Surface cleaning system, surface cleaning device and control method thereof

A cleaning system, comprising:

• a cleaning device, which comprises a floor brush assembly, a scraper plate in an interference fit with a roller brush, a dirt suction port located below the scraper plate, and a main motor for generating a suction force at the dirt suction port, the floor brush assembly comprises a floor brush housing, the roller brush and a roller brush cover, wherein the scraper plate is in contact fit with the roller brush, the roller brush is rotatably connected to the floor brush housing and configured to clean a working surface, the roller brush cover and the floor brush housing enclose a roller brush cavity for fitting with the roller brush, and the roller brush cover is configured to be operable in a first position or a second position relative to the floor brush housing, in the first position, there is a first contact area between the roller brush cover and the roller brush;
• in the second position, there is a second contact area between the roller brush cover and the roller brush, wherein, the first contact area is greater than or equal to zero, but less than the second contact area;
• and
• a tray configured for accommodating the cleaning device, the tray has a roller brush groove for receiving a roller brush, the roller brush is configured to be free to rotate relative to the roller brush groove during a self-cleaning operation;
• wherein a liquid outlet assembly is provided on the floor brush housing, the liquid outlet assembly comprises a flow guide portion extending in a direction of the roller brush, at least one flow dividing rib is provided on the flow guide portion, and the at least one flow dividing rib is configured to be distributed at a distance in the axial direction of the roller brush.