Peristaltic pump, control device therefor, injection device and method of controlling a peristaltic pump

Abstract

The present invention particularly relates to a control device (8) for a peristaltic pump (5) delivering a medium in a pulsating pressure cycle, the control device (8) controlling the speed of the peristaltic pump (5) in such a way as to not exceed the pressure limit (p) in the delivery line (9). Grenz Achieving maximum volumetric flow rate (Q) under these conditions max One task is to guide the actual pressure in the output line (9) as close as possible to the pressure limit (p). Grenz Or minimize the distance to it. To solve this problem, a method based at least on the pressure (p) in the output line (9) is proposed. ist To calculate the predicted pressure (p) for each pressure cycle (P) within the expected maximum pressure of the pressure cycle (P). futur And by using this predicted pressure, the maximum volumetric flow rate (Q) is limited. max This causes the pressure (p) in the output pipeline (9) to increase. ist ) does not exceed the pressure limit (p) in the pressure cycle (P) Grenz This invention also relates to related aspects.

Description

Technical Field

[0001] The present invention relates to a control device for a peristaltic pump according to the preamble of claim 1, a peristaltic pump having such a control device, an injection device having such a peristaltic pump, and a method for controlling a peristaltic pump. Background Technology

[0002] An injection device is a medical device by which a liquid injectable (medium) can be introduced into a human or animal in a controlled manner via a pumping device. The injection medium can be, for example, a contrast agent used to increase contrast in imaging procedures such as computed tomography or magnetic resonance imaging. In addition to controlling the injection volume and the flow rate (volume-flow rate) of the injectable, the pressure in the discharge line must be monitored, as excessive pressure can be harmful to the body and / or damage the injection device. For this purpose, known injection devices are equipped with controls or regulators that shut down the injection device or its pumping device when a pressure limit (maximum set pressure) below a defined danger pressure is exceeded. Especially in cases of cyclic oscillating pressure profiles, such as those found in axial piston pumps or roller pumps, a pressure maximum may occur that is only briefly and slightly above the pressure limit, thus causing an unnecessary shutdown of the pumping device and termination of the injection process. This prolongs the injection process and unnecessarily increases the total injection volume of the injectable.

[0003] To avoid premature termination of the injection process, US 6673033 B1 proposes defining an intermediate pressure threshold above which the output of the pumping device is initially throttled, and the pumping device is shut off only if the pressure in the syringe tubing subsequently rises above the pressure limit, regardless of the throttled output.

[0004] Similarly, as known from DE 102013113387 A1, instead of the hard pressure limit value as the standard for stopping the injection process in a peristaltic pump, the time integral of the pressure curve exceeding the pressure limit value is used as the standard for stopping the injection process, such that short-term pressure peaks can be tolerated and that only brief exceedances of the pressure limit value do not lead to immediate cessation of the injection process.

[0005] A drawback of existing control methods for injection devices is that a large safety interval must be observed, i.e., the pressure limit must be significantly lower than the danger pressure, so that there is sufficient reaction time to adjust or shut down the pump device if the pressure limit is exceeded.

[0006] Against this background, the object of the present invention is to describe in detail an improved control device for a peristaltic pump with an oscillating pressure curve (pressure pulsation), a peristaltic pump having such a control device, an injection device having such a peristaltic pump, and a control method, wherein the safety interval can be reduced and the predetermined pressure limit can be brought closer to the danger pressure without increasing the risk of damage to the patient and / or the materials of the injection device. Meanwhile, the pressure pulsation needs to be reduced. Summary of the Invention

[0007] This objective is achieved in particular by the control device of claim 1, the peristaltic pump of claim 14, the injection device of claim 16, and the control method of claim 17.

[0008] The control device according to the invention is used to control a peristaltic pump having a squeezing tube and a cyclically moving conveying element for conveying a medium guided in the squeezing tube to a discharge line connected to the squeezing tube at a controlled volumetric flow rate during conveying operations. In doing so, the conveying element cyclically compresses the squeezing tube, thereby establishing pressure in the output line using a pressure curve with cyclically repeating pressure cycles. Each pressure cycle can be defined such that it extends, for example, from a pressure minimum via a pressure increase to a pressure maximum and then decreases again to the pressure minimum of the subsequent pressure cycle. The control device according to the invention controls the speed of the peristaltic pump (in the case of a roller pump, this may be the angular velocity of the conveying element) in a way that achieves a maximum volumetric flow rate without exceeding a pressure limit in the discharge line. This pressure limit can be a desired, still permissible, set pressure. For this purpose, the control device has at least a first control loop for controlling the maximum volumetric flow rate. This receives a setpoint volumetric flow rate and a pressure limit as externally specified command variables. The control device is configured to execute a control method in which a predicted pressure for the expected maximum pressure within the pressure cycle is calculated for each pressure cycle based at least on the pressure in the discharge line, and the maximum volumetric flow rate is limited in a manner that the pressure in the discharge line does not exceed the pressure limit in the pressure cycle.

[0009] Advantageously, the first control loop detects the current pressure in the discharge line as a feedback variable, and based on this feedback variable, the control part of the control loop adjusts the maximum volumetric flow rate in a predictive manner.

[0010] Through predictive control, the speed of the peristaltic pump (specifically, the delivery element of the peristaltic pump) can be proactively adjusted and reduced at an early stage if pressure limits are about to be exceeded. As the reaction time is extended through pressure prediction, the safety margin increases. The still permissible pressure limit can then be brought closer to critical pressure values ​​(such as hazardous pressures), which in turn means higher volumetric flow rates and, therefore, shorter injection durations for a given injection volume, for example. Furthermore, as the importance of rapid response mechanisms becomes less critical to predictive control, more inert components can be used in the peristaltic pump, making its production cheaper. Calibration of this control method is not necessary if the control device is properly designed.

