The invention relates to a device for distributing a liquid substance. The liquid substance is for instance a liquid, such as water, or a mixture of liquids and/or solid substances, such as milk or mash. The liquid substance can particularly be a liquid cattle feed, such as milk or mash for feeding piglets. Such a device is used to transport the liquid substance to a number of draw-off points. Such a device is for instance applied in an animal accommodation, wherein each draw-off point debouches into a trough, so that feed is automatically guided to the troughs.

Diverse devices are known in practice for distributing liquid cattle feed, such as milk or mash, to a number of draw-off points. Such a system is for instance applied for feeding piglets. Providing milk and/or mash in the animal accommodation results among other things in fewer stragglers, i.e. fewer piglets showing insufficient growth. In known systems the feed is pumped from a central feed mixer into a conduit. A pump, for instance an air-driven diaphragm pump, is arranged for this purpose in the conduit. The conduit is usually embodied as a ring conduit, wherein the conduit in turn debouches into the central feed mixer. The feed is pumped around continuously in such a system, whereby a pressure is present in the conduit. The conduit has a number of draw-off points. The draw-off points debouch into a trough. When a draw-off point is opened, the feed will flow from the draw-off point and into the trough due to the pressure present. If the liquid cattle feed is a mixture, such as milk or mash, the pumping around moreover has the function of preventing settling of the mixture. If the cattle feed is a pulp such as mash, the continuous pumping around moreover prevents caking onto the conduit.

A drawback of conventional devices is that the pump is a vulnerable component which is prone to malfunction and susceptible to wear. It is particularly when the substance to be pumped is a pulp, such as mash, that the pumps break down quickly, for instance due to fouling of the valves of the pump. In that case the system has to be shut down in order to repair or replace the pump. For diaphragm pumps it is moreover the case that they can become jammed due to compressor air contaminated with water or oil, which is not unusual when used in an animal accommodation.

An object of the invention is to obviate or at least reduce the above stated problem and to provide a low-maintenance device for distributing a liquid substance such as liquid cattle feed.

This object is achieved with the device according to the invention for distributing a liquid substance, such as liquid cattle feed. The device comprises:

at least two containers for the liquid substance;

a conduit which mutually connects the containers for transport of the liquid substance between the containers, wherein the conduit is provided with a number of draw-off points; a pump system for pumping the liquid substance between the containers;

and a control mechanism for controlling the pump system;

wherein the pump system comprises a pneumatic system configured to adjust the gas pressure in at least one container and wherein the control mechanism is configured to control the pneumatic system in a first state to increase the gas pressure in a first container relative to the gas pressure in a second container, so that liquid substance flows from the first container to the second container.

The draw-off points for instance each debouch into a trough for the purpose of distributing cattle feed. The draw-off points comprise for instance a valve which is controlled on the basis of a sensor which registers the quantity of feed in the trough. In another example the draw-off point is connected to a trough with a so-called nipple or valve, wherein feed is admitted into the trough when an animal presses against the nipple.

Each container is for instance formed by a reservoir or tank.

The device comprises for instance 2, 3 or more containers.

The system pumps the substance pneumatically, i.e. on the basis of gas pressure. By pumping the liquid substance with gas pressure, there are no moving parts of the pump which come into contact with the substance to be pumped, as there are in conventional devices. The device according to the invention hereby requires little maintenance.

A further advantage of the invention is that the system can be cleaned with warm water. The device can for instance be cleaned with water of more than 30° Celsius, more than 40° Celsius, more than 50° Celsius or even more than 60° Celsius. This is not possible in conventional devices since the pump which is present in the conduit is not resistant to such temperatures. It is noted that the water for cleaning cools in the conduit(s) of the device. The water will have cooled

considerably in the parts of the conduit system situated a certain distance from the warm water supply. Because hot water can be used according to the invention, the water is however also sufficiently warm for effective cleaning in the remote conduit parts of the device.

A cleaning agent can if desired be used to clean the device. The device according to the invention has the advantage here over conventional devices that warm or hot water can be used, this increasing the effectiveness of the cleaning agents. The conduit and the containers can hereby be cleaned more effectively. It is moreover possible to suffice with fewer cleaning agents if desired.

A further advantage of the device according to the invention is that it is low-noise. This is because the pneumatic pumping produces less sound than if a pump with moving parts were used.

In a preferred embodiment the pneumatic system is configured to control the gas pressure individually in each container, and the control mechanism is switchable between the first state as described above and a second state in which the control mechanism controls the pneumatic system to increase the gas pressure in the second container relative to the gas pressure in the first container or a further container, so that the liquid substance flows from the second container back to the first container or to the further container.

In a system with two containers the control mechanism preferably switches in each case between the first state and second state, so that the liquid substance is pumped back and forth. In a system with a series of more than two containers the control mechanism can for instance be embodied such that the liquid substance is in each case pumped to a subsequent container in the series and then, after reaching the final container, runs through the series in reverse order. In another example the conduit is a ring conduit to which more than two containers are connected, and the control mechanism is embodied to pump the liquid substance in each case to a subsequent container of the ring conduit, so that the liquid substance is continuously pumped around the ring conduit. In a currently preferred embodiment the control mechanism is configured here to pump the liquid substance around, even when no liquid substance is being taken from the system.

