An in-tube check valve

Abstract

The invention relates to an in-tube check valve (1) which is inserted in a tube (13) for or is insertable in a tube for fluid flow. The check valve comprises a stator (12), an adjustment part (11), a closure element (16), and a spring (17). The stator comprises an inlet (14) and a valve seat (15) and the adjustment part comprises an outlet (18) and an external thread (21). The external thread is arranged to engage with the inner wall (22) of the tube, and the adjustment part (11) and the stator are placeable with an operational distance (25) between them, and said operational distance is adjustable by reversible screwing the adjustment part into the tube facilitated by the external thread's engagement with the inner wall of the tube.

Description

[0001] AN IN-TUBE CHECK VALVE

[0002] FIELD OF THE INVENTION

[0003] The present invention relates to an in-tube check valve which is inserted in a tube or is insertable in a tube.

[0004] BACKGROUND OF THE INVENTION

[0005] The present invention pertains to the realm of check valves, which are integral components in various applications. Check valves play a crucial role in controlling fluid flow, allowing the flow to move in one direction while preventing backflow. A typical check valve is a ball check valve in which the closing member, the movable part to block the flow, is a ball. The ball may be spring-loaded to help keep it shut when there is not sufficient pressure from the flow to open the valve.

[0006] Ball check valves are often very small, simple, and cheap. They are commonly used in liquid or gel minipump dispenser spigots, spray devices, some rubber bulbs for pumping air, etc., manual air pumps and some other pumps, and refillable dispensing syringes.

[0007] Among the different types of check valves, this invention specifically focuses on in-tube check valves. Unlike traditional check valves, these are designed to be inserted and concealed within a tube, offering several advantages such as improved aesthetics, simplified assembly, and a reduced risk of leaks.

[0008] While in-tube check valves have a broad range of applications, they are particularly significant in the field of medicine for the precise dosing of medications. For instance, insulin pumps, which serve as an alternative to traditional insulin injections, heavily rely on these valves for the infusion of insulin.

[0009] In an insulin pump, the in-tube check valve functions as a one-way valve within the insulin delivery system. It ensures accurate dosing by allowing fluid flow only in one direction and preventing backflow. The effectiveness of insulin delivery is contingent upon the valve's ability to achieve a tight seal, which is crucial to prevent leakage and maintain consistent insulin delivery. However, existing solutions may suffer from poor sealing properties, leading to potential inaccuracies in dosing. Over time, wear, degradation, or changes in material properties can impact the performance of check valves, affecting the precision of insulin delivery.

[0010] Patent TWM539578 describes a one-way check valve designed for inflatable beds. This valve features a slightly hollow tube-shaped body, creating an internal space housing a baffle with a central perforation surrounded by a hollow opening. The outer ring of the valve body incorporates one or more convex rings.

[0011] However, TWM539578 has a critical limitation in terms of precision position adjustability for the internal valve components. The predefined positions of the components do not allow for fine-tuned positioning within the tube, hindering the optimization of valve performance, especially in terms of modulating cracking pressure and sealing characteristics. This limitation is particularly significant when considering the sealing force adjustment, a key factor in ensuring the valve's effectiveness.

[0012] Addressing the precision adjustability issue and optimizing sealing performance remain key challenges for further advancements in in-tube check valve technology.

[0013] Hence, an improved check valve would be advantageous, and in particular a more efficient and / or reliable check valve would be advantageous.

[0014] OBJECT OF THE INVENTION

[0015] It is an object of the invention to provide an in-tube check valve which is adjustable allowing fine tuning of the components.

[0016] It is a further object of the invention to provide an in-tube check valve with improved sealing performance.

[0017] It is a further object of the present invention to provide an alternative to the prior art. In particular, it may be seen as an object of the present invention to provide an in-tube check valve that solves the above-mentioned problems of the prior art ensuring precise and reliable fluid flow.

[0018] SUMMARY OF THE INVENTION

[0019] Thus, the above-described object and several other objects are intended to be obtained in a first aspect of the invention by providing an in-tube check valve with tube for fluid flow, wherein

[0020] - the check valve is inserted within the tube,

[0021] - the check valve comprises a stator, an adjustment part, a closure element, and a spring, and

[0022] - the stator comprises an inlet and a valve seat, wherein

[0023] - the adjustment part comprises an outlet and an external thread,

[0024] - the closure element and the spring are connected to the adjustment part,

[0025] - the external thread is arranged to engage with the inner wall of the tube,

[0026] - the adjustment part and the stator are placeable with an operational distance between them, and

[0027] - said operational distance is arranged to be adjustable by screwing the adjustment part into the tube facilitated by the external thread's engagement with the inner wall of the tube.

[0028] This invention relates to a precision in-tube check valve design capable of providing high-resolution adjustment of the preload force of the closure element, for optimized sealing and pumping performance. A in-tube check valve is a check valve which may be inserted into a tube.

