Medical injection device with gas evacuation closed by a float

Abstract

An injection device for injecting into a medical tubing a medical liquid from a medical liquid container, said injection device comprising a body, a piston (6) arranged in the body for travelling along the longitudinal direction, an evacuation path traversing the piston (6) comprising a cavity (8) and a first passage (14) connecting the cavity to an inner space (4) of the body, and a float (12) configured for floating on the medical liquid and configured for travelling within the cavity (8) along the longitudinal direction between a filling configuration wherein third and fourth sealing interfaces (18, 19) cooperate to close the evacuation path (10) at a second closing location (Z2), and an injection configuration wherein first and second sealing interfaces (16, 17) cooperate to close the evacuation path (10) at a first closing location (Z1).

Description

[0001] MEDICAL INJECTION DEVICE WITH GAS EVACUATION CLOSED BY A FLOAT

[0002] TECHNICAL FIELD

[0003] The present invention generally relates to the injection of medical liquids and, more particularly, to an injection device for injecting into a medical tubing a medical liquid from a medical liquid container.

[0004] BACKGROUND OF THE INVENTION

[0005] Injection devices are commonly used for injecting into a medical tubing a medical liquid from a medical liquid container. The medical liquid may be any type of liquid to be injected into a patient, such as a drug or a contrast agent. For example, the injection of medical liquid such as iodinated contrast agent is required in 70% of CT scan diagnosis cases. This injection, in about 70% of cases, is performed using an automated contrast agent injector. Injection tubing is required to connect the automated injector to the patient.

[0006] Patent application no. US 13 / 453,335 (US Pub. No. 20120209111) discloses a bladder syringe for a fluid delivery system which includes a cylindrical body, a capbladder assembly, a plunger element disposed in the cylindrical body, and a mounting assembly to secure the cap-bladder assembly to the cylindrical body. The cylindrical body has a distal end and a proximal end and defines a throughbore. The cap-bladder assembly is adapted for connection to the distal end of the cylindrical body, and includes a cap body and a bladder. The cap body defines an interior cavity and a distal discharge conduit and is adapted to engage the distal end of the cylindrical body. A disc-shaped bladder is disposed within the interior cavity and typically includes a central membrane portion. The plunger element is disposed in the throughbore of the cylindrical body and is vented to enable evacuation of the space between the plunger element and the cap-bladder assembly in the cylindrical body.

[0007] Patent application no. US 10 / 986,416 (US Pub. No. 20060249541) discloses a fluid dispensing device that includes a bottle for receiving fluid, a discharge tube, and a pressurizing device coupled between the bottle and the discharge tube, for pressurizing the fluid and for forcing the fluid to flow through the discharge tube without gravity. The pressurizing device includes a container coupled between the bottle and the discharge tube, a piston slidably received in the container, and a moving device for moving the piston in a reciprocating action within the container. For example, a motor is coupled to the piston with a crank, to move the piston in the reciprocating action within the container.

[0008] Patent application no. US 10 / 810,686 (US Pub. No. 20050215850) discloses a syringe pump including a syringe having a plunger that slides in a body which has a discharge port, a driving mechanism coupled to the syringe, including a cylinder in which a piston mounted on a shaft slides, and a biasing device operative to apply an urging force on the piston to drive the piston distally in the cylinder, and a safety catch that initially prevents the biasing device from moving the piston, the safety catch being removable to permit the biasing device to move the piston.

[0009] Figure 1 shows an example of an injection system 100 for injecting a medical liquid from a medical liquid container 104 into a common line 102. Those skilled in the art will appreciate the medical liquid container 104 can be any type of container specifically adapted for containing medical liquids, for example, such as, but not limited to: vials, bottles, plastic containers, and any type of container manufactured to contain a medical liquid. The injection system 100 has a first connector 106 configured for connection to a medical liquid container 104, an injector 108 to which is attached an injection device 110 with a medical tubing interface 112, a medical liquid supply line 114 configured to connect the first connector 106 to the medical tubing interface 112 for supplying the medical liquid to the injection device 110, and a common line 102 configured to be connected to the medical tubing interface 112 and to a patient line 116 for injecting the medical liquid into the patient line 116. More precisely, a first tubing valve 130 connects the liquid supply line 114 to common line 102 and allows passage only to the common line 102 under a vacuum pressure. The common line 102 comprises a second tubing valve 140 downstream of the first tubing valve 130 and only authorizes passage towards the patient line 116. The injection device 110 has a body defining an inner space, and a piston driven by a plunger rod and configured for travelling within the inner space to pump fluid into the inner space or push the fluid out of the inner space.

[0010] In the depicted example, two different types of medical liquids are to be injected into the patient, and consequently, the injection system 100 is configured to be connected to two medical liquid containers 104, with two different first connectors 106 and two different medical liquid supply lines 114. However, the injection system 100 may be configured to inject only one medical liquid. For simplicity's sake, the following description will be made with reference to a configuration where only one medical liquid is to be injected, since bi-injection merely involves replicating the described features. Here “bi-injection” is understood to mean two-injections.

[0011] For economic and ecological reasons (less use of plastic), the multi-patient practice is steadily gaining market share. In the multi-patient practice, the tubing for the injection system 100 is provided with two very distinct parts: the day set 120 and the patient set 122. The patient set 122 is changed for each patient. The patient set 122 is typically used to limit risks of cross contamination between consecutive patients and thus protects the day set. Once installed and primed, the day set 120 remains connected to the power injector for several patient cases, as long as the same medical liquid is to be injected. When the medical liquid to be injected needs to be changed, then the day set 120 is changed. This day set 120 comprises the medical liquid supply line 114 which is connected to the medical liquid container 104 and to the common line 102. The patient set 122 comprises the patient line 116 which is supplied in medical liquid by the common line 102 and is connected to a catheter or a needle for injecting the medical liquid into the patient.

[0012] When the injection system 100 is set up for injecting medical liquid into a patient, it is important to ensure no gas is present in the tubing before injection. Injecting a gas such as air into a blood vessel of a patient may result in a gas embolism, i.e. a blood vessel blockage caused by one or more bubbles of air or other gas in the circulatory system. When the day set 120 or the patient set 116 is put in place, the tubes are filled with air. It is therefore necessary to evacuate the gas present in the tubes before injection. Due to the length of the tubes, a large quantity of gas is to be evacuated from the injection system 100.

[0013] For purging the injection system 100 from all the gas present before the injection, the injection device 110 draws or pulls medical liquid from the medical liquid container 104, thereby filling the medical liquid supply line 114. The injection device 110 is now filled with a mixture of medical liquid and gas. The injection device 110 is then positioned with the medical tubing interface 112 upwards so the gas is gathered at the medical tubing interface 112. It should be noted the filling of the injection device 110 causes a turbulent flow of medical liquid, generating micro-bubbles in the medical liquid. Due to the high viscosity of the medical liquid (especially for contrast agent), the micro-bubbles may need several minutes for reaching the medical tubing interface 112. It is therefore common to wait at least 2 or 3 minutes with the medical tubing interface 112 positioned upwards. Then, by actuating the piston, the gas is evacuated from the injection device 110 through the still upwards medical tubing interface 112, into the common line 102. Medical liquid is then injected into the common line 102 for pushing the gas outside the common line 102 and the patient line 116 thereby purging the injection system 100.

[0014] During injection, it may happen that gas is present in the injection device 110. For example, vaporization of the medical liquid may create gas. Also, some bubbles generated during the initial filling of the injection system 100 may be blocked in the tubing or against the walls of the injection device 110 and may not be evacuated during the initial purge. As a result, during injection, the injection device 110 is positioned with the medical tubing interface 112 downwards, so any gas present in the injection device 110 will be trapped in the injection device 110 away from the medical tubing interface 112, and will not be injected into the common line 102.