The control mechanism sets the gas pressure in the individual containers and thereby controls the direction of the transport of the substance between the containers. In the case of more than two containers, the control mechanism moreover controls between which of the containers the transport takes place.

The pneumatic system preferably comprises a compressed air supply, i.e. a supply for air under pressure. A supply of another gas or gas mixture, such as C0 ₂ and/or N ₂ , is however also possible. It is noted that the device according to the invention can also operate with unconditioned air, such as animal accommodation air or outside air. In conventional devices for feed distribution use is usually made of an air-driven diaphragm pump. In order to prevent jamming of the diaphragm pump due to contaminated air, the air for driving the diaphragm pump has to be conditioned, for instance by means of an air drier. Such air treatment installations are however expensive. An air treatment installation is not required in the device according to the invention. Conditioned air or another conditioned gas can if desired however also be applied in the device according to the invention.

In a preferred embodiment at least one container is provided with a venting valve and a supply valve which is connected to a gas supply of the pneumatic system, wherein the control mechanism is configured to control the gas pressure in the container by controlling the valves of the relevant container.

In other words, the gas pressure of at least one container is set by the control mechanism by controlling a venting valve and a supply valve of the relevant container.

Each container preferably comprises a venting valve and a supply valve which is connected to the gas supply of the pneumatic system, and the control mechanism is configured to control the gas pressure in each of the containers by controlling the valves of the relevant container. In order to increase the gas pressure in the one container relative to the gas pressure in another container it is possible to a) close the venting valve of the one container and open the supply valve of the one container, and/or b) open the venting valve of the other container and close the supply valve of the other container.

In a further preferred embodiment the control mechanism is configured to open the supply valve of the first container, close the venting valve of the first container, close the supply valve of the second container and open the venting valve of the second container in the first state, and to open the supply valve of the second container, close the venting valve of the second container, close the supply valve of the first or further container and open the venting valve of the first or further container in the second state.

The venting valve and the supply valve of one or more containers can if desired be embodied as one single multi-way valve. A 3/2 valve with three ports and two positions is for instance used for this purpose.

In a currently preferred embodiment the device comprises at most two containers, and the control mechanism is configured to switch back and forth between the first state and the second state for the purpose of pumping the liquid substance back and forth between the two containers.

In another embodiment the device comprises more than two containers. The control mechanism is configured to pump the substance in each case from a current container to a subsequent container. The control mechanism for instance switches to a state in which the subsequent container becomes the current container as soon as the current container is empty or almost empty. The substance can then be pumped from this container to a further subsequent container. In other words, the substance is pumped from the first container to the second container, and then from the second container to the third container and so on. The control mechanism is for instance configured to pump the liquid substance back and forth through a series of successive containers. Upon reaching the final container in the series, the order of pumping is reversed. In another example the conduit is a ring conduit and the liquid substance is pumped around by pumping it in each case to a subsequent container along the ring conduit.

In an embodiment with more than two containers, wherein the liquid substance is pumped from one container to a subsequent container, a part of the system, for instance one or several containers in which no liquid substance is stored, can be disconnected and cleaned. The disconnecting and/or cleaning can take place as a separate process, but can also be performed during use of the other part of the system. A variant is also possible wherein cleaning of the container takes place after the liquid substance has been pumped to a subsequent container.

In an embodiment the control mechanism is switchable from and to a rest state in which the control mechanism keeps the gas pressure in the first container and the second container substantially constant so that the liquid substance is not displaced. A gas overpressure, i.e. a pressure above atmospheric pressure, is then preferably maintained in each container.

Although pumping of the substance can be important to prevent settling, it is possible to have the pumping take place at intervals. Before the control mechanism switches from the one pumping state to the other pumping state, it is possible to switch temporarily to a rest state. A gas overpressure is preferably applied in the containers in this state, so that the substance can still be drawn off in simple manner at the draw-off points.

In a further preferred embodiment the control mechanism is configured to first remain in the rest state for a predetermined amount of time during switching between the first state and the second state. The predetermined time is for instance 1-30 minutes.

In a preferred embodiment the pump means comprise only the pneumatic system. In other words, no non-pneumatic pump systems are present for pumping the liquid substance through the conduit. In particular, the device comprises no pumps with moving parts which during use make contact with the substance to be pumped. In particular, the device comprises no rotating pumps, piston pumps or diaphragm pumps for pumping the substance.

In a preferred embodiment each container is provided with a sensor for measuring a level of the liquid substance in the relevant container.

The sensors are preferably configured to detect whether a level of the liquid substance in the relevant container lies below or above a predetermined level, and the control mechanism is configured to switch between the different states on the basis of the detection by the sensors.

The sensors measure the level of the liquid substance in the containers. The sensor is for instance a conductivity sensor or resistivity sensor, an inductive sensor, a distance sensor, a weight sensor or a capacitive sensor. The sensors generate a signal which is indicative of a level of the substance in the containers. The sensors are for instance configured to detect whether the level of the substance lies below or above a predetermined level. A conductivity sensor is for instance arranged in the relevant container. If the conductivity sensor detects no liquid substance, the liquid substance therefore lies below the sensor, i.e. below a predetermined minimum level. In another example a distance sensor is used to determine the height to which the liquid substance is present in the container. The measurement is in this case quantitive, and the level of the substance can be expressed as distance measure, for instance in centimetres.