[0029] The key innovation is a precision adjustment part with external threads that enables fine-tuned compression of the spring. By turning the adjustment part, to optimize the operational distance between the adjustment part and the stator, the spring compression can be precisely modulated to maintain sufficient sealing force on the closure element while still allowing smooth flow of the medium (liquid / air). This gives the valve the ability to be tuned for optimal trade-offs between leak- tight sealing and low cracking pressure / friction, improving performance in demanding applications. The threaded interface allows for accurate control of the spring preload, enabling high-precision valve calibration and customization for specific operating conditions. The precision adjustability of this check valve design provides enhanced flexibility and performance.

[0030] The check valve may be used in a pump for insulin delivery. Thus, the check valve's sealing capability is crucial to prevent free flow of insulin, which can be fatal to the patient. Therefore, a check valve design with superior sealing yet adequate flow is needed. Due to a relatively low pumping pressure of the insulin pump, the margin of sealing force is critically small.

[0031] When screwed into the tube, the external thread of the adjustment part engages with the flexible tube forming an inner thread in the flexible tube. Before engagement by the external thread with the inner wall of the tube the inner wall is smooth without any indents.

[0032] The thread of the adjustment part is made of a first material. The first material may be a metal, typically stainless steel. The tube is made of a second material. The second material may be a flexible material, such as a polymer. The second material may be plastic, polyethylene, polypropylene, polyester, rubber, or silicone.

[0033] The tube is made of the second material which may be formed by the external thread, made of the first material, when the check valve is screwed into the tube. Alternatively, the second material may be a metal or alloy which has a lower stiffness than the first material. The second material has a lower stiffness than the first material, that is to be understood as the second material has a lower Young Modulus than the first material, which the threads of the adjustment part is made of.

[0034] The adjustment part comprises a flow channel allowing fluid to pass through the adjustment part. The adjustment part's flow channel comprises an inlet and outlet, which also is the outlet of the check-valve. The spring is a compression spring. The closure element may be a ball. The spring and the closure element are connected to the adjustment part and is therefore inserted in the tube together with the adjustment part.

[0035] The ball is connected to the spring and is pressed against the valve seat to seal the passage when the spring force is large than the force exerted by the fluid pressure of the fluid flowing in the tube.

[0036] The stator comprises a valve seat. The stator may be an O-ring or may comprise an O-ring placed so that the O-ring comprises the valve seat. The closure element engages the valve seat, when the spring force is higher than the force from the fluid and hereby the check valve is closed, so no fluid is passing through the valve seat in the stator. Further, the stator comprises a flow channel allowing fluid to pass through the stator when the valve is open. The flow channel comprises an inlet allowing fluid to pass into the check valve. The valve seat comprises an opening, which is outlet from the stator for fluid to pass when the valve is open.

[0037] The precision in-tube check valve enables consistent flow while maintaining optimized sealing performance. While the flow rate may be lower compared to previously developed in-tube valves, the sealing capability is significantly enhanced. The key innovation is the precision adjustment part, which may have an external thread pitch of 300 pm. This means when the adjustment part is rotated 360 degrees, it advances 300 pm inside the tube. This allows very precise control of the spring preload with a high resolution of 5 pm per scale division, which is achievable with a 6-degree screwdriver turn. The fine threading enables fine-tuned modulation of the sealing force in small increments. This facilitates dialing in the optimal spring compression to strike a balance between watertight sealing and low cracking pressure. The precision adjustability sets this valve design apart from prior in-tube check valves limited to coarse, predefined settings.

[0038] The precision in-tube check valve demonstrates markedly improved sealing over prior valves, as precise adjustability prevents unwanted free flow. This tight sealing is critical for insulin delivery pump applications, where free flow can be fatal. The valve's tunable design also makes it well-suited for other drug delivery uses requiring leak-proof operation. Though flow rate is sacrificed, the precision valve's sealing adjustability provides major advantages over earlier in-tube options when leakage prevention is paramount.

[0039] There are many different possible applications of the in-tube check valve.

[0040] The in-tube check valve may be used for Drug Delivery Systems. Micropumps are employed in portable or implantable drug delivery devices, they can precisely control the release of medications, hormones, or other therapeutic substances. The in-tube check valve may be installed in or connected to such pumps.

[0041] Further, the in-tube check valve may be used for brain pressure release, wound healing by extracting liquor puris on the wound and for active intravenous therapy delivery.

[0042] The in-tube check valve may also be used in biomedical assays and lab-on-a-chip devices like micropumps play a crucial role in microfluidic analyses and lab-on-a- chip systems enabling precise fluid handling for diagnostic tests, DNA sequencing, and cell culturing.

[0043] The in-tube check valve may also be used in chemical and biological sensing, where they may be installed in micropumps which are integrated into sensors for chemical and biological detection and the in-tube check valve may facilitate sample transport and mixing in biosensors and environmental monitoring devices.

[0044] The in-tube check valve may also be used in microelectronics cooling, where they may be used in micropumps which are used for cooling electronic components in micro-integrated circuits (p-IC) enhancing heat dissipation and preventing overheating.