[0011] In a preferred embodiment of the invention, the first control loop includes pressure phase detection, which detects the end of a previous pressure cycle and the beginning of a subsequent pressure cycle. Detection can be based on characteristic variables of the pressure profile in the output line, specifically a pressure drop defined compared to the maximum pressure of the previous pressure cycle. For example, the start of a pressure cycle can be defined as the point in time at which a pressure drop compared to the maximum (absolute) pressure of the previous pressure cycle exceeds a specific relative amount (e.g., at least 1 / 6, 1 / 4, or 1 / 3) or an absolute amount (independent of the previous maximum pressure). At least 2 bar. The pressure drop is advantageously chosen to be so large that it occurs only once towards the end of the pressure cycle. The occurrence of this pressure drop is then robust enough to indicate the start of a subsequent pressure cycle. If the typical pressure cycle has large pressure fluctuations, a larger pressure drop and / or an incremental counter counting a specific minimum amount of the pressure drop can be used instead to identify the start of a subsequent pressure cycle.

[0012] At the start of each pressure cycle, control of the maximum volumetric flow rate is restarted, and the values ​​of the temporary storage are updated specifically, such as the maximum pressure value of the temporary storage from the previous pressure cycle.

[0013] A further improvement to this control device advantageously involves dividing each pressure cycle into multiple consecutive pressure stages based on predefined characteristics, and identifying the start of these individual pressure stages. Thus, the predicted pressure used to control the maximum volumetric flow rate in the first control loop is used only in specific pressure stages and is ignored or not used in other pressure stages. Therefore, the control is discontinuous.

[0014] The advantage of this pressure stage-dependent control is that pressure prediction can be precisely applied to pressure stages where pressure development in the output line is dynamic and pressure limits can be exceeded relatively suddenly. This allows for conservative control of the maximum volumetric flow rate during these pressure stages, while it can be more aggressively controlled during other pressure stages where sudden pressure limits are not expected. Another advantage is the ability to implement different controls for different pressure stages, for example, by connecting or disconnecting additional control loops superimposed on the first control loop and / or by changing the control parameters of the first control loop (such as the amplification factor or similar parameters used therein).

[0015] The predefined characteristics mentioned above can be the absolute or relative pressure change and / or the absolute or relative rate of pressure change in the output pipeline. The predefined characteristics are not necessarily time-definite values. For example, a moving average over a specific time period (such as 0.1, 0.2, or 0.5 seconds) can be selected.

[0016] Individual pressure stage identification via pressure stage identification can be based on predefined features. Alternatively, individual pressure stages can also be identified by pressure stage identification based on the position of the peristaltic pump's delivery element, as the position of the delivery element is related to individual pressure stages, as explained in more detail below. It is also possible to combine detection based on predefined features with the determination of these delivery element positions for pressure stage detection, while making the detection of individual pressure stages redundant, or to predetermine individual pressure stages based on defined features and other pressure stages based on the position of the delivery element. Preferably, pressure stage detection is redundantly designed to increase reliability. This reduces sensitivity to errors, and specifically reduces the failure safety requirements for individual components and thus reduces component costs.

[0017] In one embodiment of the invention, the pressure cycle is characterized by five consecutive pressure phases, wherein the first pressure phase is characterized by a rapid pressure drop, the second pressure phase by a rapid pressure rise, the third pressure phase by a slight pressure rise, the fourth pressure phase by a moderate pressure rise, and the fifth pressure phase by a pressure plateau with substantially constant pressure, and each pressure phase is detected by pressure phase detection. This division of the pressure cycle is a good approximation of the pressure cycle in an injection device for intravenous injection (e.g., contrast agents). Static and dynamic pressure resistances in the discharge line (and the lines connected thereto) are responsible for the individual pressure phases, which are specifically caused by the opening and closing of check valves, throttle valves, the mass inertia of the medium to be delivered, and other effects. For other applications, the pressure phases may also be defined differently from the examples above.

[0018] Preferably, the predicted pressure is used only in the fourth pressure phase to control the maximum volumetric flow rate in the first control loop, i.e., the pressure phase before the pressure plateau, where the (absolute) pressure within the pressure cycle is maximum. The fourth pressure phase is advantageously defined as extending from approximately 50% to approximately 80% of the phase progression of the pressure cycle. Phase progression means the pressure cycle in time resolution, i.e., the pressure cycle begins at 0% of the phase progression—for example, this corresponds to the pressure minimum—and ends at 100%—which then corresponds to the pressure minimum of the following pressure cycles. Because the predicted pressure is "switched on" to the first control loop to calculate the maximum volumetric flow rate in the fourth pressure phase, and otherwise "switched off," it is a discontinuous controller. By limiting the use of the predicted pressure in this way, the complex calculations of predicting the pressure in other pressure phases are eliminated.

[0019] In a simple and therefore preferred variation, the predicted pressure can be determined by linearly extrapolating the current pressure in the output line to a specific (calculated) stage of the process, preferably within the range of 80% to 95% of the total stage process, and may be, for example, 80%, 90%, or 95% of the total stage process, specifically 87% of the total stage process. When the predicted pressure is used only in the fourth pressure stage, the accuracy of the linear extrapolation is sufficiently high, even in the case of a strongly oscillating pressure process during pressure cycling. Other calculation methods for determining the predicted pressure are also possible, specifically time-series-based extrapolation.

[0020] The specific (calculated) phase sequence used to determine the predicted pressure is appropriately fixed and is, for example, a constant representing 87% of the total phase sequence. This specific phase sequence may (but must) correspond to the actual phase sequence, where the actual pressure maximum occurs within these pressure cycles. Thus, in this example, the actual pressure maximum may occur at an actual phase sequence located before or after a specific (calculated) phase sequence representing 87% of the total phase sequence.

[0021] Preferably, the determined stage sequence is selected and adjusted by calculation in a manner that achieves a predicted pressure that reflects the actual pressure maximum value as accurately as possible from the continuous pressure cycle. The determined (calculated) stage sequence to which the predicted pressure is extrapolated can be moved to the actual stage sequence where the actual pressure maximum value occurs, if this results in a better predicted pressure.

[0022] In a more specific application of the invention, the control device controls a roller pump. Roller pumps have the advantage of not undergoing directional changes, which is why they are particularly suitable for precise dosing of injection doses in injection devices. Because the pumped medium is conveyed in a squeezing tube within the roller pump, there is no direct contact between the pumped medium and the pump, which is advantageous for hygiene reasons. Furthermore, the squeezing tube can be easily replaced.