The control mechanism is configured to switch the sensors between the different states, for instance between the first state and the second state, on the basis of the signal of the sensors. The device can hereby for instance detect whether the first container has been pumped empty or almost empty, wherein the liquid substance has been displaced to the second container so that the system can switch to the second state, in which the substance is pumped from the second container, for instance back to the first container or to a further container. In another example the device switches to the second state when the device detects that the second container has been pumped full or almost full, and the device switches to the first state when the device detects that the first container has been pumped full or almost full.

The control mechanism is for instance configured to switch from the first state to the second state when the sensor measures that the level in the first container lies below or above respectively a minimum or maximum level of the first container, and to switch from the second state to the first or a further state when the sensor measures that the level in the second container lies below or above respectively a minimum or maximum level of the second container.

In the first state the substance is pumped from the first container to the second container. When the control mechanism detects on the basis of the measurement signal of the sensor of the first container that the level in the first container has dropped below the predetermined minimum level or that the level in the second container has risen above the predetermined maximum level, the control mechanism switches to the second state, in which the pneumatic system pumps the substance from the second container. The predetermined level is for instance chosen such that the control mechanism detects whether the first container has been pumped empty or almost empty or whether the second container has been pumped full or almost full. If it is detected in the second state that the level in the second container has dropped below the minimum level or that the level in the first container has risen above the maximum level, the control mechanism once again switches to a different state. In a system with only two containers, the control mechanism for instance switches back to the first state as soon as it detects that the second container in the second state has been pumped empty or is at least almost empty, or as soon as it detects that the first container in the second state has been pumped full or is at least almost full. In an exampleof a device with more than two containers the control mechanism in that case switches to a further state, in which the liquid substance is pumped from the second container to a further container.

In a further preferred embodiment the control mechanism is configured to generate a signal which indicates that the total quantity of liquid substance in the device is smaller than a predetermined minimum quantity on the basis of the levels measured by the sensors.

When substance is regularly drawn off at the draw-off points, the quantity of substance in all containers combined will eventually decrease. This can be detected with the sensors.

The control mechanism for instance registers the amount of time which passes in each case before a different state is switched to. If this amount of time is shorter than a predetermined threshold value, the above stated "empty" signal is generated. In an example of a device with only two containers, wherein the substance is continuously pumped back and forth between the two containers, switching between the two states will take place increasingly quickly as more of the substance is drawn off. If the amount of time between the switching moments is shorter than a predetermined minimum time, for instance 1-2 minutes, the "empty" signal is generated. A notification is for instance given to the operator of the device on the basis of the above stated signal. An alarm in the form of sound and/or light is for instance generated. In another example an SMS or email is sent to the operator.

In a further embodiment the device further comprises a water supply connected to one or more of the containers, and the control mechanism is configured to carry water into the containers when the signal has been generated.

In other words, the control mechanism can automatically carry water into one or more of the containers. The control mechanism for instance controls a controllable valve in a water supply conduit. The water supply can additionally or alternatively supply water under high pressure, for instance a pressure of more than 25 bar, more than 50 bar or even 100 bar or more. The water supply comprises for instance a connection for connecting a pressure cleaner to the water supply. The cleaning is improved further by guiding water into the containers under a high pressure.

If the device detects that the quantity of liquid substance, such as mash or milk, has decreased below the predetermined minimum quantity, the control mechanism switches to a state in which water is carried into at least one of the containers.

The first time that the quantity of liquid substance drops below the minimum level a switch will for instance take place to a diluting mode in which the liquid substance still present in the device is diluted by supply of water in one or more of the containers. The control mechanism then switches back to one of the pumping states, for instance the above stated first state, second state or further state, so that the substance diluted with water is then pumped between the containers. In the case that mash is distributed in an animal accommodation, diluted mash is thus supplied to the cattle at that moment. When it is then once again detected by the device that the quantity of substance, for instance the mash diluted with water, present in the device has decreased to a level below the minimum level, the control mechanism can switch to a state in which the containers are flushed clean by once again supplying water.

The device comprises for instance a discharge for carrying flushing water out of the device. The discharge is for instance coupled to a container or to the conduit connecting the containers, and the discharge comprises for instance a valve controllable by the control mechanism.

Provided in a further embodiment in each container connected to the water supply is a nozzle which is configured to spray water, supplied via the water supply, against the wall of the relevant container.

The water supply is connected to at least one nozzle in the container. If desired, each container comprises more than one nozzle connected to the water supply. The nozzle is directed toward a wall of the container such that supplied water is sprayed against the wall. The wall of the container is in this way flushed clean at the moment that water is supplied. According to the invention, the use of nozzles in the container can in particular be combined with the supply of water under high pressure for the purpose of a highly effective cleaning of the containers with water.

The device can alternatively or additionally be provided with a supply for supplying the substance, which is connected to at least one of the containers. The device can automatically fill up the containers on the basis of the "empty" signal by carrying the substance from the supply to the at least one container. In the case of for instance cattle feed a container can be connected via a supply conduit to a supply reservoir or feed mixer, wherein a valve is provided in the supply conduit. When the "empty" signal is generated, the valve is temporarily opened in order to guide new cattle feed into the container.