[0045] TWM539578 pertains to an in-tube check valve design. However, a key limitation of TWM539578 is the lack of precision position adjustability for the internal valve components. The discrete, predefined positions of the sailor sleeve do not allow fine-tuned position of the components inside the pipe / tube. This impedes optimizing valve performance by precisely modulating cracking pressure and sealing characteristics. In contrast, the threaded precision adjustment component of the current innovation enables continuous tuning of the in-tube valve by gradually increasing or decreasing the spring preload. One important factor for precision positioning is the control of the spring compression and ball sealing force of the valve inside a tube. This facilitates custom tailoring the valve parameters for optimal sealing, pressure response, and flow in each application.

[0046] While TWM539578 employs valve inserted into tube concept, it lacks the critical innovation of a precision adjustment component for fine tuning of valve sealing force and characteristics.

[0047] This distinction in precision adjustability represents a substantial advance of the current invention over the prior art including TWM539578, enabling unprecedented control over valve performance for optimizing sealing, pressure response, and flow. Hereby, the in-tube check valve of the current invention makes possible an until now unseen precision in sealing force adjustment. The miniature pump application further demonstrates the importance of customizable high-resolution tuning to strike the optimal balance between leak prevention and flow restriction in low pressure delivery devices.

[0048] According to an embodiment, the external thread of the adjustment part upon engagement with the inner wall of the tube is arranged to form indents in the tube at the points of engagement so that the indents constitute an internal thread within the tube.

[0049] Before the adjustment part is inserted into the tube, the inner surface of the tube may be smooth without any indents. But when inserting the adjustment part into the tube, the adjustment part is forming indents in the inner surface of the tube. Therefore, when the adjustment part is inserted, the thread of the adjustment part is fixed in an internal thread within the tube, where the indents formed by the adjustment part constitutes the internal thread in the tube.

[0050] According to an embodiment, the external thread of the adjustment part is made of first material and the tube is made of a second material, where the first material comprises a higher Young's modulus than the second material. The external thread of the adjustment part is made of first material, and the tube is made of a second material. The first material is stiffer or harder than the second material, so when the adjustment part is inserted in the tube, the thread of the adjustment part is able to make indents in the tube forming an internal thread in the tube.

[0051] To fine tune the operational distance between the adjustment part and the stator it is possible to reversible screw the adjustment part into the tube to decrease or increase the distance between the adjustment part and the stator and hereby finetune the spring force exerted on the closure element.

[0052] According to an embodiment, wherein the adjustment part comprises a slot to accommodate a tool to screw the adjustment part into the tube.

[0053] To adjust the position of the adjustment part, the adjustment part comprises a slot into which a tool, like a screwdriver, can be inserted and used to adjust the distance between the adjustment part and the stator to optimize the spring force.

[0054] Precision adjustment is possible by screwing the adjustment part into the optimal position relative to the stator. Further, the adjustment part is thereby also fixed in position, as the external thread is fixed in the indents / internal thread of the tube as adjustment part cannot move without an external force, like a screwdriver, adjusting it. The pressure of the fluid in the tube is not able to move the adjustment part.

[0055] According to an embodiment, the outer diameter of the external thread of the adjustment part is larger than the inner diameter of the tube.

[0056] To be able to make indents, an internal thread in the tube the outer diameter of the external thread is larger than the inner diameter of the tube.

[0057] According to an embodiment, the outer diameter of the external thread of the adjustment part is less than 10.0 cm, preferably less than 5.0 cm, more preferably less than 2.0 cm, even more preferably less than 1.0 cm and even more preferably less than 0.2 cm and even more preferably less than 0.1 cm. The in-tube check valve of the invention may be used in many different contexts, where the requirement for flow is different. Especially when the in-tube check valve is suited for medical purpose, like being used in connection with an insulin pump, the outer diameter of the external thread of the adjustment part is less than 1.5 mm, more preferably less than 1.2 mm, and even more preferably less than 1.0 mm.

[0058] According to an embodiment, the outer diameter of the external thread of the adjustment part preferably is less than 30%, more preferably less than 20%, even more preferably less than 10%larger than the inner diameter of the tube.

[0059] According to an embodiment, the outer diameter of the stator is larger than the inner diameter of the tube and the outer diameter of the stator is less than 30%, preferably less than 20%, even more preferably less than 10% larger than the inner diameter of the tube. The stator may comprise an external thread where the outer diameter of the stator thread is larger than the inner diameter of the tube.

[0060] According to an embodiment, the tube is made of a second material, such as a polymer, which is deformable by the external thread of the adjustment part.

[0061] The tube is made by a flexible material. The material may typically be a polymer material.

[0062] According to an embodiment, the tube is transparent or translucent to allow visual inspection of the check valve.

[0063] If the tube is transparent or translucent the operational distance between the adjustment part and the stator may be obtained by visual means, an operator entering the adjustment part into the tube may ensure it is placed in the operational distance by having a ruler to measure the distance between the adjustment part and the stator. According to an embodiment, the closure element is arranged to engage the valve seat to stop fluid flow through the check valve when the pressure of the fluid is less than the pressure of the spring.

[0064] The spring exerts a pressure on the closure element so that when the pressure of the fluid is less than the pressure of the spring the valve will be closed.

