Peritoneal dialysis machine having a torque limiting device

Abstract

A peritoneal dialysis machine is provided having a machine housing and a weighing pan for receiving one or more solution bags. The weighing pan is connected to a weighing cell for weight measurement, wherein one or more torque limiting devices are provided which prevent the occurrence of a torque or of a torque exceeding a limit value in the weighing cell. The torque limiting device is configured such that with a torque acting on the weighing pan, it moves the weighing pan such that it comes into contact with the machine housing or with an element connected to the machine housing such that the torque is led off into the machine housing or into the element.

Claims

1. A peritoneal dialysis machine comprising: a machine housing and having a weighing pan for receiving one or more solution bags, the weighing pan being connected to a weighing cell for weight measurement; at least one torque limiting device which prevents an occurrence of a torque or of a torque exceeding a limit value in the weighing cell, with the torque limiting device being configured such that, with a torque acting on the weighing pan, it moves the weighing pan such that it comes into contact with the machine housing or with an element connected to the machine housing such that the torque is led off into the machine housing or into the element; said torque limiting device having a first element and a second element, said first element being formed by a body which has a recess of which at least one surface extends at an inclination with respect to the horizontal and with respect to the vertical, said second element being received in the recess, with the first element being rotatable relative to the second element; and said torque limiting device including a torsion spring that has a first section which is connected to the weighing pan or to a body arranged at the weighing pan and is subjected to torsion on a tilt movement of the weighing pan.

2. The peritoneal dialysis machine in accordance with claim 1, wherein the torque limiting device is configured such that it only moves the weighing pan at a torque acting on the weighing pan and exceeding a limit value such that it comes into contact with the machine housing or with an element connected to the machine housing such that the torque is led off into the machine housing or into the element.

3. The peritoneal dialysis machine in accordance with claim 1, wherein the recess has two of the inclined surfaces which run toward one another.

4. The peritoneal dialysis machine in accordance with claim 3, wherein the two inclined surfaces form, in the plan view of the first element, the sides of a triangle whose one side is open for the introduction of the second element.

5. The peritoneal dialysis machine in accordance with claim 1, wherein the second element is designed as a rod-shaped part which is preferably cylindrical.

6. The peritoneal dialysis machine in accordance with claim 1, wherein the first element or second element is arranged rotationally fixedly relative to the weighing pan; and in that the other element is arranged rotationally fixedly relative to the machine housing.

7. The peritoneal dialysis machine in accordance with claim 1, wherein the torque limiting device is configured such that it prevent or limits the occurrence of a torque at the weighing cell when the weighing cell is rotated about its fastening axis, with provision preferably being made that the fastening axis extends vertically.

8. The peritoneal dialysis machine in accordance with claim 1, wherein the torsion spring is of plate shape.

9. The peritoneal dialysis machine in accordance with claim 1, wherein the body arranged at the weighing pan is the body that forms the first element.

10. The peritoneal dialysis machine in accordance with claim 9, wherein the first section is arranged at the center of the torsion spring and is surrounded over its full periphery or partially by a second section of the torsion spring.

11. The peritoneal dialysis machine in accordance with claim 1, wherein the torsion spring is arranged at the lower side of the weighing pan.

12. The peritoneal dialysis machine in accordance with claim 1, wherein the torque limiting device is configured such that it limits the torque acting on the weighing cell or prevents the action of a torque on the weighing cell when the weighing cell experiences a tilt movement.

13. The peritoneal dialysis machine in accordance with claim 1, wherein the weighing pan is a heated pan.

14. The peritoneal dialysis machine in accordance with claim 13, wherein a plurality of solution bags containing fresh dialyzate are arranged in the weighing cell.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Further details and advantages of the present invention will be explained in more detail with reference to an embodiment shown in the drawing. There are shown:

(2) FIG. 1: a perspective view of a peritoneal dialysis machine in accordance with the invention;

(3) FIG. 2: a perspective view of the weighing pan from below;

(4) FIG. 3: an enlarged perspective view of the weighing pan from below in the region of the torque limiting device without a torque action;

(5) FIG. 4: an enlarged perspective view of the weighing pan from below in the region of the torque limiting device with a torque action;

(6) FIG. 5: a further perspective view of the weighing pan from below with a torsion spring; and

(7) FIG. 6: a perspective view of the torsion spring with a torque action.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(8) Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.