[0015] This approach suffers from several drawbacks. First, the injection device 110 must be moved between two opposite positions: with the medical tubing interface 112 upwards or downwards. This requires the injector 108 be able to rotate. Secondly, this purge takes a significant amount of time, and the injection system 100 must be monitored by an operator during the purge. The operator must also evaluate the quality of the purge and whether the purge has completed or not. As with every human interaction, reliance on an operator may lead to errors. Thirdly, the gas is pushed along the common line 102 by medical liquid which also exits the injection system. This approach thereby involves wasting medical liquid, and requires collecting the wasted medical liquid at the output of the injection system 100, with possible handling error.

[0016] Also, gas still present in the injection device 110 after the purge may alter the operating of the injection device, even if the gas is trapped in the injection device 110. Dosage of the medical liquid is usually controlled through the stroke of the piston of the injection device 110. Gas is compressible, and the volume variation of medical liquid within the injection device will therefore be inaccurate. Also, the volume of gas trapped in the injection device 110 must be small, otherwise it risks being injected into the common line 102. Patent application WO2023 / 187114 discloses an injection device for injecting into a medical tubing a medical liquid from a medical liquid container, said injection device comprising:

[0017] - a body defining an inner space extending in a longitudinal direction between an upper end of the body and a lower end of the body, the lower end of the body comprising an interface for connecting to medical tubing through which the medical liquid can penetrate the inner space from the medical liquid container and can exit said inner space to be injected into the medical tubing;

[0018] - a piston arranged within the inner space and configured for travelling back and forth within the inner space along the longitudinal direction, said piston delimiting an upper space and a lower space of the inner space, said lower space configured to receive the medical liquid, the piston having a cavity,

[0019] - an evacuation path, said evacuation path traversing the piston from the lower space to the upper space, the cavity being part of the evacuation path, and

[0020] - a selector arranged within the evacuation path between a lower portion of the evacuation path and an intermediate portion of the evacuation path, said lower portion of the evacuation path being connected to the lower space, wherein the selector is configured for selectively allowing the gas to go through said selector and to travel along the evacuation path from the lower portion to the intermediate portion of the evacuation path, said selector configured for selectively preventing the medical liquid from going through said selector and from travelling along the evacuation path from the lower space to the upper space of the inner space, and

[0021] - a purge valve arranged in the evacuation path between the intermediate portion of the evacuation path and an upper portion of the evacuation path and configured for moving between a blocking configuration in which the purge valve closes the evacuation path and a passing configuration in which the purge valve keeps open said evacuation path, wherein the passing configuration of the purge valve requires an overpressure in the intermediate portion of the evacuation path caused by the piston travelling towards the lower end of the body.

[0022] Such an injection device allows evacuating the gas from the injection device each time the piston travels for pushing medical liquid into the medical tubing. The purge is therefore performed automatically, without requiring any operator's intervention, and ensures that no gas is injected into the medical tubing.

[0023] The injection device is however complex, and fine adjustments are required for the selector and the purge valve to work properly. This means that the injection device is not easy to manufacture. Also, a significant volume of air should be trapped between the selector and the purge valve to ensure that no fluid may pass through the purge valve, or compromise the functioning of the valve. Such a volume of air could make operation of the injection device more complex, as the compression of the trapped air must be taken into account in order to correctly pressurize the injection device and monitor the volume of injected fluid.

[0024] Accordingly, there is a need for an injection system able to evacuate the gas without requiring any operator's involvement, rapidly and each time gas is present in the injection device, with a less complex and more reliable design.

[0025] SUMMARY OF THE INVENTION

[0026] It is proposed an injection device for injecting into a medical tubing a medical liquid from a medical liquid container, said injection device comprising:

[0027] - a body defining an inner space extending in a longitudinal direction between an upper end of the body and a lower end of the body, the lower end of the body comprising a medical tubing interface for connecting to medical tubing through which the medical liquid can penetrate the inner space from the medical liquid container and can exit said inner space to be injected into the medical tubing,

[0028] - a piston arranged within the inner space and configured for travelling back and forth within the inner space along the longitudinal direction, said piston delimiting an upper space and a lower space of the inner space, said lower space configured to receive the medical liquid, the piston having a cavity,

[0029] - an evacuation path, said evacuation path traversing the piston from the lower space to the upper space, the cavity being part of the evacuation path,

[0030] - a float configured for floating on the medical liquid, wherein the cavity accommodates the float, wherein the piston comprises passages connecting the cavity to the inner space, said passages being part of the evacuation path, at least one passage connecting the cavity to the lower space and at least one passage connecting the cavity to the upper space, wherein the piston comprises a first sealing interface and the float comprises a second sealing interface configured to cooperate with the first sealing interface to close the evacuation path at a first closing location, wherein the piston comprises a third sealing interface and the float comprises a fourth sealing interface configured to cooperate with the third sealing interface to close the evacuation path at a second closing location different from the first closing location, and the float is configured to travel back and forth along the longitudinal direction between: a filling configuration in which the first sealing interface and the second sealing interface are spaced apart so that the evacuation path is not closed at the first closing location, whereas the third sealing interface and the fourth sealing interface cooperate to close the evacuation path at the second sealing location; an injection configuration in which the first sealing interface and the second sealing interface cooperate to close the evacuation path at the first sealing location, whereas the third sealing interface and the fourth sealing interface are spaced apart so that the evacuation path is not closed at the second closing location.

[0031] It is also proposed an injection system comprising:

[0032] - an injection device as defined above,

[0033] - an actuator to cause the piston to travel back and forth within the inner space,

[0034] - a first connector configured to be connected to a medical liquid container,

[0035] - a medical liquid supply line configured to connect the first connector to the medical tubing interface for supplying the medical liquid to the injection device,

[0036] - a common line configured to be connected to the medical tubing interface and to a patient line for injecting the medical liquid into the patient line.

[0037] It is further proposed a method of operating an injection system as defined above, wherein the method comprises:

[0038] - causing the piston to travel towards the upper end of the body, resulting in medical liquid in the cavity to decrease and the float to move downwards with respect to the cavity until the fourth sealing interface contacts the third sealing interface to close the evacuation path at the second closing location, the float then being in the filling configuration;

[0039] - causing the piston to travel towards the lower end of the body, resulting in medical liquid rising in the cavity and lifting the float which moves upwards with respect to the cavity until the second sealing interface contacts the first sealing interface to close the evacuation path at the first closing location, the float then floating on the medical liquid in the injection configuration.

[0040] Other preferred, although non-limitative, aspects of the invention are as follows, isolated or in a technically feasible combination:

[0041] - the injection device is configured to trap a quantity of fluid in the evacuation path due to the closure of the evacuation path at the first sealing location, the trapped fluid being either air or the medical liquid;

[0042] - the float is configured to float on the medical liquid in the cavity in the injection configuration;

[0043] - the float is configured to be kept in the filling configuration by pressure gradient and to not float on the medical liquid in the filling configuration;

[0044] - the float is configured to be in an intermediate configuration between the filling configuration and the injection configuration, wherein in the intermediate configuration the first sealing interface and the second sealing interface are spaced apart so that the evacuation path is not closed at the first closing location, and the third sealing interface and the fourth sealing interface are spaced apart so that the evacuation path is not closed at the second closing location;

[0045] - the float is configured to transition from the filling configuration to the intermediate configuration when the piston is moved towards the lower end of the body, and a pressure in the lower space is above a pressure in the upper space, causing the float to move upwards with respect to the cavity;

[0046] - the float is configured to transition from the intermediate configuration to the injection configuration when the piston is moved towards the lower end of the body, and medical liquid rises in the cavity and lift the float which moves upwards with respect to the cavity until the second sealing interface contacts the first sealing interface to close the evacuation path at the first closing location; - the float is configured to transition from the injection configuration to the filling configuration when the piston is moved towards the upper end of the body, and medical liquid in the cavity decreases and the float moves downwards with respect to the cavity until the fourth sealing interface contacts the third sealing interface to close the evacuation path at the second closing location;

[0047] - at least one sealing interface among the first sealing interface, the second sealing interface, the third sealing interface, and the fourth sealing interface, is provided with a sealing component;

[0048] - the float comprises a medical liquid retainer which is configured for providing a ballast of medical liquid to the float;

[0049] - the second sealing interface is an obturating part which belongs to an appendage of the float, the appendage of the float configured to penetrate a passage connecting the cavity to the inner space, the obturating part having a cross-section larger than a cross-section of said passage, and

[0050] - the passage connects the cavity to the lower space, and the passage is between the obturating part of the float and the cavity, or the passage connects the cavity to the upper space, and the obturating part is between the passage and the float.

