[0001 ] Fluid distribution circuits may be used for distributing a fluid, such as a gas or liquid or slurry from an inlet to one or more outlets. Fluids may be transported through such fluid distribution circuits using one or more pumps.

[0002] In certain implementations, an outlet of such a distribution circuit may be relatively wide as compared to the inlet. In these implementations a uniform fluid flow along the entire fluid outlet may not always be achieved, especially in cases in which the distance between the inlet of the circuit and the outlet is relatively short.

[0003] It is known to provide a large plurality of small nozzles along such a wide outlet and provide a high pressure gradient across these nozzles in an attempt to equalize fluid flow rate along the outlet. However, this implies that a sufficiently powerful pump needs to be used. And a high pressure gradient may be problematic when e.g. combustible fluids are to be used. Additionally, when a high pressure gradient is used, the velocity of the fluid flow at the outlet may be relatively high and the fluid flow may be turbulent. Depending on the application, this can have negative effects as well.

[0004] In systems according to the examples of the present invention, at least some of the above-mentioned problems can be resolved or reduced.

[0005] Particular examples of the present invention will be described in the following by way of non-limiting examples, with reference to the appended drawings, in which:

[0006] Figure 1 schematically illustrates an example of a fluid distribution circuit;

[0007] Figure 2 schematically illustrates another example of a fluid distribution circuit; and

[0008] Figures 3a - 3j schematically illustrate another example of a fluid distribution circuit. [0009] Figure 1 schematically illustrates an example of a fluid distribution circuit. The fluid distribution circuit may comprise an inlet 10 and an outlet 90. The outlet may be shaped as a slit. A slit in this respect may be regarded as a long and narrow opening. The outlet slit may be long in particular in comparison with the inlet. The slit may be defined as narrow since the width of the opening is several times smaller than the length of it. In figure 1 , the length of the outlet slit is defined along a first direction 1 and the width is defined along a second direction 2, perpendicular to the first direction 1 .

[0010] The fluid distribution circuit may comprise a plurality of fluid paths xi , X2, ■ x _n , Xn+i , n+2, x _n +3 etc. Each of the fluid paths leads from the inlet 10 and to the outlet 90. The flow distribution circuit may be such that all fluid paths defined between the inlet 10 and the outlet 90 have substantially the same length.

[001 1 ] If all fluid paths have substantially the same length, it can be achieved that the flow impedance of each of the channels is the same as well. In order to achieve the same flow impedance, the cross-sections of the fluid paths may be substantially the same as well. If the flow impedance of each of the channels is the same, then the fluid flow out of the outlet slit 90 may be substantially uniform along the entire length of the slit.

[0012] This kind of fluid distribution circuit does not require a high pressure gradient in order to ensure such a uniform flow rate. By maintaining the pressure gradient low, the fluid flow at the outlet may not only be uniform, but also laminar. By achieving a uniform outlet flow, the flow may have the same velocity along the entire length of the slit. Potential problems related to shear stresses in the fluid may thus also be avoided or reduced.

[0013] Figure 2 schematically illustrates another example of a fluid distribution circuit. A fluid distribution circuit may comprise a fluid inlet 10 and a fluid outlet slit 90. The fluid outlet slit has a length defined along a first direction 1 , and a width defined along a second direction 2, which is perpendicular to the first direction. The length is several times larger than the width.

[0014] The fluid distribution circuit of the example of figure 2, transports fluid from the inlet to the outlet along a third direction 3, which is perpendicular to both the first direction 1 and second directions 2.

[0015] The fluid distribution circuit in this example may comprise a plurality of consecutive parallel channels, the consecutive parallel channels having half the length of the previous parallel channel. The fluid paths from the fluid inlet to the fluid outlet may be partially defined by portions of these channels.

[0016] In the example of figure 2, the fluid distribution circuit includes various stages. These stages comprise an upstream channel 20, two channels 30 downstream from channel 20 and parallel to channel 20. The next stage may comprise four channels 40 downstream from channels 30. Similarly, eight channels 50 may be provided. These consecutive substantially parallel channels extend mainly along the first direction 1 . The channel of first stage 20 may comprise two halve channels 22 and 24. An end portion of the channel of the first stage may be connected to a central portion of a channel of the second stage 30. The end portion of half channel 22 may be connected to a central portion of a channel 30. The end portion of half channel 24 may be connected to a central portion of a second channel 30.

[0017] The channels 30 of the second stage may be substantially parallel to the channel 20 of the first stage and may have substantially half the length of the previous channel. The channels 30 also comprise two halves 32 and 34. End portions of these halves are connected to central portions of channels 40. The consecutive parallel channels have half the length of the previous parallel channel. The consecutive parallel channels wherein end portions are connected to central portions of the next parallel channel having half the length ensure that fluid paths of equal length are provided and that the end points of these channels are substantially equispaced.