In a further preferred embodiment the conduit comprises a static mixer.

A static mixer, also referred to as tube mixer, is a mixer without moving parts. A static mixer comprises a tube with a number of obstacles therein which influence the flow, for instance in the form of baffles or guides. The medium flowing through the static mixer is in this way set into turbulent flow and is thereby mixed.

Although the device already prevents settling of mixtures by means of the pumping, this effect is additionally enhanced using the static mixer. The static mixer is therefore particularly advantageous when the device is employed in the pumping of mixtures, such as milk or mash.

In an embodiment the device further comprises a heating means for heating the substance in at least one of the containers and/or the conduit.

The heating means is configured to bring and/or keep the substance in the device to or at the desired temperature.

In a further embodiment the heating means comprises at least one heated bath in which at least one of the containers is placed. The heated bath is for instance embodied as a warm water bath. The substance is in this way brought to the desired temperature and/or held at the desired temperature in a "bain-marie".

The heating means additionally or alternatively comprises a heat exchanger provided on or in the conduit.

The invention further relates to an animal accommodation provided with a device as described above. In addition, the invention relates to a method for distributing liquid cattle feed over a number of draw-off points in an animal accommodation using the above stated device. The same advantages and effects as described above in respect of the device according to the invention apply for the animal accommodation and the method.

It is noted that an animal accommodation can if desired be provided with two or more devices according to the invention as described above. An animal accommodation is for instance subdivided into a number of sections and/or stalls, and each section or each stall is provided with a device as described above for distributing liquid cattle feed in the relevant section/the relevant stall. In such a case the devices are preferably equipped with two containers. The embodiment with two containers requires fewest parts and furthermore the least complex control system. It is thereby relatively inexpensive and simple to place a plurality of such devices in an animal accommodation. Because a device is provided per section and/or stall, it is possible to control the feed per section/stall. The addition of medicines, such as antibiotics, to the feed can also be controlled per section/stall.

The devices can each be provided with a gas supply, for instance in the form of a relatively small compressor for each device. One or more larger compressors can alternatively be provided, each supplying compressed air to more than one device in the animal accommodation. Each device can moreover be equipped with its own control mechanism, or the control mechanisms of all the devices can be accommodated in a central module which controls the valves of the devices via a wire or wirelessly. A water supply and/or a feed supply can likewise be provided centrally or decentrally.

In an embodiment of the method it comprises the following steps of:

a) increasing the gas pressure in a first container relative to the gas pressure in a second container, so that liquid cattle feed flows from the first container to the second container.

The method furthermore preferably comprises the step of:

b) increasing the gas pressure in the second container relative to the gas pressure in the first container or a further container, so that the liquid cattle feed flows from the second container back to the first container or to the further container.

Further advantages, features and details of the invention are elucidated on the basis of preferred embodiments thereof, wherein reference is made to the accompanying drawings, in which:

Figure 1 shows a schematic view of a device for distributing a liquid substance according to a first embodiment of the invention, wherein the device comprises two containers;

Figure 2A shows a schematic view of a first example of an air control for the device according to the invention;

Figure 2B shows a schematic view of a second example of an air control for the device according to the invention;

Figure 3 shows a variant of the device according to figure 1, wherein each container is provided with a venting valve and a gas supply valve; Figure 4 shows a variant of the device according to figure 3, wherein the venting valve and the gas supply valve of each container are embodied as one single multi-way valve;

Figure 5 shows a variant of the device according to figure 4, with a water supply controlled by the control mechanism;

Figure 6 shows a schematic view of a device for distributing a liquid substance according to a second embodiment of the invention, wherein two containers are arranged one above the other;

Figure 7 shows a schematic view of a device for distributing a liquid substance according to a third embodiment of the invention, wherein the device comprises more than two containers,

Figure 8 shows a schematic view of a device for distributing a liquid substance according to a fourth embodiment of the invention, wherein the device comprises two containers;

- Figures 9A-B show schematic views of examples of a compressed air connection for the containers of the device according to the invention;

Figure 10 shows a schematic top view of a device for distributing a liquid substance according to a fifth embodiment of the invention, wherein the device comprises a ring conduit to which more than two containers are connected; and

- Figure 11 shows a schematic top view of an embodiment of an animal accommodation according to the invention;

Figure 12 shows a schematic view of a variant of the animal accommodation according to figure 11 ; and

Figure 13 shows a schematic view of a further embodiment of an animal accommodation according to the invention, wherein a number of devices according to the invention with two containers are provided, which are optionally connected to a central control mechanism.

Device 2 (figure 1) comprises a first container 4 and a second container 6. First container 4 and second container 6 are each provided on a lower part with a connection 8, 10. Connections 8, 10 of containers 4, 6 are mutually connected via a conduit 12 so that a liquid substance such as liquid cattle feed, particularly mash or milk, can be pumped via conduit 12 from the one container 4 to the other container 6 and vice versa. Conduit 12 has a number of draw-off points 13a, 13b, 13c. Although only three draw-off points are shown in the figure, more or fewer draw-off points can be provided as desired. In the schematic view of figure 1 the draw-off points 13a-c seem to be coupled to conduit 12 via a number of branches of this conduit 12. According to the invention, draw-off points 13a-c are however preferably directly coupled to conduit 12 so that no branch or almost no branch is present between conduit 12 and draw-off points 13a-c.