[0023] Therefore, another object of the present invention is to provide a roller pump having a rotatable rotor and a plurality of conveying elements for extruding a tube, the conveying elements being in the form of rollers (extrusion rollers) arranged on the rotor, wherein the extrusion tube is supported along a tube bed having an inlet region and an outlet region, and wherein, as the rotor rotates, when the conveying elements enter the tube bed at the level of the inlet region, each conveying element compresses a section of the extrusion tube in a fluid-tight manner until the conveying elements leave the tube bed at the level of the outlet region, and thereby the medium in the extrusion tube is conveyed in the direction of rotation to the discharge line against the dynamic pressure generated in the discharge line connected to the extrusion tube, wherein the roller pump includes a control device according to the invention.

[0024] In each case, the volume of the extrusion tube upstream of the outlet region is compressed from its maximum volume to its minimum volume until the conveying element emerges from the tube bed at the horizontal plane of the outlet region, releasing the section of the extrusion tube compressed by this conveying element, and thus increasing the volume of the extrusion tube upstream of the outlet region from its minimum volume to its maximum volume. The volume reduction and volume increase upstream of the outlet region constitute a complete pressure cycle.

[0025] The roller pump also has n delivery elements, preferably radially and evenly distributed, such that the roller pump performs n pump strokes in n pressure cycles during a full 360° rotation of the rotor. The number of roller elements is, for example, three.

[0026] Since each delivery element is involved in the pressure cycle only within a certain angular segment—that is, within which the delivery element represents a "dominant" role relative to the outlet area or discharge line—the angular position of the delivery element within that segment is related to the stage of the pressure cycle. Therefore, the individual angular range of the delivery element's angular position within that segment is also related to the individual pressure stage of the pressure cycle.

[0027] This advantageously allows for the determination of the pressure stage based on the angular position of one of the conveying elements (specifically, the 'dominant' conveying element). Instead of error-prone pressure stage detection via unreliable, predefined characteristics, it is useful if the pressure stage detection of the control device determines the start of at least one pressure stage of the pressure cycle via the angular position of the conveying element.

[0028] To enable this in the absence of a position sensor for determining the angular position of the conveying element, the angular position can be conveniently determined indirectly, for example, by time integration of the angular velocity of the conveying element or the rotor of the roller pump. The angular velocity of the rotor is typically directly available via the control unit of the roller pump. As shown above, the absolute angular position of the dominant conveying element can be approximated to a minimum by the pressure drop.

[0029] In another embodiment of the invention, the first control loop includes an averaging filter that adjusts the maximum volumetric flow rate based on the maximum pressure of the pressure cycle immediately preceding the current pressure cycle, which is temporarily stored in the control device. This compensates for errors in pressure measurements in the output line. Furthermore, the oscillating behavior of the control loop can be attenuated by the averaging filter, and specifically, overshoot of the controlled variable can be prevented or at least reduced. For this purpose, the previously measured maximum pressure is fed back to the first control loop as the ratio of the measured maximum pressure to the pressure limit (set pressure), and a new setpoint volumetric flow rate is set based on this. Thus, the deviation between the actual maximum pressure and the pressure limit (set pressure) can be reduced in each cycle.

[0030] Advantageously, the first control loop is a PID controller with proportional, integral, and derivative elements. The PID controller enables a fast and accurate approximate estimation of the controlled variable to the command variable.

[0031] In the differential element, the predicted pressure is preferably processed to control the maximum volumetric flow rate. However, other feedback variables, such as the rate of change of the rotational speed of the peristaltic pump rotor and / or the rate of change of the volumetric flow rate, may also be considered in this differential element.

[0032] The differential element is advantageously set to 0 during a specific pressure phase. In this way, the desired control intervention can be shut off if necessary.

[0033] Furthermore, the control device may include a control system for smoothing pressure peaks in the pressure curve during pressure cycling. Advantageously, this control system is a speed adapter.

[0034] The speed adapter is preferably configured such that, in each case, at a particular stage of the pressure cycle, the set speed of the delivery element of the peristaltic pump is reduced by a specific amount to a reduced set speed before the pressure cycle is completed, and / or increased by a specific amount to a higher set point speed higher than the average set speed after the pressure cycle is completed, and held for a specific duration.

[0035] Because the pressure, and therefore the necessary delivery power, drops rapidly during the transition from one pressure cycle to the next, the power requirements of the peristaltic pump also change abruptly. To maintain a constant target volumetric flow rate, the peristaltic pump power must therefore be reduced or even reversed (braked) during the transition between pressure cycles. This is not only energy-inefficient. With the proposed control system, a brief increase in the peristaltic pump rotational speed, or a corresponding brief increase in the maximum volumetric flow rate of the delivery element, is permissible when the pressure cycle changes. By increasing the target volumetric flow rate or rotational speed at the beginning of the pressure cycle, the pressure drop can be reduced, and the required injection pressure level can be reached more quickly thereafter. By reducing the target volumetric flow rate and the rotational speed at the end of the pressure cycle, the pressure can be increased over time. This provides an additional safety margin.

[0036] The speed of the conveying element suddenly increases to its increased set speed after the pressure cycle is completed, and then linearly decreases to its decreased set speed after the holding time. In this way, peak loads can be reduced.

[0037] All holding times can be the same or different. Advantageously, the increase and decrease in the set speed should be equal in magnitude. The speed of the peristaltic pump can, for example, increase or decrease by a predetermined percentage of the average set point speed, whereby the speed change is preferably between 20% and 40% of the average set point speed, and specifically can be higher or lower than 20%, 30%, or 40% of the average set point speed.

[0038] Particularly preferred is that the control system is superimposed on the first control loop via a speed adapter. In this way, changes caused by the control system can be taken into account as command variables for modifying the setpoint speed in the first control loop. Within these considerations, the rotational speed and setpoint volumetric flow rate are considered directly proportional to each other and therefore interchangeable. As already shown, the effects of the first control loop with pressure prediction and the effects of the control system reinforce each other, allowing for a disproportionate increase in the control quality of the control device.

[0039] The peristaltic pump's delivery action regularly includes more than one, preferably more than five, and specifically more than ten pressure cycles.

