Device for controlling fluid flow

Abstract

An apparatus (30) for controlling fluid flow in a flexible tube (10) includes two rotatable spools (22, 32), a motor (56), an encoder (64), and a processor (202). Each spool includes a tube-engaging surface portion having a shape that varies around at least a portion of the spool's periphery. The motor includes a rotor (62) mechanically coupled to the spools such that operation of the motor causes rotation of the spools. The encoder is mechanically coupled to the rotor and is configured to measure angular displacement of the rotor. The processor determines (902) a target angular displacement of the rotor, receives (904) a measurement signal (64) from the encoder indicative of angular displacement of the rotor, and outputs (906) a motor control signal (67) to set the angular displacement of the rotor as measured by the encoder to the target angular displacement.

Description

Technical Field

[0001] This disclosure relates to an apparatus for controlling fluid flow. More specifically, this disclosure relates to an apparatus suitable for controlling fluid flow in flexible tubing (e.g., blood lines in a medical setting). Background Technology

[0002] Flexible tubing is commonly used in medical settings to deliver fluids such as blood or solutions. A convenient way to restrict fluid flow without the risk of contamination from direct contact with the fluid is to use clamps to compress the flexible tubing. Typically, the clamps are manually operated and releasable to remove the flow restriction as needed. Various mechanisms exist, but they generally include tubing engagement elements that clamp or slide against the outer surface of the flexible tubing to compress it.

[0003] Reducing fluid flow to a specific level using manual clamps is challenging. This is because: the type of flexible tubing typically used in medical settings may have to be squeezed to about half its original diameter before a significant effect on flow can be observed, and may have to be squeezed further to restrict flow.

[0004] The applicant's earlier patent, UK Patent No. GB2547900, describes a clamping mechanism for improving manual clamping technology. More specifically, that patent discloses a clamping mechanism in which two rotatable bobbins are mounted on a translational bracket. Each bob has a tube-joining surface portion whose shape varies around the periphery of the bob. Axial rotation of the bobbins compresses the tube positioned in the space between the bobbins, the amount of compression depending on the rotation of the bobbins, thereby sufficiently deforming the tube to restrict fluid flow through it. This arrangement allows for precise control of the degree of tube deformation and, therefore, precise control of the flow rate through the flexible tube. As the bobbins rotate, the translational bracket moves the bobbins along the tube to prevent the bobbins from pulling the tube. The entire contents of GB2547900 are incorporated herein by reference.

[0005] This disclosure relates to an improvement on a clamping mechanism of the type disclosed in the applicant’s earlier patent GB2547900. Summary of the Invention

[0006] According to a first aspect of this disclosure, an apparatus for controlling fluid flow rate in a flexible tube is provided. The apparatus includes two rotatable tubes, each tube including a tube-joining surface portion, wherein the tube-joining surface portion defines a boundary of a free space between the tubes through which the tube can extend. At least one tube-joining surface portion has a shape that varies around at least a portion of the periphery of the tube, such that axial rotation of the tube reduces the free space by an amount depending on the amount of rotation of the tube. The apparatus also includes a motor including a rotor mechanically coupled to the tubes, such that operation of the motor causes rotation of the tubes. The apparatus further includes an encoder mechanically coupled to the rotor and configured to measure angular displacement of the rotor. The apparatus also includes a processor configured to determine a target angular displacement of the rotor, receive a measurement signal from the encoder indicating the angular displacement of the rotor, and output a motor control signal to set the angular displacement of the rotor measured by the encoder as the target angular displacement.

[0007] Compared to the clamping mechanism described in the applicant’s earlier patent GB2547900, the device for controlling fluid flow described herein provides even more precise control over the flow through the flexible tube, especially at low temperatures and / or lower flow rates.

[0008] Flexible tubing, commonly used in medical settings, stiffens as its temperature decreases, potentially increasing the likelihood of motor slippage. In this context, motor slippage refers to a situation where the motor rotor fails to rotate when the motor receives a control signal. If, in response to a specific control signal, the motor does not generate sufficient torque to overcome the increased stiffness of the flexible tubing, occasional motor slippage may occur at cryogenic temperatures. The device described herein mitigates the effects of motor slippage by detecting the error between the target displacement and the actual displacement of the rotor and by outputting a motor control signal to reduce or eliminate this error. Therefore, even in the event of occasional motor slippage, the device described herein can operate the motor to accurately compress the flexible tubing by the desired amount. This can provide improved control of blood flow during cardiac perfusion procedures performed under cryogenic cyclic inhibition, where the patient's body temperature is reduced to 25°C or lower.

[0009] It is difficult to accurately measure low flow rates through a flexible tube using flow sensors. The device described herein can use a measurement of the rotor's angular displacement as a representative of the flow rate measurement. Due to the mechanical connection between the rotor and the tube, the rotor's angular displacement causes considerable rotation of the tube, which in turn affects the flow rate through the flexible tube. Therefore, by using a measurement of the rotor's angular displacement as a representative of the flow rate measurement, the device disclosed herein can accurately control fluid flow at "low" flow rates. In this context, "low" flow rate refers to a flow rate where the flow sensor has poor sensitivity or is inaccurate.

[0010] As used herein, the term "target angular displacement" refers to the desired angular displacement of the rotor. A target angular displacement can be selected to achieve a specific function. For example, a target angular displacement can be selected to set the flow rate through the pipe to a specific level. As another example, a target angular displacement can be selected to set the bobbin to a fully open configuration, a fully blocked configuration, or a specific partially blocked configuration at an intermediate point between the fully open and fully blocked configurations.

[0011] Optionally, the processor can also be configured to receive a second measurement signal from the encoder after the angular displacement of the rotor, measured by the encoder, has been set to the target angular displacement. The processor can identify, based on the second measurement signal, that the angular displacement of the rotor has drifted from the target angular displacement. The processor can then output a second motor control signal to reset the angular displacement of the rotor, measured by the encoder, to the target angular displacement.

[0012] The bobbin may accidentally deviate from its intended position. For example, a clinician may unintentionally pull on the tube, causing it to rotate unintentionally. This, in turn, can affect the flow rate through the tube by increasing or decreasing the free space between the bobbins, which will increase or decrease the flow rate, respectively. Due to the mechanical connection between the rotor and the bobbin, the device disclosed herein can detect unintentional rotation of the bobbin by recognizing that the rotor's angular displacement has drifted from the target angular displacement (i.e., unintentionally moved). The device can then restore the bobbin to its intended position by actuating a motor, thereby resetting the rotor's angular displacement, as measured by the encoder, to the target angular displacement. In this way, deviations from the intended position of the bobbin can be corrected, and the flow rate through the tube can be maintained at a desired level.

[0013] Alternatively, the processor can also be configured to receive an input indicating a desired flow rate and determine a target angular displacement based on the desired flow rate and a known relationship between the flow rate in the flexible tube and the angular displacement of the rotor.

[0014] A target angular displacement of the rotor, resulting in a desired flow rate through the tube, can be determined using a known relationship between flow rate and angular displacement. This target angular displacement can then be used to set the flow rate to the desired flow rate without requiring a flow sensor, as discussed above, which may be inaccurate at lower flow rates. This desired flow rate can be a user-selected value, input into the processor by a user (e.g., a clinician, such as an perfusionist) via a user input device. Alternatively, the desired flow rate can be a programmable value, determined by a control program to achieve a specific clinical outcome.

