in the sewage suction channel, and constantly collides with each other to change direction, and continuously flushes the inner wall of the sewage suction pipe.

[0061] 4) After cleaning the sewage suction channel, the liquid supply device stops working first, and then the drive motor and the sewage suction motor continue to work for a period of time. The sewage suction power of the sewage suction motor is P2, and P2 is greater than P1, P2 is 90w, so that the cleaning liquid of the sewage suction channel is sucked into the sewage bucket. At this time, the sewage suction motor continues to work at a power of 90w, and the working time is 30s. The maximum height of the cleaning liquid when it is sprayed out from the nozzle of the sewage suction pipe is 40cm, so that the sewage generated by the sewage suction channel after cleaning can enter the storage bucket through the sewage suction pipe, and when it rushes out from the nozzle of the sewage suction pipe, it will not enter the vent. Then the drive motor and the sewage suction motor stop working at the same time, and the automatic cleaning is completed. Of course, it is understandable that the sewage suction motor in this process can also work at the rated power P.

[0062] Since the flow rate Q provided by the liquid supply device in this embodiment is 50 ml / min, the control system controls the sewage suction motor to work at a PWM duty cycle of 35%, and the waveform of the sewage suction motor controlled by the control system is as follows: Figure 7The square wave shown has a waveform duration of 500us, which allows the cleaning liquid to effectively enter the sewage suction channel and flow up and down in the sewage suction channel. When the sewage suction motor is in its first duration of 500us, the first stream of cleaning liquid is driven to rise by the sewage suction motor, and then the sewage suction motor stops working in the second duration of 500us, and the rising cleaning liquid begins to fall. Then the sewage suction motor is controlled to work again in the third duration of 500us. At this time, the second stream of cleaning liquid enters from the sewage suction port and rises, and meets the first stream of cleaning liquid that is falling but has not yet reached the bottom. The two collide and impact, and the flow direction of the cleaning liquid changes to form a shock wave, as shown in FIG. Figure 5 As shown, such repeated circulation allows the cleaning liquid to rise to the highest point of the sewage suction channel with a maximum amplitude, and does not enter the container. It repeatedly impacts the inner wall of the sewage suction channel in the sewage suction pipe, continuously flushing the inner wall of the sewage suction channel, saving resources while ensuring the cleaning effect of the sewage suction channel and maximizing resource utilization.

[0063] It is understood that the suction power of the sewage suction motor can also be alternating with multiple waveforms, so that the cleaning liquid forms turbulent flow in the sewage suction channel, continuously flushing the sewage suction port and the inner wall of the sewage suction channel. Innovations such as the sewage suction motor operating mode and the operating power variation mode that can change the direction of the cleaning liquid entering the sewage suction channel to prevent turbulent flow or laminar flow, and the cleaning liquid entering the sewage suction barrel continuously flushing the inner wall of the sewage suction channel, are all within the scope of protection of the present invention and will not be exemplified here.

[0064] Of course, it is understandable that the sewage suction process can be interspersed with the process of cleaning the sewage suction channel, or the sewage suction process can be provided before and after cleaning the sewage suction channel. Such solutions that do not deviate from the intention of the present invention are within the scope of protection of the present invention and will not be given one by one here.

[0065] Of course, it is understandable that the output flow rate Q of the liquid supply device can also operate at a dynamically changing value within the range of 25ml / min-65ml / min, such as controlling the output flow rate Q to alternate or cyclically operate at any two values ​​between 25ml / min and 65ml / min, or controlling the output flow rate Q to alternate or cyclically operate at any several fixed values ​​within the range of 25ml / min and 65ml / min, or controlling the output flow rate Q to operate linearly within the range of 25ml / min and 65ml / min, etc. At the same time, the sewage suction motor is controlled to operate at a fixed value with a PWM duty cycle in the range of 25% to 60%. Such solutions that do not deviate from the intention of the present invention are all within the scope of protection of the present invention and will not be given examples one by one here.