[0051] BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Other aspects, objects and advantages of the present invention will become better apparent upon reading the following detailed description of preferred embodiments thereof, given as non-limiting examples, and made with reference to the appended drawings wherein:

[0053] - Figure 1 is a general view of an injection system with two medical liquid containers connected to it, in accordance with a possible embodiment;

[0054] - Figure 2 is a cross-sectional view of a body an injection device, provided with a piston arranged within, in accordance with a possible embodiment;

[0055] - Figure 3 is a cross-sectional view of a piston of an injection device, in a filling configuration, in accordance with a first possible embodiment;

[0056] - Figure 4 is a cross-sectional view of a piston of an injection device in a purge configuration, in accordance with the first possible embodiment; - Figure 5 is a cross-sectional view of a piston of an injection device after the purge in an injection configuration, in accordance with the first possible embodiment;

[0057] - Figure 6 is a cross-sectional view of a piston of an injection device showing the ballast provided to the float, in accordance with the first possible embodiment;

[0058] - Figure 7 is a cross-sectional view of a piston of an injection device in a filling configuration, in accordance with a second possible embodiment;

[0059] - Figure 8 is a cross-sectional view of a piston of an injection device in a purge configuration, in accordance with the second possible embodiment;

[0060] - Figure 9 is a cross-sectional view of a piston of an injection device after the purge in an injection configuration, in accordance with the second possible embodiment;

[0061] - Figure 10 is a cross-sectional view of a piston of an injection device showing the ballast provided to the float, in accordance with the second possible embodiment;

[0062] - Figure 11 is a cross-sectional view of a piston of an injection device, in a filling configuration, in accordance with an alternate configuration of the first possible embodiment; and

[0063] - Figure 12 is a cross-sectional view of a piston of an injection device, in a filling configuration, in accordance with an alternate configuration of the second possible embodiment.

[0064] DETAILED DESCRIPTION OF THE INVENTION

[0065] The injection device of the invention can be used in an injection system 100 as previously described in relation with Figure 1. The injection system 100 will not be described any further, except for the injection device 110. In the present description, “one”, “a” or “an” mean “at least one”, except explicitly stated otherwise, for example with “single” or “unique”.

[0066] With reference to Figures 2-10, the injection device 110 includes a body 2 defining an inner space 4 extending in a longitudinal direction between an upper end 2b of the body 2 and a lower end 2a of the body 2, the lower end 2a of the body having a medical tubing interface 112 through which the medical liquid can penetrate the inner space 4 from the medical liquid container 104 and can exit said inner space 4 to be injected into the common line 102. Contrary to previous injection devices, the injection device 110 according to the invention is configured for staying with the medical tubing interface 112 downwards. Spatial terms such as "downwards", "upwards", "lower", "upper", "higher", "highest" must be understood as defining the commonly accepted relative position with respect to the vertical, i.e. the local Earth gravity direction. This is because gas and medical liquid are subjected to the gravity, and the present invention makes use of the gravity for a proper gas evacuation. As a result, in use, the lower end 2a of the body 2 is located below the upper end 2b of the body 2. The medical tubing interface 112 is arranged on the lower end 2a of the body 2. The body 2 is typically a hollow cylindric body, for example made of glass or plastic material, also called a barrel.

[0067] The injection device 110 also includes a piston 6 arranged within the inner space 4 and configured for travelling within the inner space 4 along the longitudinal direction, i.e. between the upper end 2b of the body 2 and the lower end 2a of the body 2. The piston 6 delimits an upper space 4b and a lower space 4a of the inner space 4. The lower space 4a is configured to receive the medical liquid, whereas the upper space 4b is not intended to receive any liquid. The piston 6 provides hermetic sealing between the upper space 4b and a lower space 4a. To this end, the piston 6 is provided with at least one peripheral seal 5a, 5b, for example made of rubber, and preferably two peripheral seals 5a, 5b at different height along the longitudinal direction. Each peripheral seal 5a, 5b is pressed against the wall of the body 2, ensuring tight sealing. As in the depicted example, a peripheral seal 5a, 5b can be a quad-ring, but can also be for example an O-ring.

[0068] Due to the tight sealing provided by the piston 6, pressure can significantly differ between upper space 4b and a lower space 4a of the inner space 4. The pressure within the upper space 4b is kept at a reference pressure which is roughly constant and substantially independent from the course of the piston 6. This reference pressure is typically the atmospheric pressure, e.g. the pressure of the system's environment. Preferably, the upper end 2b of the body 2 is at least partially open so the pressure inside the upper space 4b corresponds to the atmospheric pressure, regardless of the course of the piston 6. On the opposite, the pressure inside the lower space 4a of the inner space 4 depends on the content of the lower space 4a and on the stroke of the piston 6. In the description below, an overpressure is a pressure above the reference pressure, and a vacuum pressure is a pressure below the reference pressure. The piston 6 is attached to a piston rod 30, for example by a protrusion 31 on top of the piston 6 which is engaged into said piston rod 30. The piston rod 30 is driven by the injector 108 and causes the piston 6 to travel within the inner space 4 along the longitudinal direction. The piston rod 30 is an actuator configured to cause the piston 6 to travel back and forth within the inner space 4.

[0069] The piston 6 has an evacuation path arranged within the piston 6. The path traverses the piston 6 in the longitudinal direction from the lower space 4a to the upper space 4b of the inner space 4. The evacuation path is meant to evacuate the gas present in the lower space 4a into the upper space 4b. Typically, the evacuation path is not straight and can be closed or open at different points by components of the piston 6, as described below.

[0070] The piston 6 includes a lower interface 7 delimiting the lower space 4a of the inner space 4, said lower interface 7 having an entrance 9 of the evacuation path. Preferably, the entrance 9 opens in a highest portion of the lower interface 7 in order to properly evacuate all the gas present in the lower space 4a, without any gas being trapped in the lower space 4a of the inner space, against the lower interface 7. Preferably, the lower interface 7 has a surface with an apex pointing towards the upper end 2b of the body, and the entrance 9 of the evacuation path opens at said apex. For example, the lower interface 7 has a concave surface seen from the lower space 4a of the inner space, and the entrance 9 of the evacuation path opens in approximately the center of said concave surface, as in the depicted example. For instance, the surface of the lower interface 7 may correspond to a surface of a cone, a truncated cone, or a pyramid pointing upwards. Alternatively, the lower interface 7 may have a convex surface seen from the lower space 4a of the inner space and the entrance 9 of the evacuation path opens in a periphery of said convex surface. For example, the lower interface 7 may have a groove arranged in a periphery of the lower interface 7, and the entrance 9 of the evacuation path may open in said groove.

[0071] The piston 6 is hollow and has a cavity 8. The cavity 8 is enclosed in the piston 6. For example, the piston 6 may comprises a lower wall 6a, an upper wall 6b, and a peripheral wall 6c. The lower wall 6a, upper wall 6b, and peripheral wall 6c define the cavity 8. The cavity 8 is part of the evacuation path 10 through the piston 6. The piston 6 comprises passages 14, 15 connecting the cavity 8 to the inner space 4 of the body 2. The passages 14, 15 are part of the evacuation path 10, at least one passage connecting the cavity 8 to the lower space 4a and at least one passage connecting the cavity 8 to the upper space 4b. The cavity 8 therefore communicates with the inner space 4 through a first passage 14 which is part of the evacuation path 10. The cavity 8 also communicates with the inner space 4 through a second passage 15 which is also part of the evacuation path 10. The second passage 15 is opposite to the first passage 14 : when the first passage 14 connects the cavity 8 with the lower space 4a, the second passage 15 connects the cavity 8 with the upper space 4b, as in Figures 3-6, and conversely, when the first passage 14 connects the cavity 8 with the upper space 4b, the second passage 15 connects the cavity 8 with the lower space 4a, as in Figures 7-10.