[0015] The known relationship between flow rate and angular displacement can be stored in a memory communicatively connected to the processor. For example, the memory can store lookup tables that associate two or more flow rates with corresponding angular displacements of the rotor. In some embodiments, the memory can store multiple such lookup tables, each associating a flow rate with a given set amount of angular displacement. This set can be defined based on the properties of the flexible tube (e.g., its inner diameter, outer diameter, and / or material), the properties of the fluid (e.g., its composition and / or viscosity), and / or temperature. Other relevant properties of this set can be used. The values ​​in the lookup tables can be determined empirically (e.g., by measuring the flow rate achieved by a specific set at each of several different angular displacements).

[0016] Alternatively, the known relationship between flow rate and angular displacement can be presented in the form of a parametric model. The parametric model can receive inputs including the desired flow rate, and optionally one or more other parameters, such as one or more properties of the flexible tube (e.g., its inner diameter, outer diameter, and / or material), one or more properties of the fluid (e.g., its composition and / or viscosity), and / or temperature. The parametric model can output a target angular displacement that will result in a desired flow rate with a set amount of any other parameter values ​​provided to the model as input.

[0017] The desired flow rate can be expressed in any suitable unit of measurement, such as milliliters per second or liters per minute.

[0018] Alternatively, the processor can also be configured to receive an input indicating the desired blocking rate of the flexible tube, and to determine the target angular displacement based on the desired blocking rate and a known relationship between the blocking rate of the flexible tube and the angular displacement of the rotor.

[0019] In this context, "blockage (rate)" is a numerical value representing a point on a continuous interval between a fully open configuration and a fully blocked configuration of the device. The blockage (rate) can be expressed as a percentage. For example, a 0% blockage rate corresponds to a fully open configuration, where the device does not restrict the flow of fluid through the flexible tube. As another example, a 100% blockage rate corresponds to a fully blocked configuration, where the device restricts the flow of fluid through the flexible tube to the maximum possible extent, such that the flow is completely stopped or reduced to a negligible amount. As yet another example, blockage rates of 25%, 50%, and 75% correspond to partially blocked configurations, where higher percentage values ​​correspond to lower flow rates. Other blockage rates between 0% and 100% are also possible.

[0020] The target angular displacement of the rotor, which causes the desired blockage in the flexible tube, can be determined using the known relationship between blockage and angular displacement. This target angular displacement can then be used to control the flow rate through the flexible tube, eliminating the need for flow sensors, which may be inaccurate at lower flow rates, as discussed above. A blockage rate can be used as a more intuitive alternative to specifying the flow rate. The desired blockage (rate) can be a user-selected value, input by a clinician via a user input device into the processor. Alternatively, the desired blockage rate can be a programmable value, determined by a control program to achieve specific clinical outcomes.

[0021] The known relationship between blockage (rate) and angular displacement can be stored in a memory communicatively coupled to the processor. For example, the memory can store lookup tables that associate two or more blockage rates with corresponding angular displacements of the rotor. In some embodiments, the memory can store multiple such lookup tables, each associating a blockage rate with a given set amount of angular displacement. This set can be defined based on the properties of the flexible tube (e.g., its inner diameter, outer diameter, and / or material), the properties of the fluid (e.g., its composition and / or viscosity), and / or temperature. Other relevant properties of this set can be used. The values ​​in the lookup tables can be determined empirically (e.g., by measuring the free space between the tubes and / or measuring the amount of tube deformation at each of several different angular displacements).

[0022] Alternatively, the relationship between blockage (rate) and angular displacement can be presented as a parametric model. The parametric model can receive inputs including the desired blockage (rate) and optionally values ​​for one or more other parameters, such as one or more properties of the flexible tube (e.g., its inner diameter, outer diameter, and / or material), one or more properties of the fluid (e.g., its composition and / or viscosity), and / or temperature. The parametric model can output a target angular displacement that will result in a desired blockage (rate) with a set amount of any other parameter values ​​provided to the model as input.

[0023] Optionally, the device may have a second operating mode in which the processor is configured to: determine a target flow rate of fluid in the flexible tube; receive a flow signal from a flow sensor indicating the flow rate of fluid in the flexible tube as measured by the flow sensor; and output a third motor control signal to rotate the tube, thereby setting the flow rate measured by the flow sensor as the target flow rate.

[0024] A second operating mode can be provided as an alternative to the first operating mode as described above, wherein the rotor's angular displacement is set to a target value. The encoder is not used to determine the motor control signal in the second operating mode, but can still be used to provide an angular displacement measurement, based on which the position of the bobbin can be accurately determined. The second operating mode can provide more accurate flow through the flexible tube at higher temperatures and / or higher flow rates. In this case, "higher" flow rate means: a flow sensor that is accurate enough to allow the flow rate measured by the flow sensor to be within a certain tolerance of the target flow rate. "Higher" temperature means: a temperature at which the temperature-induced stiffness of the flexible tube will not cause motor slippage.

[0025] A flow sensor can be a component of a device for controlling fluid flow. Alternatively, the flow sensor can be a separate component configured to supply a signal indicating the flow rate to a processor. In either case, the flow sensor is any suitable component configured to measure the flow rate of fluid in a flexible tube and output a signal indicating the measured flow rate.

[0026] The target flow rate can be a user-selected value, which can be input into the processor by a user (e.g., a clinician, such as an infusionist) via a user input device. Alternatively, the target flow rate can be a programmable value, which can be determined by a control program to achieve a specific clinical outcome.

[0027] Optionally, the processor can also be configured to detect a fault in the flow sensor when the device is in a second operating mode. In response to detecting a fault in the flow sensor, the processor can cause the device to operate in a first operating mode. In this first operating mode, the processor determines the target angular displacement of the rotor, receives a measurement signal from the encoder, and outputs a motor control signal to set the angular displacement of the rotor measured by the encoder as the target angular displacement.

[0028] By switching from the second operating mode to the first operating mode, the device can continue to control the fluid flow through the flexible tube even in the unlikely event of a flow sensor malfunction. In this respect, "malfunction" does not necessarily mean the flow sensor is completely inoperable. Rather, a "malfunction" of the flow sensor can be detected if it is accidentally disconnected by the user, or if the processor detects an abnormal measurement from the flow sensor. Abnormal measurements may occur if air bubbles enter the flexible tube.

[0029] Optionally, the processor can also be configured to determine the target angular displacement based on the target flow rate and the known relationship between the flow rate in the flexible tube and the angular displacement of the rotor, thereby enabling the device to operate in a first operating mode.

[0030] Therefore, if the flow sensor malfunctions, the known relationship between flow rate and angular displacement can be used to maintain the flow rate at the previously set target flow rate.

[0031] Optionally, the processor can also be configured to receive a forced input and, in response to the forced input, to cause the device to operate in a second operating mode when a fault in the flow sensor has been detected.

[0032] Forced input can be provided by a user (e.g., a clinician, such as an infusionist) via a user input device. This forced input prevents the device from switching from a first operating mode to a second operating mode when the user knows that the flow sensor is not actually malfunctioning. For example, if the user observes that a significant malfunction in the flow sensor is caused by a small number of air bubbles in the flexible tube, the user can activate the forced input and determine that the device can safely continue operating in the second operating mode until those air bubbles have passed through the flow sensor.

