ADJUSTING DEVICE FOR A FLOW REGULATOR

Description

[0001] The invention relates to an adjustment device for adjusting the flow rate of a medical fluid delivery system.

[0002] A medical fluid delivery system can, for example, be an infusion device for infusion therapy or for infusing a painkiller into a patient. Such fluid delivery systems require selecting and adjusting one of several possible flow rates for the fluid delivery. The flow rate at which the fluid is delivered must be adjusted with high precision and reliability. Incorrect adjustment, especially in infusion devices, can lead to over- or underdosing, which can have critical consequences for a patient.

[0003] It is common practice to adjust the flow rate using a rotary control. A dial is used to select one of several possible flow rates. A setting disc for setting the selected flow rate is permanently connected to the dial. A locking lug interacts with the radially outer edge of the setting disc. The engagement between the locking lug and the setting disc is such that the locking lug locks the setting disc and thus also the dial in the rotational position required to set the desired flow rate.

[0004] One difficulty with existing adjustment devices is that intermediate positions can be set between adjacent rotational positions of corresponding flow rates, with neither one nor the other flow rate being selected. The accidentally set intermediate position remains set. Depending on the control mechanism, this can lead to maximum delivery or no delivery of the fluid. Especially in infusion medicine, this can have critical consequences for a patient.

[0005] From EP 0 730 876 A, an adjustment device with the preamble features of claim 1 is known. In the known adjustment device, the catch nose is designed as a flat triangular tip, wherein the tip angle of the triangular tip is greater than the angle of the zigzag lines of the adjusting disc.

[0006] The invention is based on the object of providing an improved adjustment device for adjusting the flow rate of a medical fluid delivery system.

[0007] The adjustment device according to the invention is defined by the features of patent claim 1. The adjusting disc is accordingly star-shaped. The star shape results in a rotationally symmetrical shape of the adjusting disc with a radially outer edge that has several areas with a maximum radius and several areas with a minimum radius. The areas of the radially outer edge with the maximum radius can be referred to as peaks and the areas with the minimum radius as valleys. The star shape of the adjusting disc results in a valley and a peak alternating with one another. The interaction of the catch lug with the star shape of the adjusting disc leads to stable positions of the adjusting disc when the catch lug engages with a valley and to unstable positions when the catch lug engages with a peak. It is crucial that a peak does not have a constant radius, but rather a maximum radius that decreases towards the adjacent valley.As a result, engaging the catch nose at a peak leads to an unstable rotational position of the adjusting disc. While the valleys serve as the rotational positions for setting a particular flow rate, the intermediate peaks correspond to the rotational positions between adjacent rotational positions of adjustable flow rates. Accidentally setting a rotational position between adjacent flow rates thus leads to an unstable rotational position of the adjusting disc.

[0008] A catch lug, which is mounted against the force of a spring and pressed by the spring against the radially outer edge of the adjusting disc, will, when it rests against the radially outer edge between adjacent valleys, cause the spring force to rotate the adjusting disc from its unstable position, moving the catch lug into a valley and thus into a stable position. According to the invention, the catch lug is designed as a projection on a spiral spring, namely as a triangular projection with a tip.

[0009] According to the invention, the star shape of the adjusting disc results in a zigzag shape of the radially outer edge, wherein adjacent lines of this zigzag shape are arranged inclined to one another at an angle between 10° and 155°, preferably between 90° and 135°.

[0010] An embodiment of the invention is explained in more detail below with reference to the figures. They show: Fig. 1a view of the adjustment device from the direction of the rotation axis, Fig. 2a view from the direction of arrow II in Fig. 1 , Fig. 3 a section along the line III-III in Fig. 2 in a first rotational position, Fig. 4 the section according to Fig. 3 in a second rotational position and Fig. 5 the detailed V in Fig. 4 .

[0011] Fig. 1 shows a view of the adjustment device 10, in which the surface of the dial 12 is shown from the direction of its rotational axis. Along the radially outer edge of the dial 12, the numbers 0-7 are shown at equal intervals to mark the rotational positions corresponding to these numbers. Each of the numbers 0-7 corresponds to a possible adjustable flow rate, with 0 corresponding to no flow and 7 to maximum flow.