[0072] Several second passages 15 may be provided. Even if it is possible to have several first passages 14, there is preferably only one first passage 14. Except for the first passage 14 and the second passage 15, the cavity 8 is preferably hermetically enclosed in the piston 6. Preferably, the first passage 14 has a section surface in a plane perpendicular to the longitudinal direction Z which is less than 20%, and preferably less than 10% of the surface of the piston 6 or the surface of the inner space 4 in the same plane perpendicular to the longitudinal direction Z. Similarly, the second passage 15 has a section surface in a plane perpendicular to the longitudinal direction Z which is less than 20%, and preferably less than 10% of the surface of the piston 6 or the surface of the inner space 4 in the same plane perpendicular to the longitudinal direction. If there are several first passages 14 or second passages 15, the sum of the section surfaces of the passages 14, 15 are taken into account.

[0073] The injection device comprises a float 12 configured for floating on medical liquid. Typically, the float 12 is also configured to float on water, which could be consider as a medical liquid for the purpose of testing the float 12. The cavity 8 accommodates the float 12, which means that a majority of the volume of the float 12 is contained in the cavity 8, and preferably more than 80% of the volume of the float 12 is contained in the cavity 8, between the first passage 14 and the second passage 15. The cavity 8 is configured to allow the float 12 to travel up and down the cavity 8, along the longitudinal direction Z.

[0074] The piston 6 comprises a first sealing interface 16 and the float 12 comprises a second sealing interface 17 configured to cooperate with the first sealing interface 16 to close the evacuation path 10 at a first closing location Zl. When the first sealing interface 16 and the second sealing interface 17 are spaced apart and do not contact each other, then the evacuation path 10 is not closed at the first closing location Zl. Typically, the second sealing interface 17 faces the first sealing interface 16 in the longitudinal direction, so that their positions relative to each other essentially depends on the relative position of the float 12 relative to the piston 6.

[0075] For example, the first sealing interface 16 may extend around an entrance of the first passage 14, and the second sealing interface 17 may be configured to press against the first sealing interface 16 to obturate the first passage 14. In the illustrated embodiments, the second sealing interface 17 is provided with a sealing element 17a to ensure a watertight and airtight obturation of the first passage 14. The sealing element 17a could alternatively be arranged on the first sealing interface 16, or on both the first sealing interface 16 and the second sealing interface 17, or absent from both. The sealing element 17a may be an O-Ring or a tone joint, a lip seal, or any other kind of mechanical gasket improving the sealing of the evacuation path 10 at the first closing location Zl.

[0076] When the evacuation path 10 is obturated or closed by the second sealing interface 17 cooperating with the first sealing interface 16, neither medical liquid nor air can pass through the evacuation path 10. Preferably, the first sealing interface 16 is configured to obturate the first passage 14 when the float 12 is in a top configuration, which means that the float 12 occupies an upper portion of the cavity 8 within the piston 6.

[0077] The piston 6 comprises a third sealing interface 18 and the float 12 comprises a fourth sealing interface 19 configured to cooperate with the third sealing interface 18 to close the evacuation path 10 at a second closing location Z2 different from the first closing location Zl. When the third sealing interface 18 and the fourth sealing interface 19 are spaced apart and do not contact each other, then the evacuation path 10 is not closed at the second closing location Z2. Typically, the fourth sealing interface 19 faces the third sealing interface 18 in the longitudinal direction Z, so that their positions relative to each other essentially depends on the position of the float 12 relative to the piston 6.

[0078] The fourth sealing interface 19 is for example a surface of the float 12, and preferably a surface of the lower wall 6a of the float 12 facing the lower interface 7 of the piston 6. The third sealing interface 18 is for example a lower wall of the cavity 8. In the illustrated embodiments, the third sealing interface 18 is provided with a sealing element 18a to ensure a watertight and airtight obturation of the evacuation path 10. The sealing component 18a could alternatively be arranged on the fourth sealing interface 19, or on both the third sealing interface 18 and the fourth sealing interface 19, or absent from both. The sealing component 18a may be an O-Ring or a tone joint, a lip seal, or any other kind of mechanical gasket improving the sealing of the evacuation path 10 at the second closing location Z2. In this example, the sealing component 18a is a joint, attached to the piston 6 within the cavity 8. The sealing component 18a is below the float 12 in the cavity 8. The sealing component 18a may be attached to the lower wall 6a of the piston 6. Preferably, the sealing component 18a is a peripheral joint defining an inner aperture which belongs to the evacuation path 10. Preferably, the sealing component 18a is a lip joint.

[0079] The evacuation path 10 passes between the third sealing interface 18 and the fourth sealing interface 19. The fourth sealing interface 19 is configured to, depending on the travelling of the float 12 along the longitudinal direction in the cavity 8, press on the third sealing interface 18, thereby closing the evacuation path 10, or to be away from the third sealing interface 18, letting the evacuation path 10 open.

[0080] The piston 6 and float 12 are configured to be in three configurations: a filling configuration when the lower space 4a is being filled by medical liquid in which the evacuation path 10 is closed at the second closing location Z2 but is not closed at the first closing location Zl, an intermediate configuration in which the evacuation path 10 is open, i.e. the evacuation path 10 is not closed at the first closing location Zl and is not closed at the second closing location Z2, and gas in the lower space 4a may be evacuated along the evacuation path 10 to the upper space 4b, and an injection configuration in which the evacuation path 10 is closed at the first closing location Zl but is not closed at the second closing location Z2 and the medical liquid may be expelled from the lower space 4a by the medical tubing interface 112. The intermediate configuration is a purge configuration when there is gas in the lower space 4a as the injection device 110 transitions from the filling configuration to the injection configuration.

[0081] The first closing location Zl and the second closing location Z2 are different locations of the evacuation path 10. The first closing location Zl corresponds to a location between the first sealing interface 16 and the second sealing interface 17 where the first sealing interface 16 and the second sealing interface 17 meet when the evacuation path 10 is closed at the first closing location Zl. The second closing location Z2 corresponds to a location between the third sealing interface 18 and the fourth sealing interface 19 where the third sealing interface 18 and the fourth sealing interface 19 meet when the evacuation path 10 is closed at the second closing location Z2. Preferably, the evacuation path 10 is never closed both at the first closing location Z1 and the second closing location Z2.

[0082] The float 12 is configured to travel back and forth along the longitudinal direction Z between:

[0083] - a filling configuration in which the first sealing interface 16 and the second sealing interface 17 are spaced apart so that the evacuation path is not closed at the first closing location Zl, whereas the third sealing interface 18 and the fourth sealing interface 19 cooperate to close the evacuation path 10 at the second sealing location Z2; ; and

[0084] - an injection configuration in which the first sealing interface 16 and the second sealing interface 17 cooperate to close the evacuation path 10 at the first sealing location Zl, whereas the third sealing interface 18 and the fourth sealing interface 19 are spaced apart so that the evacuation path 10 is not closed at the second closing location Z2.

[0085] The float 12 is closer to the upper space 4a in the injection configuration than in the filling configuration.

[0086] In the intermediate configuration between the filling configuration and the injection configuration, the first sealing interface 16 and the second sealing interface 17 are spaced apart so that the evacuation path is not closed at the first closing location Zl, and the third sealing interface 18 and the fourth sealing interface 19 are spaced apart so that the evacuation path 10 is not closed at the second closing location Z2.

[0087] The float 12 is configured to transition from the filling configuration to the intermediate configuration when the piston 6 is moved towards the lower end 2a of the body, and a pressure in the lower space 4a is above a pressure in the upper space 4a, causing the float to move upwards with respect to the cavity 8.