[0033] Optionally, the processor can also be configured to receive a command to stop the fluid from flowing through the flexible tube, and in response to the command to stop the fluid from flowing through the flexible tube, output a fourth motor control signal to set the angular displacement of the rotor measured by the encoder as a second target angular displacement. The second target angular displacement may correspond to a fully blocked configuration of the device, wherein the bobbin maximally restricts the flow of fluid through the flexible tube.

[0034] The command to stop fluid flow through the flexible tube can be generated in response to input provided by a user (e.g., a clinician, such as an infusionist) via a user input device. Alternatively, the command to stop fluid flow can be generated automatically by the control program. In each case, a command to stop fluid flow through the flexible tube can be generated when the clinical environment requires a temporary cessation of flow. By taking into account the angular displacement of the rotor when outputting the fourth motor control signal, the device is reliably configured for a fully blocked configuration, wherein fluid flow is stopped or reduced to a negligible amount.

[0035] Optionally, the processor can also be configured to receive a command to detach from the flexible tube, and in response to the command to detach from the flexible tube, output a fifth motor control signal to set the angular displacement of the rotor measured by the encoder as a third target angular displacement. The third target angular displacement may correspond to a fully open configuration of the device, wherein the bobbin does not restrict the flow of fluid through the flexible tube.

[0036] The command to detach from the flexible tube can be generated in response to input provided by a user (e.g., a clinician, such as an infusionist) via a user input device. Alternatively, the command to detach from the flexible tube can be generated automatically by a control program. In each case, the command to detach from the flexible tube can be generated when the clinical environment requires maximizing fluid flow in the flexible tube. By taking into account the angular displacement of the rotor when outputting the fifth motor control signal, the device is reliably configured in its fully open configuration, where fluid flow is unrestricted.

[0037] Optionally, the processor may also be configured to receive an instruction to restore fluid flow through the flexible tube, and in response to the instruction to restore fluid flow in the flexible tube, output a sixth motor control signal to set the angular displacement of the rotor measured by the encoder as the target angular displacement.

[0038] The instruction to restore fluid flow through the flexible tube can be generated in response to input provided by a user (e.g., a clinician, such as an infusionist) via a user input device. Alternatively, the instruction to restore fluid flow can be generated automatically by the control program. In each case, it may be necessary to generate the instruction to restore fluid flow through the flexible tube after the clinical situation of stopping or maximizing fluid flow has passed, and it is desired that the fluid flows through the flexible tube at its previous rate. Therefore, before receiving an instruction to stop fluid flow in the flexible tube or to detach from the flexible tube, the sixth motor controller sets the rotor's angular displacement to the target angular displacement. This is simpler and faster than requiring the user to manually reset the device to its previous settings.

[0039] The encoder can be an absolute encoder. The use of an absolute encoder ensures that the current rotational position of the bobbin can always be derived from the latest measurement signal received by the encoder. In other words, during clinical surgery, the use of an absolute encoder avoids the current rotational position of the bobbin becoming unknown.

[0040] According to another aspect of this disclosure, a cardiac perfusion system may be provided. The cardiac perfusion system includes means for controlling fluid flow as described herein.

[0041] The apparatus for controlling fluid flow described herein is particularly suitable for use in medical settings, and especially for use during cardiac perfusion procedures. This is because the apparatus described herein provides accurate flow control, which can be advantageous during cardiac perfusion. Furthermore, the ability of the apparatus disclosed herein to provide accurate flow control at cryogenic temperatures may be particularly advantageous during cardiac perfusion procedures performed under cryogenic circulatory stasis.

[0042] The devices described herein can be used in cardiac perfusion systems to control: the flow of blood from the patient to the reservoir; the flow of blood from the venous reservoir to the oxygen generator; the flow of blood from the oxygen generator to the patient; or the flow of cardioplegic solutions. Multiple such devices can be used in a single cardiac perfusion system, each configured to control the flow of a corresponding fluid.

[0043] It should be understood that the device described herein for controlling fluid flow can be used in other medical applications, or even in non-medical applications. Attached Figure Description

[0044] The embodiments will now be described by way of example only with reference to the accompanying drawings, wherein the same reference numerals are used to denote the same features, and wherein:

[0045] Figure 1 This is a perspective view of an apparatus for controlling fluid flow according to the present disclosure;

[0046] Figure 2 yes Figure 1 Front view of the device shown;

[0047] Figure 3 yes Figure 1 and Figure 2 Side view of the device shown;

[0048] Figure 4 It is along Figure 2 A cross-sectional view of the device with line AA in the middle;

[0049] Figure 5a yes Figures 1 to 4 The front view of the tube of the device shown is in a fully open configuration.

[0050] Figure 5b yes Figures 1 to 4 The front view of the tube of the device shown, wherein the tube is in a partially blocked configuration;

[0051] Figure 5c yes Figures 1 to 4 The front view of the tube of the device shown, wherein the tube is in a fully blocked configuration;

[0052] Figure 6a yes Figures 1 to 4 The side view of the tube of the device shown, wherein the tube is in a position corresponding to Figure 5a The fully open configuration shown;

[0053] Figure 6b yes Figures 1 to 4 The side view of the tube of the device shown, wherein the tube is in a position corresponding to Figure 5b The partially blocked configuration shown;

[0054] Figure 6c yes Figures 1 to 4 The side view of the tube of the device shown, wherein the tube is in a position corresponding to Figure 5c The fully blocked configuration shown;

[0055] Figure 7 yes Figures 1 to 4 A schematic diagram of the control system of the device shown;

[0056] Figure 8 yes Figure 7 A schematic diagram of the controller of the control system shown;

[0057] Figure 9 It is control Figures 1 to 4 A flowchart of a first example of the method of the apparatus shown;

[0058] Figure 10 It is control Figures 1 to 4 A flowchart of a second example of the method of the apparatus shown; and

[0059] Figure 11 It is control Figures 1 to 4 A flowchart of a third example of the method of the apparatus shown. Detailed Implementation

[0060] Now refer to Figures 1 to 4 The present disclosure describes an apparatus 30 for controlling fluid flow rate. Figures 1 to 3 These are the perspective view, front view, and side view of device 30. Figure 4 This is a cross-sectional view of device 30, wherein the shading indicates the cutting surface of device 30.

[0061] The device 30 includes a first tube 22 and a second tube 32. The first tube 22 is generally cylindrical and includes a groove 24 forming a tube-jointing surface portion on its peripheral surface. The groove 24 has a radius that increases along at least a portion of the periphery of the first tube 22 relative to a central axis of rotation 28 of the first tube 22. Thus, the shape of the groove 24 changes along the periphery of the tube and gradually becomes flatter. On its peripheral surface, the first tube 22 includes a flat portion 29 above the deepest part of the groove 24. The groove 24 terminates at one end forming a chamfered shoulder 27, which constitutes a sharply tapered profile.

[0062] The second bobbin 32 includes a groove 34, a flat portion 39 above the deepest part of the groove 34, and a chamfered shoulder 37. The second bobbin 32 is related to the first bobbin 22. Figure 2 The line AA shown is a mirror image. Therefore, the description of the first bobbin 22 given above can also be applied to the second bobbin 32.