In this example each draw-off point debouches into a trough, and the draw-off points are provided with a valve which is controlled on the basis of a sensor which registers the quantity of feed in the trough. The draw-off point can alternatively be connected to a trough with a so-called "nipple", wherein feed is let into the trough when an animal, such as a piglet, presses against the nipple.

Provided on an upper part of containers 4, 6 is a connection 14, 16 connecting each of the containers 4, 6 via conduits 18, 20 to air control 22. Air control 22 is connected via a pressure reducing valve 23 to a compressed air supply 24. In this example the compressed air supply comprises a compressor. A gas bottle with compressed air can alternatively be provided. The maximum gas pressure of the system can be set with the pressure reducing valve, for instance by turning a tap of the pressure reducing valve. The gas pressure is for instance set to 0.5 bar, 1.5 bar or even 3 bar or more relative to the atmospheric pressure.

Device 2 further comprises a control mechanism 26, for instance a programmable logical controller (PLC), a printed circuit board (PCB), an integrated circuit (IC) or other electronic control. Control mechanism 26 controls air control 22.

Arranged in each container 4, 6 in a lower part is a sensor 28, 30 for detecting the liquid substance. The level of the liquid substance in containers 4, 6 is thereby effectively measured. This is because, when a sensor 28, 30 detects no liquid substance, the level in the relevant container 4, 6 is lower than the level to which sensor 28, 30 is configured. Sensors 28, 30 are connected to control mechanism 26 via a wire or wirelessly, so that this mechanism can control air control 22 subject to the level measured by sensor 28, 30. In the shown example sensors 28, 30 are resistivity sensors, conductivity sensors or another sensor for detecting a liquid substance. Sensors 28, 30 can alternatively for instance be embodied as a distance sensor, for instance an infrared distance sensor, for measuring the distance between the upper side of the substance present in the container and a fixed sensor position, for instance a position in an upper part of the container. As further alternative, the sensor can be embodied as a weight sensor for measuring the weight of the substance present in the container.

In the shown example containers 4, 6 are provided on their upper side with an optional closure 32, 34, for instance in the form of a screw cap. Closures 32, 34 are alternatively for instance embodied as manhole, or containers 4, 6 are even embodied as split tank, i.e. a tank comprising two tank parts which can be uncoupled from each other. Closures 32, 34 can be opened in order to thus manually fill containers 4, 6 with the liquid substance. When closures 32, 34 are closed they are gastight, so that a gas pressure can be built up in containers 4, 6. Closures 32, 34 comprise for instance a seal such as an O-ring for this purpose. In a first example of air control 22 (figure 2A) each air conduit 18, 20 is connected to a venting valve VIA, V2A and a supply valve VIB, V2B. Supply valves VIB, V2B connect air conduits 18, 20 to compressor 24 for supplying compressed air in containers 18, 20. Venting valves VIA, V2A connect air conduits 18, 20 to the surround area for venting of containers 4, 6 via air conduits 18, 20. Control mechanism 26 is operatively connected to valves VIA, VIB, V2A, V2B in order to control them.

In a first state the substance is pumped from container 4 to container 6. The gas pressure PI in first container 4 is for this purpose increased relative to the gas pressure P2 in second container 6. The control mechanism closes for this purpose venting valve VIA of container 4, while it opens the supply valve VIB of container 4, so that the gas pressure PI in container 4 is increased with compressed air from compressor 24. In this first state venting valve V2A of second container 6 is preferably opened, while supply valve V2B of second container 6 is closed, so that second container 6 is vented and the gas pressure P2 corresponds to atmospheric pressure.

As soon as container 4 is empty, or at least almost empty, sensor 28 will detect no more substance in container 4. Control mechanism 26 then switches to the second state, in which the control mechanism controls air control 22 to increase gas pressure P2 relative to gas pressure PI, so that the substance is pumped back from second container 6 to first container 4. Control mechanism 26 closes venting valve V2A and opens supply valve V2B so that the gas pressure P2 in second container 6 is increased. Control mechanism 26 preferably moreover closes supply valve VIB of first container 4 and control mechanism 26 opens venting valve VIA, so that container 4 is vented and the gas pressure PI in first container 4 corresponds to atmospheric pressure. Some gas overpressure relative to atmospheric pressure can alternatively be maintained in container 4, as described above.

When second container 6 is empty, at least almost empty, sensor 30 of second container 6 detects no substance. This is registered by control mechanism 26, which switches back to the first state. Continuous switching between the first and second state takes place in this way in order to continuously pump the substance back and forth between containers 4, 6.

Before switching from the first state to the second state or vice versa, control mechanism 26 optionally switches to a rest state in which the gas pressure PI, P2 is kept constant in both containers 4, 6. In the rest state the system automatically finds a position of equilibrium in which the pressures PI and P2 are substantially equal.

A first option is to open both venting valves VIA, V2A in the rest state, so that the pressure in the two containers 4, 6 is equal to atmospheric pressure. It is however recommended to maintain some overpressure relative to atmospheric pressure in both containers 4, 6 in the rest state, so that the substance can also be drawn off from draw-off points 13a-c in the rest state. All valves VIA, VIB, V2A, V2B are for instance closed for this purpose. One or both supply valves VIB, V2B can if desired still be opened for some time.