[0088] The float 12 is configured to transition from the intermediate configuration to the injection configuration when the piston 6 is moved towards the lower end 2a of the body 2, and medical liquid rising in the cavity 8 causes the float 12 to float on the medical liquid and moves upwards with respect to the cavity 8, until the first sealing interface 16 and the second sealing interface 17 cooperate to close the evacuation path 10 at the first closing location Zl. The second sealing interface 17 is thus urged by the buoyancy of the float 12 against the first sealing interface 16 of the piston 6. The float 12 is configured to transition from the injection configuration to the filling configuration when the piston 6 is moved towards the upper end 2b of the body 2, a depression in the lower space 4a causes the float 12 to travel downwards with respect to the piston 6, and consequently causes the second sealing interface 17 to move away from the first sealing interface 16, no longer closing the evacuation path 10 at the first closing location Zl. Fluid may travel along the evacuation path 10. Air enters the cavity 8 while medical liquid leaves the cavity 8 by the passages 14, 15. The level of medical liquid in the cavity 8 thus decreases, and the float 12 floating on it goes down towards the lower end 2a, until the fourth sealing interface 19 contacts the third sealing interface 18. The fourth sealing interface 19 then cooperates with the third sealing interface 18 to close the evacuation path 10.

[0089] The second sealing interface 17 of the float 12 may be an obturating part which belongs to an appendage 24 of the float. The appendage 24 typically extends in the longitudinal direction. The appendage 24 of the float 12 is configured to penetrate the first passage 14, the obturating part 26 having a cross-section larger than a cross-section of the first passage 14.

[0090] In the example of Figures 3-6, the first passage 14 connecting the cavity 8 to the inner space 4 connects the cavity 8 to the lower space 4a. The second passage 15 connecting the cavity 8 to the inner space 4 here connects the cavity 8 to the upper space 4b. The first passage 14 is between the obturating part 26 of the float 12 and the cavity 8. The appendage 24 projects downwardly from a lower surface 12a of the body 12c of the float 12. More precisely, the appendage 24 comprises a leg 25 extending from the lower surface of the float 12 through and beyond the first passage 14. The leg 25 has a crosssection, in a plane perpendicular to the longitudinal direction, which is smaller than the cross-section of the first passage 14, so that the leg 25 does not block the first passage 14. As the float 12 travels up and down the cavity 6, the leg 25 translates through the first passage 14.

[0091] The appendage 24 comprises the obturating part 26, which is here a section of the appendage whose cross-section is greater than the cross-section of the first passage 14. The obturating part 26 is kept outside the cavity 8. In the depicted embodiment, the obturating part 26 is below the piston 6 for clarity’s sake, but it could be accommodated in a chamber above the lower interface 7 of the piston 6 if needed. The obturating part 26 is provided here with a sealing element 17a such as a seal, for example an O-ring, to ensure a watertight and airtight obturation of the first passage 14. The sealing element 17a of the obturating part preferably faces the first passage 14. As already mentioned, such a sealing element 17a could be provided on the first sealing interface 16, on both the first sealing interface 16 and the second sealing interface 17, or be omitted.

[0092] In Figure 3, the injection device 110 is in the filling configuration wherein the injection device 110 is filled with medical liquid and unwanted gas. During this filling step, the piston rod 30 is driven upwards, for example by the injector 108 acting on said piston rod 30, thereby causing the piston 6 to travel within the inner space 4 along the longitudinal direction towards the upper end 2b of the body 2, i.e. upwards. The lower space 4a expands, resulting in a pressure within said lower space 4a to drop below the reference pressure within the upper space 4b, e.g. the atmospheric pressure.

[0093] The expansion of the lower space 4a creates a pressure gradient between the upper space 4b and the lower space 4a, with a depression in the lower space 4a, i.e. a pressure below the reference pressure. Due to the pressure gradient, the float 12 is sucked downwards within the cavity 8 and moves downwards with respect to the cavity 8. If the float 12 was in an injection configuration, the second sealing interface 17 moves away from the first sealing interface 16 at the first closing location Zl. The evacuation path 10 is then no longer closed at the first closing location Zl.

[0094] As the float 12 moves downwards in the cavity 8, the fourth sealing interface 19 does not yet cooperate with the third sealing interface 18, and the evacuation path 10 is not yet closed at the second closing location Z2 either. The float 12 is in an intermediate configuration. The evacuation path 10 is therefore open, and medical liquid present in the cavity 8 may exit the cavity 8 towards the lower space 4a, through the first passage 14. The volume of medical liquid therefore decreases in the cavity 8, contributing to the float 12 moving downwards in the cavity 8.

[0095] The float 12 thus moves downwards in the cavity 8 until the fourth sealing interface 19 presses on the third sealing interface 18. The fourth sealing interface 19 then cooperates with the third sealing interface 18 to close the evacuation path 10 at the second closing location Z2. If there is no medical liquid in the cavity 8, for example during a first filling, then the float 12 is already down the cavity 8, and is merely pressed downwards, the fourth sealing interface 19 pressing on the third sealing interface 18 to close the evacuation path 10 at the second closing location Z2.

[0096] Once the evacuation path 10 closed at the second closing location Z2, air from the upper space 4b cannot enter the lower space 4a. The pressure in the lower space 4a thus decreases until reaching the opening pressure of the first tubing valve 130, which is, for example, comprised between 0.2 and 0.5 bars below the reference pressure. The opening of the first tubing valve 130 creates an aspiration of the medical liquid to compensate this vacuum pressure in the lower space 4a. The medical liquid travels through the filling line 114 connected to the medical liquid container 104 to fill the lower space 4a. Gas present in the tubing is also aspirated into the lower space 4a.

[0097] Progressively, as the lower space 4a becomes filled with medical liquid and gas, the pressure within the lower space 4a increases and becomes closer to the atmospheric pressure. When the pressure within the lower space 4a reaches the closing pressure of the first tubing valve 130 (substantially similar to the opening pressure), the first tubing valve 130 closes and the filling is stopped. At the end of the filling step, the lower space 4a is filled with a volume of gas 32 above a volume of medical liquid 34. The gas pressure within the lower space 4a is still below the gas pressure within the upper space 4b because the pressure increase was stopped by the closing of the first tubing valve 130 before the vacuum pressure had been completely compensated. The float 12 is configured to be kept in the filling configuration by the pressure gradient and to not float on the medical liquid in the filling configuration.

[0098] After the filling of the injection device 110, the gas in the lower space 4a must be evacuated during a purge. This purge is performed by driving the piston 6 downwards, as shown on Figure 4, to place the float 12 in the intermediate configuration in which gas may be evacuated. The piston 6 travels within the inner space 4 along the longitudinal direction towards the lower end 2a of the body 2. The lower space 4a shrinks, and gas pressure increases in the lower space 4a. The pressure increase causes the float 12 to move upwards in the cavity 8 with respect to the piston 6. As the piston 6 moves upwards, the fourth sealing interface 19 moves away from the third sealing interface 18, thereby placing the float 12 in the intermediate configuration. The fourth sealing interface 19 no longer cooperates with the third sealing interface 18, and the evacuation path 10 becomes open at the second sealing location Z2. As the evacuation path 10 is still open at the first sealing location Zl, fluid (liquid or gas) may circulate along the evacuation path 10. The gas is evacuated from the lower space 4a to the upper space 4b of the inner space 4 through the evacuation path 10 traversing the piston 6. More specifically, gas enters the evacuation path 10 through the entrance 9, then travels through the first passage 14, through the inner aperture defined by the sealing component 18a, then in the cavity 8 along the float 12, through the second passage 15, to finally reach the upper space 4b. This is shown by the dotted arrows in Figure 4.

[0099] As the piston 6 travels downwards while the gas is evacuated through the evacuation path 10, the piston 6 reaches the volume of medical liquid in the lower space 4a. More specifically, the lower interface 7 contacts the medical liquid, and the gas is pushed back towards the entrance 9 of the evacuation path since the entrance 9 opens in the highest portion of said lower interface 7. The gas is therefore evacuated from the lower space 4a before the medical liquid reaches the entrance 9 of the evacuation path 10.

