This invention relates to a paint toning machine for dispensing solvent-diluted colour pastes in particular, comprising a plurality of paste con¬ tainers provided with a cover preventing the evapor¬ ation of the solvent of the colour paste, and a plu¬ rality of colour paste pumps for pumping paste for the dispensing or circulation thereof, each colour paste container comprising one pump.

.» A paint toning machine of the above type is known e.g. from Australian Patent Specification 162 212. In the paint toning machine of this publica¬ tion, the dispensing and circulating pump for the col- our paste is a gear-type pump positioned outside the colour paste container and connected both to the col¬ our paste container and to a dispensing nozzle by means of hose connections. However, there always exists a risk of leaks in this kind of arrangement, because the hose connections both on the suction and delivery side of the pump are positioned in an open space. In addition, the pump itself has to be encased tightly. This is especially important when solvent-di¬ luted colour pastes are used, as the solvents very easily penetrate through the seals, which causes the colour paste to be hardened and the pipe connections to be clogged. Further, when coming into contact with the seals solvents tend to make the seals inelastic, which can lead to leaks and even to jamming of the drive shaft of the pump. The biggest problem with leaks, however, is the risk of explosion because the used solvents are very inflammable.

The object of the present invention is to pro¬ vide a paint toning machine in which the above prob- lems are essentially eliminated. This is achieved by

means of a paint toning machine according to the in¬ vention, which is characterized in that each pump is arranged in its paste container in the vicinity of a bottom thereof essentially below the surface of the colour paste contained in the container and comprises a drive shaft which is led through the cover of the container through a gas-tight through hole. As the pump is so immersed in the colour paste, neither the pump itself nor the connections of the suction and pressure conduits of the pump need be absolutely gas- tight. Since it is possible to construct the paste container into an essentially closed space wherefrom the drive shaft of the pump and possibly also a dis¬ pensing hose project through gas-tight through holes, possible leaks in the pump or the pipe connections thereof cannot have the above-mentioned adverse ef¬ fects.

In the following the paint toning machine ac¬ cording to the invention will be described in more de- tail with reference to the attached drawings, wherein Figure 1 is a cross-sectional side view of one paste container of the paint toning machine according to the invention, and

Figure 2 is a cross-sectional view of the paste container of Figure 1 along the line A-A in Figure 1. Figure 1 shows one of a plurality of paste con¬ tainers comprised in the paint toning machine accord¬ ing to the invention; this container is indicated with the reference numeral 1. A gear-type pump 2 is im- mersed in the colour paste contained in the paste con¬ tainer, and a drive shaft 5 of the pump is led through a cover 6 of the container through a gas-tight through hole 7. The cover 6 of the container is arranged on the container 1 as tightly as possible. In the embodi- ent of the invention shown in Figure 1, the pump as

such is not encased separately in such a- manner that it would comprise pipe connections for suction and pressure conduits; instead, suction and pressure con¬ duits 8 and 9 are formed by means of a floor 10 posi- tioned above a container bottom 4. The floor 10 also forms a structural part of a dispensing valve 11 at¬ tached to the colour paste container 1 in such a man- ner that it forms a seat for an upper conical surface 13 of a spindle 12 of the dispensing valve 11. When the valve 11 is in the position shown in Figure 1 and the pump 2 is on, the paste 3 flows as shown by the dark arrows in the figure in such a manner that it is sucked through the suction conduit 8 into the pump 2, and it leaves the pump through the pressure conduit 9 and a return conduit 14 going through the floor 10, and returns to the paste container. In this way, the colour paste can be circulated and mixed in the container. When the spindle 12 of the valve 11 is lifted to its upper position by means of a valve oper- ating means 15 positioned on the cover 6 and a valve drive shaft 16, a dispensing outlet of the pressure conduit is -opened through the bottom 4 of the contain¬ er 1 via a conduit 17 to a colour paste dispensing nozzle (not shown) . Figure 2 shows a section of the colour paste container of Figure 1 along the line A-A shown in Figure 1. It appears from Figure 2 that the pump 2 is a gear-type pump comprising a primary gearwheel 18 at¬ tached to the drive shaft 5 and a secondary gearwheel attached to a support shaft 19. As is to be seen in Figure 2, the colour paste container 1 is essentially round in shape with the exception of the projection formed for the dispensing valve.

The paint toning machine according to the in- vention and especially the dispensing pump immersed in

the colour paste contained in the paste container hav been described above only by way of example by mean of one specific embodiment. It is to be understoo that the idea according to the invention of immersin the dispensing pump in the colour paste could be real ized also by a conventional dispensing pump. As thi pump and the pipe connections thereof would also b wholly immersed jji the colour paste, the same advan tages as described above can be achieved in this case too, concerning leaks in the pump itself or the con nections thereof.