WO2009093906A1

WO2009093906A1 - Device and method for pressing citrus fruits

Info

Publication number: WO2009093906A1
Application number: PCT/NL2009/050035
Authority: WO
Inventors: Sander Van Leeuwen; Ronald Michiel Lewerissa
Original assignee: Princess Household Appliances B.V.
Priority date: 2008-01-25
Filing date: 2009-01-26
Publication date: 2009-07-30
Also published as: NL2001220C2

Abstract

The invention relates to a method and a device (1) for pressing citrus fruits (2), wherein the device comprises a frame (3), at least one pair of rollers (20, 21) extending substantially parallel and bearing-mounted in the frame for feeding between the rollers and pressing the citrus fruits, feed means (10) for feeding the citrus fruits to the at least one pair of rollers, at least one knife (30) for cutting into the peel of the citrus fruits and drive means (40, 41, 42) for driving the pair of rollers in rotation. A more automated pressing process is obtained by making use of feed means, a knife placed in the device and a pair of rotating rollers, whereby the citrus fruit itself need no longer be cut by hand or pressed onto a rotating part, so that the convenience of use for the consumer increases. The pressing device preferably comprises a second pair (50, 51) of rollers for pressing citrus fruit.

Description

Device and method for pressing citrus fruits

The present invention relates to a device and to a method for pressing citrus fruits.

The pressing of citrus fruits is applied on a large scale both in industry, in the catering sector and for household use. Important requirements for the user, particularly for household use, are convenience of use, a good flavour of the pressed juice, the possibility of simple cleaning of diverse components of the apparatus and the price of the apparatus. Present devices for pressing citrus fruits only partially meet these requirements. Most devices for pressing citrus fruits are for instance provided with a cone which penetrates into half a citrus fruit during a rotating movement, and in this way forces the juice out of the fruit. The use of such a device requires the citrus fruit first having to be cut in half, each of the halves then having for pressing manually onto the rotating cone and the pressed citrus fruit finally having to be removed. This is a labour-intensive process, wherein not only the device but also the hands and the immediate vicinity of the device then usually have to be thoroughly cleaned.

An apparatus for pressing citrus fruits is known from US-A-5 628 247, in which a more automated device for pressing citrus fruits is described. The use of this pressing device is hereby simplified; this is because the citrus fruits no longer need to be cut in half and pressed by hand onto a rotating element. The apparatus itself does however take a very complex form, and this has an adverse effect on the reliability and cost price. The apparatus is difficult to clean due to the large number of components. The apparatus is also expensive due to the many components used.

The present invention has for its object to provide an improved device and improved method for pressing citrus fruits, wherein the pressing process is less labour-intensive and more automated, and wherein the device takes a simple and therefore inexpensive form, and cleaning of which can be performed easily.

The invention provides for this purpose a device for pressing citrus fruits, wherein the device comprises: a frame; at least one pair of rollers extending substantially parallel and bearing-mounted in the frame for feeding between the rollers and pressing the citrus fruit for pressing; feed means for feeding the citrus fruits for pressing to the at least one pair of rollers; at least one knife for cutting into the peel of the citrus fruits for pressing; and drive means for driving the pair of rollers in rotation.

The device is dimensioned in the first instance here for pressing oranges; it will be apparent that the device can also be used to press other citrus fruits such as lemons, limes, grapefruit or mandarins. A more automated pressing process is obtained by making use of feed means, a knife placed in the device and a pair of rotating rollers, whereby the citrus fruit itself need no longer be handled for cutting by hand or for pressing onto a rotating part, so that the convenience of use for the consumer increases enormously. By cutting into the citrus fruits for pressing and subsequently carrying them through an opening between a pair of rollers a pressure is exerted on the citrus fruits for pressing whereby the juice is released from the fruits for pressing. The device also has a very limited number of components, so that cleaning thereof is considerably facilitated. It is likewise pointed out that the device makes it possible to press the citrus fruits irrespective of their orientation; the orienting of spherical fruits such as oranges is after all difficult. It is also pointed out that the knife is adapted to make only an incision in the fruit to the pressed; the fruit remains whole and is fed as a whole between the rollers.