[0100] When all the gas has been evacuated from the lower space 4a, the medical liquid penetrates through the entrance 9 in the lower interface 7 of the piston 6 and fills a lower portion of the cavity 8, as illustrated on Figure 5. The float 12 is configured to transition from the intermediate configuration to the injection configuration when the piston 6 is moved towards the lower end 2a of the body 2, and medical liquid rises in the cavity 8. When the medical liquid reaches the cavity 8, the float 12 begins floating on the medical liquid, and therefore moves up, carried by the medical liquid 34 in accordance with the upward buoyant force that is exerted on the float by the medical liquid (Archimedes' principle). Under this force, the float 12 travels upwards relative to the cavity 8. The appendage 24 travels upwards with the float 12, being affixed to or integral with the body of the float within the cavity 8. The medical liquid lifts the float 12 until the second sealing interface 17 contacts the first sealing interface 16 to close the evacuation path 10 at the first closing location Zl. The second sealing interface 17, that is the obturating part 26, indeed travels upwards and comes to obturate the first passage 14 and close the evacuation path 10 at the first closing location Zl. In the depicted example, the sealing element 17a of the obturating part 26 abuts against an outer wall of the cavity 8 around the first passage 14, and ensures a watertight sealing of the first passage 14. The corresponding part of the outer wall of the cavity 8 around the first passage 14 constitutes the first sealing interface 16 in this example. As the obturating part 26 closes the first passage 14 and cannot traverse the first passage 14, the appendage 24 cannot move any further upwards. The float 12 also cannot moves any further upwards: the first sealing interface 16 limits the stroke of the float 12 upwards in the cavity 8. Typically, the first passage 14 has a round section and the obturating part 26 of the float 12 has a round section too. For example, the obturating part 26 of the float 12 may have at least partially an ellipsoid shape, or a spherical shape or a conical shape like a pine. The obturating part 26 of the float might coated with a deformable material for a better sealing of the first passage 14. Or a sealing element 17a can be provided between the obturating part 26 and the first passage 14, as illustrated.

[0101] As the second sealing interface 17 obturates the first passage 14 and closes the evacuation path 10, the medical liquid can no longer penetrate the evacuation path 10 to fill the cavity 8. The purge is over. A quantity of fluid is now trapped in the evacuation path 10 due to the closure of the evacuation path 10 at the first sealing location Zl, the trapped fluid being here medical liquid. As the evacuation path 10 is closed, pressure increases within the lower space 4a when the piston 6 is pushed downward.

[0102] The process may include a complementary filling step which occurs after the purge step and before the injection step. The complementary filling step allows filling the lower space 4a with an accurate prescribed volume of medical liquid 34, which was not possible in the first filling step due to the gas volume 32 that led to incorrect volume measures (usually based on the stroke of the piston 6). The complementary filling step includes performing once more the filling step as described above.

[0103] The process includes an injection step wherein the piston 6 travels within the inner space 4 along the longitudinal direction Z towards the lower end 2a of the body, and wherein the medical liquid exits said lower space 4a of the inner space 4 to be injected into medical tubing. In the injection configuration, the third sealing interface 18 and the fourth sealing interface 19 are spaced apart, and the second sealing interface 17 obturates the passage 14 by cooperating with the first sealing interface 16, thereby closing the evacuation path 10. As the evacuation path 10 is closed, pressure increases within the lower space 4a when the piston 6 is pushed downward. When the pressure in the lower space 4a reaches the opening pressure of the second tubing valve 140, the second tubing valve 140 opens and the medical liquid 34 can exit the lower space 4a and travels the common line 102 to reach the patient line 116. The medical liquid can thus be injected without any gas. It shall be noted that in the injection configuration, medical liquid is present in the cavity 8, and the float 12 is in its uppermost position relative to the cavity 8. Furthermore, a quantity of medical liquid is kept trapped in the evacuation path 10 during the injection step due to the closure of the evacuation path 10 at the first sealing location Zl.

[0104] Once the injection step is over, a new filling step can be performed, merely by moving the piston 6 upwards towards the upper end 2b of the body 2, as described above. The float 12 is configured to transition from the injection configuration to the filling configuration when the piston 6 is moved towards the upper end 2b of the body 2, and medical liquid in the cavity 8 decreases and the float 12 moves downwards with respect to the cavity 8 until the fourth sealing interface 19 contacts the second sealing interface 16 to close the evacuation path 10 at the second closing location Z2.

[0105] Figure 6 illustrates the effect of an anti-corking feature which may be provided to the float 12. In the example of Figures 3-6, the float 12 comprises a medical liquid retainer 40. The medical liquid retainer 40 is configured for providing a ballast of medical liquid to the float 12. The medical liquid retainer 40 is configured to retain medical liquid when the level of medical liquid is decreased with respect to a medical liquid level in the injection configuration. The medical liquid retainer 40 delimits a volume 41 which is open to allow the medical liquid to enter the volume 41. The medical liquid retainer 40 comprises a floor 42 for supporting medical liquid and at least one peripheral wall 44 extending upwards from the floor 42 to prevent the medical liquid supported by the floor 42 from leaving the volume 41 defined by the floor 42 and the peripheral wall 44. Due to the weight of the volume 41 of medical liquid acting on the floor 42, the medical liquid retainer 40 causes a downwards force to act on the float 12. This force ensures that the float 12 will go down as soon as the upward buoyant force that is exerted on the float 12 by the medical liquid is not strong enough. The medical liquid retainer 40 also makes sure that the float 12 is not stuck in the cavity 8 and is always at the bottom of the cavity 8 except when the medical liquid reaches the buoyancy line of the float 12. In the example of Figure 6, the medical liquid retainer 40 is part of the appendage 24, and is arranged below the obturating part 26. The floor 42 terminates the appendage 24 and extends in a plane perpendicular to the longitudinal direction. The peripheral wall 44 projects upwardly from the floor 42, and may be slanted. In an alternate configuration as illustrated in Figure 11, the injection device 110 includes an alternate float 1112. The alternate float 1112 is configured without a medical liquid retainer.

[0106] In the example of Figures 7-10, the first passage 14 connecting the cavity 8 to the inner space 4 connects the cavity 8 to the upper space 4b. The second passage 15 connecting the cavity 8 to the inner space 4 here connects the cavity 8 to the lower space 4a. The first passage 14 is between the obturating part 26 of the float 12 and the cavity 8. More precisely, the appendage 24 projects upwardly from an upper surface 12b of the body 12c of the float in the direction of the first passage 14. The appendage 24 comprises the obturating part 26, whose cross-section is greater than the cross-section of the first passage 14. The obturating part 26 is kept within the cavity 8.

[0107] In Figure 7, the injection device 110 is in the filling configuration wherein the injection device 110 is filled with medical liquid and unwanted gas. During this filling step, the piston rod 30 is driven upwards, for example by the injector 108 acting on said piston rod 30, thereby causing the piston 6 to travel within the inner space 4 along the longitudinal direction Z towards the upper end 2b of the body 2, i.e. upwards. The lower space 4a expands, resulting in a gas pressure within said lower space 4a to drop below the reference gas pressure within the upper space 4b, e.g. the atmospheric pressure.

[0108] The expansion of the lower space 4a creates a pressure gradient between the upper space 4b and the lower space 4a, with a depression in the lower space 4a, i.e. a pressure below the reference pressure. Due to the pressure difference, the float 12 is sucked downwards within the cavity 8 and moves downwards with respect to the cavity 8. If the float 12 was in an injection configuration, the second sealing interface 17 moves away from the first sealing interface 16 at the first closing location Zl. The evacuation path 10 is then no longer closed at the first closing location Zl.

[0109] As the float 12 moves downwards in the cavity 8, the fourth sealing interface 19 does not yet cooperate with the third sealing interface 18, and the evacuation path 10 is not yet closed at the second closing location Z2 either. The float 12 is in an intermediate configuration. The evacuation path 10 is therefore open, and medical liquid present in the cavity 8 may exit the cavity 8 towards the lower space 4a, through the second passage 15. The volume of medical liquid therefore decreases in the cavity 8, contributing to the float 12 moving downwards in the cavity 8. The float 12 thus moves downwards in the cavity 8 until the fourth sealing interface 19 presses on the third sealing interface 18. The fourth sealing interface 19 then cooperates with the third sealing interface 18 to close the evacuation path 10 at the second closing location Z2. If there is no medical liquid in the cavity 8, for example during a first filling, then the float 12 is already down the cavity 8, and is merely pressed downwards, the fourth sealing interface 19 pressing on the third sealing interface 18 to close the evacuation path 10 at the second closing location Z2.

