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A paint circulating system is suitable for providing paint to applicators in a product finishing facility. The system includes a pump for pumping paint around the system and a back-pressure regulator (BPR), which substantially eliminates pressure fluctuations of paint in the system upstream of the B

A paint circulating system is suitable for providing paint to applicators in a product finishing facility. The system includes a pump for pumping paint around the system and a back-pressure regulator (BPR), which substantially eliminates pressure fluctuations of paint in the system upstream of the BPR. A controller is provided for controlling the pump and the BPR to operate in one of a flow mode, wherein a required flow rate of paint around the system is maintained, and a pressure mode, wherein a pressure of paint between the pump and the BPR is maintained. The paint circulating method includes switching operation of the pump and the BPR between the flow mode and the pressure mode.

대표청구항 ▼

We claim: 1. A paint circulating system suitable for providing paint to applicators in a product finishing facility, the system comprising: a pump for pumping paint around the system; a back-pressure regulator operable in an activated state to substantially eliminate pressure fluctuations of paint

We claim: 1. A paint circulating system suitable for providing paint to applicators in a product finishing facility, the system comprising: a pump for pumping paint around the system; a back-pressure regulator operable in an activated state to substantially eliminate pressure fluctuations of paint upstream of the back-pressure regulator, and operable in a deactivated state to enable paint flow without being responsive to pressure fluctuations, wherein the applicators are configured to dispense paint when the back-pressure regulator is operating in the activated state, and wherein the applicators are configured to not dispense paint when the back-pressure regulator is operating in the deactivated state; and a controller comprising circuitry configured to provide one or more electronic control signals for controlling the pump and the back-pressure regulator to operate in one of a flow mode, wherein the back-pressure regulator is deactivated and a required flow rate of paint around the system is maintained, and a pressure mode, wherein the back-pressure regulator is activated and a pressure of paint between the pump and the back-pressure regulator is maintained. 2. The paint circulating system of claim 1, comprising an actuator to activate and/or deactivate the back-pressure regulator. 3. The paint circulating system of claim 2, wherein the actuator comprises compressed air. 4. The paint circulating system of claim 2, wherein the actuator comprises an hydraulic fluid. 5. The paint circulating system of claim 2, wherein the back-pressure regulator comprises a diaphragm that is acted upon by a spring on one side and by the paint pressure on the other side. 6. The paint circulating system of claim 2, wherein the back-pressure regulator comprises a diaphragm that is acted upon by fluid pressure on one side and by the paint pressure on the other side. 7. The paint circulating system of claim 1, wherein, in the flow mode, the controller is configured to control the pump to pump paint at a fixed flow rate. 8. The paint circulating system of claim 7, wherein the fixed flow rate is a low flow rate, at or just above a minimum flow rate required for the paint. 9. The paint circulating system of claim 1, wherein, in the pressure mode, the back-pressure regulator is configured to be activated to respond to variations in the paint pressure to maintain a substantially constant pressure upstream of the back-pressure regulator. 10. The paint circulating system of claim 1, wherein, in the pressure mode, the pump is configured to deliver paint at a predetermined pressure. 11. The paint circulating system of claim 10, wherein the pump is a variable speed pump responsive to a control signal to maintain the predetermined pressure. 12. The paint circulating system of claim 10, wherein the pump is a variable capacity pump responsive to a control signal to maintain the predetermined pressure. 13. The paint circulating system of claim 1, comprising a pressure sensor to provide a pressure signal as a basis for a control signal. 14. The paint circulating system of claim 13, wherein the controller is arranged to receive the pressure signal and to provide the control signal to the pump for maintaining the pressure when in the pressure mode. 15. The paint circulating system of claim 1, wherein the controller is operable to switch the system between the flow mode and the pressure mode in response to a demand signal. 16. The paint circulating system of claim 15, wherein the demand signal is provided from a plant scheduling apparatus. 17. The paint circulating system of claim 15, wherein the demand signal is provided from a ‘job queue’ data processing apparatus. 18. The paint circulating system of claim 1, wherein the controller comprises a control card configured to mount in a programmable computing device. 19. The paint circulating system of claim 18, wherein the control card is provided with a plurality of input and output terminals for receiving signals from sensors in the system and for providing control signals to the back-pressure regulator and the pump. 20. The paint circulating system of claim 18, wherein the control card is provided with a data link to a graphics system for set-up and monitoring purposes. 21. The paint circulating system of claim 18, wherein the control card includes a plurality of channels for controlling a plurality of paint circulating systems, each providing paint to a spray booth. 22. The paint circulating system of claim 21, wherein each of the plurality of paint circulating systems provides a different color of paint to the spray booth. 