Foam proportional mixing device

A foam proportional mixing device, wherein the foam proportional mixing device comprises:

• a pump comprising:
• a housing, wherein a cavity is formed in the housing;
• an inlet pipe connected to an outer side of the housing and in fluid communication with the cavity;
• a foam receiving port arranged on the inlet pipe;
• and
• a pair of rotors, the pair of rotors being located in the cavity;
• and
• a gear pump, the gear pump comprising:
• a gear pump housing, wherein a gear pump cavity is formed in the gear pump housing, a gear pump inlet, and a gear pump outlet;
• and
• a pair of gears located within the gear pump cavity, one of the pair of gears connected to one of the pair of rotors via at least one shaft;
• wherein the foam receiving port is in communication with the gear pump outlet, such that the gear pump outlet is in fluid communication with the cavity.

A Roots pump for a foam proportional mixing device, the Roots pump comprising:

• a Roots pump housing, wherein a Roots pump cavity is formed in the Roots pump housing;
• a Roots pump inlet and a Roots pump outlet, wherein the Roots pump inlet and the Roots pump outlet are respectively arranged on two opposite sides of the Roots pump housing, and the Roots pump inlet and the Roots pump outlet are respectively in communication with the Roots pump cavity;
• a Roots pump inlet pipe connected to an outer side of the Roots pump housing;
• a foam receiving port arranged on the Roots pump inlet pipe and in communication with an outlet of a gear pump, such that the outlet of the gear pump is in fluid communication with the Roots pump cavity;
• a pair of rotors, the pair of rotors being located in the Roots pump cavity;
• and
• a fluid guide member, wherein the fluid guide member is arranged in the Roots pump inlet, and is configured to guide a fluid to flow to the pair of rotors and to provide driving forces to the pair of rotors for rotating same in opposite directions from each other.