[0063] The first tube 22 and the second tube 32 are rotatably arranged adjacent to each other, such that the outer surfaces of the tubes 22 and 32 face each other. Grooves 24 and 34 define the boundaries of the free space 15. The tube 10 can extend through the free space 15, such as... Figures 5a to 5c As shown. Tube 10 is not part of device 30, but rather a replaceable (and optionally disposable) component supplied separately from device 30. Tube 10 can be any suitable tube capable of elastic deformation, whereby its internal volume decreases when compressive force is applied to its outer surface and returns to its previous internal volume when the compressive force is removed. Figure 2 As shown, when the flat portions 29 of the first tube 22 and 32 and the flat portions 39 of the second tube 32 are aligned to face each other, the flat portions 29 and 39 provide a channel 55 through which the tube 10 can be inserted into the free space 15 between the tubes 22 and 32, and through which the tube 10 can be removed from the free space 15. The device 30 may include a housing (not shown) to support the tube 10 on both sides of the tubes 22 and 32 and to hold the tube 10 in a defined spatial relationship relative to the tubes 22 and 32.

[0064] refer to Figures 5a to 5c The area of ​​the free space 15 between the tubes 22 and 32 can be changed by rotating the tubes. This, in turn, can affect the flow of fluid through the tube 10 positioned within the free space 15. Figure 5a In this arrangement, the tubes 22 and 32 are oriented such that the deepest portions of the grooves 24 and 34 face each other. In this orientation, the area of ​​the free space 15 between the tubes 22 and 32 is at its maximum, and the tube 10 experiences little or no deformation from the tubes 22 and 32. Therefore, Figure 5a The device 30 is described as being in a “fully open” configuration because the tubes 22 and 32 do not cause the tube 10 to deform sufficiently to affect the flow of fluid through the tube 10.

[0065] To reduce the area of ​​free space 15, the tubes 22 and 32 rotate about their respective axes 28 and 38 in the directions indicated by arrows 36 and 35. It will be noted that the first tube 22 rotates in the opposite direction to the second tube 32. Figure 5b The diagram shows the tubes 22 and 32 after being rotated approximately 45° about their respective axes 28 and 38. In this orientation, the shallower portions of the grooves 24 and 34 face each other, and the free space 15 between the tubes 22 and 32 is reduced relative to the free space in the fully open configuration. The outer surfaces of the tubes 22 and 32 abut against and compress the tube 10, causing the tube 10 to deform, as... Figure 5b As shown. When the tube deforms, its internal cross-sectional area decreases, and the rate at which fluid can pass through tube 10 decreases. Therefore, Figure 5b The device 30 is described as having a “partial blockage” configuration because the tubes 22 and 32 deform the tube 10 sufficiently to reduce the flow of fluid through the tube 10, but do not completely stop the flow.

[0066] Further rotation of the tubes 22 and 32 about their respective axes 28 and 38 in the directions indicated by arrows 36 and 35 causes the area of ​​the free space 15 to gradually decrease. Therefore, the rate at which fluid can flow through the tube 10 also gradually decreases.

[0067] When the tubes 22 and 32 rotate approximately 180° around their respective axes 28 and 38, the chamfered shoulders 27 and 37 face each other, as... Figure 5c As shown. In this orientation, the area of ​​the free space 15 between the cylinders 22 and 32 is at its maximum, and the pipe 10 is deformed by the cylinders 22 and 32 to the point that fluid cannot flow through the pipe 10. Therefore, Figure 5c The device 30 is described as a “completely blocked” configuration because the tubes 22, 32 completely stop the flow of fluid through the tube 10 (or at least reduce the rate of fluid flow through the tube to a negligible amount).

[0068] It should be understood that the bobbins 22 and 32 have multiple intermediate orientations between the two extremes of a fully open and fully closed configuration. Due to the gradually flattening shape of the grooves 24 and 34, each intermediate orientation of the bobbins 22 and 32 corresponds to a different area of ​​the free space 15. Therefore, the deformation of the pipe 10 depends on the orientation of the bobbins 22 and 32. Furthermore, the fluid flow rate through the pipe 10 also depends on the orientation of the bobbins 22 and 32, but the relationship between the fluid flow rate and the orientation of the bobbins 22 and 32 is non-linear. Therefore, the fluid flow rate through the pipe 10 can be changed by rotating the bobbins 22 and 32. By rotating the bobbins 22 and 32 about their respective axes 28 and 38 in the directions indicated by arrows 36 and 35, the fluid flow rate can be reduced. By rotating the bobbins 22 and 32 about their respective axes 28 and 38 in the opposite direction indicated by arrows 36 and 35, the fluid flow rate can be increased.

[0069] Now refer to Figures 1 to 4 The mechanism for rotating the bobbins 22 and 32 is described below. The device 30 includes a frame 40 and a bracket 46. The frame 40 supports the other components of the device 30, including the bracket 46. The bracket 46 supports the bobbins 22 and 32. The bracket 46 is movable relative to the frame 40. More specifically, the bracket 46 can translate relative to the frame 40 along a generally linear path indicated by arrow 18. Although the accompanying drawings show arrow 18 pointing in only one direction, it should be understood that the bracket 46 is capable of translating in two directions along the linear path. The translation of the bracket 46 causes rotation of the bobbins 22 and 32, as explained in more detail below.

[0070] A first bobbin 22 is fixed to a first end of a first rotating shaft 23, wherein the first rotating shaft 23 and the first bobbin 22 are rotatable about a common axis 28. A first pinion 25 is located at a second end of the first rotating shaft 33. Similarly, a second bobbin 32 is fixed to a first end of a second rotating shaft 33, wherein the second rotating shaft 33 and the second bobbin 32 are rotatable about a common axis 38. A second pinion 45 is located at a second end of the second rotating shaft 33. The first pinion 25 and the second pinion 45 each have teeth that mesh with the teeth of a first rack and a second rack 44, respectively. In the figures, only the second rack 44 is visible, but it will be understood that the first rack extends parallel to the second rack 44. The first rack and the second rack extend substantially perpendicular to the axis 28 of the first bobbin 22 and the axis 38 of the second bobbin 32, and in use are substantially parallel to the tube 10.

[0071] The bracket 46 includes a first bracket portion 46a and a second bracket portion 46b. It can be used... Figure 4 The second bracket section 46a can be seen, but from... Figures 1 to 3The second bracket portion 46a is omitted to avoid obscuring other features of the device 30. In an alternative embodiment not shown in the drawings, the bracket 46 does not have different first portions 46a and second portions 46b, but has an integral construction. The first bracket portion 46a includes internal threads 47a. The second bracket portion 46b is rigidly connected to the first bracket portion 46a such that translation of the first bracket portion 46a causes an equal translation of the second bracket portion 46b. The first rotating shaft 23 and the second rotating shaft 33 extend vertically through corresponding holes in the second bracket portion 46b. The first rotating shaft 23 and the second rotating shaft 33 are capable of rotating freely within their respective holes in the second bracket portion 46b. However, when the second bracket portion 46b undergoes translational movement, the inner surface of its holes is supported on the first rotating shaft 23 and the second rotating shaft 33, thereby causing the first bobbin 22 and the second bobbin 32 to translate.