[0066] The self-cleaning method of the present invention is that after the liquid supply device is turned on, the control system obtains the output flow of the liquid supply device, and controls the PWM duty cycle of the sewage suction motor according to the output flow, so that the cleaning liquid in the sewage suction channel collides with each other during the up and down fluctuation process, so that the flow rate or direction of the cleaning liquid in the sewage suction channel changes, forming a shock wave on the inner wall of the sewage suction channel, so that the cleaning liquid in the sewage suction channel no longer flows along the inner wall, but instead continuously sprays toward the inner wall while moving upward, thereby flushing the inner wall. In particular, the impact force of this shock wave is large, which easily washes away dirt or hair stuck on the inner wall, causing it to follow the flow of the cleaning liquid and then enter the sewage suction channel. Moreover, the maximum amplitude of the shock wave of this cleaning liquid is controlled to be no greater than the height of the sewage suction channel. Since this cleaning liquid is non-directional and has a short-term impact force in a small space, and can be concentrated in the sewage suction channel to repeatedly impact the inner wall to flush it, it can also produce impact on the connection of the sewage suction channel, eliminating cleaning dead corners, saving resources, and having a good flushing effect. Therefore, this automatic cleaning method of the sewage suction channel is both energy-saving and efficient, and has an excellent cleaning effect. At the same time, there is no need to change the structure of the floor scrubber itself to achieve automatic cleaning of the cleaning roller, suction port and suction channel, which saves resources, makes the floor scrubber more intelligent, and is easy to maintain, more convenient and hygienic to use, and also reduces the time and labor of customers in maintaining the floor scrubber, providing a better experience.

[0067] Example 2:

[0068] The difference between this embodiment and the first embodiment is that the control system in the sewage suction pipe self-cleaning method has a different control method for the sewage suction motor.

[0069] In this embodiment, the rated power of the sewage suction motor is 120w, the control system controls the output flow rate Q of the liquid supply device to be 30ml / min, and works at this fixed value, and controls the waveform of the sewage suction motor to change in a step-by-step manner, such as Figure 8As shown, the PWM duty cycle of the sewage suction motor is controlled to alternate between two fixed values ​​of 25% and 60%, that is, the suction power P1 of the sewage suction motor is switched between 30W and 72W. Under the control of this waveform, the PWM duty cycle of the sewage suction motor is 25%. In the first time period, the first stream of cleaning liquid rises in the sewage suction channel driven by the sewage suction motor. In the second working time period, the first stream of cleaning liquid falls back. In the third time period, the PWM duty cycle of the sewage suction motor is controlled to be 60%. The second stream of cleaning liquid then enters the sewage suction channel from the sewage suction port and meets the first stream of cleaning liquid that is falling back. Since the working power of the sewage suction motor of the second cleaning liquid is large, at this time, the power of the cleaning liquid is greater than that of the first cleaning liquid, so it collides with the first cleaning liquid and deflects it, not only generating a shock wave that hits the inner wall of the sewage suction channel, but also causing the cleaning liquid to rise further, and so on repeatedly, so that the cleaning liquid can continue to rise or the two generate a torrent after collision to rise to the highest point in the sewage suction channel, and then fall back again before the arrival of the next cleaning liquid, so that shock waves and vortexes are formed in the sewage suction channel, flowing up and down, constantly flushing the inner wall of the sewage suction channel, saving resources and ensuring the cleaning effect of the sewage suction channel, and maximizing resource utilization.

[0070] The specific self-cleaning method is as follows:

[0071] 1) Enter step A - cleaning roller cleaning stage: At this time, first turn on the liquid supply device. In this embodiment, the liquid supply device includes a water tank and a liquid spray port. The cleaning liquid in the water tank is sent to the liquid spray port through the water supply channel and sprayed onto the cleaning roller or the cleaning tank; then turn on the drive motor, and the drive motor drives the cleaning roller to rotate to clean the roller brush on the cleaning roller.

[0072] 2) After the cleaning roller is cleaned, step B - the sewage suction stage is entered: the sewage suction motor is turned on. In this step, the liquid supply device is turned off, the drive motor continues to work, and the cleaning roller is driven to rotate continuously. The sewage suction motor sucks the dirty cleaning liquid on the roller brush of the cleaning roller through the sewage suction port and the sewage suction channel into the sewage bucket. The working power of the sewage suction motor is P.

