Variable grass-length injector

Abstract

Yarn injection device for injecting yarn sections into the ground, wherein the yarn injection device comprises: - a yarn storage comprising a number of spool holders for holding a number of spools with yarn, - a feeding assembly configured to feed lengths of yarn from the yarn storage to an injection device, the feeding assembly comprising: o a number of supply channels, o a number of cutting devices, o a fluid flow assembly which is configured to create a flow of fluid through each supply channel in order to apply a drag force on the yarns, - the injection device comprising: o an injection needle guide, o a number of moveable injection needles, wherein the feeding assembly is configured to feed an adjustable length of yarn to the injection device, and wherein each supply channel comprises an exchangeable tube between the injection device and the cutting device.

Description

[0001] Title: Variable grass-length injector

[0002] FIELD OF THE INVENTION

[0003] The invention relates to the field of inserting yarn sections into the ground and relates in particular to a device and a method to insert yarn sections into the ground.

[0004] BACKGROUND OF THE INVENTION

[0005] The integration of artificial grass into a natural grass field to create a hybrid grass pitch holds paramount importance for professional sports. This innovative approach combines the resilience and durability of synthetic turf with the aesthetic and natural feel of real grass, offering a surface that can withstand the rigorous demands of intense sporting activities. The hybrid pitch ensures consistent playability in various weather conditions, reducing the likelihood of the field turning into a muddy quagmire during rain or becoming excessively worn during periods of heavy use. This not only minimizes the risk of injuries to athletes but also enhances the overall performance quality of the game. Additionally, the hybrid solution allows for more frequent use of the field, making it a sustainable choice for professional sports organizations by optimizing maintenance and ensuring a longer lifespan for the playing surface. Overall, the integration of artificial grass in a natural grass field presents a symbiotic solution, marrying the best attributes of both natural and synthetic turfs to create a reliable and high-performance sports surface.

[0006] In the field of inserting artificial grass strands into the ground, various devices and methods exist.

[0007] An example of such a device and method is disclosed in WO0179611A1. In the device, a fiber is fed through a tube to a position under an insertion device that is configured to insert the fiber into the ground below. The fiber which is unwound from a roll first passes through a tube before being pulled by a pair of rollers that are configured to feed the fiber further into the device. The fiber is then passed through a venturi device that blows the fiber further through the device. Subsequently a clamp closes, and the fiber is cut into a section by a rotatable element. The rotatable element is provided with a passage that is initially coaxial with the tube. By rotating the element, an edge of the passage moves past an edge of the tube, and in doing so shears the fiber. Thereafter, the fiber is inserted into the ground by a pin. A drawback of the machine is that pressurized air is fed into the tube to force the fiber through the tube. The pressurized air is fed into the tube via a venturi device. Just after the pressurized air joins the tube, the pressure and the velocity of the air will rapidly decrease inside the tube. This means that the force exerted on the fiber will also rapidly decrease. To overcome this issue, a large compressor is necessary. The large compressor is expensive, heavy, and requires a lot of power to operate.

[0008] Also, with compressed air, the air may escape at the location where the injection pin is positioned, because the pin must move downwards there. There is an open space through which the pin moves in a vertical direction. This open space intersects the tube through which the fiber is fed. The pressurized air may leak at the intersection and escape outwards via the open space. On the other (downstream) side of the open space, a subsequent tube is positioned into which the fiber must be moved. The interruption of the tubes guiding the fiber causes a decrease in the force exerted on the fiber because air leaks away via the open space. Also, the air escaping through the open space between the tubes may take the fiber with it and out of the system. This may jam the device.

[0009] Further, it was fond that overpressure affects the tip of the grass strands. The divergent air flow due to overpressure blows the tip of the woven thread apart. This will further increase the risk that a grass strand gets stuck in any of the leaks. Also, once the knife closes off the feed channel to inhibit a fluid flow in the tube, an overpressure air flow will seek the path of least resistance. This will blow the wire back up to the only open exit, which is the entrance of the wire feed tube upstream of the venturi device.

[0010] Additionally, the moving of the injection pins relative to the cutting device and caterpillar tracks in order to adjust the length of the fiber that is to be injected disturbs the pattern of injected grass strands in the ground. The first row which is injected with the moved insertion mechanism at a new, different length would be at a different distance from the previous rows, at least if the forward movement of the machine as a whole is not compensated.

[0011] WO2016122312A1 discloses a device for inserting artificial grass strands into the ground and makes use of a rotating drum on which several grass strands are placed next to each other. On the drums, clamps are provided that clamp down the strands between a front clamp and rear clamp so that the strands rotate with the drum. Subsequently, a cutting device then cuts the strands into sections and these sections are rotated to below injection needles that inject the sections into the ground. A potential drawback of the device of this document is that the drum is a large and heavy moving object that has to be intermittently rotated and stopped. Accelerating and decelerating heavy components takes a relatively large amount of energy and requires a strong frame to be able to react to the accelerations and decelerations. The relation between accelerating and decelerating and the required energy and strong frame limit the number of strands that can be inserted into the ground. A higher insertion frequency would mean faster movements of the heavy drum and would need an increasingly stronger frame and more powerful actuation.

[0012] Also, because the drum is rotating and it comprises moveable actuated components such as clamps, a complex control system for these components must be present that is able to communicate with the moving, rotating components while being stationary itself.

[0013] AU2020101010A4 discloses a device for making a stitched hybrid turf and makes use of an airflow to deliver the fiber to the injection pins. The device comprises a translatable tube through which compressed air flows to an extremity, wherein the compressed air delivers a fiber to the extremity of the tube. The tube is subsequently moved in a lateral direction to a position under a plurality of pins. In this position, the fiber inside the tube is clamped by a clamp before the tube returns to its initial position. Here, the fiber is clamped by another clamp located at the extremity of the tube. Thereafter, the fiber is pressed against the ground by pressing elements, cut by cutting elements and inserted into the ground by injection pins.

[0014] A drawback of the device is that for it to function, the pressing elements, cutting elements, and insertion pins have to be placed so far apart that the distance between each subsequent needle has to be twice the penetration depth of the needle. This means that the tube transporting the fiber must be extremely long for an increasing number of pins.

[0015] WO2019027317A1 discloses a device and method for inserting yarn sections into substrates. The device comprises a drum with a plurality of clamps positioned around the circumference of the drum. The device has a capability of inserting yarn sections in two different depths. This is a drawback in the sense that it would be advantageous to have a capability of inserting yarn sections in more than two different depths into a substrate.