[0040] In another aspect of the invention, an injection device is provided for injecting an injectable into an animal or human body via a peristaltic pump in the form of a roller pump, the injection device having a control device according to the invention for controlling the roller pump. Using an injection device with such a control device, a uniform pressure cycle with a low pressure amplitude can be achieved with the roller pump.

[0041] In another aspect of the invention, a control method for a peristaltic pump is proposed, the pump comprising a squeeze tube and a cyclically moving delivery element for delivering a medium guided in the squeeze tube to a discharge line connected to the squeeze tube at a controlled volumetric flow rate during delivery operations. The delivery element cyclically compresses the squeeze tube, establishing a pressure profile in the discharge line with cyclically repeating pressure cycles, each pressure cycle having a minimum pressure, a pressure rise, a maximum pressure, and a pressure drop. The control method controls the speed of the peristaltic pump in such a way that a maximum volumetric flow rate is achieved without exceeding a pressure limit in the discharge line. The control method includes a first control loop for controlling the maximum volumetric flow rate, the first control loop receiving a target volumetric flow rate and the pressure limit as command variables, and for each pressure cycle, calculating a predicted pressure of the expected maximum pressure within the pressure cycle based on the pressure in the discharge line. Then, taking into account the predicted pressure, the maximum volumetric flow rate is limited such that the pressure in the output line does not exceed the pressure limit in the pressure cycle. Attached Figure Description

[0042] Further features and advantageous embodiments of the invention will become clear from these dependent claims and the following description, in which the invention is illustrated by means of several exemplary embodiments and with reference to the accompanying drawings, in each case of which the control device according to the invention, the method according to the invention, and the roller pump and injection device according to the invention are equally referenced.

[0043] This shows

[0044] Figure 1 Schematic diagram of a contrast agent injection device with a roller pump.

[0045] Figure 2 Detailed diagram of a roller pump with conveying elements.

[0046] Figure 3 Graphs showing the general pressure curve of a roller pump over time, as well as the associated pressure stages and the rotation angle of the conveying element over time.

[0047] Figure 4 A typical pressure curve of a roller pump with stage detection and pressure prediction controlled according to the present invention is shown in the figure.

[0048] Figure 5 According to the circuit diagram of the control device of the present invention,

[0049] Figure 6 :have Figure 5 The control response of the control device to the pressure curve of the blocked discharge line,

[0050] Figure 7A A graph for pressure stage-related control of maximum volumetric flow rate in the control device according to the invention, and

[0051] Figure 7B : based on Figure 7A A diagram showing the pressure curves, volumetric flow rate, and angular velocity of a roller pump with volumetric flow control (left) and without volumetric flow control (right).

[0052] In the accompanying drawings, the same or similar parts, functions, or elements are given the same or similar reference numerals. If reference numerals are used repeatedly, refer to the corresponding prior description. Detailed Implementation

[0053] Figure 1 An injection device 1 for intravenous administration of injectable agents is shown. The injection device 1 has a base mounted on a roller, with a plurality of injection containers 2a, 2b, and 2c arranged at the upper end of the base. Contrast agent and saline solution are stored in the injection medium containers 2a, 2b, and 2c. The injection medium containers 2a, 2b, and 2c are connected to a squeeze tube 4 via a supply line 3. The squeeze tube 4 is inserted into the tubing bed 6 of a roller pump 5 and connected to a discharge line 9 on the outlet side. The discharge line 9 is in turn connected to the patient's blood flow via a catheter through an adjacent patient tubing (not shown).

[0054] The roller pump 5 has three rollers 5-1, 5-2, and 5-3 rotatably mounted on a motor-driven rotor 7. These three rollers 5-1, 5-2, and 5-3 are guided along the tubing bed 6 of the peristaltic pump 5, as... Figure 2 As shown, and in doing so, the extrusion tube 4 is pressed against the reverse bearing portion of the tube bed 6 in a specific area, such that when the rotor 7 rotates about its axis of rotation, the injection medium in the extrusion tube 4 is partially delivered into the outlet line 9 against the back pressure in the outlet line 9. The injection device 1 has a control device 8 for controlling the roller pump 5 (and other components of the injection device 1).

[0055] Figure 2 A detailed perspective view of the roller pump 5 is shown. (As shown in...) Figure 2 As can be seen, the extrusion tube 4 extends at an angle of approximately 260° relative to the rotation axis X of the roller pump 5 between the inlet region 6-1 and the outlet region 6-2 of the tube bed 6. Since the three rollers 5-1, 5-2, and 5-3 are evenly arranged on the rotor 7 at 120° angular intervals, there are always at least two rollers between the inlet region 6-1 and the outlet region 6-2 of the tube bed 6, which compress the extrusion tube 4 against the reverse bearing portion of the tube bed 6. Therefore, the extrusion tube 4 is always compressed at at least two locations during the operation of the roller pump.

[0056] The rotor 7 of the peristaltic pump is in the direction of rotation ( Figure 2 The compression zone of the extrusion tube 4 rotates clockwise (as shown in the diagram), causing the rollers 5-1, 5-2, and 5-3 to move in the direction of rotation. Between the two compression zones, a fluid-sealed tube section with a specific volume is formed in each case, such that the injection medium contained therein is encapsulated between the two rollers 5-1, 5-2, and 5-3 and moves in the direction of rotation to the outlet zone 6-2. When the roller 5-1 begins to lift from the tube bed 6 in the outlet zone 6-2, the injection medium is conveyed in the tube section against the back pressure that dominates in the remainder of the discharge line 9. Figure 2 In the middle, roller 5-1 has completely left the outlet area 6-2 in the direction of rotation (the extrusion tube 4 is therefore no longer compressed by roller 5-1), and the injection resists the dynamic pressure that dominates in the remaining part of the discharge line 9 in the pipe section.

[0057] Figure 5 The pressure sensor 9-1 shown is arranged in the discharge line 9, and the pressure sensor 9-1 continuously measures the pressure p present therein. ist And this pressure p ist Transmitted to control device 8.