In a preferred embodiment the diameter of at least one roller decreases from each of the ends of the roller toward a position of the roller located between the ends of the roller. The citrus fruits for pressing will hereby tend to displace to this position on the roller where the diameter of the roller is smaller. This is because the normal force of the rollers on the citrus fruit has a component in the direction toward a position on the rollers where the diameter of the rollers is smaller. This results in a more unambiguous positioning of the citrus fruits for pressing at a distance from the walls of the pressing device during the pressing process. This prevents the citrus fruits becoming jammed against the wall, thereby increasing the reliability of the pressing device.

In another embodiment at least one roller is provided with a friction-increasing surface. By providing at least one roller with a friction-increasing surface the citrus fruits for pressing are carried better between the rollers, and the rollers will not begin to slip relative to the citrus fruits. The danger of an accumulation of citrus fruits inside the pressing device will hereby be reduced, thereby further increasing the reliability of the pressing process. Both rollers are preferably provided with a friction-increasing surface, whereby the play of forces on the citrus fruits for pressing is symmetrical and the predictability of the pressing process is increased.

In yet another embodiment the pressing device comprises a second pair of rollers for pressing citrus fruit which extend mutually parallel and are placed at a distance from the first pair of rollers. By placing a second pair of rollers below the first pair of rollers more juice is pressed out of the citrus fruits for pressing in that pressure is exerted on the citrus fruits for a second time. It is otherwise also possible for the device to comprise a further third or fourth pair of rollers for even further pressing of the fruits.

Although it is not precluded that the second pair of rollers extend at an angle relative to the first pair of rollers, which it is expected would result in a good pressing result, according to a structurally attractive embodiment the second pair of rollers extends parallel to the first pair of rollers. Owing to this measure the drive means can be given a simple and inexpensive form. If use is for instance made of an electric motor, the mechanical transmission from electric motor to the first and second pair of rollers can take a very simple form.

In yet another advantageous embodiment the second pair of rollers has a larger diameter than the first pair of rollers. When the distance between the shafts of the second pair of rollers is the same, the opening between the second pair of rollers is hereby smaller than that in the case of the first pair of rollers. A higher pressure can hereby be exerted on the citrus fruits, whereby still more juice will be pressed from the citrus fruits. Because the citrus fruit for pressing has already been carried through the first pair of rollers and a quantity of juice has been released and the citrus fruit will therefore take up less volume, the danger of undesirable damage to the citrus fruits or device and the chance of disruption of the pressing process during feed of the citrus fruit through the second pair of rollers is still very small, while the fruit can moreover be further pressed. The use of rollers with a larger diameter also results in a more gradual pressure increase during pressing, this enhancing the juice yield. When the drive remains the same, the speed at the surface of the second pair of rollers with a larger diameter is also greater than the speed at the surface of the first pair of rollers, whereby citrus fruit is fed through more quickly. This accelerates the pressing process and reduces still further the danger of jamming due to an accumulation of citrus fruits inside the pressing device. This measure can likewise be applied with a number of pairs of rollers greater than two, wherein the diameter of the rollers of each successive pair is then preferably greater in each case.

By temporarily driving the second pair of rollers alternatingly in opposite directions a more prolonged pressure is exerted on a citrus fruit for pressing lying between the second pair of rollers, whereby still more juice is pressed from the citrus fruits. In yet another embodiment the drive means are thus adapted for temporary driving of the second pair of rollers in opposite directions. The same effect can likewise be obtained with more than two pairs of rollers, although this requires many components.

In another embodiment one of the rollers of the lower pair of rollers is provided with engaging elements for engaging the citrus fruits. During feed of a citrus fruit between the lower pair the citrus fruit is hereby engaged so that it can be discharged laterally.

The pressing process is hereby further automated, thereby increasing the convenience of use of the device and simplifying the separation of juice and pressed citrus fruits.

In a further advantageous embodiment the engaging elements comprise pins extending substantially in radial direction from the roller, these pins being provided locally with a thickened portion. These pins extending substantially in radial direction from the roller engage deeply into the citrus fruit, whereby a high engaging force is achieved. The thickened portion ensures that the pins hold the citrus fruit better, this being particularly important when the force of gravity has a component directed away from the roller. This measure increases the reliability of the device still further.

In another embodiment at least one roller is provided with separating means for separating the pressed citrus fruits from the roller. The separation of the pressed citrus fruit and the roller takes place automatically due to this measure in that the rotating roller urges the citrus fruits into the direction of the separating means, which then separate the citrus fruits from the roller.