[0016] WO2022223538A1 discloses a yarn injection device for injecting yarn sections into a substrate. The yarn injection device comprises a yarn storage, a feeding device, an injection unit and a fluid flow assembly. The fluid flow assembly comprises at least one fluid communication channel and a depressurized compartment having an underpressure. The fluid flow assembly is configured to create a flow of fluid in order to apply a drag force on the yarns and move the yarns to the injection unit. The feeding device comprises multiple extendable tubes to feed an adjustable length of yarn to the injection device. The device of WO2022223538A1 solves several problems of the device of WO0179611A1 relating to the overpressure. Also, the problem of disturbing the pattern of the grass strands due to the movement of the injection pins is solved by moving the cutting device. The device of WO2022223538A1 is also an improvement of the device of WO2019027317A1 in that more than two different lengths of yarn can be inserted.

[0017] It was recognized in the present invention that the extendable tubes are vulnerable. Damage to the extendable tubes leads to malfunctioning and downtime of the device. Also, the extendable tubes tend to leak, thereby reducing the drag force on the yarn.

[0018] OBJECT OF THE INVENTION

[0019] It is an object of the invention to provide a device and a method for inserting yarn sections into the ground, and, in doing so, overcoming at least one of the abovementioned drawbacks.

[0020] It is a further object to provide a device and a method for inserting yarn sections into the ground wherein the device has a capability of inserting in more than two different insertion depths and has less downtime than the device of WO2022223538A1.

[0021] SUMMARY OF THE INVENTION

[0022] In order to achieve at least one of the objectives, the present invention provides a yarn injection device for injecting yarn sections into the ground, wherein the yarn injection device comprises:

[0023] - a yarn storage comprising a number of spool holders for holding a number of spools with yarn,

[0024] - a feeding assembly configured to feed lengths of yarn from the yarn storage to an injection device, the feeding assembly comprising: o a number of supply channels defining a number of supply paths extending from the yarn storage to a fluid flow assembly, o a number of cutting devices configured to cut a yarn section from each yarn extending from the yarn storage into a respective supply channel, o the fluid flow assembly which is configured to create a flow of fluid through each supply channel in order to apply a drag force on the yarns and move the yarns through each supply channel, wherein the fluid flow device comprises a depressurized compartment having an underpressure,

[0025] - the injection device comprising: o an injection needle guide defining a number of vertical passages, wherein each supply channel comprises a horizontal injection passage extending through the injection needle guide, and wherein each vertical passage intersects the respective horizontal injection passage to form an injection intersection, o a number of moveable injection needles which are moveable between an upper needle position and a lower needle position and configured to pass through the vertical passages of the injection needle guide, wherein when yarn sections in the supply channel are located below the moveable injection needles and the moveable injection needles move downward through the injection needle guide, the yarn sections are injected into the ground, o at least one needle actuator configured to move the number of moveable injection needles between the upper needle position and the lower needle position, wherein the cutting device and the injection device are movable with respect to each other, wherein the feeding assembly is configured to feed an adjustable length of yarn to the injection device, and wherein the yarn injection device further comprises at least a first set of exchangeable tubes and a second set of exchangeable tubes, each exchangeable tube being configured to be removably positioned between the injection needle guide and the cutting device to form a part of the respective supply channel, wherein the tubes of the first set have a different length than the tubes of the second set.

[0026] By having exchangeable tubes between the injection device and the cutting device, it becomes possible to insert yarn sections of adjustable lengths. For each desired length, a different set of tubes is provided. When the insertion depth needs to be changed to a different length, the first set of tubes in the device is removed and replaced by the second set of tubes having a different length. The tubes of each set will typically have a same length.

[0027] The exchangeable tubes form a robust solution to fill a space of varying size between the cutting device and the injection device. In doing so, no more than the necessary amount of yarn is injected into the ground. Not only does this enable the user of the device to tailor the injected yarns, i.e. , a hybrid pitch, to the required needs, it also means that no more plastic than necessary is injected into the ground. Besides reducing costs, it also reduces the impact on the environment.

[0028] Additionally, in this way, the length of a yarn section can be varied without increasing the open space through which leakage could occur. This is beneficial because the system can easily be adjusted for the circumstances required. For example, when injecting yarn sections in a football pitch, a desired injection depth could vary as a function of underground obstacles such as irrigation pipes, regions with rocks or other underground obstacles. By easily being able to adjust the length of the yarn sections, the injection depth can be adapted over a continuous range without a risk of downtime due to damage to the tubes between the cutting device and the injection needle guide. The present invention forms an improvement over the device of WO2022223538A1 .

[0029] By using such a device, a flow of fluid can be used to exert a drag force on the yarns, pulling the yarns through the device. The yarns are pulled through the injection needle guide. In the injection needle guide, the use of the vertical and horizontal injection passages reduces the leakage through open spaces and advantageously reduces the pressure drop in the device. It may also be envisaged that multiple or all passages may be connected with each other. An example of this would be at least two passages being horizontally connected to form a slit instead of two separate passages. This may be beneficial for the weight of the system and may reduce pressure difference loss due to a smaller friction surface for the fluid travelling inside the horizontal injection passage.

[0030] An advantage of underpressure over overpressure is that the air flow is converging for underpressure whereas it is diverging (or bifurcating) for overpressure. A diverging air flow brings with it a higher risk that in case of a leak or gap in the system, air will flow out of the system, away from the supply path of the yarn. A front tip of the yarn strand may follow the leaking air flow and enter into the leak. This risk is smaller with underpressure, because if there is a leak, the air will enter the system through the leak and converge towards the intended supply path. The tip of the yarn strand will not have the tendency to exit through the leak. The converging air flow keeps the yarn strands on the intended supply path.

[0031] In some embodiments, the exchangeable tubes of each set may have a fixed and non- adjustable length. By having a fixed and non-adjustable length, the exchangeable tubes are robust and less sensitive to failure. In some embodiments, the yarn injection device may comprise at least one cartridge which allows the exchange of multiple exchangeable tubes with a single action, wherein the cartridge comprises:

[0032] - multiple exchangeable tubes,

[0033] - a cartridge frame configured to hold the multiple exchangeable tubes adjacent to each other and arranged in a row.

[0034] In doing so, the time required to adjust the length of the yarn inserted into the ground is significantly reduced. Replacing up to 200 individual exchangeable tubes could be a timeconsuming task. Arranging multiple exchangeable tubes in a cartridge greatly reduces the number of actions required to adjust the length. The position of the exchangeable tubes is relatively low and close to the ground. Replacing the tubes or cartridges forces the operators in uncomfortable postures, the cartridges are therefore also profitable for the healthiness of the operators.