[0073] 3) After the sewage suction stage is over, the process enters step C - the stage of cleaning the sewage suction channel: the liquid supply device is started again, and the liquid supply device supplies water to the cleaning roller or the cleaning tank at a fixed flow rate Q of 30 ml / min. The sewage suction motor 13 and the drive motor continue to move. The drive motor is turned on first to drive the cleaning roller to rotate, and then the sewage suction motor and the liquid supply device are turned on and run according to the preset value. The process of cleaning the sewage suction channel includes n sub-cycles, where n≥1. In this embodiment, the rated power of the sewage suction motor is 120w, and the sewage suction motor 13 is turned on and works at the first power P1. The control system obtains the output flow rate Q of the liquid supply device and controls the PWM duty cycle of the sewage suction motor according to the output flow rate Q. Under the action of the sewage suction motor and the cleaning roller, the cleaning liquid in the cleaning tank is sucked into the sewage suction channel through the sewage suction port, and drives the cleaning liquid to fluctuate up and down in the sewage suction channel to continuously flush the inner wall of the sewage suction channel and the sewage suction port; in this embodiment, the waveform of the sewage suction motor controlled by the control system is a square wave with a waveform duration of 300us, such as Figure 8 As shown, the suction motor is controlled to alternate between fixed PWM duty cycles of 25% and 60%, with the P1 value varying between 40W and 75W for 20 seconds. This allows the cleaning fluid in the suction channel to collide with each other during its up-and-down motion, generating shock waves against the inner wall. The maximum amplitude of these shock waves is guaranteed to be no greater than the height of the suction channel. This means that the cleaning fluid continuously flushes the inner wall of the channel without entering the storage tank. A very small amount of liquid droplets are permitted to splash into the tank. After the suction pipe cleaning process has been cycled for n = 5 times, the automatic cleaning of the suction channel is complete.

[0074] 4) After cleaning the sewage suction channel, enter step D-sewage suction stage, the liquid supply device stops working first, and then the drive motor and the sewage suction motor continue to work for a period of time, thereby sucking the cleaning liquid for cleaning the sewage suction channel into the sewage bucket. The sewage suction motor works for 20S, the sewage suction power of the sewage suction motor is P2, and P2 is greater than P1, P2 is 100w, and then the drive motor and the sewage suction motor stop working at the same time, and the automatic cleaning is completed.

[0075] 5) Then enter step E-air drying stage: at this time, the drive motor works intermittently, driving the cleaning roller to rotate intermittently. At the same time, the fan on the cleaning seat starts and blows towards the cleaning roller. The fan continues to work for 20 minutes until the bristles on the cleaning roller are dried.

[0076] In this embodiment, in the self-cleaning method, since the control system controls the sewage suction motor to operate at a PWM duty cycle of 25% and 60%, the working time is shorter, and the rising forces of the two cleaning liquids are different, making the collision between the two more intense, thereby increasing the impact force of the shock wave rushing towards the inner wall, and the sewage suction motor drives the movement of the latter cleaning liquid with a larger power, its lifting force is increased, which is more conducive to the cleaning liquid to effectively flush the inner wall of the sewage suction channel inside the sewage suction channel, and move upward, so that the cleaning is more reliable, and it can more reliably ensure that the sewage suction channel is cleaned from top to bottom, and the cleaning effect is better. In addition, due to the addition of the sewage suction and drying stage, the dirty liquid cleaning the sewage suction port and the sewage suction channel is collected in the storage barrel. At the same time, the cleaning roller, sewage suction port and sewage suction channel are air-dried again, which not only ensures the cleanliness of the cleaning roller, sewage suction port and sewage suction channel, but also ensures the dryness of the three through air drying, avoiding the breeding of bacteria and the generation of odor due to long-term moisture.

[0077] Of course, it is understood that step C, cleaning the sewage suction channel, can also be performed during step B, suctioning the sewage, and can be performed interleaved with step B; or, step C, cleaning the sewage suction channel, can also be performed before step B, suctioning the sewage. Such modifications that do not depart from the intent of the present invention are also within the scope of protection of the present invention and will not be listed here one by one.