In an advantageous embodiment the separating means comprise a separating member which extends between the pins and is provided with a separating surface extending with a component in the direction of movement of the roller. Owing to this measure the separating means are situated very closely to the roller provided with engaging elements. This ensures that the citrus fruits are separated from the roller and that the danger of the pressed citrus fruits becoming jammed during separation is very small.

In yet another embodiment the at least one knife is rigidly connected for rotation to at least one roller of the first pair of rollers. Owing to this measure use is made of the existing drive for a gripping and cutting movement of the knife connected rigidly for rotation to at least one roller. By making use of a mechanical movement for cutting into the citrus fruits for pressing, this cutting will become more efficient. By rigidly connecting the knife for rotation to a rotating roller use is made of an existing drive, this keeping the pressing device simple and inexpensive. The convenience of use of the pressing device is also increased due to this measure since the knife does not have to be separately operated.

In an advantageous embodiment the knife takes the form of a circle sector and the axis of the circle sector coincides with that of the roller on which the knife is placed. A well- defined cutting edge is hereby obtained relative to the rollers, whereby the predictability of the cutting is increased. The part of the circle sector left clear by the knife produces a space which can be used to position the citrus fruits for pressing. Obtained between the part of the circle sector left clear by the knife and the part of the circle sector covered by the knife is a sharp transition which can be effectively used for the purpose of penetrating into the peel of the citrus fruit for pressing without the citrus fruit undergoing a great displacement. Owing to penetration of the knife into the peel in this way a minimum amount of material is released from the peel of the citrus fruit, which has a positive effect on the taste. This is because so-called limonene is found in the peel of citrus fruits which, if it gets into the pressed juice, imparts a bitter taste to the pressed juice. The circle sector can herein comprise an arc which is preferably greater than 180°, so that the fruit can then be engaged and carried along more easily by the knife.

In an even more advantageous embodiment the pressing device comprises two knives, each connected to a roller of the first pair of rollers. The citrus fruits for pressing are hereby gripped and cut into on two sides, this resulting in a more efficient pressing process. In yet another more advantageous embodiment the knives are placed mirror- symmetrically on the shafts of the first pair of rollers. By making use of two knives, each taking the form of a circle sector, and placing these mirror-symmetrically on the rollers, a space is created by the part of the circle sector of each knife that is left clear into which the citrus fruits for pressing can be easily fed by the feed means. As a result of this measure the forces applied to the citrus fruits by the knives produce a symmetrical play of forces. The citrus fruits for pressing hereby remained better positioned during cutting. The reliability of the pressing device is thus further improved.

In another embodiment the knives are positioned at an axial distance from each other relative to the rollers. Knives of larger diameter can hereby be used, while the distance between the axes of shafts forming part of a pair can remain small. The knives do not then interfere with each other. The advantage of larger knives is that the cutting action is better.

In yet another embodiment the radius of the at least one knife is greater than the difference in the distance between the axes of the first pair of rollers and the radius of the other roller of the first pair of rollers on which the knife is not mounted at the position of the knife, and the other roller of the first pair of rollers on which the knife is not mounted is provided with a groove at the position of the knife. Even larger knives can hereby be placed on the rotating rollers without the distance between the rollers having to be increased.

It is advantageous to cut the citrus fruits into pieces at least at two locations. This facilitates throughfeed between the rollers and a large surface area is obtained from which the pressed juice can be pressed out of the citrus fruit. In another embodiment the diameter of the at least one knife is thus at least 60 mm. Owing to this measure the forces acting on the citrus fruit through this knife also have a downward directed component which, in combination with the sharp transition between the part of the circle sector left clear by the knife and the part of the circle sector covered by the knife, produces a good cutting action. The citrus fruits are therefore not so much crushed, but the peel thereof is properly cut so that the pressed juice can find its way out of the peel. In another embodiment the rollers bearing-mounted in the frame are mutually connected for rotation, and that part of the frame in which the rollers are mounted is releasable. The advantage of these measures is that the frame part together with the rollers mounted therein, being the parts most susceptible to contamination, can be removed as a whole from the frame, this considerably simplifying cleaning of the device. The thus created unit can in particular be cleaned by a so-called automatic dishwasher.