[0035] In some embodiments, each cartridge frame may comprise a series of first holes and a series of second holes, each second hole positioned at a distance from an associated first hole, wherein each exchangeable tube extends through one of the first holes and through one of the second holes.

[0036] In some embodiments, the exchangeable tubes in each cartridge may have play with respect to each other.

[0037] Play between the exchangeable tubes in each cartridge is important to ensure that the exchangeable tubes will fit between the cutting device and the injection device. A small deviation in size and / or orientation of the exchangeable tubes in a cartridge or any adjacent component could make it difficult to fit the cartridge between the cutting device and injection device. Having play provides the operator with some space to make minor adjustments to the orientation of individual exchangeable tubes in a cartridge to properly fit them in the injection needle guide.

[0038] In some embodiments, a hole diameter may be larger than an outer tube diameter to provide space between each hole and the exchangeable tube in order to create play between each exchangeable tube and the cartridge frame, and to create play between the exchangeable tubes. This provides a relatively simple solution to create play without additional components. Each tube may comprise one or more stopper member to prevent the tubes from falling out of the cartridge frame.

[0039] In some embodiments, each set of tubes may comprise multiple exchangeable cartridges, each cartridge having multiple tubes, wherein the total number of tubes equals the number of supply paths of the yarn injection device. In particular, each cartridge may for instance comprise 5-50 exchangeable tubes, in particular about 10-20 tubes. However, any number which results in a practical cartridge may be used. It is even possible to use a single cartridge for each set , the single cartridge having a number of tubes which is equal to the total number of tubes of the yarn injection device. Since this cartridge would then be fairly large, a loader mechanism in the form of a slider mechanism could be used to slide the cartridge horizontally in and out of the yarn injection device, in a direction which is transvers to the direction of movement. This facilitates an easy exchange. Alternatively, a loader mechanism which allows the cartridge to be lifted from its active position in a vertical upward direction followed by a downward movement of the replacing cartridge in a downward movment is possible. Alternatively, the cartridge which is to be replaced can be moved away from its active position in a downward direction, in particular to a position to below the yarn injection device during the exchange. The replacing cartridge would then follow the reverse path.

[0040] By having multiple exchangeable cartridges comprising of up to 50 tubes each, the amount of replacement actions can be significantly reduced. The yarn injection device may comprise up to 200 supply paths. Replacing cartridges of 10 tubes each as opposed to replacing 200 individual tubes reduces the number of actions from 200 to 20.

[0041] In some embodiments, the exchangeable tubes may be at least partially tapered inwardly in the direction of the displacement of the yarn to prevent and / or reduce the risk of jamming of the yarn injection device due to a stranded yarn.

[0042] In doing so, the supply path does not comprise any protruding sections, due to the transitions between components, seen from the yarn storage side in the direction of the fluid flow assembly. Tapering the separate sections of the supply path prevents that the diameter of the first section of the supply paths needs to be very large to prevent that the final section of the supply path becomes very small. The upstream diameter of the exchangeable tube is therefore larger than the downstream diameter off the exchangeable tube.

[0043] In some embodiments, the exchangeable tubes may comprise a first, upstream end configured to be positioned near the cutting device, wherein the internal cross-section, i.e., the bore, of the upstream end is tapered inwardly in the direction of the displacement of the yarn to prevent and / or reduce the risk of jamming of the yarn injection device due to a stranded yarn. The bore may have a uniform diameter over the remainder of the length of the tube or at least over a central portion of the tube.

[0044] In doing so, the production process of the exchangeable tubes is simplified. Tapering over the entire length of the exchangeable tube could be challenging and would require complex tools. When only the first, upstream end is tapered, and the remaining part of the tube is straight, simple tools can be used.

[0045] In some embodiments, each exchangeable tube may comprise a seal on an outer surface of the exchangeable tube to prevent and / or reduce leakage of the flow of fluid, wherein the seal is in particular positioned on a second, downstream end of the exchangeable tube. Seals on both ends are also possible.

[0046] In some embodiments, the exchangeable tube may comprise a first coupling part provided by the seal, wherein each horizontal injection passage of the injection needle guide comprises a second coupling part, wherein the first coupling part and the second coupling part provide a coupling between the exchangeable tube and the injection needle guide.

[0047] The seal is a flexible socket made of an elastic material, in particular of silicone rubber. The seal increases the outer diameter of each tube. Due to the elastic properties and increment in diameter, the seal provides the connection between the tube and the injection needle guide. This connection may be relatively stiff, but the tube is still easily removable from the injection needle guide by the operator. The connection may be sufficiently stiff to prevent that the tube is dropped once the injection device and cutting device are moved with respect to each other.

[0048] In some embodiments, the injection needle guide may comprise a number of first bores (110) and the cutting device may comprise a number of second bores (111), and wherein each exchangeable tube is configured to be positioned with one end in a respective first bore and with the other end in a respective second bore.

[0049] In some embodiments, an internal diameter of a second downstream end of each exchangeable tube may be smaller than an internal diameter of the respective horizontal injection passage. The tip of the yarn moves along the supply path from the exchangeable tube to the horizontal injection passage. Jamming of the yarn along the supply path is prevented by reducing and / or completely removing any protruding portions, in particular ridges at a transition from one part of the supply channel to a next part. At each transition between one part of the supply channel and a next part of the supply channel, the upstream part has a greater diameter than the downstream part. Going from a larger diameter to a smaller diameter ensures that there are no protruding portions in the direction of the movement of the yarn at a transition.

[0050] In some embodiments, the yarn injection device may comprise at least five consecutive sets of exchangeable tubes having exchangeable tubes of incrementally longer lengths, wherein the increment is between 15 - 25 mm.

[0051] Having at least five consecutive sets of exchangeable tubes ensures that an operator has sufficient freedom in selecting the optimal insertion depth for the entire range in different circumstances.

[0052] In some embodiments, each cutting device may comprise a number of yarn passages and a moveable knife, wherein each yarn passage is fluidly connected to the respective exchangeable tube.

[0053] In some embodiments, the moveable knife may be tapered inwardly to prevent and / or reduce the risk of jamming of the yarn injection device due to a stranded yarn.

[0054] The tip of the yarn moves along the supply path from the feeding tube to the exchangeable tube. Jamming of the yarn along the supply path is prevented by reducing and / or completely removing any protruding portions. Going from a larger diameter to a smaller diameter ensures that there are no protruding portions in the direction of the movement of the yarn. In addition, this also creates a slightly inclined angle between the static part and moveable knife of the cutting device. This improves cutting of the yarn.

[0055] The present invention also relates to a set of exchangeable tubes for use in the yarn injection device according to the invention.