[0065] According to an embodiment, the check valve is arranged to allow fluid flow through the valve when the closure element is not engaged with the valve seat.

[0066] When the pressure exerted by the spring is less than the pressure of the fluid entering the check valve, then the valve will be open for fluid flow through the valve.

[0067] A second aspect of the invention relates to a medical pump, such as an insulin pump, comprising the in-tube check valve according to the first aspect of the invention.

[0068] Insulin pumps are crucial devices for many individuals with diabetes, as they deliver precise doses of insulin to help maintain optimal blood glucose levels. The sealing of an insulin pump plays a vital role in its operation for several reasons:

[0069] • Prevention of Insulin Leakage: A well-sealed insulin pump ensures that insulin does not leak out of the device. This is crucial because any leakage could lead to an insufficient amount of insulin being delivered to the body, potentially resulting in high blood glucose levels, a condition known as hyperglycemia.

[0070] • Avoidance of Overdosing: Conversely, if the seal is not intact, it could potentially allow a free flow of insulin into the body, leading to an overdose. This could result in dangerously low blood glucose levels, a condition known as hypoglycemia, which can be life-threatening.

[0071] • Maintaining Sterility: The seal helps to keep the insulin sterile and free from contamination. Any breach in the seal could expose the insulin to bacteria or other contaminants, which could pose serious health risks. Device Longevity: A secure seal helps maintain the overall integrity and longevity of the insulin pump.

[0072] The in-tube check valves may be used in connection to an insulin pump. The insulin pumps insulin into the body. An in-tube check valve may be ensuring that only when the pressure of the fluid from the pump is high enough to open the check valve, insulin passes through the check valve to the human. Also, the check valve ensures there is no backflow into the pump.

[0073] A third aspect of the invention relates to the use of a medical pump comprising the in-tube check valve according to the first aspect of the invention for the delivery of medicine to a patient.

[0074] According to an embodiment the medicine is one of: insulin, nicotine, fentanyl, nitroglycerin, scopolamine, estradiol, testosterone, clonidine, rivastigmine, selegiline, methylphenidate.

[0075] The check valve may be used in a pump for drugs that have similar viscosity to insulin, which is drugs with similar molecular weights and formulations. Drugs that have similar viscosity to insulin may be

[0076] Nicotine: Used for smoking cessation.

[0077] Fentanyl: An opioid used for pain management.

[0078] Nitroglycerin: Used for angina treatment.

[0079] Scopolamine: Used for motion sickness prevention.

[0080] Estradiol: Used for hormone replacement therapy.

[0081] - Testosterone: Used for hormone replacement therapy in both men and women.

[0082] Clonidine: Used for treating hypertension.

[0083] Rivastigmine: Used for Alzheimer's disease treatment.

[0084] Selegiline (Emsam): An antidepressant.

[0085] Methylphenidate (Daytrana): Used for treating attention deficit hyperactivity disorder (ADHD).

[0086] Semaglutid: Used for controlling blood sugar levels in adults with type 2 diabetes and for weight management. A fourth aspect of the invention relates to method for inserting the in-tube check valve according to the first aspect of the invention into the tube, wherein the method comprises:

[0087] - inserting the stator into the tube by pushing or screwing the stator into the tube,

[0088] - inserting the adjustment part into the tube by screwing the adjustment part into the tube,

[0089] - positioning the adjustment part at the operational distance relative to the stator.

[0090] The stator is inserted into the tube by pushing or screwing the stator into the tube. The stator may be inserted from either end of the tube, if it is inserted from the opposite end of the end where the adjustment part is inserting the stator may have an external thread and be screwed into the tube. However, the stator may not have an external thread, in this case the stator is pushed into the tube.

[0091] The adjustment part is inserted into the tube by screwing the adjustment part into the tube, so the external thread of the adjustment part is making indents in the inner surface of the tube creating an internal thread in the tube.

[0092] The adjustment part is positioned at the operational distance relative to the stator. By positioning the adjustment part precisely at the operational distance, it is ensured that the pressure exerted by the spring on the closure element, the spring preload, is correct to ensure the valve is closed when no fluid is intended pass through the check valve.

[0093] A fifth aspect of the invention relates to method for calibrating the in-tube check valve according to the first aspect of the invention, wherein the method comprises,

[0094] - providing a pressure sensor for measuring the pressure in the tube upstream of the check valve or providing a flow meter for measuring the flow in the tube upstream of the check valve, - adjusting the operational distance between the adjustment part and the stator by inversible screwing the adjustment part into the tube facilitated by the external thread's engagement with the inner wall of the tube, until the pressure measured by the pressure sensor reaches a predetermined pressure or until the flow measured by the flow meter reaches a predetermined flow.

[0095] Precision calibration of the in-tube check valve may be performed. To achieve this a pressure sensor or a flow meter may be provided. If a pressure sensor is provided it is measuring the pressure in the tube upstream of the check valve. If a flow meter is provided it is measuring the measuring the flow in the tube upstream of the check valve. The operational distance between the adjustment part and the stator is adjusted by inversible screwing the adjustment part into the tube facilitated by the external thread's engagement with the inner wall of the tube, until the pressure measured by the pressure sensor reaches a predetermined pressure or until the flow measured by the flow meter reaches a predetermined flow, which typically is zero flow.