[0078] Of course, it is understandable that the output flow rate Q of the liquid supply device can also be controlled to work at a fixed value within the range of 25ml / min-65ml / min, and the PWM duty cycle of the sewage suction motor can be controlled to work for two fixed periods of 500us, and then the sewage suction motor can be controlled to work at a 60% PWM duty cycle for a fixed period of 300us, or the sewage suction motor can be controlled to work at a 45% PWM duty cycle for two fixed periods of 300us, and then the sewage suction motor can be controlled to work at a 30% PWM duty cycle for a fixed period of 500us, etc.; by controlling the working mode of the sewage suction motor with this waveform, the cleaning liquid with this direction change can be obtained, generating a shock wave flowing toward the inner wall of the sewage suction channel, so that the sewage suction channel is repeatedly flushed by the cleaning liquid, thereby cleaning the sewage suction channel. Such improvements that do not deviate from the intention of the present invention are also within the scope of protection of the present invention, and no further examples are given here.

[0079] Of course, it is understandable that the output flow rate Q of the liquid supply device can also be controlled to work at a fixed value in the range of 25ml / min-65ml / min, and the sewage suction motor can be controlled to work alternately or cyclically at 3 or more fixed values ​​in the range of PWM duty cycle of 25% to 60%; or, alternatively, the sewage suction motor can be controlled to work with a linear change between any two fixed values ​​in the range of PWM duty cycle of 25% to 60%, and this working mode is cycled several times, etc. At the same time, such solutions that do not deviate from the intention of the present invention are all within the scope of protection of the present invention, and no examples will be given here one by one.

[0080] Of course, it is understandable that a stepped waveform may be used first and then a pulsed waveform, or a sine waveform and a stepped waveform may be combined, etc. Such improvements that do not deviate from the intention of the present invention are also within the scope of protection of the present invention and will not be listed here one by one.

[0081] Of course, it is understandable that the above process method is also applicable to a double-roller floor scrubber with a sewage suction channel or other types of floor scrubbers with a sewage suction channel.

[0082] Of course, it is understandable that we can also set a dirt detection sensor on the sewage suction channel, and then set the number of sub-cycles of cleaning the sewage suction channel to n, where n is determined by the dirt level detected by the dirt sensor. For example, if the dirt sensor detects that the sewage suction channel is relatively dirty, the control system will increase the number of cycles of cleaning the sewage suction channel, and when the sewage suction channel is relatively clean, the number of cycles can be reduced. Alternatively, the number n of sub-cycles can be determined by a predetermined time length set in the control system, and the maximum amplitude of the shock wave in each sub-cycle is not the same value. For example, the predetermined time length is repeated 5 times, and the PWM duty cycle of controlling the sewage suction motor in each sub-cycle is different, and the duty cycle of the sewage suction motor is within the range of 25% to 60%. Therefore, the height of each shock wave rises to a different level, thereby better concentrating on repeatedly flushing any section of the sewage suction channel. Since the flushing height is different each time, any section can be flushed cleanly, and then each section is well cleaned. The shock wave will not rush out of the sewage suction pipe into the container, ensuring that the cleaning of the entire sewage suction channel is more thorough and resources are not wasted. Such improvements that do not depart from the intent of the present invention are also within the scope of protection of the present invention and are not listed here one by one.

[0083] So far, the technical solutions of the present application have been described in conjunction with the foregoing multiple embodiments. However, it is easy for those skilled in the art to understand that the scope of protection of the present application is not limited to these specific embodiments. Without departing from the technical principles of the present application, those skilled in the art can split and combine the technical solutions in the above-mentioned various embodiments, and can also make equivalent changes or replacements to the relevant technical features. Any changes, equivalent replacements, improvements, etc. made within the technical concept and / or technical principles of the present application will fall within the scope of protection of the present application.

Claims

1. A self-cleaning method for a surface cleaning machine, comprising a process of cleaning a dirt suction channel: The liquid supply device is turned on to spray cleaning liquid onto the cleaning roller or into the cleaning tank. The drive motor is turned on to drive the cleaning roller to rotate. The sewage suction motor is turned on and operates at a first power P1 to suck the cleaning liquid into the sewage suction channel through the sewage suction port, and drives the cleaning liquid to fluctuate up and down in the sewage suction channel to continuously flush the inner wall of the sewage suction channel and the sewage suction port; It is characterized by: After the liquid supply device is turned on, the control system obtains the output flow of the liquid supply device and controls the PWM duty cycle of the sewage suction motor according to the output flow, so that the cleaning liquid in the sewage suction channel collides with each other during the up and down fluctuation process to generate shock waves on the inner wall of the sewage suction channel, and the maximum amplitude of the shock wave is not greater than the height of the sewage suction channel.