[0072] The second bracket portion 46b is slidably mounted on a guide rail 48. This guide rail 48 extends substantially perpendicular to the axis 28 of the first bobbin 22 and the axis 38 of the second bobbin 32, and in use is substantially parallel to the tube 10. The guide rail 48 constrains the translational movement of the bracket 46, allowing it to translate only along a linear path generally indicated by arrow 18. This, in turn, constrains the translational movement of the first bobbin 22 and the second bobbin 32, allowing them to translate only along a generally linear path indicated by arrow 18. The guide rail 48 is rigidly mounted to the frame 40.

[0073] The guide screw 42 extends substantially perpendicular to the axis 28 of the first bobbin 22 and the axis 38 of the second bobbin 22. The guide screw 42 also extends substantially parallel to the first and second racks, and in use, substantially parallel to the tube 10. The guide screw 42 has an external thread 47b that engages with the internal thread 47a of the first bracket portion 46a. Although the external thread 47b only extends along... Figure 4 A smaller area of ​​the guide screw 42 is visible, but it should be understood that the external thread 47b extends substantially along the entire length of the guide screw 42.

[0074] Motor 56 is rigidly attached to frame 40. Motor 56 includes rotor 62 configured to rotate during operation. Motor 56 can rotate rotor 62 in a clockwise or counterclockwise direction. Rotor 62 may include a shaft. Figure 4 In the illustrated embodiment, the first end 63a of the rotor 62 is rigidly connected to the end of the guide screw 42. Therefore, rotation of the rotor 62 causes an equal rotation of the guide screw 42. In other embodiments, the guide screw 42 and the rotor 62 may not be separate components, but may have an integrated construction. The motor 56 may be a stepper motor, or any other suitable type of motor.

[0075] Encoder 64 is connected to rotor 62 of motor 56. For example... Figure 4 As shown, encoder 64 is directly coupled to the second end 63b of rotor 62, which is opposite to the first end 63a of rotor 62, and guide screw 42 is coupled to the first end 63a of rotor 62. In an alternative embodiment, encoder 64 may be inserted between the body of motor 56 and guide screw 42. In another alternative embodiment, encoder 42 may be coupled to the end of guide screw 42 away from motor 56, such that encoder 64 is indirectly coupled to rotor 62 via guide screw 42. Regardless of its position, encoder 64 is configured to measure the angular displacement (in other words, rotation) of rotor 62. Encoder 64 is also configured to output a measurement signal indicating the measured angular displacement of rotor 62. Therefore, encoder 64 may be an electronic component referred to in the art as a rotary encoder or shaft encoder. Reference is made below. Figure 7 , Figure 9 ,as well as Figure 10 This explains how the measurement signal is used via device 30.

[0076] To rotate the bobbins 22 and 32, and thereby control the fluid flow in the tube 10, a motor control signal is supplied to the motor 56. This motor control signal causes the motor 56 to operate, and more specifically, causes the rotor 62 of the motor 56 to rotate. The rotation of the rotor 62 causes the guide screw 42 to rotate. When the guide screw 42 rotates, its external thread 47b engages with the internal thread 47a of the first bracket portion 46a, thereby causing the first bracket portion 46a to translate along the guide screw 42. The direction of translation of the first bracket portion 46a depends on the direction of rotation of the rotor 62, and can be in the direction of arrow 18 or in the opposite direction. The translation of the first bracket portion 46a causes the translation of the second bracket portion 46b, which in turn causes the bobbins 22 and 32 to translate. As the bobbins 22 and 32 translate, the pinions 25 and 45 engage with the rack, causing the pinions 25 and 45 to rotate. The rotation of each pinion 25, 45 causes the corresponding shaft 23, 33 to rotate, which in turn causes the corresponding bobbin 22, 32 to rotate. In this way, the rotation of the rotor 62 of the motor 56 causes both translational and rotational motions of the first bobbin 22 and the second bobbin 32. The direction of rotation of each bobbin 22, 32 depends on the direction of rotation of the rotor 62. The angle of rotation of each bobbin 22, 32 depends on the angular displacement of the rotor 62.

[0077] Figures 6a to 6c This illustrates how the bobbins 22 and 32 translate and rotate to control the fluid flow in the tube 10. Figures 6a to 6cOnly the second bobbin 32 is shown, but it will be understood that the translational and rotational movements of the first bobbin 22 will be similar to those of the second bobbin 32. More specifically, the translational movement of the first bobbin 22 will be the same as that of the second bobbin 32, such as... Figures 6a to 6c As shown. The first tube 22 will be in Figures 6a to 6c At each of the shown bobbin positions, the first bobbin 22 rotates by the same angle as the second bobbin 32, but the direction of rotation of the first bobbin 22 will be opposite to the direction of rotation of the second bobbin 32.

[0078] exist Figure 6a In the middle, the first tube 22 and the second tube 32 are in a fully open configuration, corresponding to Figure 5a The spools 22 and 32 do not translate relative to the frame 40 or the tube 10. In this configuration, the spools 22 and 32 do not deform the tube 10 and do not restrict the flow of fluid through the tube 10.

[0079] exist Figure 6b In this configuration, the first tube 22 and the second tube 32 have been rotated approximately 45° in opposite directions about their respective axes 22 and 38. The first tube 22 and the second tube 32 are in a partially blocked configuration, corresponding to... Figure 5b .and Figure 6a In contrast, the tubes 22 and 32 have also been translated relative to the frame 40 and the tube 10 by an amount proportional to their rotation angle. The direction of this translation is indicated by arrow 18.

[0080] exist Figure 6c In this configuration, the first tube 22 and the second tube 32 have been rotated approximately 180° in opposite directions about their respective axes 22 and 38. The first tube 22 and the second tube 32 are in a fully blocked configuration, corresponding to... Figure 5c The 22 and 32 tubes are already... Figure 6b The translation is shown to be further. In some embodiments, when in the fully blocked position, the tubes 22, 32 may have already translated along the entire length of the guide screw 42, resulting in further translation in the direction of arrow 18 (intentionally from...). Figure 6c (omitted) is impossible. In this configuration, the deformation of tube 10 caused by bobbins 22 and 32 is the largest. The fluid flow through tube 10 is blocked, or at least reduced to a negligible level.

[0081] exist Figure 6b and Figure 6cAt the locations shown, the clamping amount of the grooves 24 and 34 on the tube 10 can be quite considerable. Without translational movement of the bobbins 22 and 32 relative to the tube 10, the simultaneous clamping and rotation could pull the tube 10 along its length, potentially risking pulling it from other connected devices. Translation of the bobbins 22 and 32 eliminates (or at least reduces) the tendency of the bobbins 22 and 32 to pull the tube 10. Instead of pulling the tube 10 relative to a fixed bobbin, the bobbins 22 and 32 roll along the tube 10, gradually restricting fluid flow.

[0082] Now will refer to Figure 7 To describe the control system of device 30. For example... Figure 7 As shown, in addition to the bobbins 22 and 32, motor 56, and encoder 64 described above, device 30 also includes a controller 66. Device 30 may also optionally include a user input device 68 and / or a flow sensor 70.

[0083] exist Figure 8 The controller 66 is shown in more detail below. The controller 66 includes a processor 202 and a memory 204. The processor 202 can be any suitable type of data processing device, such as a microprocessor, microcontroller, or application-specific integrated circuit (ASIC). The processor 202 is communicatively coupled to the memory 204. The memory 204 can include volatile memory, non-volatile memory, or both. The memory 204 stores a control program 206. The control program 206 includes processor-executable instructions that, when executed by the processor 202, cause the controller 66 to perform the following described in reference. Figure 9 , Figure 10 ,as well as Figure 11 Any or all of the methods described.