[0018] Several fluid paths may be defined by different portions of the channels 20, 30, 40, and 50. A fluid path 71 may comprise the "left" (see figure 2) halves of each of the channels. A fluid path 72 may comprise the left portion of channel 20, the right portions of channels 30 and 40 and a left portion of channel 50.

[0019] A plurality of divergent openings 62 may be equispaced along the outlet slit. These openings may form the last stage 60 of the distribution circuit. The downstream ends of the divergent openings form the outlet slit.

[0020] Many different fluid paths may be defined along the various portions of the channel, but they all have substantially the same length. All fluid paths may thus also have the same flow impedance.

[0021 ] Figures 3a - 3j schematically illustrate another example of a fluid distribution circuit.

[0022] The fluid distribution circuit in this example may comprise a stack of layers and channels may be defined in each of these layers. The fluid paths in communication with the inlet and outlet may be defined by portions of these channels. The fluid paths extending through several layers make it possible to distribute fluid from a relatively narrow inlet to a wide slot and achieve a plurality of fluid paths of substantially the same length when the distance between the inlet and the outlet is small.

[0023] The fluid distribution circuit of this example may include a central layer, an upper layer and a lower layer. The upper layer may include a first upper level and a second upper level and the lower layer may include a first lower level and a second lower level as will be explained now. In this example, identical channels may be provided in the upper layer and lower layer, i.e. the fluid distribution circuit may be symmetric with respect to the central layer.

[0024] Figure 3a shows an isometric view of the stack of layers, and figure 3b shows an exploded view of the same stack. Figure 3c shows a view of a first upper level of the stack and figure 3d shows a part of the first upper level in more detail. Figure 3e shows a view of a second upper level of the stack and figure 3f shows a part of the second upper level in more detail. Figure 3g shows a view of a central level of the stack and figure 3h shows a part of the central level in more detail. Figure 3i shows the distribution circuit of this example mounted in a fluid chamber. Figure 3j shows the fluid flows through the distribution circuit of this example.

[0025] The fluid outlet slit 90 may extend substantially along the first direction 1 . The width of the slit is defined in a second direction 2 perpendicular to the first direction. [0026] In the example of figure 3, the upper layer may have a first level 500 and a second level 200. Similarly, the lower layer may have a first level 500' and a second level 200'. In this case, the first level may have twice the thickness of the second level, the first upper level comprising two identical layers 300 and 400 and the first lower level comprising two layers 300' and 400'.

[0027] Each of the layers may have the same thickness, and may be made from the same material e.g. metal sheet or another suitable material. The channels may be made e.g. by punching or stamping or laser cutting, although other manufacturing methods may be used. They may thus be considered as cut-outs from the layers of material.

[0028] The cross-sections of the channels may vary in accordance with circumstances, e.g. pump performance, and required fluid flow rate at the outlet. The first levels of the upper and lower layer having twice the thickness of the other layers in this case may simplify manufacturing as two identical sheets may be used.

[0029] The parallel channels defined in the first upper level 300, 400 extend substantially along a first direction 1 . Similarly, the first lower level defines the same channels. With reference to figure 3c, the inlet of layer 300 of the first upper level may be connected to opening 310 of layer 300. A first channel 320 extends substantially along the first direction.

[0030] The next channel 330 is substantially parallel to the first channel 320 and has about half the length of the first channel. Two of such channels 330 are provided. Similarly, the next consecutive channel 340 is parallel to these channels but has about half the length of the previous channel. Thus, four of these channels may be provided. And similarly again, eight parallel channels 350 may be provided that have substantially half the length of the previous parallel channels 340. And sixteen channels 360 parallel to the previously defined channels and having half the length of the channels 350 may form the last stage of the first upper level.

[0031 ] With reference to figure 3e, channels are also defined in the second level (of both the lower and upper layer). Opening 210 is connected to the inlet. A first channel 220 may be defined that substantially coincides with the channel 320. An end portion 227 of channel 220 extends substantially in the third direction and thereby connects an end portion of channel 310 to a central portion of channel 320.

[0032] Similarly, channel 230 may comprise a portion that extends in the first direction 233 and a portion that extends in the third direction 237. First portion 233 extending in the first direction coincides with a part of channel 330. The portion 237 extending in the third direction, i.e. "in the direction of the outlet", connects an end portion of channel 330 with a central portion 340.

[0033] Channel 240 of the next stage in the second level comprises a portion 243 extending in the first direction that coincides with an end portion of channel 340 of the first level, and a portion 247 extending in the third direction. The portion 247 extending in the third direction serves to connect an end portion of channel 340 of the first level with a central portion of channel 350 of the first level. Similarly, the channels 350 of the first level may be connected to channels 360 of the first level through channels 250 of the second level. In particular, the portions 257 of the channels 250 that extend in the third direction serve to connect channels 350 with the channels 360.