[0110] Once the evacuation path 10 is closed at the second closing location Z2, air from the upper space 4b cannot enter the lower space 4a. The pressure in the lower space 4a thus decreases until reaching the opening pressure of the first tubing valve 130, which is, for example, comprised between 0.2 and 0.5 bars below the reference pressure. The opening of the first tubing valve 130 creates an aspiration of the medical liquid to compensate this vacuum pressure in the lower space 4a. The medical liquid travels through the filling line 114 connected to the medical liquid container 104 to fill the lower space 4a. Gas present in the tubing is also aspirated into the lower space 4a.

[0111] Progressively, as the lower space 4a becomes filled with medical liquid and gas, the pressure within the lower space 4a increases and becomes closer to the atmospheric pressure. When the pressure within the lower space 4a reaches the closing pressure of the first tubing valve 130 (substantially similar to the opening pressure), the first tubing valve 130 closes and the filling is stopped. At the end of the filling step, the lower space 4a is filled with a volume of gas 32 above a volume of medical liquid 34. The gas pressure within the lower space 4a is still below the gas pressure within the upper space 4b because the pressure increase was stopped by the closing of the first tubing valve 130 before the vacuum pressure had been completely compensated. The float 12 is configured to be kept in the filling configuration by the pressure gradient and to not float on the medical liquid in the filling configuration.

[0112] After the filling of the injection device 110, the gas in the lower space 4a must be evacuated during a purge. This purge is performed by driving the piston 6 downwards, as shown on Figure 8, to place the float 12 in the intermediate configuration in which gas may be evacuated. The piston 6 travels within the inner space 4 along the longitudinal direction towards the lower end 2a of the body 2. The lower space 4a shrinks, and gas pressure increases in the lower space 4a. The pressure increase causes the float 12 to move upwards in the cavity 8 with respect to the piston 6. As the piston 6 moves upwards, the fourth sealing interface 19 moves away from the third sealing interface 18, thereby placing the float 12 in the intermediate configuration. The fourth sealing interface 19 no longer cooperates with the third sealing interface 18, and the evacuation path 10 becomes open at the second sealing location Z2. As the evacuation path 10 is still open at the first sealing location Zl, fluid (liquid or gas) may circulate along the evacuation path 10. The gas is evacuated from the lower space 4a to the upper space 4b of the inner space 4 through the evacuation path 10 traversing the piston 6. More specifically, gas enters the evacuation path 10 through the entrance 9, then travels through the second passage 15 to enter the cavity 8, then through the inner aperture defined by the sealing component 18a, then in the cavity 8 along the float 12, through the first passage 14, to finally reach the upper space 4b. This is shown by the dotted arrows in Figure 8.

[0113] As the piston 6 travels downwards while the gas is evacuated through the evacuation path 10, the piston 6 reaches the medical liquid 34 in the lower space 4a. More specifically, the lower interface 7 contacts the medical liquid 34, and the gas is pushed back towards the entrance 9 of the evacuation path 10 since the entrance 9 opens in the highest portion of said lower interface 7. The gas is therefore evacuated from the lower space 4a before the medical liquid reaches the entrance 9 of the evacuation path.

[0114] When all the gas has been evacuated from the lower space 4a, the medical liquid penetrates through the entrance 9 in the lower interface 7 of the piston 6 and fills a lower portion of the cavity 8, as illustrated on Figure 9. The float 12 is configured to transition from the intermediate configuration to the injection configuration when the piston 6 is moved towards the lower end 2a of the body 2, and medical liquid rises in the cavity 8. When the medical liquid reaches the cavity 8, the float 12 begins floating on the medical liquid, and therefore moves up, carried by the medical liquid 34 in accordance with the upward buoyant force that is exerted on the float by the medical liquid (Archimedes' principle). Under this force, the float 12 travels upwards relative to the cavity 8. The appendage 24 travels upwards with the float 12, being affixed to or integral with the body 12c of the float 12 within the cavity 8. The medical liquid lifts the float 12 until the second sealing interface 17 contacts the first sealing interface 16 to close the evacuation path 10 at the first closing location Zl. The second sealing interface 17, that is the obturating part 26, also travels upwards and comes into contact with the first sealing interface 16 to obturate the first passage 14 and close the evacuation path 10 at the first closing location Zl. In the depicted example, the sealing element 17a of the obturating part 26 abuts against an inner wall of the cavity 8 around the first passage 14, and ensures a watertight sealing of the first passage 14. In this example, the corresponding part of the inner wall of the cavity 8 around the first passage 14 constitutes the first sealing interface 16.

[0115] As the obturating part 26 closes the first passage 14 and cannot traverse the first passage 14, the appendage 24 cannot move any further upwards. The float 12 also cannot moves upwards: the first sealing interface 16 limits the stroke of the float 12 upwards in the cavity 8. Typically, the first passage 14 has a round section and the obturating part 26 of the float 12 has a round section too. For example, the obturating part 26 of the float 12 may have at least partially an ellipsoid shape, or a spherical shape or a conical shape like a pine. The obturating part 26 of the float might coated with a deformable material for a better sealing of the first passage 14. Or a sealing element 17a can be provided between the obturating part 26 and the shoulder part 27 of the first passage 14, as illustrated.

[0116] As the second sealing interface 17 obturates the first passage 14 and closes the evacuation path 10, the medical liquid can no longer penetrate the evacuation path 10 to fill the cavity 8. The purge is over. A quantity of fluid is now trapped in the evacuation path 10 due to the closure of the evacuation path 10 at the first sealing location Zl, the trapped fluid being air here. As the evacuation path 10 is closed, pressure increases within the lower space 4a when the piston 6 is pushed downward.

[0117] The process may include a complementary filling step which occurs after the purge step and before the injection step. The complementary filling step allows filling the lower space 4a with an accurate prescribed medical liquid volume 34, which was not possible in the first filling step due to the gas volume 32 that led to incorrect volume measures (usually based on the stroke of the piston 6). The complementary filling step includes performing once more the filling step as described above.

[0118] The process includes an injection step wherein the piston 6 travels within the inner space 4 along the longitudinal direction Z towards the lower end 2a of the body, and wherein the medical liquid exits said lower space 4a of the inner space 4 to be injected into medical tubing. In the injection configuration, the third sealing interface 18 and the fourth sealing interface 19 are spaced apart, and the second sealing interface 17 obturates the first passage 14 and closes the evacuation path 10. As the evacuation path 10 is closed, TJ pressure increases within the lower space 4a when the piston 6 is pushed downward. When the pressure in the lower space 4a reaches the opening pressure of the second tubing valve 140, the second tubing valve 140 opens and the medical liquid 34 can exit the lower space 4a and travels the common line 102 to reach the patient line 116. The medical liquid can thus be injected without any gas. It shall be noted that in the injection configuration, medical liquid is present in the cavity 8, and the float 12 is in its uppermost position relative to the cavity 8. Further, a constant quantity of air is kept trapped in the evacuation path 10 during the injection step due to the closure of the evacuation path 10 at the first sealing location Zl.

[0119] Once the injection step is over, a new filling step can be performed, merely by moving the piston 6 upwards towards the upper end 2b of the body 2, as described above. The float 12 is configured to transition from the injection configuration to the filling configuration when the piston 6 is moved towards the upper end 2b of the body 2, and medical liquid in the cavity 8 decreases and the float 12 moves downwards with respect to the cavity 8 until the fourth sealing interface 19 contacts the second sealing interface 16 to close the evacuation path 10 at the second closing location Z2.