[0058] The circulation exit of roller 5-1 in outlet area 6-2 results in a pressure cycle P that is repeatedly applied in discharge line 9. ist The characteristic pressure curve. The characteristic pressure curve p with several pressure cycles P, P', P'". ist exist Figure 3 This is illustrated exemplarily at the top of its timeline. During pressure cycle P, the pressure is the minimum pressure p at the beginning of pressure cycle P. min The pressure fluctuates between these ranges, initially rising rapidly, then entering a range with a moderate increase in pressure, and reaching a brief period of stable pressure or maximum pressure p before a rapid drop in pressure and the start of the next pressure cycle P'. max .

[0059] The start of pressure cycle P is related to the first roller 5-1 exiting the tube bed 6 in the outlet region 6-2, at which time the second roller 5-2 is in the... Figure 2 The figures are labeled in the attached diagram. The marked angular position. The second roller 5-2 represents the dominant roller at this point (and until it leaves through the outlet region 6-2), and, with further rotation, the tube volume of the extrusion tube 4 in front of it continues to decrease against the back pressure in the discharge line 9, which leads to an increase in characteristic pressure. When the second roller leaves the tube bed 6 in the outlet region 6-2, that is, approximately at Figure 2 The attached diagram is marked with a symbol. At the angular position, the compression of the extrusion tube 4 terminates in this region, causing the volume to increase approximately abruptly until the subsequent third roller 5-3. This results in the characteristic pressure drop at the end of the pressure cycle P.

[0060] like Figure 3 As shown, as long as the check valve 9-2 in the discharge line 9 (see...) Figure 5 The pressure curve at the start of the pressure cycle is relatively steep (range II). Once the closing pressure of check valve 9-2 is reached, check valve 9-2 opens, and the pressure increases and decreases (range III). At this point, the column of injection medium present in discharge line 9 and the downstream patient tubing must move against mass inertia and further throttling resistance, causing a further pressure increase. This further pressure increase occurs in range IV, due to another check valve in the catheter. After overcoming the pressure resistance, a quasi-static flow state with approximately constant pressure is established before the pressure drops again when the roller leaves the tubing bed 6 (range I).

[0061] During the full rotation of rotor 7, each of the three rollers 5-1, 5-2, and 5-3 will therefore pass through once, as designated... and Between The angle range, and generates a pressure cycle P. Therefore, the angle range Angles including 0° and 120° This is specified as the angle of the pressure stage, where the subscript i represents that angle. Clearly, the angle of the pressure stage... via modular relations Angular position relative to rotor 7 or individual rollers Directly related.

[0062] For clarity, in the following... Figure 3 Draw the angle of the pressure stage. The timeline.

[0063] To guide the actual volumetric flow rate Q in discharge line 9 as close as possible to the specified target volumetric flow rate. ist It is necessary to get as close as possible to the still permissible pressure limit p. Grenz Guiding pressure p ist The actual pressure curve. In the current embodiment example of the present invention, the roller pump 5 is controlled to the maximum volumetric flow rate Q. max And not exceeding the still permissible pressure limit p Grenz Pressure limit p Greenz Therefore, it can also be understood as pressure p ist The (maximum) set pressure. Exceeding the limit value p. Grenz . Figure 3It also displays dangerous pressure. Under dangerous pressure This could result in irreparable damage to the device or the patient. Therefore, it is essential to ensure that the dangerous pressure is not exceeded under any circumstances.

[0064] Unlike syringe pumps (where the piston is pushed into the cylinder at a controlled rate), roller pumps maintain the pressure limit p due to pressure pulsation. Grenz It is more difficult. For this reason, a high-safety buffer solution (p) must typically be incorporated into known roller pumps. Grenz and (The distance between them) to prevent dangerous pressures from being reached or even exceeded during further stages of the pressure cycle. If the pressure limit p has been exceeded at the beginning of the pressure cycle Grenz If so.

[0065] To compensate for the drawbacks associated with this system, the control device 8 of this embodiment provides according to Figure 5 The control scheme shown is as follows. Control device 8 includes: a second control loop 10 for controlling the rotational (angular) speed ω of the rotor 7 of the roller pump 5; and a pump speed PID controller that receives the maximum volumetric flow rate Q. max It is used as a command variable and converted into the set rotational (angular) speed ω. Soll Or it can be used to control the corresponding rotational field of the roller pump. Actual rotational (angular) speed ω ist As a measurement variable feedback, the control deviation between the setpoint and the actual rotational (angular) speed is minimized through feedback.

[0066] To determine the maximum volumetric flow rate Q max The first control loop 11 is connected upstream of the second control loop 10, and the setpoint volumetric flow rate Q Soll and the permissible pressure limit p Grenz It is specified externally as a command variable. Setpoint volumetric flow rate Q Soll (Unchanged) Pressure p measured in discharge line 9 ist and the angular velocity ω of the rotor 7 of the roller pump 5 measured at the roller pump 5. ist This variable is fed back into the first control loop 11. This eliminates the need to control the actual volumetric flow rate Q in the discharge pipeline 9. ist Measurement and feedback.

[0067] The first control loop 11 is designed as a discontinuous PID controller, which adjusts the maximum volumetric flow rate Q according to the different pressure stages of the pressure cycle. max The controlled variables.

[0068] The first control loop 11 includes a pressure phase detection 12, a pressure prediction 13, a first control component 14, and a second control component 15. The pressure phase detection 12 includes a pressure phase reversing detector 12-1 and a pressure phase switch 12-2.

[0069] The pressure phase reversal detector 12-1 is used to detect the start of a pressure phase. For this purpose, it continuously transmits the current pressure p. ist Compared to the reference value (i.e., the maximum pressure p temporarily stored in the previous pressure cycle P), max The pressure cycle P is compared, and the start of the pressure cycle P is set when the pressure of the temporary storage is at its maximum p. max Compared to the pressure p in the discharge line 9 at that time ist The pressure drop is greater than 1 / 6 of the time point. At this time, one of the rollers 5-1, 5-2, and 5-3 of the roller pump 5 is approximately at... Figure 2 Middle Mark The angle position. Angle during the pressure phase. Set to zero, that is, Furthermore, it is used as a reference value to determine subsequent pressure stages during the further progress of pressure cycle P. Set "Stage I" as the current pressure stage.

[0070] Pressure stage switch 12-2 toggles upwards or counts individual pressure stages II to V. The start of a single pressure stage or a single pressure stage is determined by an angle. Determined. The time integral of the actual rotational angular velocity of the roller pump is obtained from the reference value. To begin, the angle of the pressure stage is detected or approximated.