In yet another embodiment the feed means are provided with detection mean for detecting the presence of citrus fruits for pressing, and the pressing device is provided with a control circuit adapted to switch on the drive means and keep them switched on for a desired period of time when the detection means detects the presence of a citrus fruit for pressing. Owing to these measures the pressing device is switched on by feeding citrus fruits through the feed means. Keeping the pressing device switched on for a predetermined time guarantees that every citrus fruit for pressing undergoes the whole pressing process before the device stops. By keeping the pressing device switched on for a desired period of time and subsequently switching it off, the pressing device not only becomes more automatic and safer, it will also not consume energy unnecessarily. This improves the efficiency of the pressing device.

The invention also provides a method for pressing citrus fruits, comprising the steps of: providing citrus fruits for pressing, cutting into citrus fruits with movable knives, feeding between a first pair of rollers and pressing the citrus fruits for pressing. This method of pressing citrus fruits can take place in fully automated manner. The pressing process is hereby not very labour-intensive.

Another method also comprises the step of: feeding between a second pair of rollers and pressing the citrus fruits for pressing. More juice is hereby pressed out of the citrus fruits.

An advantageous method also comprises the step of: temporarily driving the pair of rollers between which the citrus fruit is situated at least once in reverse direction. This achieves that even more juice is pressed out of the citrus fruits. Particularly in the case of a citrus fruit lying between the second pair of rollers, the second pair of rollers are repeatedly driven temporarily in reverse direction. Yet another method also comprises the step of: engaging citrus fruits with engaging elements placed on a roller forming part of a lower- lying pair of rollers, and separating pressed citrus fruits with a separating member from the roller provided with engaging elements. Without additional operations by the user the pressed citrus fruit is separated with this method from the roller and therefore also from the pressed juice.

The present invention will be further elucidated on the basis of the non- limitative exemplary embodiments shown in the following figures. Herein:

figure 1 shows a perspective, partly cut-away view of a device according to the present invention, wherein a citrus fruit for pressing is fed through the feed means to the first pair of rollers; figure 2 is a cross-section through the device shown in figure 1 ; figure 3 is a perspective view of the first and second pair of rollers of the device shown in figures 1 and 2; figure 4 is a perspective view of the second pair of rollers shown in figure 3; figure 5a shows a cross-section through the first pair of rollers, wherein the two knives are placed in a position for feeding a citrus fruit for pressing; figure 5b shows a cross-sectional view corresponding to figure 5 a, wherein the two knives of figure 5 a have cut into the citrus fruit for pressing; figure 5 c shows a cross-sectional view corresponding to figure 5 a, wherein the two knives of figure 5 a have cut further into the citrus fruit for pressing and wherein the citrus fruit for pressing has already been carried partially between the first pair of rollers; and figure 5d shows a cross-sectional view corresponding to figure 5 a, wherein the two knives of figure 5a have cut fully into the citrus fruit for pressing and wherein the citrus fruit for pressing has been carried further between the first pair of rollers.

Figure 1 shows a device 1 for pressing citrus fruits 2, wherein feed means embodied as a shaft 10 are adapted to feed citrus fruits 2 for pressing to a first pair of rollers 20,21 extending substantially parallel and horizontally. The first pair of rollers 20,21 is bearing-mounted in a partially shown frame 3 by means of bearings 24. Frame 3 is formed substantially by two plates 4a, 4b extending parallel in vertical direction. The first pair of rollers 20,21 are drivable by drive means, in the form of a combination 40 of an electric motor and a reduction gear unit 41, in mutually opposed rotation directions using a series of gear wheels 42 placed on the outer side of the frame with rollers 20,21. Situated between the first pair of rollers 20,21 is an opening 22 for feed between the first pair of rollers of the citrus fruit 2 for pressing. Rollers 20, 21 are provided with a rough surface in order to enhance co-displacing of the citrus fruits.

Connected to each of the rollers 20,21 is a knife 30 which has the form of a circle sector and wherein axes 31 of knives 30 coincide with axes 23 of the respective rollers 20,21. The first pair of rollers 20,21 are driven by drive means 40,41,42 in opposite rotation directions, wherein the first pair of rollers 20,21 urges the citrus fruit 2 for pressing downward into opening 22 between rollers 20,21. By driving the first pair of rollers 20,21 in rotation the knives 30 penetrate into the citrus fruit 2 for pressing and cut into the citrus fruit 2 for pressing. This creates an opening to the fruit pulp, whereby the juice can flow out of the citrus fruit 2 for pressing. The further the first pair of rollers 20,21 are rotated by drive means 40, the deeper knives 30 penetrate into the citrus fruit 2 for pressing, which is carried through opening 22 between the first pair of rollers 20,21. During feed of the citrus fruit 2 for pressing between the first pair of rollers a pressure is exerted on the citrus fruit 2 for pressing by the first pair of rollers 20,21, whereby juice is pressed out of the citrus fruit 2 for pressing in which a cut has been made and flows outward through the opening formed by knives 30 in the peel of the citrus fruit.