2. The self-cleaning method of a surface cleaning machine according to claim 1, characterized in that: If the output flow rate Q of the liquid supply device is a fixed value within the range of 25ml / min-65ml / min, the sewage suction motor is controlled to operate at a fixed value with a PWM duty cycle within the range of 25% to 60%; or, if the output flow rate Q of the liquid supply device is a fixed value within the range of 25ml / min-65ml / min, the sewage suction motor is controlled to operate at a dynamically changing value with a PWM duty cycle within the range of 25% to 60%.

3. The self-cleaning method of a surface cleaning machine according to claim 1, characterized in that: If the output flow rate Q of the liquid supply device is a dynamic changing value within the range of 25ml / min-65ml / min, the sewage suction motor is controlled to operate with a fixed value of PWM duty cycle within the range of 25% to 60%; or, if the output flow rate Q of the liquid supply device is a dynamic changing value within the range of 25ml / min-65ml / min, the sewage suction motor is controlled to operate with a dynamic changing value of PWM duty cycle within the range of 25% to 60%.

4. A self-cleaning method for a surface cleaning machine according to claim 2 or 3, characterized in that: The driving motor is turned on first to drive the cleaning roller to rotate, and then the sewage suction motor and the liquid supply device are turned on and run according to the preset value. The duration of the sewage suction channel cleaning process is T, 20s≤T≤120s.

5. A self-cleaning method for a surface cleaning machine according to claim 2 or 3, characterized in that: The driving motor is turned on first to drive the cleaning roller to rotate, and then the sewage suction motor and the liquid supply device are turned on and run according to the preset value. The process of cleaning the sewage suction channel includes n sub-cycles, where n≥1.

6. The self-cleaning method of a surface cleaning machine according to claim 5, characterized in that: A dirt detection sensor is provided on the dirt suction channel, and the number n of sub-cycles is determined by the dirt level detected by the dirt sensor; alternatively, the number n of sub-cycles is determined by a predetermined duration set in the control system, and the maximum amplitude of the shock wave in each sub-cycle is not the same value.

7. The self-cleaning method of a surface cleaning machine according to claim 1, characterized in that: The sewage suction channel includes a sewage suction pipe arranged in the sewage bucket and a sewage suction hose arranged between the floor brush and the body. One end of the sewage suction hose is connected to the sewage suction pipe, and the other end of the sewage suction hose is connected and connected to the sewage suction port in the roller brush cavity. The height between the top of the sewage suction pipe and the vent of the sewage bucket is H. The maximum height to which the sewage suction motor drives the cleaning liquid to be sprayed out from the sewage suction pipe is h, where h≤0.5H.

8. The self-cleaning method of a surface cleaning machine according to claim 7, characterized in that: It also includes a sewage suction process: the driving motor continues to drive the cleaning roller to rotate, the liquid supply device stops supplying liquid, and the sewage suction motor operates at the second power P2 to suck the generated dirt or dirty liquid into the sewage bucket through the sewage suction port and the sewage suction channel. The running time is t, 20s≤t≤30s, where P1<P2. During the sewage suction process, the maximum height h of the cleaning liquid when it is sprayed out from the sewage suction pipe satisfies 0.2H≤h≤0.5H.

9. The self-cleaning method of a surface cleaning machine according to claim 8, characterized in that: The sewage suction process is interspersed with the process of cleaning the sewage suction channel; or, the sewage suction process is set after cleaning the sewage suction channel; or, the sewage suction process is set before cleaning the sewage suction channel; or, the sewage suction process is set before and after cleaning the sewage suction channel.

10. The self-cleaning method of a surface cleaning machine according to claim 2, characterized in that: If the output flow rate Q of the liquid supply device is a fixed value of 35ml / min or 50ml / min, the sewage suction motor is controlled to cycle at any two fixed values ​​within the PWM duty cycle range of 25% to 60%; or, if the output flow rate Q of the liquid supply device is a fixed value of 35ml / min or 50ml / min, the sewage suction motor is controlled to cycle at any two dynamically changing values ​​within the PWM duty cycle range of 25% to 60%.

Images