[0056] Method steps

[0057] In an independent aspect, the invention relates to a method for feeding an adjustable length of yarn to a yarn injection device comprising: - a yarn storage comprising a number of spool holders for holding a number of spools with yarn,

[0058] - a feeding assembly comprising:

[0059] - a number of supply channels configured to accommodate yarn, a number of cutting devices,

[0060] - the fluid flow device configured to create a flow of fluid through each supply channel in order to apply a drag force on the yarns and move the yarns through each supply channel, wherein the fluid flow assembly comprises a depressurized compartment having an underpressure,

[0061] - the injection device comprising: o an injection needle guide defining a number of vertical passages intersecting a respective supply channel, o a number of moveable injection needles, o at least one needle actuator, wherein the cutting device and the injection device are movable with respect to each other, and wherein the yarn injection device further comprises at least a first set of exchangeable tubes and a second set of exchangeable tubes, each exchangeable tube being configured to be removably positioned between the injection needle guide and the cutting device to form a part of the respective supply channel, wherein the tubes of the first set have a different length than the tubes of the second set, the method comprising the steps: a) discontinuing the injection process of the yarn injection device, b) moving the cutting device and the injection device away from each other, c) removing the first set of exchangeable tubes between the cutting device and the injection device, d) replacing the first set of exchangeable tubes with the second set of exchangeable tubes having a different length, e) moving the cutting device and the injection device towards each other, f) continuing the injection process of the yarn injection device.

[0062] By using exchangeable tubes, and moveable cutting devices and / or moveable injection devices, the length of a yarn section can be varied without increasing the open space through which leakage could occur. This is beneficial because the system can easily be adjusted for the circumstances required. For example, when injecting yarn sections in a football pitch, a desired injection depth could vary as a function of underground obstacles such as irrigation pipes. By easily being able to adjust the length of the yarn sections, the injection depth can be adapted without having to change out component and the like.

[0063] In some embodiments, multiple exchangeable tubes may be arranged in a cartridge, wherein each exchangeable tube in the cartridge has an equal length, wherein during steps c) and d) one or more cartridges having multiple exchangeable tubes of a first length are removed and replaced by one or more cartridges having exchangeable tubes of a second, different length.

[0064] By using cartridges to hold multiple exchangeable tubes adjacent to each other, multiple exchangeable tubes can be exchanged with a single action. This shortens the process of feeding yarns of adjustable lengths to the injection device.

[0065] In some embodiments, the device may further comprise a cutting device moving system configured to move the number of cutting devices towards or away from the injection device, wherein during steps b) and e) the cutting device is moved towards or away from the injection device.

[0066] These and other aspects of the invention will be more readily appreciated as the same becomes better understood by reference to the following detailed description and considered in connection with the accompanying drawings in which like reference symbols designate like parts.

[0067] BRIEF DESCRIPTION OF THE DRAWINGS

[0068] Figure 1A shows an isometric view of the yarn injection device comprising a moving assembly.

[0069] Figure 1 B shows a side view of the yarn injection device comprising a moving assembly.

[0070] Figures 2A and 2B show an isometric view of a yarn injection device.

[0071] Figures 3A and 3B show a side view of a yarn injection device.

[0072] Figures 4A and 4B show an isometric view of the cartridge.

[0073] Figures 5A, 5B and 5C show the cartridge.

[0074] Figures 6A, 6B, and 6C show isometric views of a part of the feeding assembly.

[0075] Figures 7A and 7B show the injection device.

[0076] Figure 8A shows an isometric view of the cutting device and injection needle guide.

[0077] Figure 8B shows a side view of the cutting device and injection needle guide.

[0078] Figures 9A and 9B show the injection device and a part of the feeding assembly.

[0079] Figures 10A, 10B and 10C show the injection device and a part of the feeding assembly. Figures 11 A and 11 B show the cartridge with an exchangeable tube.

[0080] Figures 12A, 12B, 12C, 12D, 12E and 12F show a side view of the yarn injection device.

[0081] DETAILED DESCRIPTION OF THE DRAWINGS

[0082] Turning to figures 1A and 1 B, a general overview of a yarn injection device 10 for injecting yarn sections 1 into the ground is shown. The yarn injection device 10 comprises a feeding assembly 20, an injection device 30, a fluid flow assembly 40 and a moving assembly 60. The moving assembly 60 is connected to the feeding assembly 20, the injection device 30 and the fluid flow assembly 40. The area denoted by numeral 99 is depicted in detail in figures 3A and 3B. The moving assembly 60 comprises a frame 62 and wheels 64 that are mounted to the frame. When the injection device 30 has injected a row of yarn sections into the ground, the moving assembly 60 can be used to move the device over a surface of the ground to move to a subsequent injection location. Here, the yarn injection device can inject a next row of yarns sections.

[0083] Besides being connected to the feeding assembly 20, the injection device 30, and the fluid flow assembly 40, the moving assembly 60 also supports the yarn storage 12. This yarn storage comprises spool holders 122 for holding spools 124 of yarn to store the yarns that are to be fed to the injection device.

[0084] To create an even weight distribution, the depressurized compartment 44, i.e. , the suction buffer tank, and the suction pump 46 are located forward of the injection device 30 and a drive system 66 of the moving assembly 60 is located to the rear of the injection device 30. These parts are relatively heavy and therefore contribute significantly to the weight distribution.

[0085] Turning to figures 2A, 2B, 3A and 3B, a general overview of the feeding assembly 20, injection device 30 and fluid flow assembly 40 for injecting yarn sections 1 into the ground is shown. A feeding assembly 20 is configured to feed lengths of yarn via supply paths 23 from spool holders 122 of a yarn storage 12 (depicted in figures 1A and 1 B) via the feeding assembly 20 and to an injection device 30. To do so, the feeding assembly 20 comprises a number of supply channels 22 that each define the supply paths 23 which are configured to accommodate yarn that is to be fed to the injection device 30. The number of supply channels 22 extend from the yarn storage 12 to the fluid flow assembly 40. In operation, when a desired length of yarn has been fed into and through the injection device 30, a number of cutting devices 26 which are located at the number of supply channels 22 cut a number of yarn sections 1 from the yarn extending from the yarn storage 12 into the supply channels 22. When the yarn sections have been cut, the injection device 30 injects them into the ground. To this end, the injection device comprises an injection needle guide 32 that guides a number of moveable injection needles 38 into the ground. The injection needle guide 32 defines a number of vertical passages 34 which are intended to guide the number of moveable injection needles 38. Each supply channel 22 comprises a horizontal injection passage 36 extending through the injection needle guide 32. The horizontal injection passages 36 are intended to guide yarn through the injection needle guide 32 and to below the number of moveable injection needles. Each vertical passage 34 intersects the respective horizontal injection passage 36 to form an injection intersection 35.