A second pair of rollers 50,51 is also bearing-mounted under the first pair of rollers 20,21 in frame 3 by means of bearings 53. The second pair of rollers 50,51 is also connected to drive means 40,41,42 for driving in mutually opposed directions. Because the distance between the shafts of rollers 20,21 is the same as the distance between the shafts of rollers 50,51, and rollers 50,51 have a larger diameter than rollers 20,21, the distance between rollers 50,51 is smaller than the distance between rollers 20,21.

Once citrus fruit 2 has been carried between the first pair of rollers 20,21 it is fed between a second pair of rollers 50,51. An opening 52 is situated between the second pair of rollers 50,51. Because rollers 50,51 have a larger diameter than rollers 20,21, more pressure is exerted on the citrus fruit 2 for pressing by rollers 50,51, and extra juice is thereby pressed out of the citrus fruit 2 for pressing.

A roller 50 of the second pair of rollers 50,51 is provided with pins 54 extending in radial direction and having a locally thickened portion 55. Also arranged are separating means, to be elucidated hereinbelow, for the purpose of separating the pressed citrus fruits from roller 50. During feed of a citrus fruit 2 between rollers 50,51 the pens 54 will engage the citrus fruit. When citrus fruit 2 is fed through rollers 50,51 the pins 54 will urge citrus fruit 2 in the direction of the separating means (not shown), wherein the separating means separate citrus fruit 2 from roller 50. A discharge member 70 located below roller 50 will discharge the pressed citrus fruit 2 to a bin 80. A plurality of citrus fruits 2 can in this way be automatically pressed. The pressed juice is guided through an opening 90 in the direction of a container, such as a glass 91 or a jug, to be placed under the device and in which the juice can be collected.

Figure 2 shows a cross-section of the device 1 of figure 1, wherein the citrus fruit 2a for pressing is fed by feed means 10 to the first pair of rollers 20,21. A second citrus fruit 2b for pressing is still situated in feed means 10. Feed means 10 are provided with detection means 11, for instance in the form of a switch provided with a lever or a light detector which detects the presence of a citrus fruit 2 for pressing and which then sends a signal to a control circuit (not shown) which keeps the drive means 40 (not shown) switched on for a desired period of time and switches them off after this period of time if no citrus fruit is present.

This figure shows clearly that knives 30 take the form of a circle sector and that axis 31 of each of the knives 30 coincides with shaft 23 of one of the rollers 20,21. The part of the circle sector covered by knife 30 forms a sharp transition 32 with the part of the circle sector left clear by the knife. This transition 32 ensures that during rotation of rollers 20,21 the knives 30 penetrate easily into the citrus fruit 2 for pressing. Knives 30 have a relatively large diameter for the purpose of cutting properly into particularly the peel of citrus fruits 2. The construction together with a diameter of each of the knives 30 requires that each of the rollers 20,21 is provided with a groove 25 at the position of the knife 30 mounted on the other roller. In order to keep device 1 compact the second pair of rollers 50,51 is placed close to the first pair of rollers 20,21. Each of the rollers 50,51 of the second pair of rollers 50,51 is provided with a groove 56 at the position of knife 30 mounted on one of the rollers of the first pair of rollers 20,21. This provides space for the knife placed on the opposite roller. This measure is otherwise only necessary with a corresponding dimensioning of the knives and rollers. It can also be readily seen in this figure that knives 30 are mounted relative to each other on shafts 20,21 such that a citrus fruit 2 for pressing can be fed onto rollers 20,21. The relative orientation of knives 30 is further elucidated in figures 5a-5b.

The pins 54 placed extending in radial direction on roller 50 will engage citrus fruit 2 fed through the second pair of rollers 50,51. As the second pair of rollers 50,51 are further rotated, citrus fruit 2 will be urged in the direction of a separating member in the form of a toothed plate 60, whereby citrus fruit 2 will be separated from pins 54 and roller 50. The teeth of the toothed plate extend between the pins 54 placed on roller 50. Once the pressed citrus fruit 2 on roller 50 has been released from pins 54, the citrus fruit will be discharged by a discharge member 70 to a waste bin 80.