[0071] The different pressure stages I to V are defined as follows:

[0072] The first pressure stage I begins with a pressure drop greater than 1 / 6 of the maximum pressure of the previous pressure cycle. The second pressure stage 11 begins at a predetermined time point of pressure increase. The third pressure stage III corresponds to the first compression stage, which begins at a pressure stage angle of 45° (corresponding to the full angular range). The fourth pressure stage (IV) is defined at a pressure stage angle of 60° (50% of the stage progress). The fifth pressure stage (V) begins at a pressure stage angle of 97.2° (81% of the stage progress).

[0073] The pressure stages I to V of several consecutive pressure cycles P, P', P'" can be derived from... Figure 4 Obtained from.

[0074] When the current pressure cycle P is in the fourth pressure stage IV, the first control unit 14 is activated via pressure stage detection 12. In all other pressure stages (I to III and V), the first control unit 14 is deactivated, i.e., set to zero.

[0075] The first control unit 14 is the differentiating element of the PID controller. Within it, the correction factor Q is calculated. D Its flow rate from the target volume Q Soll Subtract. Calculate it as the predicted pressure p according to the following formula. futur (or p) forecast ) and pressure limit p Grenz Multiply by the currently calculated maximum volumetric flow rate Q max ratio

[0076]

[0077] Where KD is the fixed gain factor.

[0078] The pressure prediction 13 continuously provides the predicted pressure p futur According to the formula Predicted pressure p futur Determined as the current pressure p ist Linear extrapolation to a defined pressure stage angle of 105° (or 87.5% of the stage progression), where, The measured pressure p ist The time derivative, and Determine the angle of the current pressure stage at time t. The ratio of the pressure stage angle at 87.5% of the stage progress (which corresponds to the full 120° angle range). (105° pressure stage angle). Predicted pressure represents the prediction of the maximum expected pressure in the current pressure cycle at the defined pressure stage angle. Figure 4 The lieutenant general predicts the pressure P output and plots it over time.

[0079] The terms “prediction pressure” and “predicted pressure” should be understood synonymously.

[0080] The second control unit 15 is the proportional and integral element of a PID controller. It calculates a correction factor QI, which is derived from the setpoint volumetric flow rate Q. Soll Subtract from the middle, and calculate using three components α, β, and γ:

[0081] The first component α of the second control component 15 is an averaging filter, which is activated by the maximum pressure p of the immediately preceding pressure cycle P according to the following formula.max With pressure limit p Grenz The ratio is multiplied by the gain factor KI to adjust the maximum volumetric flow rate Q. max

[0082]

[0083] For this purpose, the maximum pressure p in each pressure cycle max It is temporarily stored in the memory of control unit 8. Pressure p ist Measurement errors can be smoothed out using a mean filter.

[0084] The second component β of the second control component 15 is a proportional element, which is a correction factor Q calculated by the first control component 14 in the previous pressure cycle P according to the following formula. D Increase gain factor

[0085] β=KD→ⅠQD

[0086] Since the first control unit 14 only calculates the correction factor Q in the pressure phase IV. D Therefore, when the pressure cycle is outside the pressure phase IV, the second component β of the second control component 15 is zero.

[0087] The third component γ of the second control component 15 is an integrator element, which is corrected for Q by the previous volumetric flow rate of these individual pressure phases of the current pressure cycle according to the following formula. In-1 γ is calculated by summing the sums of all γ and ∑ n-1 Q Ⅰn-1

[0088] Where n is the number of pressure cycles, Q In-1 It is a volumetric flow rate correction for continuous pressure cycles.

[0089] The three components α, β, and γ of the second control unit are added to the correction variable Q. I (Q I =To the correction variable). And the correction variable Q I Volumetric flow rate Q at the setpoint Soll Subtract from the middle.

[0090] Therefore, the maximum setpoint volumetric flow rate Q max It is determined by the setpoint volumetric flow rate Q Soll Subtract the correction variable Q of the first control component 14 and the second control component 15 D and Q I And the resulting (Q) max =Q Soll -Q I -Q D ).

[0091] With the control device 8 designed in this way, the output of the roller pump 5 or its rotational speed ω can be adjusted and regulated in a desired manner. Due to the maximum volumetric flow rate Q... max The calculations are performed differently in pressure stages I through III and V compared to pressure stage IV, therefore this is discontinuous control.

[0092] exist Figure 6 The diagram shows the control response for a pinched, fluid-impermeable discharge line 9, where six consecutive pressure cycles A to F show the measured pressure p. ist The predicted pressure p calculated through pressure prediction 13 futur And the associated pressure stages I to V of the individual pressure cycles A to F. As a result of the disconnected discharge line 9, the maximum absolute pressure p in each pressure cycle max Steadily increasing: pA max <pB max <pC max <pD max wait.

[0093] In the fourth pressure stage IV of pressure cycle F, the predicted pressure P futur First time exceeding the pressure limit p Grenz In other phases, predicting stress P futu Other excesses exceeding the pressure limit p Greenz For example, in pressure stage II of pressure cycle D, it is irrelevant because control device 8 only considers the predicted pressure P in pressure stage IV via control unit 14. futur .

[0094] Because each fourth pressure stage IV begins at a pressure stage angle of 60° (or 50% of the stage progress), the maximum setpoint volumetric flow rate Q in the pressure cycle F is... max And therefore the rotational speed ω ist The pressure is reduced by control device 8 as pressure stage IV begins in pressure cycle F. The throttling of speed ω at the start of stage IV is... Figure 6 Clearly visible in the middle. Due to the pressure limit p Grenz The impending detection and maximum pressure p F max <p Grenz Sufficient lead time between occurrence and pressure limit p Grenz .