[0084] Return to Figure 7 The controller 66 is communicatively connected to the motor 56 and the encoder 64. For example, the controller 66 can be connected to the motor 56 and the encoder 64 via one or more conductive wires, which can be in the form of a bus. The controller 66 is configured to output a motor control signal 67 to the motor 56. As discussed above, the motor control signal 67 causes the rotor 62 of the motor 56 to rotate. The controller 66 is also configured to receive a measurement signal 65 from the encoder 64. As discussed above, the measurement signal 65 indicates the angular displacement of the rotor 62. Therefore, the rotation of the rotor 62 caused by the motor control signal 67 is measured by the encoder 64, which in turn provides the measurement signal 65 to the controller 66. This forms a closed control loop.

[0085] Thanks to the mechanical connection between the rotor 62 of the motor 56 and the bobbins 22, 32, any movement of the rotor 62 and / or the bobbins 22, 32 can be detected as a change in angular displacement measured by the encoder 64. More specifically, the mechanical connection between the rotor 62, the guide screw 42, the bracket 46, the shafts 23, 32, the pinions 25, 45, the rack, and the bobbins 22, 32 allows little or no mechanical slippage, such that the angular displacement measured by the encoder 64 always provides an accurate indication of the current position of the bobbins 22, 32.

[0086] In one example implementation, encoder 64 is an incremental encoder. In this implementation, encoder 64 measures the occurrence and direction of rotor rotation, but does not measure the absolute angular displacement of rotor 62. In this implementation, the measurement signal output by encoder 64 is a pair of orthogonally coded pulse trains. Each pulse indicates that rotor 62 has rotated through a specific angle determined by the angular resolution of encoder 64. The phase relationship between the two pulse trains indicates whether rotor 62 has rotated in a clockwise or counterclockwise direction. The measurement signal output by the incremental encoder itself does not provide sufficient information to determine the absolute position of bobbins 22, 32. To allow determination of the absolute position of bobbins 22, 32, one or more additional position sensors are used in addition to the incremental encoder. One or more additional position sensors can be configured to detect the position of bracket 46. In one example, the one or more additional position sensors include a pair of Hall effect sensors, wherein one Hall effect sensor is mounted to frame 40 near each of the two movement limits of bracket 46. A permanent magnet can be mounted on bracket 46. When bracket 46 is at a movement limit (e.g., at...), Figures 1 to 4 When the permanent magnet is at the position shown, the first Hall effect sensor in the Hall effect sensor outputs a signal. When the bracket 46 is at another movement limit (e.g., towards...), the permanent magnet causes the first Hall effect sensor in the Hall effect sensor to output a signal. Figure 3 and Figure 4When the permanent magnet is positioned at the left side of the bracket 46, it causes another Hall effect sensor in the Hall effect sensor array to output a signal. This Hall effect sensor can be a digital sensor, such that neither sensor outputs a signal when the bracket 46 is in a mid-position between the two movement limits. To determine the position of the bracket 46, the bracket 46 is moved (by operating the motor 56) until one of the Hall effect sensors outputs a signal; this indicates that the bracket 46 is positioned at one of its movement limits. Starting from this known position of the bracket 46, the processor 202 counts the pulses output by the encoder 64 each time the operation of the motor 56 causes a subsequent movement of the bracket 46. The position of the bracket 46 can be derived from the number of counted pulses, and the positions of the bobbins 22 and 32 can be calculated from the position of the bracket 46 thus derived. Other suitable position sensors (e.g., microswitches) can be used instead of the Hall effect sensors to detect the position of the bracket 46. In one example, the incremental encoder has a resolution of 1000 pulses per revolution, which allows the bracket 46 to be positioned with an accuracy of 0.5 micrometers.

[0087] In an alternative embodiment, encoder 64 is an absolute encoder. In this embodiment, encoder 64 measures the absolute angular displacement of rotor 62. In this embodiment, the measurement signal output by encoder 64 is a binary word indicating the absolute angular displacement of rotor 62. The absolute encoder may be a single-turn encoder, wherein the measurement signal indicates an angular displacement between 0° and 360°. Alternatively, the absolute encoder may be a multi-turn encoder, wherein the measurement signal indicates an angular displacement between 0° and an upper limit greater than 360°. The measurement signal output by the absolute encoder is directly related to the absolute position of bobbins 22, 32. The positions of bobbins 22, 32 can be calculated based on the most recent measurement signal from the absolute encoder.

[0088] A motor driver (not shown) may optionally be inserted between the controller 66 and the motor 56. The motor driver is configured to convert the motor control signal 67 output by the controller 66 into a signal that meets the current, voltage, and / or timing requirements necessary for the proper operation of the motor 56.

[0089] User input device 68 can be any suitable device configured to receive one or more inputs 69 from a user and transmit these inputs 69 to controller 66. For example, user input device 68 may include a keyboard, typing pad, touchscreen display, or one or more discrete buttons. Inputs 69 received via user input device 68 may include, but are not limited to: inputs indicating desired flow through pipe 10; inputs indicating desired blockage (rate) of pipe 10; and inputs for preventing device 30 from exiting a second operating mode (such as...). Figure 10 (As shown) Switch to the first operating mode (such as) Figure 9The inputs are: a forced input (shown); an input indicating a command to stop fluid flow through pipe 10; an input indicating a command to detach the bobbins 22 and 32 from the flexible pipe 32; and / or an input indicating a command to resume fluid flow through the flexible pipe 10.

[0090] The flow sensor 70 can be any suitable component configured to measure the flow rate of the fluid in the pipe 10 and output a flow signal 71 indicating the measured flow rate to the controller 66. The flow sensor 70 can be a non-invasive flow sensor, fitting onto the outer surface of the pipe 10 but not in contact with the fluid inside the pipe. For example, the flow sensor 70 can be an ultrasonic sensor.

[0091] exist Figure 9 The diagram illustrates a first example of a method 900 for controlling fluid flow in a flexible tube using device 30. Method 900 is executed by processor 202 of controller 66. For ease of reference, Figure 9 Method 900 is referred to as the first operating mode of device 30.

[0092] Method 900 begins at operation 902, where a target angular displacement of rotor 62 is determined. This target angular displacement is the desired angular displacement of the rotor and can be selected to achieve a specific function (e.g., a specific flow rate through pipe 10). The target angular displacement of rotor 62 can be determined in a variety of ways.

[0093] In a first example implementation of operation 902, the user provides user input indicating the desired flow rate via user input device 68. For example, the user may specify a desired flow rate of one liter per minute. Processor 202 then determines the target flow rate of rotor 62 that will result in the user-specified blockage (rate). The processor may determine the target angular displacement based on the desired flow rate and a known relationship between the flow rate in pipe 10 and the angular displacement of rotor 62. This known relationship may be stored in a "lookup table" in memory 204. Alternatively or additionally, the known relationship between flow rate and angular displacement may be in the form of a parametric model. In this case, processor 202 calculates the target angular displacement based on the user-specified desired flow rate and any other values ​​of the model parameters. The values ​​of the model parameters may be input by the user via user input device 68, and / or the values ​​of the model parameters may be stored in memory 204.