[0096] A sixth aspect of the invention relates to an in-tube check valve which is insertable into a tube for fluid flow, wherein

[0097] - the check valve comprises a stator, an adjustment part, a closure element (16), and a spring (17), and

[0098] - the stator comprises an inlet and a valve seat; wherein

[0099] - the adjustment part comprises an outlet and an external thread,

[0100] - the closure element and the spring are connected to the adjustment part,

[0101] - the external thread is arranged to engage with the inner wall of the tube,

[0102] - the adjustment part and the stator are placeable with an operational distance between them, and

[0103] - the operational distance is arranged to be adjustable by reversible screwing the adjustment part into the tube facilitated by the external thread's engagement with the inner wall of the tube.

[0104] The check valve comprising a stator, an adjustment part, a closure element, and a spring, is insertable into a tube for fluid flow. In this aspect the check valve is not with a tube, but insertable in a tube. This is to be understood as the manufacture may provide only the check valve but not the tube, the buyer of the check valve may provide the tube and insert the check valve into the tube.

[0105] In an insulin pump often connecting tubes are supplied with the insulin pump, in this case the check valve may be inserted into a connecting tube. Then the check valve is insertable in the tube provided by the manufacturer of the insulin pump.

[0106] The first, second, third, fourth, fifth and sixth aspect of the present invention may each be combined with any of the other aspects. These and other aspects of the invention will be apparent from and elucidated with reference to the embodiments described hereinafter.

[0107] BRIEF DESCRIPTION OF THE FIGURES

[0108] The check valve according to the invention will now be described in more detail regarding the accompanying figures. The figures show one way of implementing the present invention and are not to be construed as being limiting to other possible embodiments falling within the scope of the attached claim set.

[0109] Fig. 1 illustrates the in-tube check valve with a tube.

[0110] Fig. 2 illustrates the parts of the check valve and the tube.

[0111] Fig. 3 illustrates the calibration of the in-tube check valve.

[0112] Fig. 4 illustrates the in-tube check valves being used in connection with an insulin pump.

[0113] Fig. 5 is a flow-chart illustrating the method for inserting the in-tube check valve in the tube.

[0114] Fig. 6 is a flow-chart illustrating the method for calibrating the in-tube check valve.

[0115] DETAILED DESCRIPTION OF AN EMBODIMENT

[0116] Fig. 1 illustrates the in-tube check valve 1 with a tube 13. The check valve comprises a stator 12, an adjustment part 11, a closure element 16, and a spring 17. The stator comprises an inlet 14 to a flow channel 19 which is allowing fluid to flow through the stator. The flow channel 19 is indicated by the shaded area in the stator. The adjustment part 11 comprises an outlet 18 and a flow channel 20 allowing fluid to flow through the adjustment part. The closure element 16 and the spring 17 are connected to the adjustment part.

[0117] Further, the adjustment part comprises an external thread 21. When the adjustment part 11 is inserted in the tube 13, the adjustment part is screwed into the tube. The adjustment part comprises a slot 24 to accommodate a tool, like a screwdriver, to screw the adjustment part into the tube. The double arrow 51 is indicating the adjustment part 11 can be reversible inserted into the tube 13, and the round double arrow 52 indicates that the adjustment part 11 is screwed into the tube making it possible to fine tune the valve, by making small adjustments to regulate the operational distance 25 between the adjustment part 11 and the stator 12. Hereby the force that the spring 17 exert on the closure element 16 when the closure element is engaging the valve seat 15 can be fine-tuned.

[0118] The external thread is arranged to engage with the inner wall 22 of the tube 13. The external thread 21 of the adjustment part 11 upon engagement with the inner wall 22 of the tube 13 is arranged to form indents 23 in the tube 13 at the points of engagement so that the indents 23 constitute an internal thread within the tube. Also, the internal thread by engaging into the tube fixes the adjustment part 11 in the tube 13 so that the pressure from the fluid is not sufficient to push or move the adjustment part.

[0119] The stator 12 may also comprise a stator external thread 61 and a stator slot 62. Thereby, the stator 12 may be inserted into the tube 13 by the same method as the adjustment part 11, by being screwed into the tube. However, it must be done from the opposite end of the tube. Alternatively, the stator 12 does not comprise a stator external thread 61 but is just pushed into the tube 13, this may then be from the same end of the tube that the adjustment part 11 enters the tube. In this case the stator 12 is fixed in the tube 13 by that the stator has an outer diameter that is larger than the inner diameter of the tube, so the stator is extending the inner diameter of the tube, which is then fixing the stator in the tube. Fig. 2 illustrates the parts of the check valve and the tube 13. The check valve comprises a stator 12, an adjustment part 11, a closure element 16, and a spring 17. The closure element and the spring are connected to the adjustment part. The stator may comprise an external thread 61, or it may not comprise an external thread. The outer diameter 31 of the external thread 21 is larger than the inner diameter 32 of the tube 13, so when the adjustment part 11 is screwed into the tube 13 it makes indents 23 in the inner wall of the tube forming an internal thread in the tube. However, as can be seen in fig. 2, before the adjustment part is screwed into the tube, the inner surface 22 of the tube does not have any indents or an internal thread.