[0095] To achieve this pressure p ist The pressure curve is leveled, that is, the amplitude is reduced, according to Figure 5 The control device 8 in the example embodiment can also be derived from... Figure 5The control system (not shown) further supplements this by increasing or decreasing the maximum setpoint volumetric flow rate Q according to the stage progress. Soll This control manipulates the setpoint volumetric flow rate Q. Soll The command variable is used to make the setpoint volumetric flow rate Q. Soll At the start of the pressure cycle, increase the setpoint volumetric flow rate by 30% to the increased amount Q. + And at the end of the pressure cycle, reduce the volumetric flow rate Q by 30% to the reduced setpoint. - The changing setpoint flow rate Q Soll The holding time x-hold. The holding time x-hold can correspond to a specific stage of the process, such as, for example, 25% or the duration of stage I. This is due to the increase or decrease in the setpoint volumetric flow rate Q. + Or Q - Conversely, the average setpoint volumetric flow rate remains unchanged on pressure cycle P. For pressure cycle P with pressure stages I to V, the corresponding preset for the target volumetric flow rate is as follows: Figure 7A As shown. (As in...) Figure 7A As can be seen from this, at the start of the pressure cycle P, the volumetric flow rate Q is set. Soll Sudden increase to the set volumetric flow rate Q + And then linearly decrease to a reduced set volumetric flow rate Q. - The setpoint volumetric flow rate Q is changed in this way. Soll The command variable (which is now time-varying on pressure cycle P) is fed into the first control loop 11.

[0096] Such control results in a smoother pressure curve with less pressure fluctuation, specifically a flatter pressure peak. This is in Figure 7B The text shows: Figure 7B The pressure curves for several pressure cycles A to F are shown, from which... Figure 7A Variable setpoint volumetric flow rate Q Soll Adjust the setpoint volumetric flow rate Q at the beginning of pressure cycles A through C and pressure cycle D. Soll And specify a constant setpoint volumetric flow rate in subsequent pressure cycles. For example, in Figure 7B As can be seen from this, the pressure peaks p in pressure cycles D, E, and F are related. max In comparison, the peak pressure p in pressure cycles A, B, and C max Therefore, it can be reduced.

[0097] Another effect of this control is that, after the sudden pressure drop at the end of pressure cycle P, the motor power of peristaltic pump 5 does not need to decrease abruptly or even slow down to maintain a constant volumetric flow rate. This saves energy and reduces motor noise.

[0098] Due to the setpoint volumetric flow rate Q Soll Approximately the angular velocity ω of peristaltic pump 5 ist Proportional, therefore the angular velocity ω of peristaltic pump 5 ist (Ignoring measurement inaccuracies and the effects of the controlled system) has the same characteristics as the target volumetric flow rate Q. Soll A fairly consistent curve. Therefore, it is possible to increase the angular velocity ω of the peristaltic pump at the start of the pressure cycle. Soll Increase the speed ω to the increased set point + And / or reduce it to a lower setpoint speed ω at the end of the pressure cycle. - Instead of setpoint volumetric flow rate.

[0099] The invention, as illustrated in the described embodiments, enables safer operation of peristaltic pumps with higher media throughput and lower pressure fluctuations.

[0100] In addition to peristaltic pumps, this control device can also be used with other pumps that have cyclically repeating pressure curves, such as diaphragm pumps with oscillating diaphragms, piston pumps with reciprocating pistons, sinusoidal pumps, or gear pumps. This control device is particularly suitable for applications where the overpressure valve for releasing the medium is incompatible with the system to be used.

[0101] List of reference numerals

[0102] Pressure stages of pressure cycles I to V

[0103] p Grenz Pressure limit (target pressure)

[0104] p futur Predicting pressure

[0105] Dangerous pressure

[0106] P Pressure cycle (period)

[0107] Q max Maximum volumetric flow rate

[0108] Q Soll Target volumetric flow rate / Setpoint volumetric flow rate

[0109] X-axis rotation (roller pump)

[0110] Pressure stage angle (at angle i)

[0111] ω ist Rotational angular velocity (actual value) of roller pumps / rollers 5-1, 5-2, and 5-3. Ω SollRotational angular velocity (setpoint)

[0112] 1. Injection device

[0113] 2a-c Injection media container

[0114] 3, 3', 3" supply lines

[0115] 4. Extruded tube

[0116] 5. Peristaltic pump (roller pump)

[0117] 5-1 Rollers (Extrusion Rollers)

[0118] 5-2 Rollers (Extrusion Rollers)

[0119] 5-3 Rollers (Extrusion Rollers)

[0120] 5' Dominant Roller

[0121] 6. Tube Bed

[0122] 6-1 Entrance Area

[0123] 6-2 Export Regions

[0124] 7 rotors

[0125] 8. Control device

[0126] 9. Discharge pipeline

[0127] 9-1 Pressure sensor (injection line)

[0128] 9-2 Check valve (injection line)

[0129] 10. Second control loop (pump speed controller)

[0130] 11 First Control Loop

[0131] 12. Pressure Stage Testing

[0132] 12-1 Pressure Stage Commutator

[0133] 12-2 Pressure Stage Switch

[0134] 13 Pressure Predictor

[0135] 14 First control unit

[0136] 15 Second control unit

Claims

1. A control device (8) for a peristaltic pump (5), the peristaltic pump (5) having a squeezing tube (4) and circulating moving conveying elements (5-1, 5-2, 5-3), the circulating moving conveying elements (5-1, 5-2, 5-3) being used to convey, during conveying operations, a medium guided in the squeezing tube (4) to a discharge line (9) connected to the squeezing tube (4) at a controlled volumetric flow rate. in, The conveying elements (5-1, 5-2, 5-3) cyclically compress the extrusion tube (4), thereby establishing a pressure curve of actual pressure in the discharge line (9), the pressure curve having a cyclically repeating pressure cycle. Each pressure cycle includes a minimum pressure, a pressure rise, a maximum pressure, and a pressure drop. The control device (8) controls the speed of the peristaltic pump (5) to achieve the maximum volumetric flow rate without exceeding the pressure limit in the discharge pipeline (9). Furthermore, the control device (8) has a first control loop (11) for controlling the maximum volumetric flow rate, the first control loop (11) receiving the setpoint volumetric flow rate and the pressure limit as command variables and being configured to execute a control method. Its features are, For each pressure cycle, a predicted pressure is calculated based on the actual pressure in at least the discharge line (9) against the expected maximum pressure within the pressure cycle. Furthermore, taking the predicted pressure into account, the maximum volumetric flow rate is limited so that the actual pressure in the discharge line (9) does not exceed the pressure limit in the pressure cycle.

