Carpet and upholstery cleaning with fluid pumping safety feature

Claim 1

In a two tank cleaning apparatus for cleaning carpets and the like in situ comprising a cleaning solution reservoir tank system, a vacuum tank pick-up system, and a remote cleaning head; said reservoir tank system comprising a reservoir tank, electric heater means having an inlet and an outlet, a liquid pump having an inlet for receiving liquid from said reservoir tank and an outlet for supplying it under pressure to the inlet of said heater means, a first electric drive motor for actuating said liquid pump, conductor means for connecting said first motor to a source of electrical power, and first flexible hose means for receiving heated liquid from the outlet of said heater means and supplying it under pressure to said cleaning head; said vacuum tank pick-up system including a vacuum tank, second flexible hose means coupling the interior of said vacuum tank to said cleaning head, an air suctionblower having an outlet and an inlet, said inlet being coupled to said vacuum tank for evacuating air from said vacuum tank, and a second electric drive motor for actuating said suction-blower, the improvement comprising: a. a first liquid supply line coupling said reservoir tank to said pump inlet, said first line (for) supplying liquid to said pump inlet only from said reservoir tank; b. a second liquid supply line coupling the outlet of said pump to the inlet of said heater means ,said second line (for) supplying liquid only to said heater means; c. a third liquid supply line coupling the outlet of said heater means to said reservoir tank; d. a fourth liquid supply line having one end coupled to the outlet of said heater means for suPplying heated fluid to said cleaning head; e. pressure regulator means for permitting liquid to flow from said heater and back to said reservoir tank through said third liquid supply line when flow through said fourth line is prevented, said first, second and third liquid supply lines, pump, heater, and pressure regulator means comprising a liquid pumping circuit whereby liquid may flow from said reservoir tank, through said liquid pumping circuit and back to said reservoir tank when flow through said fourth line is blocked, liquid supplied to said pump inlet flowing thereto only from said reservoir tank and liquid from said pump outlet flowing only to said heater means; and f. liquid flow operated switch means actuated by fluid flow in said liquid pumping circuit effective to prevent the application of electrical power to said first drive motor when liquid flow in said liquid pumping circuit drops below a predetermined level.