[0086] In the side views of figures 3A and 3B, the injection needle 38 is located above the injection needle guide 32 in the upper needle position and the exchangeable tubes 50 are located on the right of the injection needle guide 32. The area denoted by numeral 98 in figure 3A is depicted in detail in figure 3B. The cutting devices 26 are located on the right of the exchangeable tubes 50 and can be actuated by a cutting actuator 261. The roller device 21 is located on the right of the number of cutting devices 26, and the fluid communication channel 42 is located on the left injection needle guide 32. The cutting device 26 comprises a knife 266 that is moved with respect to a static part 267 by the cutting actuator 261 to cut the yarn. Here, the knife 266 is moved in a direction normal to the plane of the cross-section. However, other directions are also possible. The fluid communication channel 42 serves the purpose of communicating an underpressure from a depressurized compartment 44 located on the left of injection needle guide 32 to the injection needle guide and the feeding assembly. The depressurized compartment 44 is located on the left of the injection needle guide. As can be seen, no clamping is done and is necessary to be done to be able to cut the yarn section 1.

[0087] When a yarn is located below the moveable injection needles 38, the moveable injection needles 38 can move from an upper needle position to a lower needle position while passing through the holes of the injection needle guide 32. This movement is actuated by at least one needle actuator 37. The yarn sections 1 in the supply channel 22 are then injected into the ground during this movement. In order for the yarn section 1 not to get stuck in the device, a fluid flow assembly 40 comprising at least one fluid communication channel 42 and a depressurized compartment 44 is provided. Here, the fluid flow assembly is located on an opposite side of the injection needle guide 32 relative to the exchangeable tubes 50 and the depressurized compartment 44 has an underpressure. Because the fluid communication channel 42 extends between the injection needle guide 32 and the depressurized compartment 44, a flow of fluid can be created through the fluid communication channel 42, the injection needle guide 32 and the exchangeable tube 50 in order to apply a drag force on a yarn and move the yarn through the injection needle guide 32.

[0088] Because it would require a lot of energy to keep the depressurised compartment 44 under a constant underpressure while also communicating this underpressure with the outside world via any of the other components, a channel valve 422 is located between the depressurized compartment 44 and the injection needle guide 32. The channel valve 422 regulates the flow of fluid in the supply channel 22. In an open state the channel valve 422 allows communication of a fluid flow between the depressurized compartment 44 and the injection needle guide 32, the number of yarn tubes 24 and / or the feeding assembly 20. In a closed state, the channel valve 422 inhibits communication of a fluid flow between the depressurized compartment 44 and the injection needle guide 32, the number of exchangeable tubes 50, and / or the feeding assembly 20.

[0089] Since an underpressure is communicated to the injection needle guide 32, when an injection needle 38 moves to an upper position after having injected a yarn section 1 into the ground, a small amount of fluid will be sucked in through the vertical passage 34. The sucked in fluid will travel to the depressurized vessel and in doing so may suck along some debris (substrate that has attached itself to the injection needle, yarn waste, etc.). In order to prevent this debris to loosely fly around, a waste receptacle 442 is removably located within the depressurized compartment 44. Because the waste receptacle comprises a plurality of holes and acts like a filter, waste entering the depressurized compartment can be collected and retained before being thrown out after removing the receptacle.

[0090] Also, because fluid is not only sucked in through the injection needle 32 but also through other nooks and crannies, the underpressure in the depressurized compartment 44 may drop over time. To overcome this a suction pump 46, see figure 1 B, may be connected to the depressurized compartment 44. A pressure sensor 47 is located within the depressurized compartment 44 and is connected to a control unit 70 that is configured to read out the pressure sensor 47 and to provide a user with pressure data so the user may intervene. The control unit 70 may also control any of the cutting device 26, the channel valve 422, the feeding assembly 20, the shutter assembly 33, the moveable injection needles 38, and / or the fluid flow assembly 40. In particular, the control unit 70 is configured to control a cycle, wherein in the cycle, the roller device 21 is operated to feed lengths of yarn to the injection device 30, thereafter the number of cutting devices 26 cut the lengths of yarn and the injection needles 38 inject the lengths of yarn in the ground. Different substrate conditions may require different injection depths of yarn, e.g., an irrigation pipe may be located close to the surface and requires a smaller injection depth than directly besides the pipe. When the depth of the injection needs to be varied, to create a uniform yarn length above the ground, the yarn section must be shortened. To be able to adjust the length of the yarn section 1, feeding assembly 20 can feed an adjustable length of yarn to the injection device 30. A deeper penetration will require a longer length and a shallower penetration will require a shorter length. The cutting device 26 is moveable along the direction indicated by arrow 263 (see also fig. 3A) by a cutting device moving system 262 with respect to the injection intersection 35 of the vertical passages 34 and the horizontal injection passages 36 to adjust the cut length of the yarn section 1. The cutting device 26 is movable along guide rods 265.

[0091] To be able to operate under a wide variety of substrate conditions, the distance from the cutting device 26 to the injection intersection 35 is adjustable over a range of preferably 40-300mm, more preferably 55-350mm, even more preferably 90-200mm. In order to be able to adjust the length of the yarn section 1 and to communicate a pressure from the depressurized compartment 44 to the feeding assembly, the exchangeable tubes 50 are exchangeable. The exchangeable tubes 50 have a fixed and non-adjustable length.

[0092] T urning to figures 11 A and 11 B, to allow the movement of the cutting device 26 without creating a gap between the injection device and the cutting device, a first set of exchangeable tubes 50A having a first length 75A can be replaced by a second set of exchangeable tubes 50B having a second length 75B different length from the first length 75A. The yarn injection device 10, the first set of exchangeable tubes 50A and second set of exchangeable tubes 50B form a kit of parts for injecting yarn sections 1 into the ground. The yarn injection device 10 comprises at least five consecutive sets of exchangeable tubes 50 having exchangeable tubes 50 of incrementally longer lengths. The increment between the consecutive sets is between 15 - 25 mm.

[0093] Turning to figures 4A, 4B, 5A, 5B and 5C, a cartridge 80 which allows the exchange of multiple exchangeable tubes 50 with a single action is shown. The cartridge 80 comprises multiple exchangeable tubes and a cartridge frame 82. The cartridge frame 82 is configured to hold the multiple exchangeable tubes adjacent to each other and to arrange the multiple exchangeable tubes in a row. The yarn injection device 10 may comprise multiple exchangeable cartridges. Each cartridge has multiple tubes, in the shown example 10 tubes. The total number of tubes equals the number of supply paths 22 of the yarn injection device 10, wherein in particular each cartridge comprises 5-50 exchangeable tubes. A cartridge may even contain a same number of tubes as the total number of supply channels of the yarn injection device, in which case a single cartridge for each tube length and each insertion depth is sufficient. A loader mechanism for the cartridge is then practical, because the cartridges would become fairly large. The cartridges of figures 4A and 4B are small enough to be handled manually.