[0120] Figure 10 illustrates the effect of an anti-corking feature which may be provided to the float 12. In the example of Figures 7-10, the float 12 comprises a medical liquid retainer 50. The medical liquid retainer 50 is configured for providing a ballast of medical liquid to the float 12. The medical liquid retainer 50 is configured to retain medical liquid when the level of medical liquid is decreased with respect to a medical liquid level in the injection configuration. The medical liquid retainer 50 delimits a volume 51 which is open to allow the medical liquid to enter the volume 51. The medical liquid retainer 50 comprises a floor 52 for supporting medical liquid and at least one peripheral wall 54 extending upwards from the floor 42 to prevent the medical liquid supported by the floor 42 from leaving the volume 51 defined by the floor 52 and the peripheral wall 54. Due to the weight of the volume 41 of medical liquid acting on the floor 42, the medical liquid retainer 50 causes a downwards force to act on the float 12. This force ensures that the float 12 will go down as soon as the upward buoyant force that is exerted on the float 12 by the medical liquid is not strong enough. The medical liquid retainer 50 also makes sure that the float 12 is not stuck in the cavity 8 and is always at the bottom of the cavity 8 except when the medical liquid reaches the buoyancy line of the float 12. In the example of Figure 10, a medical liquid retainer is a chamber arranged in the body 12c of the float 12, with a channel 56 located at a distance from the floor 52 and opening on a surface of the body 12c of the float 12.

[0121] In an alternate configuration as illustrated in Figure 12, the injection device 110 includes an alternate float 1212. The alternate float 1212 is configured without a medical liquid retainer.

[0122] While the present invention has been described with respect to certain preferred embodiments, it is obvious that it is in no way limited thereto and it comprises all the technical equivalents of the means described and their combinations. In particular, it will be apparent to those skilled in the art that various changes and modifications may be made without departing from the scope of the invention as defined in the appended claims.

Claims

1. CLAIMS1. An injection device (110) for injecting into a medical tubing a medical liquid from a medical liquid container, said injection device comprising:- a body (2) defining an inner space (4) extending in a longitudinal direction (Z) between an upper end (2b) of the body (2) and a lower end (2a) of the body (2), the lower end (2a) of the body comprising a medical tubing interface (112) for connecting to medical tubing through which the medical liquid can penetrate the inner space (4) from the medical liquid container and can exit said inner space (4) to be injected into the medical tubing,- a piston (6) arranged within the inner space (4) and configured for travelling back and forth within the inner space (4) along the longitudinal direction (Z), said piston delimiting an upper space (4a) and a lower space (4b) of the inner space (4), said lower space (4a) configured to receive the medical liquid, the piston having a cavity (8),- an evacuation path (10), said evacuation path (10) traversing the piston (6) from the lower space (4a) to the upper space (4b), the cavity (8) being part of the evacuation path (10),- a float (12) configured for floating on the medical liquid, wherein the cavity (8) accommodates the float (12), wherein the piston (6) comprises passages (14, 15) connecting the cavity (8) to the inner space (4), said passages being part of the evacuation path (10), at least one passage connecting the cavity (8) to the lower space (4a) and at least one passage connecting the cavity (8) to the upper space (4b), wherein the piston (6) comprises a first sealing interface (16) and the float (12) comprises a second sealing interface (17) configured to cooperate with the first sealing interface (16) to close the evacuation path (10) at a first closing location (Zl), wherein the piston (6) comprises a third sealing interface (18) and the float (12) comprises a fourth sealing interface (19) configured to cooperate with the third sealing interface (18) to close the evacuation path at a second closing location (Z2) different from the first closing location, and the float (12) is configured to travel back and forth along the longitudinal direction (Z) between:a filling configuration in which the first sealing interface (16) and the second sealing interface (17) are spaced apart so that the evacuation path is not closed at the first closing location (Zl), whereas the third sealing interface (18) and the fourth sealing interface (19) cooperate to close the evacuation path (10) at the second sealing location (Z2); an injection configuration in which the first sealing interface (16) and the second sealing interface (17) cooperate to close the evacuation path (10) at the first sealing location (Zl), whereas the third sealing interface (18) and the fourth sealing interface (19) are spaced apart so that the evacuation path (10) is not closed at the second closing location (Z2).

2. The injection device of claim 1, wherein the injection device is configured to trap a quantity of fluid in the evacuation path (10) due to the closure of the evacuation path (10) at the first sealing location (Zl), the trapped fluid being either air or the medical liquid.

3. The injection device of any one of the preceding claims, wherein the float (12) is configured to float on the medical liquid in the cavity (8) in the injection configuration.

4. The injection device of any one of the preceding claims, wherein the float (12) is configured to be kept in the filling configuration by pressure gradient and to not float on the medical liquid in the filling configuration.

5. The injection device of any one of the preceding claims, wherein the float (12) is configured to be in an intermediate configuration between the filling configuration and the injection configuration, wherein in the intermediate configuration the first sealing interface (16) and the second sealing interface (17) are spaced apart so that the evacuation path is not closed at the first closing location (Zl), and the third sealing interface (18) and the fourth sealing interface (19) are spaced apart so that the evacuation path (10) is not closed at the second closing location (Z2).

6. The injection device of the preceding claim, wherein the float (12) is configured to transition from the filling configuration to the intermediate configuration when the piston (6) is moved towards the lower end (2a) of the body, and a pressure in the lower space (4a) is above a pressure in the upper space (4b), causing the float (12) to move upwards with respect to the cavity (8).

7. The injection device of the preceding claim, wherein the float (12) is configured to transition from the intermediate configuration to the injection configuration when the piston (6) is moved towards the lower end (2a) of the body (2), and medical liquid rises in the cavity (8) and lift the float (12) which moves upwards with respect to the cavity (8) until the second sealing interface (17) contacts the first sealing interface (16) to close the evacuation path (10) at the first closing location (Zl).

8. The injection device of any one of the preceding claims, wherein the float is configured to transition from the injection configuration to the filling configuration when the piston (6) is moved towards the upper end (2b) of the body (2), and medical liquid in the cavity (8) decreases and the float (12) moves downwards with respect to the cavity (8) until the fourth sealing interface (19) contacts the third sealing interface (18) to close the evacuation path (10) at the second closing location (Z2).

9. The injection device of any one of the preceding claims, wherein at least one sealing interface among the first sealing interface (16), the second sealing interface (17), the third sealing interface (18), and the fourth sealing interface (19), is provided with a sealing component (17a, 18a).

10. The injection device of any one of the preceding claims, wherein the float (12) comprises a medical liquid retainer (40, 50) which is configured for providing a ballast of medical liquid to the float (12).

11. The injection device of any one of the preceding claims, wherein the second sealing interface (17) is an obturating part (26) which belongs to an appendage (24) of the float (12), the appendage (24) of the float (12) configured to penetrate a passage (14)connecting the cavity (8) to the inner space (4), the obturating part (26) having a crosssection larger than a cross-section of said passage (14).

12. The injection device of the preceding claim, wherein the passage (14) connects the cavity (8) to the lower space (4b), and the passage (14) is between the obturating part (26) of the float (12) and the cavity (8).

13. The injection device of the claim 11, wherein the passage (14) connects the cavity (8) to the upper space (4a), and the obturating part (26) is between the passage (14) and the float (12).

14. An injection system comprising:- the injection device (110) of any one of the preceding claims,- an actuator (30) to cause the piston (6) to travel back and forth within the inner space (4),- a first connector (106) configured to be connected to a medical liquid container,- a medical liquid supply line (114) configured to connect the first connector (106) to the medical tubing interface (112) for supplying the medical liquid to the injection device (110),- a common line (102) configured to be connected to the medical tubing interface (3) and to a patient line (116) for injecting the medical liquid into the patient line.

15. A method of operating the injection system of the preceding claim, wherein the method comprises:- causing the piston (6) to travel towards the upper end (2b) of the body (2), resulting in medical liquid in the cavity (8) to decrease and the float (12) to move downwards with respect to the cavity (8) until the fourth sealing interface (19) contacts the third sealing interface (18) to close the evacuation path (10) at the second closing location (Z2), the float (12) then being in the filling configuration;- causing the piston (6) to travel towards the lower end (2a) of the body (2), resulting in medical liquid rising in the cavity (8) and lifting the float (12) which moves upwards with respect to the cavity (8) until the second sealing interface (17) contacts the first sealing interface (16) to close the evacuation path (10) at the first closing location (Zl), the float (12) then floating on the medical liquid in the injection configuration.

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