[0094] In a second example implementation of operation 902, the user provides user input indicating desired blocking via user input device 68. Hereinafter, the terms "blocking" and "blocking rate" are used to describe numerical values ​​representing points on a continuous interval between the fully open and fully blocked configurations of device 30. Blocking (rate) can be expressed as a percentage. For example, the user can specify a 50% desired blocking rate, which corresponds to... Figure 5a and Figure 6a The fully open configuration shown is Figure 5c and Figure 6c The processor 202 then determines the target angular displacement of rotor 62 that will result in a user-specified blocking rate. The processor can determine the target angular displacement based on the desired blocking rate and a known relationship between blocking and the angular displacement of rotor 62. This known relationship can be stored in a lookup table in memory 204. Alternatively or additionally, the known relationship between flow rate and angular displacement can be in the form of a parametric model. In this case, the processor 202 calculates the target angular displacement based on the user-specified desired blocking and any other values ​​of the model parameters. The values ​​of the model parameters can be input by the user via user input device 68, and / or the values ​​of the model parameters can be stored in memory 204.

[0095] The result of operation 902 is the target angular displacement of rotor 62, which represents the angle by which rotor 62 will perform a specific function relative to any reference. For example, the target angular displacement can be determined as 30° clockwise relative to any reference.

[0096] Method 900 continues at operation 904, where a measurement signal 65 is received from encoder 64. Measurement signal 65 indicates the current angular displacement of rotor 62. Continuing with the previous example, the measurement signal could indicate that rotor 62 is currently oriented 60° clockwise relative to any reference.

[0097] Then, method 900 proceeds to operation 906, where processor 202 outputs a motor control signal 67 to set the angular displacement of rotor 62, measured by encoder 64, to a target angular displacement. Operation 906 may include: the processor determining the motor control signal 67 required to rotate rotor 62 from its current angular displacement measured by encoder 64 to the target angular displacement. Continuing with the previous example, where the target angular displacement is determined to be 30° clockwise relative to an arbitrary reference, and rotor 62 is currently oriented 60° clockwise relative to the same arbitrary reference, processor 202 determines that the rotor needs to be rotated 30° counterclockwise. In a simplified example where motor 56 is a stepper motor with an angular resolution of 1°, processor 202 may then determine that the motor control signal 67 should consist of 30 pulses to rotate rotor 62 from its current angular displacement to the target angular displacement. Processor 202 then outputs the motor control signal 67 thus determined.

[0098] Then, as indicated by arrow 908, method 900 optionally returns to operation 904, where another measurement signal 65 is received from encoder 64. Processor 202 can then compare the actual angular displacement of rotor 62 with the target angular displacement, which is the actual angular displacement measured by encoder 64 after the motor control signal was output at operation 906. If there is an error in the angular displacement of rotor 62 (i.e., the actual angular displacement is not equal to the target angular displacement, or is not within a specific tolerance of the target angular displacement), the method returns to operation 906 and outputs another motor control signal 67 to correct the error. Errors in the angular displacement of rotor 62 can have many possible causes. One possible cause is motor slippage, which may cause rotor 62 to fail to reach the target angular displacement. Another possible cause is unintentional movement of bobbins 22, 32, which could occur if a clinician unintentionally pulls on tube 10. Encoder 64 allows the detection and correction of such errors, and thus provides accurate control of the flow through tube 10.

[0099] At any point during the execution of method 900, processor 202 may receive an instruction requiring it to determine a new target angular displacement of rotor 62. For example, a user may provide user input indicating a new desired flow rate or a new desired blockage via user input device 68. In this case, the method returns to operation 902 and iterates again.

[0100] In some cases, processor 202 may receive instructions to stop fluid flow through pipe 10 or to disconnect fluid from pipe 10 while executing method 900. In these cases, the method returns to operation 902, whereby processor 202 determines a new target angular displacement of rotor 62 that places the device in a fully blocked configuration (e.g., ...). Figure 5c and Figure 6c(as shown) or fully open configuration (such as) Figure 5a and Figure 6a (As shown). Processor 202 may subsequently receive an instruction to restore fluid flow through pipe 10. The method returns to operation 902, whereby processor 202 determines a new target angular displacement of rotor 62, and thus sets the angular displacement back to its target angular displacement before receiving an instruction to stop fluid flow or to detach it from pipe 10.

[0101] exist Figure 10 A second example of a method 1000 for controlling fluid flow in a flexible tube using device 30 is shown. Method 1000 is executed by processor 202 of controller 66. For ease of reference, Figure 10 Method 1000 is referred to as the second operating mode of device 30.

[0102] Method 1000 begins at operation 1002, where a target flow rate of fluid in tube 10 is determined. This target flow rate can be selected to achieve a specific clinical outcome. For example, a user can provide user input indicating the target flow rate via user input device 68.

[0103] Method 1000 continues at operation 1004, where a flow signal 71 is received from flow sensor 70. This flow signal 71 indicates the fluid flow rate through pipe 10.

[0104] Then, method 1000 proceeds to operation 1006, where processor 202 outputs a motor control signal 67 to set the flow rate measured by flow sensor 70 as the target flow rate. For example, if the flow rate measured by flow sensor 70 is less than the target flow rate, processor 202 may output a motor control signal 67 to move the bobbins 22, 32 toward a fully open configuration. Conversely, if the flow rate measured by flow sensor 70 is greater than the target flow rate, processor 202 may output a motor control signal 67 to move the bobbins 22, 32 toward a fully closed configuration. Processor 202 uses feedback from flow sensor 70 (typically as indicated by arrow 1008) to maintain the flow rate measured by flow sensor 70 at the target flow rate.

[0105] exist Figure 11 The diagram illustrates a third example of a method 1100 for controlling fluid flow in a flexible tube using device 30. Method 1100 is executed by processor 202 of controller 66. Figure 11 Method 1100 combines the first and second operating modes of device 30.

[0106] Method 1100 may begin at operation 1102, wherein processor 202 causes device 30 to operate in a first operating mode. That is, at operation 1102, processor 202 performs some or all of the operations of method 900. When operating in the first operating mode, processor 202 may receive instructions to operate according to a second operating mode. For example, a user provides input via user input device 68 to guide device 30 to operate according to the second operating mode. In response to receiving instructions to operate in the second operating mode, the method proceeds to operation 1104. Method 1100 does not need to begin at operation 1102, but may begin at operation 1104.

[0107] At operation 1104, processor 202 causes device 30 to operate in a second operating mode. That is, at operation 1104, processor 202 performs some or all of the operations of method 1000.

[0108] At operation 1106, processor 202 detects a malfunction of flow sensor 70 when operating in the second operating mode. For example, processor 202 may detect the absence of a signal from flow sensor 70, which could occur if flow sensor 70 is accidentally disconnected by the user. As another example, processor 202 may detect abnormal measurement signals from flow sensor 70, such as unexpectedly high or low flow measurements, or rapidly changing flow measurements.

[0109] In response to the detection of a malfunction in flow sensor 70, processor 202 determines (at operation 1108) whether a forced input has been received. This forced input is the input that instructs processor 202 not to switch to a first operating mode when a malfunction in flow sensor 70 is detected. The forced input can be provided by a user via user input device 68. Control program 206 may have default values ​​stored therein that, in the absence of user input via user input device 68, treat the forced input as either received or not received.

