Dual heater system for spray dispenser

Patent metadata

Field	Value
Publication number	US-9849475-B2
Application number	US-201314650758-A
Country	US
Kind code	B2
Filing date	Dec 16, 2013
Priority date	Dec 17, 2012
Publication date	Dec 26, 2017
Grant date	Dec 26, 2017

Abstract

A mobile spray dispenser comprises a fluid circulation system and a heating unit. The fluid circulation system has a motorized pump capable of circulating fluid from a fluid reservoir in a high-pressure spray mode and a low-pressure recirculation mode, and of providing the fluid to a sprayer. The motorized pump draws lower power in the low-pressure recirculation mode than in the high-pressure spray mode. The heating unit is disposed within the fluid circulation system to heat the fluid to a target temperature, and comprises a primary heater and a boost heater. The primary heater is configured to be active during both the high-pressure spray mode and the low-pressure recirculation mode. The boost heater is in fluid series with the primary heater, and is configured to be active only during the low-pressure recirculation mode.

First claim

The invention claimed is:

1. A mobile spray dispenser comprising:
a fluid reservoir;
a motorized pump disposed to pump fluid from the fluid reservoir;
a sprayer
a fluid circulation system capable of operating in a plurality of alternative modes, the modes comprising:
wherein the motorized pump has a high-pressure spray mode wherein fluid from the fluid reservoir is provided to the sprayer; and
wherein the motorized pump has a low-pressure recirculation mode wherein fluid is circulated to a return hose back to the reservoir via the sprayer, and wherein the motorized pump draws lower power in the low-pressure recirculation mode than in the high-pressure spray mode;

a heating unit disposed within the fluid circulation system to heat the fluid to a target temperature, the heating unit comprising:
a primary heater configured to be active during both the high-pressure spray mode and the low-pressure recirculation mode; and
a boost heater in fluid series with the primary heater and configured to be active only during the low-pressure recirculation mode; and
wherein during both the high-pressure spray mode and the low-pressure spray mode the fluid flows from the motorized pump to the boost heater to the primary heater and the sprayer.

2. The mobile spray dispenser of claim 1 , wherein the primary heater and the boost heater are resistive heaters.

3. The mobile spray dispenser of claim 2 , wherein the primary heater and the boost heater each comprise a helical fluid path about a resistive cylindrical element.

4. The mobile spray dispenser of claim 2 , wherein the primary heater and the boost heater draw power from a shared electrical contactor.

5. The mobile spray dispenser of claim 2 , and further comprising a primary heater control module and a logic control module, wherein current to the primary heater is regulated by the primary heater control module according to a control signal from the logic control module that sets a current pulse interval to achieve and maintain the target temperature.

6. The mobile spray dispenser of claim 5 , wherein current to the boost heater is regulated by a solid state auxiliary relay chained from the primary heater control module, such that the boost heater receives current pulses only when the primary heater receives current pulses.

7. The mobile spray dispenser of claim 1 , further comprising a primary controller that controls power to the motorized pump such that the motorized pump draws more current in the high-pressure spray mode than in the low-pressure recirculation mode.

8. The mobile spray dispenser of claim 7 , wherein the primary controller controls power to the motorized pump to achieve a target fluid pressure.

9. The mobile spray dispenser of claim 7 , further comprising an electromechanical relay that enables the boost heater in the low-pressure recirculation mode and disables the boost heater in the high-pressure spray mode based on a low-voltage signal from the motor controller.

10. The mobile spray dispenser of claim 9 , wherein a delineation between the low-pressure recirculation mode and the high-pressure spray mode ensures that the total power draw of the motorized pump and the heating unit does not exceed a maximum current limit.

11. The mobile spray dispenser of claim 10 , wherein the primary heater receives power via a first power circuit, and motorized pump and boost heater draw power via a second power circuit, and wherein the first power circuit and the second power circuit have separate maximum current limits.

12. The mobile spray dispenser of claim 11 , wherein the maximum current limits of the first and second power circuits are 15 A or 20 A.

13. The mobile spray dispenser of claim 1 , wherein the fluid circulation system contains separate motorized pumps, fluid reservoirs, and fluid lines for two distinct fluids mixed at the sprayer, and the heating unit comprises separate primary and boost heaters for each fluid.

14. The mobile spray dispenser of claim 13 , wherein the separate primary and boost heaters for each fluid are separately controlled to achieve different target temperatures.

15. A heater control method comprising: a mobile spray dispenser as from claim 1 ;
powering the motorized pump to circulate fluid at a required pressure;
pulsing power to the primary heater in regular intervals selected to heat the circulating fluid to a target temperature;
pulsing power to the boost heater in synchronously with the primary heater while the motorized pump operates in the low-pressure recirculation mode; and
cutting power to the boost heater while the motorized pump operates in the high-pressure spray mode.

16. The heater control method of claim 15 , further comprising determining power draw of the motorized pump and comparing the power draw of the motorized pump to a threshold power draw, and wherein the low-pressure recirculation mode is defined by power draw of the motorized pump falling below the threshold power value, while the high-pressure spray mode is defined by power draw of the motorized pump exceeding the threshold power value.

17. The heater control method of claim 15 , further comprising controlling power to the motorized pump based on a commanded value of the required pressure and comparing the commanded value to a threshold pressure value, and wherein the low-pressure recirculation mode is defined by the commanded value falling below the threshold pressure value, while the high-pressure spray mode is defined by the commanded value exceeding the threshold pressure value.

Assignees

• Graco Minnesota Inc

Inventors

• Pellin Christopher J
• Velgersdyk Jeffrey N
• Roden Joshua D
• Colby Bryan K

Classifications

• B05B9/002

  incorporating means for heating or cooling, e.g. the material to be sprayed · CPC title

• H05B1/0202

  Switches · CPC title

• B05B7/1693 Primary

  with means for heating the material to be sprayed or an atomizing fluid in a supply hose or the like · CPC title

• H05B1/0244

  Heating of fluids (H05B1/0247 takes precedence) · CPC title

• B05B7/0408

  with arrangements for mixing two or more liquids · CPC title