[0094] The cartridge frame 82 further comprises a series of first holes 83 and a series of second holes 84. Each exchangeable tube extends through one of the first holes and through one of the second holes. The second hole is positioned opposite to the respective first hole. The exchangeable tubes 50 in each cartridge 80 have play with respect to each other. Play between the exchangeable tubes 50 in each cartridge 80 is important to ensure that the exchangeable tubes 50 will fit between the cutting device 26 and the injection device 30. A small deviation in size and / or orientation of the exchangeable tubes 50 in a cartridge 80 could make it difficult to fit the cartridge 80 between the cutting device 26 and injection device 30. A hole diameter 85 is larger than an outer tube diameter 52 to provide space between each hole and the exchangeable tube in order to create play between each exchangeable tube and the cartridge frame, and to create play between the exchangeable tubes. The exchangeable tubes 50 further comprise a stopper member 88, positioned between the first and second holes, to prevent that the exchangeable tubes 50 fall out of the cartridge frame 82. The stopper members 88 can be flexible sockets made of an elastic material, in particular of silicone rubber, but can also be made from a different material. The stopper member 88 increases the outer diameter of each tube.

[0095] The bore of each exchangeable tubes 50 is at least partially tapered inwardly in the direction of the displacement of the yarn to prevent and / or reduce the risk of jamming of the yarn injection device due to a stranded yarn, see figure 5C. The exchangeable tubes 50 comprises a first, upstream end 56 configured to be positioned near the cutting device 26. The internal cross-section 54 of an end portion 55 of the first, upstream end 56 is tapered inwardly in the direction of the displacement of the yarn to prevent and / or reduce the risk of jamming of the yarn injection device due to a stranded yarn. The exchangeable tubes 50 further comprises a second, downstream end 59 configured to be positioned near the injection needle guide 32. An internal diameter 57 of an end portion 58 of the second, downstream end 59 of each exchangeable tube 50 is smaller than an internal diameter 39 of the respective horizontal injection passage 36 of the injection needle guide 32. Moving the yarn from a section with a smaller diameter to a section with a larger diameter prevents the risk of jamming due to a stranded yarn in a transition between two components. Each exchangeable tube 50 comprises a seal 51 on an outer surface 53 of the exchangeable tube 50 to prevent and / or reduce leakage of the flow of fluid. The seal is a flexible socket made of an elastic material, in particular of silicone rubber, but can also be made from a different material. The seal 51 is in particular positioned on a second, downstream end 59 of the exchangeable tube 50. The exchangeable tube 50 comprises a first coupling part 91 provided by the seal 51 and each horizontal injection passage 36 of the injection needle guide 32 comprises a second coupling part 92. The first coupling part 91 and the second coupling part 92 provide a coupling 90 between the exchangeable tube 50 and the injection needle guide 32.

[0096] Exchange procedure

[0097] Turning to figures 12A, 12B, 12C, 12D, 12E and 12F, the exchangeable tubes 50 can be exchanged to feed an adjustable length of yarn to a yarn injection device 10 using the following steps: a) discontinuing the injection process of the yarn injection device, b) moving the cutting device and the injection device away from each other. The cutting device is moved in a first direction 101 by the cutting device moving system 262. The first set of exchangeable tubes 50A remains positioned in the injection needle guide 32 when the cutting device 26 is moved in the first direction 101, c) removing the exchangeable tubes between the cutting device and the injection device. The first set of exchangeable tubes 50A is removed from the injection needle guide 32 by moving it in a second direction 102, the first set of exchangeable tubes 50A is then removed from the yarn injection device 10 in a third direction 103, e.g. upward or downward or laterally. d) replacing each exchangeable tube with an exchangeable tube having a different length, the second set of exchangeable tubes 50B could be inserted into the yarn injection device 10 in a fourth direction 104, e.g. upward or downward or laterally. Subsequently the second set of exchangeable tubes 50B is moved in a fifth direction 105 to position them in the injection needle guide 32. e) moving the cutting device and the injection device towards each other. The cutting device 26 is moved in a sixth direction 106 to move the cutting device and injection device towards each other, f) continuing the injection process of the yarn injection device.

[0098] The replacement process is simplified by arranging the exchangeable tubes 50 in a cartridge 80. Each exchangeable tube 50 in the cartridge has an equal length. During steps c) and d) one or more cartridges 80 having multiple exchangeable tubes 50 of a first length are removed and replaced by one or more cartridges having exchangeable tubes of a second, different length. In figures 12C and 12D, third direction 103 and fourth direction 104 may also be downwards, upwards, sidewards or any other direction through which the exchangeable tubes could be removed from, or inserted in, the yarn injection device 10.

[0099] The injection needle guide 32 comprises a number of first bores 110 and the cutting device 26 comprises a number of second bores 111. The internal diameters of the first and second bores is larger than the internal diameter of the horizontal injection passage in the injection device and larger than the internal diameter of the yarn passage in the cutting device. Each exchangeable tube is configured to be positioned with one end in a first bore and with the other end in a second bore.

[0100] Turning to figures 8A, 8B, 9A, 9B, 10A, 10B and 10C, the cutting device 26 is shown together with the injection needle guide 32. When a pressure is communicated to the injection needle guide 32, the fluid may escape through the vertical passages 34. To reduce the amount of lost pressure, the injection needle guide 32 comprises a shutter assembly 33 that is moveable between a closed and an open state in which it respectively closes off the vertical passages 34 and doesn’t close off the vertical passages 34.

[0101] The shutter assembly comprises a first slider located 334A located below the horizontal injection passages 36 and a second slider 334B located above the horizontal injection passages 36. Each slider can be moved in a lateral direction by a slider actuator 336 between the closed state and the open state. In the open state, a number of slider holes 338A defined in the first slider 334A and a number of holes 338B defined in the second slider 334B substantially align with the vertical passages 34 for the moveable injection needles to be moveable through the vertical passages and the slider holes. In order for the moveable injection pin to be able to pass through the injection needle guide and the sliders, at least the number of slider holes 338A defined in the first slider 334A and the vertical passages 34 are larger than the moveable injection needle in a direction substantially parallel to the horizontal injection passages 36. This is schematically depicted in figure 10C. Here, the large circular part of the hole 338 allows the needle to pass through and the oval sections extending to the sides accommodate the yarn when the needle passes through the injection needle guide together with the yarn. This allows the injection needle to extend through the slider hole and the vertical passage together with two ends of the yarn section next to it without jamming.