[0012] The dial 12 is circular when viewed from Fig. 1and mounted for rotation about a rotation axis 16. The dial 12 is fixedly connected to a rotationally symmetrical adjusting disc 14 so that the adjusting disc 14 can rotate about the same rotation axis 16. The dial 12 and the adjusting disc 14 are rotationally fixedly coupled to each other. Fig. 1 the adjusting disc 14 is shown by dashed lines as a hidden element behind the selector wheel 12.

[0013] The adjusting disc 14 is star-shaped by zigzag lines 18, 20 along its outer circumference. The star shape is as seen from the direction of rotation axis 16, as shown in the Fig. 3 and 4 shown, visible.

[0014] The zigzag lines 18, 20 of the radially outer edge of the adjusting disc 14 are straight lines and are arranged at shallow angles to each other in a range between approximately 110° and 130°. Adjacent zigzag lines 18, 20 form valleys 22 and peaks 24 at their points of contact. Each peak 24, as a radially outward-pointing vertex, forms a point with a maximum radius. Correspondingly, each valley 22, as a radially inward-pointing vertex, forms a point with a minimum radius. The radii of all valleys 22 are equal, and the radii of all peaks 24 are equal.

[0015] A catch nose 26 engages with the zigzag lines 18, 20 of the star-shaped radial outer edge of the adjusting disc 14, which, as shown in the Fig. 3 - 5is shown, is designed as a triangular tip of a spiral spring 28. In the exemplary embodiment, the spiral spring 28 is a bent leaf spring. The spiral spring 28 is arranged with respect to the adjusting disc 14 in such a way that the spring force moves the catch 26 in the direction of the arrow 30 into the Fig. 3 and 4 radially inwards against the adjusting disc 14.

[0016] Fig. 3 shows the stable position of the adjusting disc 14, in which the spring 28 presses the catch 26 into a valley 22 of the star shape. When rotating the adjusting disc 14 by turning the dial 12, a force must be applied that counteracts the force that the spiral spring 28 exerts on the outer edge of the adjusting disc 14 via the catch 26. If an intermediate position between adjacent valleys is accidentally set, the adjusting disc 14 is always in an unstable position. Such an intermediate position is shown in the Fig. 4 and 5The star-shaped locking lug 26 presses diagonally against the edge of the adjusting disc 14 with the force of the spiral spring 28, causing the adjusting disc 14 to rotate until the locking lug comes to rest in one of the valleys 22. This prevents the setting of an intermediate position between adjacent valleys.

Claims

1. Adjusting device (10) for adjusting the flow rate of a medical fluid delivery system, comprising a selector wheel (12) for selecting one of a plurality of possible flow rates, a setting disc (14), which is connected to the selector wheel (12), for adjusting the selected flow rate, and a catch nose (26) which interacts with the outer periphery of the setting disc (14), wherein the setting disc (14) is formed so as to be star-shaped by zigzag lines (18, 20) along its outer periphery, wherein the zigzag lines (18, 20) are straight lines and disposed relative to one another at an angle between 10° and 155°, wherein adjacent zigzag lines (18, 20) form alternating peaks (24) and troughs (22), wherein the setting disc (14) is co-rotationally coupled to the selector wheel (12), wherein the catch nose (26) is mounted counter to the force of a bending spring (28) in such a manner that an engagement of the catch nose (26) in a trough (22) causes a stable, and an engagement of the catch nose (26) with the peak (24) causes an unstable, position of the setting disc (14), and wherein the catch nose (26) is formed as a triangular tip of the bending spring (28), characterized in that a tip angle of the triangular tip is smaller than the angle of the zigzag lines (18, 20).

2. Adjusting device (10) according to Claim 1, characterized in that each trough (22) corresponds to the rotational position of the selector wheel (12) and of the setting disc (14) required for setting a flow rate.

3. Adjusting device (10) according to Claim 1 or 2, characterized in that each peak (24) corresponds to the rotational position of the selector wheel (12) and of the setting disc (14) exactly between two adjacent rotational positions of corresponding flow rates.

4. Adjusting device (10) according to one of the preceding claims, characterized in that the peaks (24) and / or the troughs (22) are each radiused.