[0120] Fig. 3 is basically identical to fig. 1 with the exception that a sensor is added, the sensor may be a pressure sensor 35 or a flow meter 36. The sensor is used for calibrating the in-tube check valve 1. When a pressure sensor 35 is used to calibrate the valve, the pressure sensor is measuring the pressure in the tube 13 upstream of the check valve. The operational distance 25 between the stator 12 and the adjustment part 11 is then adjusted by turning a tool, like a screwdriver, in the slot 24 until the pressure measured by the pressure sensor reached a predetermine pressure, which indicates that the valve is closed. Hereby it is possible to adjust the valve by screwing the adjustment part 11 exactly into the operational distance 25 from the stator 12 that the spring force exerted by the closure element 16 on the valve seat 15 exactly is sufficient to close the valve at the predetermined pressure, without risking having to high a spring force, which may require a higher fluid pressure to open the valve.

[0121] Alternatively, the check valve may be calibrated using a flow meter 36 measuring the flow through the tube 13. The position of the adjustment part 11 is then adjusted to exactly the point where the flow reached a predetermined flow with may be zero flow. The adjustment part 11 is then placed with an operational distance 25 to the stator 12 which is exactly where the flow stops avoiding screwing the adjustment part 11 to far into the tube 13 and thereby avoiding that to high fluid pressure is needed to open the valve.

[0122] Fig. 4 illustrates a situation where the in-tube check valves are used in connection with an insulin pump. The insulin pump 51 is controlled by a controller 52 and is pumping insulin through a needle 53 into a human body 54. An in-tube check valve 1 is ensuring that only when the pressure of the fluid from the pump is high enough to open the check valve, insulin passes through the check valve to the human.

[0123] Further an in-tube check valve 1 is also controlling the flow of insulin from an insulin reservoir 55 to the flow pump, ensuring that there is no backflow to the insulin reservoir.

[0124] Fig. 5 illustrates the method for inserting the in-tube check valve in the tube. The first step SI is to insert the stator 12 into the tube by pushing or screwing the stator into the tube, then in the second step S2 the adjustment part 11 is inserted into the tube 13 by screwing the adjustment part into the tube, and the third step S3 is to position the adjustment part at the operational distance 25 relative to the stator. By positioning the adjustment part at the operational distance, it is ensured that the pressure exerted by the spring on the closure element is the correct pressure to ensure the valve is closed when no fluid is to pass through the check valve.

[0125] Fig. 6 illustrates a method for calibrating the in-tube check valve. In the step Sil a pressure sensor or a flow meter is provided. If a pressure sensor is provided it is measuring the pressure in the tube 13 upstream of the check valve. If a flow meter is provided it is measuring the measuring the flow in the tube upstream of the check valve. The next step S12 is to adjust the operational distance 25 between the adjustment part 11 and the stator 12 by inversible screwing the adjustment part into the tube 13 facilitated by the external thread's 21 engagement with the inner wall 22 of the tube, until the pressure measured by the pressure sensor 35 reaches a predetermined pressure or until the flow measured by the flow meter 36 reaches a predetermined flow, which typically is zero flow.

[0126] In an experiment, a specific pump was used: the Atto pump. Please bear in mind that different pumps can provide different output pressures. The spring in the intube check valve was set to seal at a sealing pressure of 200.4 mBar, which is a pressure at which the pump can still pump liquid out. The Precision in-tube check valve can achieve higher or lower output pressures and sealing pressures by adjusting the spring that presses the ball. In the experiment, the obtained pressure output after the fluid passed through the check valve was 185.1 mBar.

[0127] The minimum pressure required for insulin delivery to get insulin through the needle is 150 mBar.

[0128] In exemplary embodiments E1-E15, the invention may relate to:

[0129] El. An in-tube check valve with a tube for a fluid flow, wherein

[0130] - the check valve (1) is inserted within the tube (13),

[0131] - the check valve comprises a stator (12), an adjustment part (11), a closure element (16), and a spring (17), and

[0132] - the stator comprises an inlet (14) and a valve seat (15); wherein

[0133] - the adjustment part comprises an outlet (18) and an external thread (21), - the closure element (16) and the spring (17) are connected to the adjustment part (11),

[0134] - the external thread (21) is arranged to engage with the inner wall (22) of the tube (13),

[0135] - the adjustment part (11) and the stator (12) are placeable with an operational distance (25) between them, and

[0136] - said operational distance (25) is arranged to be adjustable by reversible screwing the adjustment part (11) into the tube (13) facilitated by the external thread's (21) engagement with the inner wall (22) of the tube (13).

[0137] E2. The in-tube check valve according to embodiment El, wherein the external thread (21) of the adjustment part (11) upon engagement with the inner wall (22) of the tube (13) is arranged to form indents (23) in the tube (13) at the points of engagement so that the indents (23) constitute an internal thread within the tube.