Figure 3 shows a perspective detail view of the first pair of rollers 20,21 and the second pair of rollers 50,51 with bearings 24,53 of device 1 of figure 1. The diameter of rollers 20,21,50,51 decreases from each end of rollers 20,21,50,51 toward a position located between the ends of the relevant roller 20,21,50,51. Particularly during feed of the citrus fruit 2 for pressing (not shown) between rollers 20,21 and 50,51 respectively this fruit is hereby urged to that position on rollers 20,21,50,51 where the diameter is smaller. This prevents the citrus fruit 2 for pressing on rollers 20,21,50,51 moving in the direction of frame 3 (not shown), thereby reducing the chance of jamming of rollers 20,21,50,51.

This figure also shows clearly the grooves 25,56 on rollers 20,21,50,51 which provide space for knives 30. Likewise shown are the pins 54 with thickened portion 55 for engaging the pressed citrus fruit 2 (not shown).

Figure 4 shows a perspective detail view of roller 50 with bearings 53 of device 1 of figure 1. Likewise shown are pins 54 with thickened portion 55 for engaging the pressed citrus fruit 2 (not shown). Also shown clearly in this figure is that from each of the ends of rollers 50,51 the diameter decreases toward a position of rollers 50,51 located between the ends of the corresponding rollers 50,51.

Figure 5a shows a cross-section through the first pair of rollers of device 1 of figure 1, wherein knives 30 connected to rollers 20,21 are placed in a position for feeding of a citrus fruit 2 for pressing. Knives 30 are connected mirror-symmetrically to rollers 20,21. Because rollers 20,21 are driven in rotation in opposing directions, knives 30 remain positioned mirror-symmetrically of each other during rotation of rollers 20,21.

Knives 30 have a large diameter such that they must be positioned at a distance from each other on rollers 20,21. Knife 30 connected to roller 20 is placed in this view in front of knife 30 connected to roller 21. The cross-section of this figure is made at the position of the groove of roller 21.

Figure 5b shows a cross-section through the first pair of rollers 20,21 of device 1 of figure 1, wherein the two knives 30 have cut into the citrus fruit 2 for pressing. Because knives 30 are connected mirror-symmetrically to rollers 20,21, the forces exerted on citrus fruit 2 for pressing by knives 30 are symmetrical. The citrus fruit for pressing hereby remains well-positioned on rollers 20,21 and a good cut is made in the citrus fruit 2 for pressing.

During rotation of rollers 20,21 the citrus fruit 2 for pressing is carried through opening 22. A pressure is here exerted on the citrus fruit for pressing, whereby pressed juice flows out of the cut citrus fruit 2. The cross-section of this figure is made at the position of the groove of roller 21.

Figure 5c shows a cross-section through the first pair of rollers 20,21 of device 1 of figure 1, wherein the two knives 30 have cut further into the citrus fruit 2 for pressing and wherein the first pair of rollers 20,21 have carried the citrus fruit 2 for pressing partially through opening 22 between the first pair of rollers 20,21. The citrus fruit 2 for pressing has now been fed a long way between rollers 20,21, whereby a large quantity of juice has been pressed therefrom. During further rotation of rollers 20,21 the knives 30 will cut even further into the citrus fruit 2 for pressing, whereby even more juice can readily be pressed out of citrus fruit 2. The cross-section of this figure is made at the position of the groove of roller 21.

Figure 5d shows a cross-section through the first pair of rollers 20,21 of device 1 of figure 1, wherein the two knives 30 of figure 5 a have cut fully into the citrus fruit 2 for pressing and wherein the first pair of rollers 20,21 have carried the citrus fruit 2 for pressing further through opening 22 between the first pair of rollers 20,21. Rollers 20,21 have rotated 180° relative to the position of the rollers as shown in figure 5a. By now further rotating rollers 20,21 through another 180° the citrus fruit 2 will be carried wholly through opening 22 between rollers 20,21, and knives 30 are once again positioned as shown in figure 5 a. Another citrus fruit 2 for pressing can now be fed through the feed means to rollers 20,21. It will be seen from the above that the knives have a dual function, i.e. cutting into the peel of the citrus fruits and pushing the citrus fruits between the first rollers.

It will be apparent that numerous modifications can be made to the above shown embodiment of the invention without departing from the invention as defined by the claims.

