Coating agent pump

Abstract

A coating agent pump for conveying a coating agent, in particular a paint, an adhesive or a sealing agent. The coating agent pump comprises a pump inlet for admitting the coating agent to be conveyed and a pump outlet for delivering the coating agent conveyed by the coating agent pump. In addition to the pump inlet and the pump outlet, a cleaning opening is provided for cleaning the coating agent pump of the coating agent situated in the coating agent pump.

Claims

1. A positive displacement coating agent pump for conveying a coating agent, comprising: a pump chamber, having a pump inlet arranged to receive the coating agent and a pump outlet arranged to deliver a coating agent, the pump inlet and pump outlet being connected to the pump chamber; a displacing element arranged in the pump chamber; a drive arranged to move the displacing element; an inlet valve between the pump inlet and the pump chamber; and an outlet valve between the pump chamber and the pump outlet an ejection opening arranged to allow cleaning of the coating agent from within the coating agent pump, the ejection opening opens into the inlet valve to rinse the inlet valve.

2. The coating agent pump of claim 1, wherein the ejection opening opens from above into the inlet valve.

3. The coating agent pump of claim 2, wherein the inlet valve includes a valve body and the ejection opening opens into the inlet valve at a site downstream of the valve body to allow the ejection medium to flow into the pump chamber in the closed position of the inlet valve.

4. The coating agent pump of claim 3, wherein the closing spring of the inlet valve is supported on a spring seat and presses the valve body into a valve seat, wherein the ejection opening opens into the spring seat.

5. The coating agent pump of claim 4, wherein the closing spring of the inlet valve is a helical spring which is supported on the bottom of the spring seat, wherein the ejection opening opens into the bottom of the spring seat.

6. The coating agent pump of claim 5, wherein the ejection opening opens essentially coaxially with the helical spring into the bottom of the spring seat.

7. The coating agent pump of claim 1, further comprising a controllable ejection valve which is integrated into one of the coating agent pump and the feed line of the ejection medium, and controls the feed flow of the ejection medium through the ejection opening into the coating agent pump.

8. A method for removing coating agent from a coating agent pump, wherein the coating agent pump comprises a pump inlet and a pump outlet, the method comprising: removing coating agent situated in the coating agent pump using an ejection opening that is provided in the coating agent pump in addition to the pump inlet and the pump outlet operating the coating agent pump with a first coating agent; switching off the coating agent pump so that the coating agent pump conveys no further coating agent; feeding in blowing-out air via the ejection opening to eject the remaining coating agent situated in the coating agent pump; feeding in a mixture of blowing-out air and rinsing agent via the ejection opening; feeding in rinsing agent via the pump inlet to rinse the coating agent pump with the rinsing agent, wherein the rinsing agent is ejected with the rinsed out coating agent via the pump outlet; feeding in blowing-out air via the ejection opening to eject the rinsing agent situated in the coating agent pump; and operating the coating agent pump with a second coating agent.

Description

BRIEF SUMMARY OF THE DRAWINGS

(1) Other advantageous developments are disclosed in the claims or are described below in greater detail together with the description of the preferred exemplary embodiment of the invention, making reference to the drawings. In the drawings:

(2) FIG. 1 shows a cross-sectional view of an example coating agent pump in a painting system,

(3) FIG. 2 shows a cross-sectional view of the coating agent pump of FIG. 1 along the section line A-A in FIG. 1,

(4) FIG. 3 shows an enlarged cross-sectional view through an inlet valve of the coating agent pump of FIGS. 1 and 2, and

(5) FIG. 4 shows a flow diagram to illustrate a cleaning process.

DESCRIPTION

(6) FIGS. 1 to 3 show an example coating agent pump 1 in a painting system for painting motor vehicle bodywork components, wherein the painting system is otherwise shown only rudimentarily because the painting system per se can be configured in a conventional manner.

(7) The coating agent pump 1 conveys the paint to be applied from a feed line 2 to an outlet line 3, as is per se known from the prior art. For connecting to the feed line 2, the coating agent pump 1 has two pump inlets 4, 5, whilst for connecting to the outlet line 3, the coating agent pump 1 has two pump outlets 6, 7.

(8) In this exemplary embodiment, the coating agent pump 1 is configured as a double diaphragm pump and has two pump chambers 8, 9 in each of which a flexible diaphragm 10, 11 is arranged as the displacing element.