(9) A peritoneal dialysis machine in accordance with the invention can be seen from FIG. 1.

(10) It has a machine stand 100, a housing carrier 110 extending upwardly from this and a machine housing 120 which is arranged at the housing carrier 110. The control required for the operation of the machine and optionally display and/or operating elements are located in the machine housing 120.

(11) The weighing pan 130 is located above the machine housing 120; the weighing pan is heatable and will therefore be called a heating pan 130 in the following. The heating pan 130 has a width B and a depth T, with the width B being larger than the depth T.

(12) The heating pan 130 is connected via a fastening rod 200 to a weighing cell arranged in the machine housing 120, with the fastening rod 200 being visible, for example, from FIG. 2. The fastening rod 200 is arranged vertically.

(13) In accordance with the coordinate system shown in FIG. 1, the x axis extends in the depth direction of the heating pan 130, the z axis extends in the width direction of the heating pan 130 and the y axis extends in the direction of the fastening rod 200, i.e. vertically upwardly.

(14) The peritoneal dialysis machine in accordance with the present invention has two torque limiting devices which have the object of keeping torques which are too large or of keeping any torque at all away from the weighing cell and of protecting the weighing cell in this manner.

(15) FIG. 2 shows the heating pan 130 from below in a perspective view. The fastening rod 200 which supports the heating pan 130 and conducts its weight onto the weighing cell, not shown, extends downwardly from the heating pan 130.

(16) Two torque limiting devices, of which the first one is shown enlarged in FIG. 3 and in FIG. 4, are located at the bottom at the heating pan.

(17) The first torque limiting device comprises a first element in the form of the body 300. The body 300 has a substantially cylindrical design. It is fixedly connected to the lower side of the heating pan so that a movement of the heating pan produces a corresponding movement of the body.

(18) A V-shaped incision or a V-shaped recess 310, whose tip S faces upwardly and whose lower side is open, is located at the lower side of the body 300.

(19) The free surfaces of the recess 310 are marked by reference numerals 320 and 330 in FIG. 2. These surfaces 320, 330 can be planar or curved.

(20) The second element is located in the form of the rod 400 at the fastening rod 200 and extends in a direction perpendicular to or also slanted with respect to the longitudinal direction of the fastening rod 200. The rod 400 is arranged fixedly at the fastening rod 200. The body 300 is rotatable relative to the fastening rod 200.

(21) As can be seen from FIG. 3, the rod 400 is located at the highest point, i.e. at the tip S of the recess 300, when no torque acts on the heating pan 130.

(22) The fastening rod 200 is rotationally fixedly arranged at the machine housing 120 or at the weighing cell arranged therein. A torque acting on the fastening rod about the longitudinal axis of the fastening rod would thus be transmitted to the weighing cell.

(23) The rod 400 is arranged rotationally fixedly at the fastening rod 200.

(24) If now a torque acts on the heating pan 130, for example because a user turns it, this torque is not transmitted to the fastening rod 200. The torque rather has the result that the body 300 is rotated about the fastening rod 200. This has the consequence that the rod 400 is moved out of the tip V of the recess 310 and now contacts the surface 320 or 330 of the recess 310depending on the direction of rotation. This state is shown in FIG. 4.

(25) The surfaces 320 and 330 can be curved such that the rod always contacts the surface 320 or 330 over its total length in which it is received in the recess 300. In this case, the contact between the rod 400 and the surface 320 or 300 respectively is linear, independently of the angle of rotation, due to the cylindrical shape of the rod 400.

(26) Shapes of the rod differing from a cylindrical shape are also covered by the invention.

(27) Due to the fact that the two slanted surfaces 320, 330 extend upwardly toward one another and that the rod 400 is arranged in a fixed position, the body 300 and thus also the total heating pan 130 is moved upwardly due to the rotary movement of the heating pan 130.

(28) There is in this respect a contact between the heating pan 130 and a part of the upper side of the machine housing 120. This part serves as an abutment which prevents a further rotation of the heating pan 130 and leads the torque off into the machine housing 120.