Claims

1. Device for pressing citrus fruits, comprising:

- a frame; - at least one pair of rollers extending substantially parallel and bearing-mounted in the frame for feeding between the rollers and pressing the citrus fruit for pressing;

- feed means for feeding the citrus fruits for pressing to the at least one pair of rollers;

- at least one knife for cutting into the peel of the citrus fruits for pressing; and - drive means for driving the pair of rollers in rotation.

2. Pressing device as claimed in claim 1, characterized in that the diameter of at least one roller decreases from each of the ends of the roller toward a position of the roller located between the ends of the roller.

3. Pressing device as claimed in either of the foregoing claims, characterized in that at least one roller is provided with a friction-increasing surface.

4. Pressing device as claimed in any of the foregoing claims, characterized in that the pressing device comprises a second pair of rollers for pressing citrus fruit which extend mutually parallel and are placed at a distance from the first pair of rollers.

5. Pressing device as claimed in claim 4, characterized in that the second pair of rollers extends parallel to the first pair of rollers.

6. Pressing device as claimed in claim 4 or 5, characterized in that the second pair of rollers has a larger diameter than the first pair of rollers.

7. Pressing device as claimed in any of the claims 4-6, characterized in that the drive means are adapted for temporary driving of the second pair of rollers in opposite directions.

8. Pressing device as claimed in any of the foregoing claims, characterized in that one of the rollers of the lower- lying pair is provided with engaging elements for engaging the citrus fruits.

9. Pressing device as claimed in claim 8, characterized in that the engaging elements comprise pins extending substantially in radial direction from the roller, these pins being provided locally with a thickened portion.

10. Pressing device as claimed in any of the foregoing claims, characterized in that at least one roller of the lower- lying pair is provided with separating means for separating the pressed citrus fruits from the roller.

11. Pressing device as claimed in claim 10, characterized in that the separating means comprise a separating member which extends between the pins and is provided with a separating surface extending with a component in the direction of movement of the roller.

12. Pressing device as claimed in any of the foregoing claims, characterized in that the at least one knife is rigidly connected for rotation to at least one roller of the first pair of rollers.

13. Pressing device as claimed in claim 12, characterized in that the knife takes the form of a circle sector and that the axis of the circle sector coincides with that of the roller on which the knife is placed.

14. Pressing device as claimed in claims 12-13, characterized in that the device comprises two knives, each rigidly connected for rotation to a roller of the first pair of rollers.

15. Pressing device as claimed in claims 13 and 14, characterized in that the knives are placed mirror-symmetrically on the shafts of the first pair of rollers.

16. Pressing device as claimed in claims 14-15, characterized in that the knives are positioned at an axial distance from each other relative to the rollers.

17. Pressing device as claimed in any of the claims 14-16, characterized in that the radius of the at least one knife is greater than the difference in the distance between the axes of the first pair of rollers and the radius of the other roller of the first pair of rollers on which the knife is not mounted at the position of the knife, and that the other roller of the first pair of rollers on which the knife is not mounted is provided with a groove at the position of the knife.

18. Pressing device as claimed in any of the claims 14-17, characterized in that the diameter of the at least one knife is at least 60 mm.

19. Pressing device as claimed in any of the foregoing claims, characterized in that the rollers bearing-mounted in the frame are mutually connected for rotation, and that that part of the frame in which the rollers are mounted is releasable.

20. Pressing device as claimed in any of the foregoing claims, characterized in that the feed means are provided with detection mean for detecting the presence of citrus fruits for pressing, and that the pressing device is provided with a control circuit adapted to switch on the drive means and keep them switched on for a desired period of time when the detection means detects the presence of a citrus fruit for pressing.

21. Method for pressing citrus fruits, comprising the steps of:

(A) providing citrus fruits for pressing,

(B) cutting into citrus fruits with movable knives, and (C) feeding between a first pair of rollers and pressing the citrus fruits for pressing.

22. Method as claimed in claim 21, also comprising the step of: feeding between a second pair of rollers and pressing the citrus fruits for pressing.

23. Method as claimed in claim 22, also comprising the step of: temporarily driving the pair of rollers between which the citrus fruit is situated at least once in reverse direction.

24. Method as claimed in any of the claims 21-23, also comprising the step of: engaging citrus fruits with engaging elements placed on a roller forming part of a lower- lying pair of rollers, and separating pressed citrus fruits with a separating member from the roller provided with engaging elements.