The gas pressure in containers 4, 6 is in the rest state for instance set to 1.1 - 2 bar, or even more than 2 bar.

A gas pressure sensor can optionally be provided in one or more of the containers 4, 6, which is connected to control mechanism 26 as feedback so that control mechanism 26 can control valves VIA, VIB, V2A, V2B in order to set a predetermined gas pressure in the relevant container 4, 6.

Because substance will regularly be drawn off at draw-off points 13a-c during use, the total quantity of liquid substance in device 102 decreases. In an exemplary embodiment control mechanism 26 tracks the time which passes between successive switching moments in order to register this decrease. This means that control mechanism 26 registers the amount of time between switching from the first to the second state and switching back again from the second to the first state. If this period of time is shorter than a predetermined lower limit, for instance 1 - 2 minutes, control mechanism 26 generates an "empty" signal which indicates that the quantity of feed is less than a predetermined lower limit. This predetermined lower limit otherwise need not be expressed in terms of volume or weight: the time between switching can function as a measure for the quantity of feed still present in the system. On the basis of the signal an alarm in the form of light and/or sound is for instance generated, or a message is sent, for instance via SMS or email. On the basis of the signal water and/or feed is for instance automatically supplied to one or more of the containers, which will be elucidated in the description below with reference to figure 5.

The control mechanism alternatively detects that the total quantity of substance has decreased on the basis of one or more sensors. Each container comprises for instance a sensor for measuring a level of the substance in the relevant container. In the example of figure 1 the control mechanism can be configured to generate the "empty" signal when the two sensors 28, 30 detect no substance.

In a second example of air control 22 (figure 2B) each air conduit 18, 20 is connected to an electrically controlled 3/2 valve V3, V4. Air conduit 18, 20 is connected to the first port of respectively valve V3 or valve V4, a second port of valve V3, V4 is connected to the surrounding area for venting and a third port of valve V3, V4 is connected to gas supply 24. Valves V3, V4 thus connect air conduit 18, 20 to either gas supply 24 or the surrounding area. Valves V3, V4 are controlled by control mechanism 26 in a similar manner as described above in respect of figure 2A.

Device 102 (figure 3) largely corresponds to device 2 of figure 1. Instead of an air control 22, each of the containers 4, 6 is however provided with a venting valve VIA, V2A and a gas supply valve VIB, V2B. Valves VIA, V2A, VIB, V2B are controlled by control mechanism 26 in a similar manner as described above in respect of figures 2A-B. Device 202 (figure 4) largely corresponds to device 102 of figure 3. Instead of a separate venting valve VIA, V2A and gas supply valve V1B, V2B, containers 4, 6 of device 202 are however provided with a three-way valve VI, V2 which fulfil the same function as respectively valves VIA, V IB and V2A, V2B.

Device 302 (figure 5) largely corresponds to device 202 of figure 4. Device 302 additionally comprises a water supply 50. Water supply 50 is for instance coupled to a drinking water system or other water conduit.

Water supply 50 can also be a supply for water under high pressure, for instance more than 25 bar, more than 50 bar or even 100 bar or more. Water supply 50 comprises for instance a connection for connecting a pressure cleaner to the supply. The cleaning is further improved by guiding water into the containers under a high pressure.

Water supply 50 optionally comprises a heater for heating water, for instance to more than 30°C, more than 40°C, more than 50°C or even more than 60°C.

Provided in container 4 is a nozzle 52 which is connected to water supply 50 via a conduit in which a controllable valve V5 is provided. Controllable valve V5 is controlled by control mechanism 26.

Three nozzles 54, 56, 58 are arranged in container 6 for the purpose of illustration. These nozzles are connected via a conduit to water supply 50. Provided in this conduit is a controllable valve V6 which is coupled to control mechanism 26. The number of nozzles 52, 54, 56, 58 in each container can differ from the shown example. The two containers 4, 6 for instance comprise only one nozzle, or two, three or more nozzles are provided in each container 4, 6. It is also possible to connect the nozzles 52, 54, 56, 58 of the two containers 4, 6 via one single controllable valve to water supply 50. The water supply for each container 4, 6 can however preferably be controlled individually in that individually controllable valves V5, V6 are provided.

Nozzles 52, 54, 56, 58 are directed toward a wall of the relevant container 4, 6. When water is sprayed into containers 4, 6 by the nozzles, possible feed residues are sprayed from the wall. Nozzles 54, 56, 58 of container 6 are shown schematically one above the other. Nozzles 54, 56, 58 can if desired however be distributed at the same height, or roughly the same height, over the inner wall of container 6 so that water is sprayed over a large area of the inner wall of container 6 using the nozzles.