[0138] E3. The in-tube check valve according to embodiments El or E2, wherein the external thread (21) of the adjustment part (11) is made of first material and the tube (13) is made of a second material, where the first material comprises a higher Young's modulus than the second material.

[0139] E4. The in-tube check valve according to any of the embodiments El to E3, wherein the adjustment part (11) comprises a slot (24) to accommodate a tool to screw the adjustment part into the tube (13).

[0140] E5. The in-tube check valve according to any of the embodiments El to E4, wherein the outer diameter (31) of the external thread (21) of the adjustment part (11) is larger than the inner diameter (32) of the tube (13).

[0141] E6. The in-tube check valve according to any of the embodiments El to E5, wherein the outer diameter (32) of the external thread (21) of the adjustment part (11) is less than 10.0 cm, preferably less than 5.0 cm, more preferably less than 2.0 cm, even more preferable less than 1.0 cm and even more preferable less than 0.2 cm and even more preferable less than 0.1 cm.

[0142] E7. The in-tube check valve according to any of the preceding embodiments, wherein the outer diameter (31) of the external thread (21) of the adjustment part (11) preferably is less than 30%, more preferably less than 20%, even more preferably less than 10% larger than the inner diameter (32) of the tube (13).

[0143] E8. The in-tube check valve according to any of the preceding embodiments, wherein the tube (13) is made of a second material, such as a polymer, which is deformable by the external thread (21) of the adjustment part (11).

[0144] E9. The in-tube check valve according to any of the preceding embodiments, wherein the tube (13) is transparent or translucent to allow visual inspection of the check valve (1).

[0145] E10. The in-tube check valve according to any of the preceding embodiments, wherein the closure element (16) is arranged to engage the valve seat (15) to stop fluid flow through the check valve (1) when the pressure of the fluid is less than the pressure of the spring (17).

[0146] Ell. The in-tube check valve according to any of the preceding embodiments, wherein the check valve (1) is arranged to allow fluid flow through the valve when the closure element (16) is not engaged with the valve seat (15). E12. A medical pump (51), such as an insulin pump, comprising the in-tube check valve (1) according to any of the embodiments El-Ell.

[0147] E13. A method for inserting the in-tube check valve (1) according to any of the embodiments El-Ell into the tube (13), wherein the method comprises:

[0148] - inserting (SI) the stator (12) into the tube by pushing or screwing the stator into the tube,

[0149] - inserting (S2) the adjustment part (11) into the tube (13) by screwing the adjustment part into the tube,

[0150] - positioning (S3) the adjustment part (11) at the operational distance (25) relative to the stator (12).

[0151] E14. A method for calibrating the in-tube check valve (1) according to any of the embodiments El-Ell, wherein the method comprises,

[0152] - providing a pressure sensor (35) for measuring the pressure in the tube (13) upstream of the check valve (1) or providing a flow meter (36) for measuring the flow in the tube upstream of the check valve (1),

[0153] - adjusting the operational distance (25) between the adjustment part (11) and the stator (12) by inversible screwing the adjustment part into the tube (13) facilitated by the external thread's (21) engagement with the inner wall (22) of the tube, until the pressure measured by the pressure sensor (35) reaches a predetermined pressure or until the flow measured by the flow meter (36) reaches a predetermined flow.

[0154] E15. A in-tube check valve which is insertable into a tube for fluid flow, wherein

[0155] - the check valve (1) comprises a stator (12), an adjustment part (11), a closure element (16), and a spring (17), and

[0156] - the stator comprises an inlet (14) and a valve seat (15); wherein

[0157] - the adjustment part (11) comprises an outlet (18) and an external thread (21),

[0158] - the closure element (16) and the spring (17) are connected to the adjustment part (11),

[0159] - the external thread (21) is arranged to engage with the inner wall (22) of the tube (13), - the adjustment part (11) and the stator (12) are placeable with an operational distance (25) between them, and

[0160] - said operational distance (25) is arranged to be adjustable by reversible screwing the adjustment part (11) into the tube (13) facilitated by the external thread's (21) engagement with the inner wall (22) of the tube (13).

[0161] Although the present invention has been described in connection with the specified embodiments, it should not be construed as being in any way limited to the presented examples. The scope of the present invention is set out by the accompanying claim set. In the context of the claims, the terms "comprising" or "comprises" do not exclude other possible elements or steps. Also, the mentioning of references such as "a" or "an" etc. should not be construed as excluding a plurality. The use of reference signs in the claims with respect to elements indicated in the figures shall also not be construed as limiting the scope of the invention. Furthermore, individual features mentioned in different claims, may possibly be advantageously combined, and the mentioning of these features in different claims does not exclude that a combination of features is not possible and advantageous.