[0102] In the figures, only one of multiple feeding tubes 27 is shown to more clearly show the cutting device 26. The cutting device comprises a yarn passage 264 to which a feeding tube 27 extends. The yarn passage 264 is formed in the static part 267. After the yarn exits the feeding tube 27, the yarn passes through the yarn passage 264 of the cutting device 26 and into the exchangeable tube 50 located on the opposite side of the cutting device 26 relative to the feeding tube 27. A knife 266 is disposed in front of the yarn passages 264 and is moveable between an open state and a closed state by a knife actuator 261. The knife may have the form of a plate 268 with a number of holes 269, see figure 3B. Each hole is associated with a yarn passage 264. The holes 269 may be conical. In the open state the holes 269 are aligned with the respective yarn passages 264. In the closed state the holes 269 are non-aligned with the yarn passages. By moving from the open state to the closed state, the knife cuts each yarn in each yarn passage. Because, in the closed state, the knife 266 closes off the yarn passage 264, it inhibits a fluid flow in the yarn tube 24. The moveable knife 266 is tapered inwardly to prevent and / or reduce the risk of jamming of the yarn injection device 10 due to a stranded yarn.

[0103] Turning to figures 6A, 6B, and 6C, the feeding assembly 20 comprises a roller device 21 which is shown independently. The roller device 21 comprises two rollers 28A, 28B that have a continuous surface and are pressed together by a roller presser 282A, 282B. A roller presser can take multiple forms such as a spring or an actuator. During operation, a first end of a yarn is placed between the rollers and the rollers are driven by a roller actuator 202. The rotation of the rollers 28A, 28B then feeds the yarn to the injection needle guide. By letting the control unit 70 control a number of revolutions of the rollers 28A, 28B the length of the yarn section fed to the injection device 30 can be controlled. To guide the yarn to the exchangeable tubes 50, a feeding guide 272 guides individual yarns into feeding tubes 27 that extend to the cutting device 26. Because the feeding tubes 27 are of a constant length and are flexible and / or moveable, when the cutting device 26 is moved relative to the roller device 21 a distance between the cutting device 26 and the rollers 28A, 28B along which a yarn extends, remains constant. The roller device 21 may be located at a distance above the injection needle guide to make it easily accessible to an operator for the operator to place yarn between the rollers. Because the injection needle guide is located close to the ground, if the roller device would be close to it, an operator would have to bend over to reach it. Therefore, the distance is in the range of 50-150cm for the operator to easily reach the roller device.

[0104] Turning to figures 7A and 7B, part of the injection device is shown. In particular, a needle beam 385 is shown located above the injection needle guide 32. In order for the actuators 37 to move all injection needles 38 (of which only one is depicted) simultaneously, all the injection needles 38 are fixed to the needle beam 385. The needles are placed in needles holes 386 that extend through the needle beam. The needle beam 385 further defines fixating holes 381 in which a fixating means such as a screw can be threaded against the injection needle to fix the injection needle 38 to the needle beam 385. When the needle beam is moved in a vertical direction between an upper position and a lower position, the injection needles move through the injection needle guide 32.

[0105] The terms "a" or "an", as used herein, are defined as one or more than one. The term plurality, as used herein, is defined as two or more than two. The term another, as used herein, is defined as at least a second or more. The terms including and / or having, as used herein, are defined as comprising i.e. , open language, not excluding other elements or steps. Any reference signs in the claims should not be construed as limiting the scope of the claims or the invention. It will be recognized that a specific embodiment as claimed may not achieve all of the stated objects. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. White lines between text paragraphs in the text above indicate that the technical features presented in the paragraph may be considered independent from technical features discussed in a preceding paragraph or in a subsequent paragraph. When a feature is present in the description but not in the claims, this should be interpreted as a statement by the patentee that the feature is not essential for the invention, unless indicated otherwise.

Claims

CLAIMS1. Yarn injection device (10) for injecting yarn sections (1) into the ground, wherein the yarn injection device comprises:- a yarn storage (12) comprising a number of spool holders (122) for holding a number of spools (124) with yarn,- a feeding assembly (20) configured to feed lengths of yarn from the yarn storage to an injection device (30), the feeding assembly comprising: o a number of supply channels (22) defining a number of supply paths (23) extending from the yarn storage to a fluid flow assembly (40), o a number of cutting devices (26) configured to cut a yarn section from each yarn extending from the yarn storage into a respective supply channel, o the fluid flow assembly which is configured to create a flow of fluid through each supply channel in order to apply a drag force on the yarns and move the yarns through each supply channel, wherein the fluid flow device comprises a depressurized compartment (44) having an underpressure,- the injection device comprising: o an injection needle guide (32) defining a number of vertical passages (34), wherein each supply channel comprises a horizontal injection passage (36) extending through the injection needle guide, and wherein each vertical passage intersects the respective horizontal injection passage to form an injection intersection (35), o a number of moveable injection needles (38) which are moveable between an upper needle position (382) and a lower needle position (384) and configured to pass through the vertical passages of the injection needle guide, wherein when yarn sections in the supply channel are located below the moveable injection needles and the moveable injection needles move downward through the injection needle guide, the yarn sections are injected into the ground, o at least one needle actuator (37) configured to move the number of moveable injection needles between the upper needle position and the lower needle position, wherein the cutting device and the injection device are movable with respect to each other, wherein the feeding assembly is configured to feed an adjustable length of yarn to the injection device, andwherein the yarn injection device further comprises at least a first set of exchangeable tubes and a second set of exchangeable tubes, each exchangeable tube (50) being configured to be removably positioned between the injection needle guide and the cutting device to form a part of the respective supply channel, wherein the tubes of the first set have a different length than the tubes of the second set.

2. Yarn injection device according to the preceding claim, wherein the exchangeable tubes have a fixed and non-adjustable length.

3. Yarn injection device according to any of the two preceding claims, comprising at least one cartridge (80) which allows the exchange of multiple exchangeable tubes with a single action, wherein the cartridge comprises:- multiple exchangeable tubes,- a cartridge frame (82) configured to hold the multiple exchangeable tubes adjacent to each other and arranged in a row.

4. Yarn injection device according to the preceding claim, wherein each cartridge frame comprises a series of first holes (83) and a series of second holes (84), each second hole positioned at a distance from an associated first hole, wherein each exchangeable tube extends through one of the first holes and through one of the second holes.