2. The control device (8) according to claim 1, characterized in that, The first control loop (11) includes a pressure phase detection (12) that detects the end of a previous pressure cycle and the beginning of a subsequent pressure cycle based on a characteristic variable in order to initiate control of the maximum volumetric flow rate of the subsequent pressure cycle. The characteristic variable includes at least a pressure drop defined relative to the maximum pressure value of the previous pressure cycle.

3. The control device (8) according to claim 2, characterized in that, Each pressure cycle is divided into continuous pressure stages based on predefined pressure characteristics, wherein the predefined pressure characteristics include at least the pressure change of the actual pressure and / or the rate of pressure change of the actual pressure. The pressure phase detection (12) detects the start of a separate pressure phase based on the predefined pressure characteristics and / or on the position of the delivery elements (5-1, 5-2, 5-3) of the peristaltic pump (5). Furthermore, the predicted pressure used to regulate the maximum volumetric flow rate in the first control loop (11) is used only in the defined pressure phase and is ignored in other pressure phases.

4. The control device (8) according to claim 3, wherein, The individual pressure phases include a first pressure phase, a second pressure phase, a third pressure phase, a fourth pressure phase, and a fifth pressure phase; the first pressure phase is characterized by rapid pressure loss, the second pressure phase is characterized by rapid pressure rise, the third pressure phase is characterized by mild pressure rise, the fourth pressure phase is characterized by moderate pressure rise, and the fifth pressure phase is characterized by a pressure plateau with constant pressure, and each pressure phase is detected by the pressure phase detection (12).

5. The control device (8) according to claim 4, characterized in that, In the first control loop (11), the predicted pressure is used to limit the maximum volumetric flow rate only during the fourth pressure phase.

6. The control device (8) according to claim 2 or 3, characterized in that, The pressure phase detection (12) determines the start of at least one pressure phase of the pressure cycle based on the pressure change of the actual pressure and / or the rate of pressure change of the actual pressure.

7. The control device (8) according to claim 2 or 3, characterized in that, The control device is configured to determine the predicted pressure as a linear extrapolation of the actual pressure increase to a calculated or predetermined stage of the pressure cycle.

8. The control device (8) according to claim 7, characterized in that, The calculated or predetermined stage of the predicted pressure is inconsistent with the actual stage of the actual maximum pressure at which the pressure cycle occurs.

9. The control device (8) according to claim 1 or 2, characterized in that, The first control loop (11) includes an average filter that adjusts the maximum volumetric flow rate based on the maximum pressure of the previous pressure cycle preceding the current pressure cycle, wherein the maximum pressure of the previous pressure cycle is temporarily stored in the control device (8).

10. The control device (8) according to claim 4, characterized in that, The first control loop (11) is a PID controller with a proportional element, an integral element and a differential element, wherein the differential element is set to zero in the first pressure stage, the second pressure stage, the third pressure stage and the fifth pressure stage.

11. The control device (8) according to claim 3 or 4, characterized in that, The control device (8) includes a control system for smoothing the pressure peak of the pressure curve of the actual pressure during the pressure cycle. The control system is arranged as a speed adapter that, at a specific stage of the pressure cycle, adapts a predetermined setpoint speed of the delivery elements (5-1, 5-2, 5-3) of the peristaltic pump (5) to a new setpoint speed, which is either reduced by a predetermined amount to a low setpoint speed lower than the average setpoint speed before the pressure cycle is completed, or increased by a predetermined amount to a high setpoint speed higher than the average setpoint speed after the pressure cycle is completed, wherein the new setpoint speed is maintained for a specific duration.

12. The control device (8) according to claim 11, characterized in that, The actual speed of the conveying elements (5-1, 5-2, 5-3) increases suddenly by a predetermined amount after the pressure cycle is completed, and then decreases linearly to the low setpoint speed.

13. The control device (8) according to claim 1 or 2, characterized in that, The pressure curve includes more than 10 pressure cycles.

14. A peristaltic pump (5), the peristaltic pump (5) having a rotatable rotor (7) and a control device (8) according to any one of claims 1-13, characterized in that, The conveying elements (5-1, 5-2, 5-3) are designed as rollers and arranged on the rotor (7). The extrusion tube (4) is supported along a tube bed (6) having an inlet region (6-1) and an outlet region (6-2). When one of the conveying elements (5-1, 5-2, 5-3) enters the tube bed (6) at the horizontal plane of the inlet region (6-1), as the rotor (7) rotates, the conveying element (5-1, 5-2, 5-3) continuously compresses a section of the extrusion tube (4) in a fluid-tight manner until the conveying element (5-1, 5-2, 5-3) leaves the tube bed (6) at the outlet region (6-2), thereby the medium in the extrusion tube (4) is conveyed to the discharge line (9) against the dynamic pressure generated in the discharge line (9). During the volume reduction phase of the continuous pressure cycle, the volume of the extrusion tube (4) located upstream of the outlet region (6-2) is compressed from its maximum volume to its minimum volume until the conveying elements (5-1, 5-2, 5-3) leave the tube bed (6) at the horizontal plane of the outlet region (6-2), thereby releasing the compressed section of the extrusion tube (4) compressed by the conveying elements (5-1, 5-2, 5-3). During the volume increase phase of the continuous pressure cycle, the volume upstream of the outlet region (6-2) of the extrusion tube (4) increases from a minimum volume to a maximum volume. The volume decrease phase and the subsequent volume increase phase define the complete pressure cycle. The peristaltic pump (5) has n conveying elements (5-1, 5-2, 5-3), and the peristaltic pump (5) performs n pump strokes in n pressure cycles during the 360° rotation of the rotor (7). Furthermore, each pressure stage of the pressure cycle corresponds to an angular range of one of the angular positions of the conveying elements (5-1, 5-2, 5-3).

15. The peristaltic pump (5) according to claim 14, characterized in that, The start of at least one pressure phase of the pressure cycle is indirectly determined by the angular position of one of the conveying elements (5-1, 5-2, 5-3).

16. An injection device (1) for injecting an injection medium into an animal or human body via a peristaltic pump, characterized in that, The injection device (1) includes a peristaltic pump (5) according to claim 14 or 15.

Images