23. A paint circulating system for use in association with a paint spray-booth, the system comprising: a variable speed pump for pumping paint around the system; a back-pressure regulator operable in an active condition for varying a flow rate of paint in response to pressure fluctuations of paint flowing into the back-pressure regulator to maintain upstream paint pressure, and in an inactive condition wherein paint is free to flow through the back-pressure regulator; and a controller comprising circuitry configured to provide one or more electronic control signals for controlling the system to operate in one of a flow mode and a pressure mode; wherein: in the flow mode, the controller is configured to place the back-pressure regulator in the inactive condition and to operate the pump at a fixed speed to provide a required flow rate of paint around the system at a minimum pressure; and in the pressure mode, the controller is configured to place the back-pressure regulator in the active condition and to control the pump speed to maintain a pressure of paint at the spray booth, the controller being further operable to switch the system between the flow mode and the pressure mode in response to a demand signal. 24. A paint circulating system, comprising: a paint source; a paint application system comprising one or more applicators; a pump configured to circulate paint through the system; a back pressure regulator back-pressure regulator disposed downstream of the paint application system, wherein paint flowing through the paint application system that is not dispensed via the one or more applicators flows through the back-pressure regulator and returns to the paint source; and a controller configured to control the pump and the back-pressure regulator to selectively operate in one of a pressure mode and a flow mode, wherein: when in the pressure mode, the back-pressure regulator is active, and the back-pressure regulator and the pump operate together to maintain a pressure at the paint application system; and when in the flow mode, the back-pressure regulator is inactive, and the pump operates to maintain a flow rate of paint through the system. 25. The system of claim 24, wherein, when in the flow mode, the pump operates at a generally constant frequency corresponding to a desired flow rate of paint through the system. 26. The paint circulating system of claim 23, wherein the controller includes a plurality of channels for controlling a plurality of paint circulating systems, each providing paint to a spray booth. 27. A paint application system, comprising: a paint application booth having first and second sets of paint applicators; a first paint circulating system, comprising: a first paint source; a first pump configured to circulate paint through the first paint circulating system to the first set of paint applicators; and a first back pressure regulator back-pressure regulator disposed downstream of the paint application booth; a second paint circulating system, comprising: a second paint source; a second pump configured to circulate paint through the second paint circulating system to the second set of paint applicators; and a second back pressure regulator back-pressure regulator disposed downstream of the paint application booth; and a controller configured to control the first and second paint circulating systems, wherein controlling comprises operating each of the paint circulating systems in a flow mode or a pressure mode, and wherein: the flow mode of operating a desired paint circulating system comprises deactivating the back-pressure regulator associated with the desired paint circulating system and maintaining a required flow rate of paint through the desired paint circulating system via the pump associated with the desired paint circulating system; and the pressure mode of operating the desired paint circulating system comprises activating the back-pressure regulator associated with the desired paint circulating system and maintaining a pressure of paint between the pump associated with the desired paint circulating system and the back-pressure regulator associated with the desired paint circulating system, wherein the set of paint applicators corresponding to the desired paint circulating system is configured to dispense paint when the back-pressure regulator is activated, and wherein the set of paint applicators corresponding to the desired paint circulating system is configured to not dispense paint when the back-pressure regulator is deactivated. 28. The paint application system of claim 27, comprising first and second pressure sensors disposed in the first and second paint circulating systems, respectively, wherein each pressure sensor is configured to provide a pressure signal to the controller when the corresponding paint circulating system is in the pressure mode. 29. The paint application system of claim 27, wherein the controller is configured to control the first and second paint circulating systems based on signals received from a plant scheduling apparatus. 30. The paint application system of claim 27, wherein the controller is configured to control the first and second paint circulating systems based on signals received from a ‘job queue’ data processing apparatus. 31. The paint circulating system of claim 1, wherein the paint circulating system comprises: a second pump for pumping a second paint around the system; a second back-pressure regulator operable in activated state to substantially eliminate pressure fluctuations of the second paint upstream of the second back-pressure regulator, and operable in a deactivated state to enable a second paint flow without being responsive to pressure fluctuations, wherein the applicators are configured to dispense the second paint when the second back-pressure regulator is operating in the activated state, and wherein the applicators are configured to not dispense the second paint when the second back-pressure regulator is operating in the deactivated state; and the controller comprises circuitry to provide one or more electronic control signals for controlling the second pump and the second back-pressure regulator to operate in one of a second flow mode, wherein the second back-pressure regulator is deactivated and a second required flow rate of the second paint around the system is maintained, and a second pressure mode, wherein the second back-pressure regulator is activated and a second pressure of the second paint between the second pump and the second back-pressure regulator is maintained. 32. The paint circulating system of claim 1, wherein the controller comprises a programmable memory for storing a predetermined pressure at which to maintain the pressure of paint between the pump and the back-pressure regulator. 33. The system of claim 24, wherein the back-pressure regulator is disposed downstream of the one or more applicators.