[0110] If no forced input is received, processor 202 causes device 30 to operate in the first operating mode. That is, processor 202 returns to operation 1102, and thus performs some or all of the operations of method 900. On the other hand, if a forced input has been received, device 30 continues to operate in the second operating mode. That is, processor 202 returns to operation 1104, and thus performs some or all of the operations of method 1000. When device 30 is operating in the second operating mode, the forced input can be received at any time; therefore, if a fault in flow sensor 70 is still detected during a subsequent iteration of operation 1106, processor 202 can switch device 30 back to the first operating mode. Conversely, when device 30 is operating in the first operating mode, the forced input can be canceled at any time; therefore, when the fault in flow sensor 70 has been resolved, processor 202 can switch device 30 back to the second operating mode.

[0111] Device 30 can be advantageously integrated into a cardiac perfusion system to control the flow rate of various fluids. Cardiac perfusion is a medical procedure involving the extracorporeal oxygenation of a patient's blood. For example, cardiac perfusion is performed when (e.g., during cardiac and / or lung surgery) a patient is unable to oxygenate their own blood through breathing. Examples of cardiac perfusion systems in which device 30 can be used include venous reservoirs, one or more pumps, and an oxygen generator. In use, the cardiac perfusion system receives deoxygenated blood from the patient via a venous line and stores the deoxygenated blood in the venous reservoir. The pumps drive the deoxygenated blood from the venous reservoir through the oxygen generator. As the blood passes through the oxygen generator, gases dissolved in the blood (e.g., carbon dioxide) are exchanged with other gases (e.g., oxygen) to convert the deoxygenated blood into oxygenated blood. The pump (or another pump) returns the oxygenated blood to the patient via an arterial line. The cardiac perfusion system 100 may optionally include any or all of the following: a cardiac arrest device that stops the patient's heart; a heater-cooler device that regulates the temperature of the blood; and a gas mixer that mixes the gas supplied to the oxygen generator. The device 30 disclosed herein may be positioned on any or all blood lines (e.g., venous lines and / or arterial lines) to control blood flow. Alternatively or additionally, the device 30 disclosed herein may be positioned on a cardiac arrest line to control the delivery of a cardiac arrest agent.

[0112] It will be understood that the invention has been described above by way of example only, and modifications to the details are possible within the scope of the claims. In particular, Figure 9 , Figure 10 ,as well as Figure 11The sequence of operations shown is merely exemplary. Any of the operations shown in methods 900, 1000, and 1100 can be performed in different sequences to achieve substantially the same result. The rotor 62 of motor 56 and... Figure 1 The mechanical connection between the tubes 22 and 32 shown in Figure 6 is intended as an example only, and other suitable mechanical connection arrangements can be used. Figure 1 The wheels of the bobbins 22 and 32 shown in Figure 6 are intended only as examples, and different results can be achieved using bobbins 22 and 32 with different shapes (e.g., to provide different relationships between the rotation angle of the bobbins 22 and 32 and the final blockage (rate) of the tube 10).

Claims

1. A device for controlling the flow rate of fluid in a flexible tube, the device comprising: Two rotatable tubes, each tube including a tube engagement surface portion, wherein the tube engagement surface portion defines a boundary of a free space between the tubes through which the tubes can extend, and wherein at least one tube engagement surface portion has a shape that varies around at least a portion of the periphery of the tube such that axial rotation of the tube reduces the free space by an amount depending on the rotation of the tube. A motor, the motor including a rotor, the rotor being mechanically coupled to the bobbin, such that operation of the motor causes rotation of the bobbin; An encoder, mechanically coupled to the rotor and configured to measure the angular displacement of the rotor; and Processor, the processor being configured to: Determine the target angular displacement of the rotor. Receive a measurement signal from the encoder, the measurement signal indicating the angular displacement of the rotor, and Output motor control signals to set the angular displacement of the rotor measured by the encoder as the target angular displacement.

2. The apparatus according to claim 1, wherein, The processor is also configured to: After the angular displacement of the rotor measured by the encoder has been set to the target angular displacement, a second measurement signal from the encoder is received; Based on the second measurement signal, it is identified that the angular displacement of the rotor has drifted from the target angular displacement; as well as A second motor control signal is output to reset the angular displacement of the rotor measured by the encoder to the target angular displacement.

3. The apparatus according to claim 1 or 2, wherein, The processor is also configured to: Receive input indicating the desired flow rate; and The target angular displacement is determined based on the desired flow rate and the known relationship between the flow rate in the flexible tube and the angular displacement of the rotor.

4. The apparatus according to any one of the preceding claims, wherein, The processor is also configured to: Receive an input indicating the desired blockage of the flexible tube; and The target angular displacement is determined based on the known relationship between the desired blockage, the blockage of the flexible tube, and the angular displacement of the rotor.

5. The apparatus according to any one of the preceding claims, wherein, The device has a second operating mode, wherein the processor is configured to: Determine the target flow rate of the fluid in the flexible tube; Receive a flow signal from a flow sensor, the flow signal indicating the flow rate of fluid in the flexible tube as measured by the flow sensor; and A third motor control signal is output to rotate the bobbin, thereby setting the flow rate measured by the flow sensor as the target flow rate.

6. The apparatus according to claim 5, wherein, The processor is also configured to: When the device is in the second operating mode, a fault in the flow sensor is detected; as well as In response to the detection of a fault in the flow sensor, the device operates in a first operating mode, in which the processor determines the target angular displacement of the rotor, receives the measurement signal from the encoder, and outputs the motor control signal to set the angular displacement of the rotor measured by the encoder as the target angular displacement.

7. The apparatus according to claim 6, wherein, The processor is also configured to determine the target angular displacement based on the target flow rate and a known relationship between the flow rate in the flexible tube and the angular displacement of the rotor, so that the device operates in the first operating mode.

8. The apparatus according to claim 6 or 7, wherein, The processor is also configured to: Receive forced input; and In response to the forced input, when a fault of the flow sensor has been detected, the device is made to operate in the second operating mode.

9. The apparatus according to any one of the preceding claims, wherein, The processor is also configured to: Receive a command to stop the fluid from flowing through the flexible tube; and In response to the command to stop the fluid from flowing through the flexible tube, a fourth motor control signal is output to set the angular displacement of the rotor measured by the encoder as a second target angular displacement, wherein the second target angular displacement corresponds to a fully blocked configuration of the device, in which the tube maximally restricts the flow of fluid through the flexible tube.

10. The apparatus according to any one of the preceding claims, wherein, The processor is also configured to: Receive a command to detach from the flexible tube; and In response to the command to detach from the flexible tube, a fifth motor control signal is output to set the angular displacement of the rotor measured by the encoder as a third target angular displacement, wherein the third target angular displacement corresponds to the fully open configuration of the device, in which the tube does not restrict the flow of fluid through the flexible tube.

11. The apparatus according to claim 9 or 10, wherein, The processor is also configured to: Receives an instruction to restore fluid flow through the flexible tube; and In response to the instruction to restore fluid flow in the flexible tube, a sixth motor control signal is output to set the angular displacement of the rotor measured by the encoder as the target angular displacement.

12. A cardiac perfusion system comprising means for controlling the flow rate of fluid in a flexible tube according to any one of the preceding claims.

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