(29) It is also conceivable, instead of the arrangement shown in FIGS. 3 and 4, to arrange the body 300 at the fastening rod 200 and to arrange the rod 400 at the heating pan 130. In this case, the open side of the recess 130 faces upwardly in the body 300.

(30) The arrangement in accordance with FIGS. 2 to 4 is active on a torque or on a rotation about the y axis (cf. FIG. 1), i.e. on a rotation about the fastening rod 200. Since the heating pan 130 is to this extent decoupled from the fastening rod 200, the fastening rod 200 does not follow the rotary movement of the heating pan and also is not subject to any torque or is only subject to a small torque. The weighing cell is consequently also not acted on by a torque or is only acted on by a small torque.

(31) A second torque limiting device of the peritoneal dialysis machine can be seen from FIG. 5 which prevents an unduly high torque from acting on the weighing cell when a torque about the x axis acts on the heating pan in accordance with FIG. 1. This can be the case, for example, when the heating pan is unevenly loaded with heating bags.

(32) As can be seen from FIG. 5, the second torque limiting device comprises a plate-shaped torsion spring 500 which is located on the lower side of the heating pan 130. The torsion spring 500 as such is shown in FIG. 6.

(33) The torsion spring 500 has an outer ring 510 of which two oppositely disposed sides are connected to one another by a web 520. An opening 530 is located in the web 520, said opening being surrounded by a part-circular parts 521 of the web and through which the body 300 of the first torque limiting device extends.

(34) This can be seen from FIG. 5, for example.

(35) If now a torque acts about the axis formed by the web 520 and which corresponds to the x axis in FIG. 1, the central section of the web 520 and the region 521 of the web 520 surrounding the opening 530 is subjected to torsion and bent by the body 300 extending through the opening 530.

(36) The fastening rod 200 and the weighing cell connected thereto do not, however, experience any torque on this tilt movement of the heating pan 130.

(37) The bending of this region results in an inclination of the heating pan 130 overall. As soon as the heating pan 130 contacts a part of the housing, a further bending or a further tilting of the heating pan 130 is prevented and the torque is led off into the machine housing. The weighing cell is thus not only protected from a torque on a rotation about the axis of the fastening rod 200, but also from a torque which occurs on a rotation or on a tiling of the heating pan.

(38) Exemplary bag sizes which are received on the heating pan amount to (widthlengthheight, each in cm): 29288 with 5 liter bags or 293110 with 6 liter bags or 42434.5 with 5 liter bags or 42464.5 with 6 liter bags with respect to the last bag 17307 as a 2.5 liter bag.

(39) Other bag sizes (volumes and/or dimensions) or multi-chamber bags are also conceivable and covered by the invention.

(40) Each of the four different bag sizes or bag arrangements produce, together with the last bag, the following torques on a support offset from the support point of the heating pan, i.e. from the point at which the fastening rod engages at the heating pan, said torques resulting from the fact that the center of gravity of the loaded heating pan does not coincide with the support point of the heating pan or with the location of the heating cell:

(41) 5 liter bag 29288 and last bag with an offset of 20 mm toward the right: 140 N0.02 m=2.8 Nm

(42) 6 liter bag 293110 and last bag with an offset of 15 mm toward the right: 160 N0.015 m=2.4 Nm

(43) 5 liter bag 42434.5 and last bag with an offset of 31 mm toward the left: 140 N0.031 m=4.3 Nm

(44) 6 liter bag 42464.5 and last bag with an offset of 44 mm toward the left: 160 N0.044 m=7.0 Nm

(45) The stiffness of the torsion disk or torsion spring has to be so large that under these loads no inclination of the heating pan occurs which is so large that said heating pan contacts the housing since otherwise no reliable measurement of the weight is possible. The safety factor between the maximum load to be expected and a load which produces a contact of the heating pan on the housing can lie in the region between 2 and 3, such as at 2.5.

(46) It is possible by the present invention, on the one hand, to achieve an exact weighing of the heating pan or of the solution bags located thereon and, on the other hand, reliably to prevent damage to the weighing cell by loads or torques which are too large.

(47) The invention being thus described, it will be apparent that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be recognized by one skilled in the art are intended to be included within the scope of the following claims.