Control mechanism 26 is for instance configured to measure the amount of time between instance of switching from the first state to the second state or vice versa. If this switching time is shorter than a preset lower limit, for instance 1 minute, control mechanism 26 switches to a diluting state. In the diluting state water is supplied in one or both containers 4, 6 from water supply 50 via the relevant nozzles 52, 54, 56, 58 by operating the corresponding valve V5, V6. The supplied water need not be heated in the diluting state, the temperature of the supplied water being for instance 5 - 30° Celsius in the diluting state. The feed which is still present is diluted with the supplied water. Control mechanism 26 then switches back to the first state or the second state, so that the now diluted feed is pumped back and forth between containers 4, 6. If it is once again detected that the quantity of feed, in this case diluted feed, has decreased, for instance in that the amount of time between switching is shorter than the preset time, control mechanism 26 switches to a flushing state. In the flushing state water is once again supplied in containers 4, 6. Warm or hot water is preferably supplied in the flushing state, the supplied water for instance having a temperature of more than 30°C, more preferably more than 40°C, still more preferably more than 50°C and most preferably more than 60°C. Cleaning agents can optionally be added (not shown in the figure). The flushing water, optionally with cleaning agent, is in the flushing state for instance pumped back and forth between the containers a number of times, after which it is removed from the containers, for instance via an outlet (not shown in the figure).

Device 402 (figure 6) comprises a first container 4 which largely corresponds to container 4 of figure 3 and a second container 406 in the form of a supply reservoir. Supply reservoir 406 for instance has a volume of more than 100 litres, more than 250 litres, more than 500 litres or even more than 1000 litres. Device 402 also comprises a conduit 12 which is connected to a lower part of first container 4 via connection 8. A number of draw-off points 13 are provided on conduit 12. The conduit is finally guided upward and debouches into supply reservoir 406 situated above first container 4. The underside of supply reservoir 406 is coupled via a valve V7 to the upper side of first container 4. Valve V7 is controlled by control mechanism 26.

In device 402 the feed is pumped from container 4 through conduit 12 toward supply reservoir 406. Valve V1B is opened for this purpose, so that the gas pressure in container 4 is increased relative to the atmospheric gas pressure prevailing in supply reservoir 406. Valve V7 is preferably closed or kept closed during pumping of feed from container 4.

By operating valve V7 container 4 can be filled up with feed from supply reservoir 406. In short, the feed is pumped around effectively in device 402. Container 4 is for instance equipped with a sensor, as described above for devices 2, 102, 202, 302. Control mechanism 26 opens valve V7 for filling up container 4 on the basis of the signal measured by the sensor. The force of gravity in this case ensures that feed flows from supply reservoir 406 into container 4. Valve VIA can if desired be opened during filling up of container 4, so that the pressure in container 4 is reduced.

Device 602 of figure 8 largely corresponds to device 2 of figure 1. Only the differences will be discussed in the following.

Each container 4, 6 of device 602 comprises a plurality of sensors 28a-g, 30a-g for measuring the level of substance in the relevant container. Each sensor 28a-g, 30a-g is operatively connected to control mechanism 26. Where sensors 28, 30 of device 2 only indicate whether the level in containers 4, 6 lies below or above a determined minimum level, control mechanism 26 of device 602 can distinguish a plurality of levels of containers 4, 6 on the basis of the measurements of sensors 28a-g, 30a-g.

Control mechanism 26 of device 602 is for instance configured to reverse the pumping direction when one of the sensors 28g or 30g detects the substance, i.e. the pumping direction is reversed as soon as the level in one of the containers 4, 6 reaches the upper sensor 28g, 30g.

A number of stages of the control are for instance defined. In a first stage the control mechanism switches between the first and second state on the basis of detection of the substance by upper sensors 28g, 30g as described in the previous paragraph. In a second stage the control mechanism switches between the first and second state on the basis of detection by one of the other sensors, for instance the bottom sensors 28a, 30a. The control mechanism for instance passes from the first stage to the second stage when the control mechanism detects that the time between the switching moments is greater than a predetermined time or that the total quantity of substance is smaller than a predetermined quantity.

Connections 14, 16 of containers 4, 6 of device 602 moreover comprise an overpressure valve 36, 38. An overpressure valve which opens automatically at a pressure of more than 3 bar is for instance opted for. The safety of device 602 is hereby increased.

Container 4 of device 102 is optionally connected via conduit 44 to a supply reservoir 42. Arranged in conduit 44 is a valve V7 which is controlled by control mechanism 26. Control mechanism 26 is for instance configured to open valve V7 when the "empty" signal is generated. In short, when the control mechanism detects on the basis of the amount of time between the switching moments and/or the values measured by sensor 28a-g, 30a-g that device 602 is empty, at least that the total quantity of substance is less than a predetermined minimum quantity, valve V7 is automatically opened in order to carry substance from supply reservoir 42 into container 4. A number of supply reservoirs 42, each containing a different component of the substance, can also be provided instead of supply reservoir 42. Reservoir 42 is for instance embodied for this purpose as a mixer.

It is noted that a mixing member for mixing the substance can also be arranged in at least one of the containers 4, 6 of devices 2, 102, 202, 302, 402, 502, 602.

Connections 14, 16 of device 602 with overpressure valve 36, 38 can for instance be embodied as in figure 9A and/or figure 9B. Provided in figure 9B is a float which closes connection 14, 16 on the underside so that no substance can enter into air conduit 18, 20. The same is achieved in figure 4 by means of a mesh cylinder. This mesh cylinder does admit air, although this will diminish with a combination of water and foam. The valve will then move upward, and thus close the relevant air conduit 18, 20, because of the pressure difference.

