The present invention relates to a device and method for applying a food fluid or suspension to a substrate formed by a food too.

Devices and methods for applying a fluid on a substrate are known in the art. One example are so-called nozzle-jets, that make individual droplets from a fluid, which droplets are then applied to the substrate. The droplets are made and applied by a nozzle-jet. A nozzle is an orifice through which a small amount of liquid can be shot at a high velocity. When the nozzle-opening is closed by the closing a membrane and the space around the nozzle is filled with fluid under a certain pressure, then the gap can be opened during a few milliseconds to allow a small amount to escape.

When the pressure in an air chamber is at a higher pressure than the liquid in a container, the liquid can be recirculated through the printing head, back to the return piping without depositing.

When during a very short time the pressure in the chamber air pressure drops to zero, the mass pressure lifts the membrane from the spray nozzle.

When the pressure comes back to the air chamber, the membrane is pushed back onto the nozzle. This occurs with a considerable speed which helps a droplet to break away from the surface tension.

By using a plurality of abovementioned nozzlejets in combination with a moving target, matrix-like patterns can be deposited. In addition, by using an array of nozzle-jets in an oblique angle with a time lag compensation, the resolution of the pattern can be higher than the array line pitch. An example of the thus described state of the art is described in the European Patent EP1958517 from the same applicant.

From US 2003/178504 it is generally known to use pinch valves instead of nozzle jets. This type of valve has a the transport channel made out of a flexible material. When this flexible part of the channel is pressurized from the outside, it will collapse and stop the internal flow of material. However, both devices according to the state of the art were never developed for substances that may exert forces on the throughput channels of the valves, for instance because they contain relatively big particles; as an example sauces with pureed vegetables and meats. Additionally, the devices according to the state of the art are not suitable for the high speeds required for nowadays applications.

In devices with nozzles, if these substances are used as a liquid, nozzles may tend to block or give distorted droplet jets, since small fibrous coagulates will get stuck at the nozzle orifices. This may for instance be a result from a separation effect between the liquid part and the solid part of the to be printed suspension, which can be a puree or the like. The effect may in particular be present with materials that had been frozen first.

In devices with pinch valves according to the state of the art, due to the particle sizes, the channels of the pinch valves tend to constipate, and as a result of the forces exerted on them they may even get loose from their position.

It is therefore a goal of the present invention to take away the disadvantages of the prior art and to provide a solution for printing fluids or suspensions with a higher viscosity. The invention thereto proposes a device for applying a food fluid or suspension onto a substrate, comprising a reservoir for the fluid or suspension, means for bringing the fluid or suspension under pressure above atmosphere pressure, a plurality of outlet channels, extending from the reservoir to a delivery-position for the fluid above the substrate, a plurality of controllable valves, each incorporated in one of the outlet channels, a controller for controlling the valves individually, wherein the valves are pinch valves; each comprising an elastic hollow throughput channel, surrounded by a pressure chamber for a medium, wherein the channel can be opened and closed by respectively decreasing and increasing the medium pressure, characterized in that the channel comprises a cylindrical body, stretching between two annular flanges, wherein the flanges each have an inwardly protruding circumferential wall.

The annular flanges having an inwardly protruding circumferential wall assure that the channel is not pushed of pulled off its place due to the (under) pressure exerted on it. These walls are facing each other, and thus surrounding the channel. The forces acting on the channel may both be the pressure on the fluid or suspension, or a vacuum applied in the chamber surrounding the channel. The apparatus according to the invention may for instance be used for applying unsieved tomato sauce, unsieved potato mash, viscous aerated cream - sugar mixture, marinade (fat pepper salt) and/or chocolate compounds with high milk powder content. The controller is designed for controlling the controllable valves with frequencies of between 0,5 and 10 Hz, and in particular between 1 and more than 5 Hz, and in order to be able to reach these frequencies, the elastic hollow throughput channels have a wall with an inner diameter between 3 and 5 mm, an outer diameter between 4 and 8 millimeter, a flange diameter C between 12 and 16 millimeter and a channel length between 10 and 20 millimeter.

In order to accommodate the flexible parts of the pinch valves, the device according to the invention may comprise an essentially massive block, comprising a number of through holes, each with a bore larger than the diameter of the hollow throughput channel, for each forming a pressure chamber, wherein at both ends of each through-hole a recess is provided for form- fittingly receiving the annular flange and the inwardly protruding circumferential wall.

The elastic hollow throughput channel may be manufactured with the aid of silicone injection moulds, and in a pressurized state, the connection of the cylindrical body to the annular flanges may comprise a funnel, widening towards the annular flanges, so that an hour-glass shape is obtained.

Materials that have proved to be suitable for the elastic hollow throughput channel are silicone rubber or EPDM, while the inner diameter lies between 1 and 10 millimeter and the outer diameter lies between 1 and 10 millimeter. The length of the channel between the flanges is typically 3 to 5 times the diameter, and a threshold pressure for an (empty) elastic hollow throughput channel to close or open may lie between 0,2 and 6 bar. In a practical embodiment, the outlet channels are formed by bores in an essentially massive block. Such block may be formed by at least two parts, wherein the elastic hollow throughput channels are arranged in recesses at the plane of intersection of the two parts. This construction has appeared to be very robust and is relatively easy to manufacture.