[0034] Central layer 100 in this example may include an opening 1 10 in connection with the fluid inlet. Thus at this first stage of the distribution circuit, the fluid may flow into the upper layer or the lower layer of the stack, thus starting two alternative fluid paths. Two holes 120 of a first stage connect the lower layer with the upper layer at the point where channel 220 of the second level connects channel 310 of the first level with channel 320 of the first level. The effect of the connections between the upper layer and the lower layer is that the fluid flows between these layers may be more equalized.

[0035] Similarly, central layer 100 may comprise four holes 130, and eight holes 140 and sixteen holes 150 for the connections between the upper layer and the lower layer at the next consecutive parallel channels defined in the first levels of the upper layer and lower layer. Since the length of the fluid channels in the first direction in the first level of the upper and lower layers are cut in half at each consecutive stage, the number of channels is doubled at each consecutive stage. [0036] A plurality of divergent openings 160 is arranged along the outlet slit. The divergent openings form the last stage of the fluid paths. In this example, the divergent openings 160 may have a concave portion 163 and a convex portion 167. The openings are thus shaped in the form of consecutive waves. The fillet radius of the portions may be large enough in order to avoid flow separation and turbulence in the fluid. Alternative shapes for the openings may be used. If laminar fluid flow is to be maintained, sharp edges and bends and curves with small fillet radius are to be avoided.

[0037] Fluid flow from channels 360 in the first level reaches the divergent openings 160 through the end portions 361 of channel 360, see e.g. figure 3d. These end portions connect with openings 260 in the second level, see e.g. figure 3f.

[0038] The channels 350 may have a central protuberant hole 357, see figure 2d. This hole 357 may coincide with hole 257 in the second level, see figure 2f and with hole 157 in the central layer, see figure 3h. Thus also at this point, a fluid communication between the upper and lower layer may be established with a goal to further equalize flows at all points of the distribution circuit.

[0039] Central layer 170 may furthermore comprise a forward extending lug 170 at each end. With reference to figure 3i in particular, the stack of layers forming the fluid distribution circuit may be mounted between two housing portions 610 and 620. In order to house the distribution circuit, an appropriate recess may be provided mounted in each of the housing portions.

[0040] The forward extending lugs 170 separates the housing portions and thus defined the width of the outlet slit, i.e. the divergent openings 160 in the central layer form the opening of the outlet slit.

[0041 ] Similarly, at the entry side of the fluid distribution circuit, the central layer may comprise a portion 180 (see figure 3a) which sticks out rearwardly in comparison with the other layers. When the distribution circuit is mounted between the housing portions 610 and 620, this rearward portion 180 of the central layer may be used for fitting fasteners such as e.g. screws or bolts to attach the housing portions. Similarly, the forward extending lugs 170 in some examples may also comprise holes for fitting fasteners used in connecting the housing portions.

[0042] Such an arrangement may be used in various different implementations. In one implementation, a cleaning fluid may be provided to a drum of a photo imaging plate (PIP) of a printing apparatus in order to clean and cool the drum. A foam roller may be pressed against the outlet 90 in figure 3i, the foam roller being in contact with the PIP drum.

[0043] A resultant fluid flow of the previously described example of a fluid distribution circuit may be illustrated with the help of figure 3j. Flow 610 represents the supply of the fluid to the inlet of the distribution circuit. It may be seen that flow 610 is split in a flow 620a and 620b in the upper and lower layer. These flows are formed by the channels 320 in the first upper and first lower level. At an end of this channel, a connection may be seen between the upper flow and the lower flow established by a hole in the central layer. As previously explained, this connection may be established by openings 120 in the central layer, see e.g. figure 3a.

[0044] The flows on both the left hand and right hand side are then split, both in the upper and lower layer, in multiple flows 630. The splitting of the flows in consecutive parallel channels, each having half the length of the channel directly upstream may be seen in flows, 630, 640, 650 and 660. Fluid communication between the lower layer and upper layer may be established at each of the junctions between these parallel channels as may be seen in figure 3j.

[0045] The flow 670 corresponds to the flow at the divergent openings of the central layer. The shape of the divergent openings may be recognized at this stage. Flow 690 is a substantially uniform flow at the outlet 90. Flow 695 represents the fluid flow around a foam roller as previously explained.

[0046] Although only a number of particular embodiments and examples of the invention have been disclosed herein, it will be understood by those skilled in the art that other alternative embodiments and/or uses of the invention and obvious modifications and equivalents thereof are possible. Furthermore, the present invention covers all possible combinations of the particular embodiments described. Thus, the scope of the present invention should not be limited by particular embodiments, but should be determined only by a fair reading of the claims that follow.