5. Yarn injection device according to any of the preceding claims, wherein the exchangeable tubes in each cartridge have play with respect to each other.

6. Yarn injection device according to the preceding claim, wherein a hole diameter (85) is larger than an outer tube diameter (52) to provide space between each hole and the exchangeable tube in order to create play between each exchangeable tube and the cartridge frame, and to create play between the exchangeable tubes.

7. Yarn injection device according to any of claims 3-6, comprising multiple exchangeable cartridges, each cartridge having multiple tubes, wherein the total number of tubes equals the number of supply paths of the yarn injection device, wherein in particular each cartridge comprises 5-20 exchangeable tubes.

8. Yarn injection device according to any of the preceding claims, wherein the exchangeable tubes are at least partially tapered inwardly in the direction of thedisplacement of the yarn to prevent and / or reduce the risk of jamming of the yarn injection device due to a stranded yarn.

9. Yarn injection device according to the preceding claim, wherein the exchangeable tubes comprise a first, upstream end (56) configured to be positioned near the cutting device, wherein the internal cross-section (54) of the first, upstream end is tapered inwardly in the direction of the displacement of the yarn to prevent and / or reduce the risk of jamming of the yarn injection device due to a stranded yarn.

10. Yarn injection device according to any of the preceding claims, wherein each exchangeable tube comprises a seal (51) on an outer surface (53) of the exchangeable tube to prevent or reduce leakage of the flow of fluid, wherein the seal is in particular positioned on a second, downstream end (59) of the exchangeable tube.

11. Yarn injection device according to any of the preceding claims, wherein the injection needle guide comprises a number of first bores (110) and the cutting device comprises a number of second bores (111), and wherein each exchangeable tube is configured to be positioned with one end in a respective first bore and with the other end in a respective second bore.

12. Yarn injection device according to the preceding claim, wherein the exchangeable tube comprises a first coupling part (91) provided by the seal, wherein each horizontal injection passage (36) of the injection needle guide comprises a second coupling part (92), wherein the first coupling part and the second coupling part provide a coupling (90) between the exchangeable tube and the injection needle guide.

13. Yarn injection device according to any of the preceding claims, wherein an internal diameter (57) of an end portion (58) of the second, downstream end of each exchangeable tube is smaller than an internal diameter (39) of the respective horizontal injection passage.

14. Yarn injection device according to any of the preceding claims, comprising at least five consecutive sets of exchangeable tubes having exchangeable tubes of incrementally longer lengths, wherein the increment is between 15 - 25 mm.

15. Yarn injection device according to any of the preceding claims, wherein the device further comprises a cutting device moving system (262) configured to move the number of cutting devices towards or away from the injection device.

16. Yarn injection device according to any of the preceding claims, wherein each cutting device comprises a number of yarn passages (264) and a moveable knife (266), wherein each yarn passage is fluidly connected to the respective exchangeable tube.

17. Yarn injection device according to the preceding claim, wherein the moveable knife is tapered inwardly to prevent and / or reduce the risk of jamming of the yarn injection device due to a stranded yarn.

18. Yarn injection device according to any of claims 15-16, wherein the knife is moveable between an open state and a closed state, and wherein the knife is configured to cut the yarn at the yarn passage when moved from the open state to the closed state, wherein the knife closes off the yarn passage in the closed state and inhibits a fluid flow in the supply channel.

19. Yarn injection device according to any of the preceding claims, wherein the assembly device comprises at least one roller (28), and wherein a rotation of the at least one roller feeds yarn to the injection device, and wherein the distance between the number of cutting devices and the at least one roller remains constant when the number of cutting devices and injection device are moved with respect to each other.

20. Yarn injection device according to any of the preceding claims, wherein the depressurized compartment of the fluid flow device is located downstream of the injection device.

21. Yarn injection device according to any of the previous claims, wherein the fluid flow device comprises a channel valve (422) located between the depressurized compartment and a number of fluid communication channels (42) extending between the injection device and the fluid flow device, wherein the channel valve regulates the flow of fluid in the supply channel, wherein in a closed state (424) the channel valve inhibits a flow of fluid in the supply channel, and wherein in particular the fluid is air.

22. Yarn injection device according to any of the preceding claims, wherein each supply channel comprises a number of feeding tubes (27) extending between the at least oneroller and a number of cutting devices, wherein each feeding tube is flexible and / or movable.

23. Yarn injection device according to any of the previous claims, wherein the device comprises:- a moving assembly (60), the moving assembly comprising a frame (62) and wheels (64) and / or tracks mounted to the frame, configured to allow the device to move over a surface,- a suction buffer tank, and- a suction pump (46), wherein the suction buffer tank and the suction pump (46) are located left of the injection needle guide and a drive system (66) of the moving assembly is located right of the injection needle guide in side view to create an even weight distribution.

24. A set of exchangeable tubes (50A) for use in a yarn injection device according to claim 1.

25. Method for feeding an adjustable length of yarn to a yarn injection device (10) comprising:- a yarn storage (12) comprising a number of spool holders (122) for holding a number of spools (124) with yarn,- a feeding assembly (20) comprising: o a number of supply channels (22) configured to accommodate yarn, o a number of cutting devices (26), o the fluid flow device configured to create a flow of fluid through each supply channel in order to apply a drag force on the yarns and move the yarns through each supply channel, wherein the fluid flow assembly comprises a depressurized compartment (44) having an underpressure,- the injection device (30) comprising: o an injection needle guide (32) defining a number of vertical passages (34) intersecting a respective supply channel, o a number of moveable injection needles (38), o at least one needle actuator (37), wherein the cutting device and the injection device are movable with respect to each other, and wherein each supply channel comprises an exchangeable tube (50) between the injection device and a cutting device (26),the method comprising the steps: a) discontinuing the injection process of the yarn injection device, b) moving the cutting device and the injection device away from each other, c) removing the exchangeable tubes between the cutting device and the injection device, d) replacing each exchangeable tube with an exchangeable tube having a different length, e) moving the cutting device and the injection device towards each other, f) continuing the injection process of the yarn injection device.

26. Method according to the previous claim, wherein multiple exchangeable tubes are arranged in a cartridge (80), wherein each exchangeable tube in the cartridge has an equal length, wherein during steps c) and d) one or more cartridges having multiple exchangeable tubes of a first length are removed and replaced by one or more cartridges having exchangeable tubes of a second, different length.

27. Method according to any of the previous method claims, wherein the device further comprises a cutting device moving system (262) configured to move the number of cutting devices towards or away from the injection device, wherein during steps (b and (e the cutting device is moved towards or away from the injection device.

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