The massive block comprises channels for the medium, that extend from an actuator for delivering medium under pressure, to the medium chamber, surrounding the elastic hollow throughput channel.

A higher flexibility and an increased number of possibilities can be obtained when the device according to the invention is suspended movable, in particular translatable and/or rotatable with respect to the substrate.

The controller may be configured for controlling the volume or the launching speed of droplet of the fluid.

The invention further relates to a device for applying a fluid or suspension, in particular a food fluid or suspension onto a substrate, comprising a reservoir for the fluid or suspension, means for bringing the fluid or suspension under pressure above atmosphere pressure, a plurality of outlet channels, extending from the reservoir to a delivery-position for the fluid above the substrate, a plurality of controllable valves, each incorporated in one of the outlet channels, a controller for controlling the valves individually, wherein the valves are pinch valves; each comprising an elastic hollow throughput channel, surrounded by a pressure chamber for a medium, wherein the channel can be opened and closed by respectively decreasing and increasing the medium pressure, characterized in that the elastic hollow throughput channels have a wall with an inner diameter between 3 and 5 mm, an outer diameter between 4 and 8 millimeter, a flange diameter C between 12 and 16 millimeter and a channel length between 10 and 20 millimeter. In an embodiment thereof, the controller is configured for switching the valves between an open and a closed position with a frequency between 0,5 and 10 Hz., and in particular between 1 and 5 Hz. The invention will now be elucidated into more detail with reference to the following figures. Herein:

Figure 1 shows a perspective sectional view of a pinch valve according to the state of the art;

- Figure 2 shows an elastic hollow throughput channel according to the invention and a perspective sectional view thereof;

Figure 3A shows an exploded view of a device according to the present invention;

Figure 3B shows a perspective sectional view of a device according to the present invention;

Figure 4 shows a perspective view of a device according to the present invention;

Figure 5 shows a perspective view of an alternative embodiment of a device according to the present invention;

- Figure 6 shows a perspective view of an assembly of elastic hollow throughput channels, formed integrally in one block; and

Figure 7 shows an essentially massive block, for receiving the assembly of figure 6. Figure 1 shows a perspective sectional view of a pinch valve 1 in general. The pinch valve 1 comprises an elastic hollow throughput channel 2, 3, surrounded by a pressure chamber 4 for a medium, wherein the channel can be opened and closed by increasing respectively decreasing the medium pressure via a medium channel 5. Figure 2 shows an elastic hollow throughput channel 2, 3 in a perspective and sectional view thereof. The elastic hollow throughput channel has a wall with an inner diameter A between 3 and 5 mm, an outer diameter B between 4 and 8 millimeter, a flange diameter C between 12 and 16 millimeter and a channel length D between 10 and 20 millimeter. The wall thickness of the channel may be between 1 and 2, and preferably between 1 and 1,5 mm.

Figure 3A shows an exploded view 6 of a device according to the present invention, and figure 3B a perspective sectional view 7 of the same. The device comprises a reservoir 8 for the fluid or suspension, (non depicted) means for bringing the fluid or suspension under pressure above atmosphere pressure, and a plurality of outlet channels 9, extending from the reservoir 8 to a delivery-position 10 for the fluid above the (non-depicted) substrate, a plurality of controllable valves 11, each incorporated in one of the outlet channels 9, a controller 12 for controlling the valves 11, wherein the valves are pinch valves and the controller 12 is configured for controlling the valves 11 individually.

Figure 4 shows a perspective view of a device 13 according to the present invention, for applying a fluid or suspension 16, in particular a food fluid or suspension onto a substrate 17, suspended 15 movable, in particular translatable and/or rotatable with respect to the substrate 15, which is transported on a transport belt 14.

Figure 5 shows an alternative embodiment 18 of the present invention. Instead of a configuration wherein the nozzles 19 have a fixed mutual distance, the distance of the nozzles 19 can be changed, by removing them from a central tube and replacing them at a desired distance. This way, there is no need to place the head diagonally oriented above a transport belt for a substrate, but a rectangular orientation can be used at all time. Figure 6 shows a perspective view of an assembly 20 of elastic hollow throughput channels 21, formed integrally in one block, according to yet another embodiment of the present invention.

Figure 7 shows (half of a) block 22, arranged for forming, together with a complementary block 22' (indicated with a dashed line, and to be put against block

22 in the direction G) a number of through holes 23, each with a bore larger than the outer diameter 21 ' of the hollow throughput channel 21 from the device 20 from figure 6, each hole 23 for forming a pressure chamber. Block 22 is provided with hollow connections 24 that each lead to a corresponding valve 25, for providing pressure for closing the throughput channels 21. Suitable valves for the various embodiments of the present invention are for instance the Matrix 320 series.