(9) The driving of the coating agent pump 1 is carried out by a pneumatic air motor, which is shown here schematically. The air motor comprises a piston 12 which is displaceably arranged in a cylinder 13, the piston 12 being connected by a piston rod 14 to the two diaphragms 10, 11, so that the position of the piston 12 also determines the position of the two diaphragms 10, 11 within the pump chambers 8, 9. The driving of the piston 12 takes place pneumatically in that compressed air is applied (not shown in the drawing) to the left or right side of the piston 12. In normal pumping operation, the piston 12 carries out an oscillating linear movement within the cylinder 13 and this movement is transmitted by the piston rod 14 to the two diaphragms 10, 11.

(10) The pump inlets 4, 5 are each connected via an inlet valve 15, 16 (alternately referred to as a non-return valve) to the respective pump chamber 8 or 9.

(11) In the same way, the pump inlets 6, 7 are each connected via an outlet valve 17, 18 (alternately referred to as a non-return valve) to the respective pump chamber 8, 9.

(12) During the oscillating movement of the diaphragms 10, 11, therefore, coating agent is alternately drawn in via the respective pump inlet 4 or 5 and the inlet valve 15 or 16 into the pump chamber 8 or 9 and is then ejected via the respective outlet valve 17 or 18 and the pump outlet 6 or 7. The two pump chambers 8, 9 herein operate phase-shifted, so that a relatively small degree of ripple results in the pumping output of the coating agent pump 1.

(13) Furthermore, for each of the two pump chambers 8, 9, the coating agent pump 1 has an ejection opening 19, 20 (alternately referred to as a blowing-out opening) which is connected to a compressed air line 21.

(14) The feeding of compressed air via the ejection opening 19, 20 enables cleaning of the coating agent pump 1, as described in detail below.

(15) In the interior of the coating agent pump 1, the ejection openings 19, 20 are each connected via an ejection valve 22, 23 to the respective non-return valve 15 or 16.

(16) The inlet valves 15, 16 each have a closing spring 24, 25 which presses a valve ball 26, 27 into a valve seat 28, 29 to close the respective inlet valve 15 or 16. The spring seat of the closing springs 24, 25 forms a dead space within the coating agent pump 1 which does not lie in the flow path between the pump inlet 4, 5 on one side and the pump outlet 6, 7 on the other side, so that this dead space is difficult to clean in the conventional manner. The blowing-out openings 19, 20 therefore each open coaxially into a bottom 30 (see FIG. 3) of the spring seat, so that the blowing-out air introduced is introduced essentially coaxially to the respective closing spring 24, 25.

(17) Firstly, thereby, the dead space situated in the region of the closing springs 24, 25 is effectively cleaned of coating agent.

(18) Secondly, it should be considered that the blowing-out air is introduced from above, which contributes to an effective cleaning action. This is due thereto that the blowing-out air is lighter than the liquid coating agent so that the blowing-out air introduced effectively removes the coating agent from the inlet valves 15, 16 and thereby thoroughly cleans the coating agent pump 1.

(19) The cleaning method which is carried out on a paint change of the coating agent pump 1 will now be described making reference to the flow diagram in FIG. 4.

(20) In a first step S1, initially operation of the coating agent pump 1 with a coating agent A is still taking place.

(21) On a paint change, next in step S2, the coating agent pump 1 is stopped, i.e. no further driving of the piston 12 takes place.

(22) In a subsequent step S3, blowing-out air is then fed in via the ejection openings 19, 20 to remove the coating agent A remaining in the coating agent pump 1 as fully as possible from the coating agent pump 1. The coating agent remaining in the coating agent pump 1 is herein blown out of the coating agent pump 1 via the pump outlets 6, 7.

(23) Subsequently, in step S4, feeding in of a pulsed mixture of rinsing agent and blowing-out air takes place via the blowing-out openings 19, 20 to optimise the subsequent rinsing process.

(24) During the actual rinsing in step S5, the rinsing agent is then fed in via the pump inlets 4, 5 and ejected again via the pump outlets 6, 7.

(25) In step S6, blowing-out air is then fed in via the ejection openings 19, 20 to rinse out the rinsing agent remaining in the coating agent pump 1 via the pump outlets 6, 7.

(26) The invention is not restricted to the above-described preferred exemplary embodiments. Rather a plurality of variants and derivations is possible which also make use of the inventive concept and therefore fall within the scope of protection. In particular, the invention also claims protection for the subject matter and the features of the subclaims separately from the claims to which they each refer.