Device 502 (figure 7) comprises three containers 204, 205, 206. It is noted that the device can if desired comprise more than three containers. The pressure in each container 204, 205, 206 is once again set by control mechanism 26. In the shown example each valve is connected via a wire to the control mechanism, although the control can also take place wirelessly. In device 502 each container 204, 205, 206 also comprises a sensor 228, 229, 230 for measuring the level in the relevant container, although such a sensor is optional. This is because switching between the different states can for instance also take place on the basis of time, i.e. switching to the subsequent state in each case takes place after a predetermined amount of time.

Conduit 12 of device 502 is connected to each of the containers 204, 205, 206 and comprises a number of draw-off points 213a-f. Six draw-off points 213a-f are shown in the shown example, although this number can also be higher or lower.

The control mechanism controls the gas pressure PI, P2, P3 in containers 204, 205, 206 by controlling the supply valves and venting valves of containers 204, 205, 206. In a first state the substance is pumped from first container 204 to second container 205. Gas pressure PI is hereby increased relative to P2, while the gas pressure P3 is kept constant or is at least set to be higher than P2. The supply valve of container 204 is for instance opened and the venting valve of container 204 closed, while the venting valve of container 205 is opened and the supply valve of container 205 is closed and the two valves of container 206 are closed. The substance will then be forced from container 204 to 205. The system then switches to a second state, preferably when sensor 228 detects that the level in container 204 lies below a predetermined minimum level. In the second state the gas pressure P2 is increased relative to P3, while gas pressure PI is kept constant or is at least set to be higher than P3. The substance is thereby displaced to container 206. When sensor 229 detects that the level in container 205 lies below a predetermined minimum level, a switch to a third state takes place.

In the third state the substance is for instance pumped back from container 206 to container 205. When sensor 230 detects that the level in container 206 lies below a predetermined minimum, a switch can then take place to a fourth state, in which the substance of container 205 is displaced back to container 204. When sensor 229 detects in this fourth state that the substance in container 205 lies below the minimum level, a switch back to the first state takes place and the cycle starts again.

In another example the substance is in the third state pumped from container 206 directly back into container 204 by increasing pressure P3 relative to pressure PI, P3 > PI, while likewise P2 > PI . When sensor 230 then detects that the level in container 206 lies below the minimum level, control mechanism 26 switches back to the first state and the cycle starts again.

Figures 1, 3, 4, 5, 7 and 8 show systems in which conduit 12 is embodied as a finite conduit, i.e. conduit 12 is not a ring conduit. Such a conduit is also referred to as a blind conduit. Figure 10 shows a schematic top view of a device 302 in which conduit 12 is embodied as a ring conduit. A number of containers 304, 306, 308, 310, 312, 314 are connected to the conduit. The ring conduit moreover comprises a number of draw-off points 313.

The control mechanism of device 302 is preferably set to pump the substance in each case to a subsequent container along the ring conduit. In a first state the substance is for instance pumped from container 304 to container 306, in a second state from container 306 to container 308, in a third state from container 308 to container 310, in a fourth state from container 310 to 312, in a fifth state from container 312 to container 314 and in a sixth state from container 314 to container 304. The cycle then starts again. It is of course also possible to pump the substance around the ring conduit in the other direction.

A pig pen 400 (figure 11) comprises a number of sections 402, 404, 406. A number of stalls is arranged in each section 402, 404, 406. Only the stalls of section 404 are shown for the sake of clarity. A sow with a number of piglets can for instance be accommodated in each stall. A passageway 408 runs along the sections. It is noted that a pig pen can also be laid out in other manner. The invention can moreover also be applied for other types of cattle, for instance cows, chickens or sheep.

A device 2 according to figure 1 is arranged in each section 404 of animal accommodation 400. In the shown embodiment one draw-off point 13a-f is arranged in each stall. It is however possible to apply a plurality of draw-off points per stall. One of the containers 4 is optionally configured close to or even in passageway 408, as shown in figure 11, so that a pig farmer has good access to container 4, for instance in order to fill it up manually. As described above, containers 4, 6 can alternatively also be filled up automatically.

In another example (figure 12) the two containers 4, 6 are arranged in or close to the passageway.

In an example of an animal accommodation in which a plurality of devices 2 (figure 13) are placed, one central control mechanism 726 is provided. Each individual device 2 can alternatively comprise its own control mechanism 26, as described above.

A central water supply is preferably likewise used for all devices in the animal accommodation. A central gas supply to which each device is connected can moreover be provided. Each device in the animal accommodation can alternatively be provided with a relatively small compressor, or a number of devices in the animal accommodation can share a compressor.

Devices 2, 102, 202, 302, 402, 502, 602 can be provided with a heating means for heating the substance. One or more containers 4, 6, 204, 205, 206 are for instance accommodated at least partially in a heated bath, for instance in a warm water bath. The substance is in this way brought to the desired temperature and/or held at the desired temperature in a "bain-marie". Conduit 12 is alternatively accommodated in a heated bath. In another example the heating means comprises a heat exchanger which keeps the substance in the containers and/or the conduit heated/at temperature.

The present invention is by no means limited to the above described preferred embodiments thereof. The rights sought are defined by the following claims, within the scope of which many modifications can be envisaged.