Claims

CLAIMS1. An in-tube check valve with a tube for a fluid flow, wherein- the check valve (1) is inserted within the tube (13),- the check valve comprises a stator (12), an adjustment part (11), a closure element (16), and a spring (17), and- the stator comprises an inlet (14) and a valve seat (15); wherein- the adjustment part comprises an outlet (18) and an external thread (21), - the closure element (16) and the spring (17) are connected to the adjustment part (11),- the external thread (21) is arranged to engage with the inner wall (22) of the tube (13),- the adjustment part (11) and the stator (12) are placeable with an operational distance (25) between them, and- said operational distance (25) is arranged to be adjustable by reversible screwing the adjustment part (11) into the tube (13) facilitated by the external thread's (21) engagement with the inner wall (22) of the tube (13); wherein the external thread (21) of the adjustment part (11) upon engagement with the inner wall (22) of the tube (13) is arranged to form indents (23) in the tube (13) at the points of engagement so that the indents (23) constitute an internal thread within the tube.

2. The in-tube check valve according to claim 1, wherein the external thread (21) of the adjustment part (11) is made of first material and the tube (13) is made of a second material, where the first material comprises a higher Young's modulus than the second material.

3. The in-tube check valve according to any of the claims 1 or 2, wherein the adjustment part (11) comprises a slot (24) to accommodate a tool to screw the adjustment part into the tube (13).

4. The in-tube check valve according to any of the claims 1 to 3, wherein the outer diameter (31) of the external thread (21) of the adjustment part (11) is larger than the inner diameter (32) of the tube (13).

5. The in-tube check valve according to any of the claims 1 to 4, wherein the outer diameter (32) of the external thread (21) of the adjustment part (11) is less than 10.0 cm, preferably less than 5.0 cm, more preferably less than 2.0 cm, even more preferable less than 1.0 cm and even more preferable less than 0.2 cm and even more preferable less than 0.1 cm.

6. The in-tube check valve according to any of the preceding claims, wherein the outer diameter (31) of the external thread (21) of the adjustment part (11) preferably is less than 30%, more preferably less than 20%, even more preferably less than 10% larger than the inner diameter (32) of the tube (13).

7. The in-tube check valve according to any of the preceding claims, wherein the tube (13) is made of a second material, such as a polymer, which is deformable by the external thread (21) of the adjustment part (11).

8. The in-tube check valve according to any of the preceding claims, wherein the tube (13) is transparent or translucent to allow visual inspection of the check valve (1).

9. The in-tube check valve according to any of the preceding claims, wherein the closure element (16) is arranged to engage the valve seat (15) to stop fluid flow through the check valve (1) when the pressure of the fluid is less than the pressure of the spring (17).

10. The in-tube check valve according to any of the preceding claims, wherein the check valve (1) is arranged to allow fluid flow through the valve when the closure element (16) is not engaged with the valve seat (15).

11. A medical pump (51), such as an insulin pump, comprising the in-tube check valve (1) according to any of the claims 1-10.

12. The use of a medical pump (51) comprising the in-tube check valve (1) according to any of the claims 1 to 10 for the delivery of medicine to a patient.

13. The use of the medical pump (51) according to claim 12, wherein the medicine is one of: insulin, nicotine, fentanyl, nitroglycerin, scopolamine, estradiol, testosterone, clonidine, rivastigmine, selegiline, methylphenidate, semaglutid.

14. A method for inserting the in-tube check valve (1) according to any of the claims 1-10 into the tube (13), wherein the method comprises:- inserting (SI) the stator (12) into the tube by pushing or screwing the stator into the tube,- inserting (S2) the adjustment part (11) into the tube (13) by screwing the adjustment part into the tube,- positioning (S3) the adjustment part (11) at the operational distance (25) relative to the stator (12).

15. A method for calibrating the in-tube check valve (1) according to any of the claims 1-10, wherein the method comprises,- providing a pressure sensor (35) for measuring the pressure in the tube (13) upstream of the check valve (1) or providing a flow meter (36) for measuring the flow in the tube upstream of the check valve (1),- adjusting the operational distance (25) between the adjustment part (11) and the stator (12) by inversible screwing the adjustment part into the tube (13) facilitated by the external thread's (21) engagement with the inner wall (22) of the tube, until the pressure measured by the pressure sensor (35) reaches a predetermined pressure or until the flow measured by the flow meter (36) reaches a predetermined flow.

16. A in-tube check valve (1) which is insertable into a tube for fluid flow, wherein- the check valve comprises a stator (12), an adjustment part (11), a closure element (16), and a spring (17), and- the stator comprises an inlet (14) and a valve seat (15); wherein- the adjustment part (11) comprises an outlet (18) and an external thread (21),- the closure element (16) and the spring (17) are connected to the adjustment part (11), - the external thread (21) is arranged to engage with the inner wall (22) of the tube (13),- the adjustment part (11) and the stator (12) are placeable with an operational distance (25) between them, and- said operational distance (25) is arranged to be adjustable by reversible screwing the adjustment part (11) into the tube (13) facilitated by the external thread's (21) engagement with the inner wall (22) of the tube (13) wherein the external thread (21) of the adjustment part (11) upon engagement with the inner wall (22) of the tube (13) is arranged to form indents (23) in the tube (13) at the points of engagement so that the indents (23) constitute an internal thread within the tube.

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