Linear peristaltic pump

Abstract

A peristaltic pump (1) including a tray, referred to as a pump body (3), which includes a substantially planar surface (32) against which a flexible tube (5) for the passage of fluid is intended to be positioned, and a system (2) for applying force including a plurality of support members (7), such as rollers, and drive elements for moving the support members against the tube in order to deform it against the pump body (3). The pump body (3) is movably mounted relative to the system (2) for applying force between a position spaced apart from the system (2) for applying force, and a position adjacent to the system (2) for applying force. The pump (1) also includes elements (36) for controlling the movement of the pump body (3) relative to the system (2) on the basis of a predetermined magnitude corresponding to the force applied to the tube.

Claims

1. A peristaltic pump comprising: a pump body plate that includes a substantially plane surface against which a flexible tube for passing fluid is to be positioned, a force application system comprising a plurality of presser members, and a drive for moving said presser members, enabling said presser members to be moved while pressed against the tube in order to deform it against said pump body plate; and a motor for moving said pump body plate relative to the force application system, between a first position spaced apart from said force application system and a second position closer to said force application system; wherein said peristaltic pump includes at least one gauge for determining a magnitude representative of the force applied to the tube, when said tube is in a state positioned between the force application system and the pump body plate; said peristaltic pump further comprising a governor processor for controlling the movement of the pump body plate relative to the force application system as a function of said determined magnitude representative of the force applied to the tube; and a memory for said governor processor defining storing a setpoint value for said magnitude representative of the force applied to the tube, said governor processor comprising instructions for: acquiring said determined value magnitude representative of the force applied to the flexible tube, comparing said determined value magnitude representative of the force applied to the flexible tube with said memorized setpoint value of the magnitude representative of the force applied to the flexible tube, and in function of the result of the comparison, controlling the motor to move the pump body toward or away from the force application system until said determined value magnitude reaches said setpoint value.

2. The pump according to claim 1, wherein said at least one gauge is a strain gauge.

3. The pump according to claim 1, wherein said drive for moving the presser members includes a loop element that connects the presser members to one another, and two rotary cylinders positioned inside said loop element at opposite ends, at least one of the cylinders being motor-driven in order to drive said loop element around said cylinders.

4. The pump according to claim 1, wherein said peristaltic pump includes a housing in which the force application system and the pump body plate are housed; and the pump body plate being mounted to move relative to said housing.

5. The pump according to claim 1, wherein said pump body is a movable pump body.

6. The pump according to claim 1, wherein said pump body plate is mounted to move in translation along a direction that is transvers, relative to said plane surface of the pump body plate.

7. The pump according to claim 6, wherein said at least one gauge is a strain gauge.

8. The pump according to claim 6, wherein said drive for moving the presser members includes a loop element that connects the presser members to one another, and two rotary cylinders positioned inside said loop element at opposite ends, at least one of the cylinders being motor-driven in order to drive said loop element around said cylinders.

9. The pump according to claim 6, wherein said peristaltic pump includes a housing in which the force application system and the pump body plate are housed; and the pump body plate being mounted to move relative to said housing.

Description

(1) The invention can be readily understood on reading the following description of embodiments, given with reference to the accompanying drawings, in which: FIG. 1 is a diagrammatic view of a linear peristaltic pump in an embodiment of the invention; FIG. 2 is a perspective view of the inside of a portion of the FIG. 1 pump; FIG. 3 is a perspective view of a leakproof diaphragm for surrounding the tube inserted into the FIG. 1 pump; FIG. 4 is a perspective view of the pump body and of the force application system of the FIG. 1 pump in a spaced apart position so as to allow insertion of said tube; and FIG. 5 is a perspective view of the pump body and of the force application system of the FIG. 1 pump in the close position.

(2) With reference to the figures and as mentioned above, the invention relates to a linear peristaltic pump 1 for a dialysis machine. Said peristaltic pump 1 comprises a plate, known as a pump body 3, that includes a substantially plane surface 32 against which a flexible tube 5 for passing fluid is to be positioned. Said surface 32 is considered to be plane, or flat, i.e. straight, as opposed to contact surfaces in contact with the tube of so-called rotary peristaltic pump bodies that present a circularly arcuate shape.

(3) The peristaltic pump 1 also comprises a force application system 2, the system having a plurality of presser members 7 and drive means for moving said presser members 7 enabling said presser members to be moved while pressed against the tube in order to deform it against said pump body 3.

(4) Said pump body 3 and said system 2 are arranged relative to each other so as to allow a flexible tube 5 for passing fluid to be positioned between the plane surface 32 of the pump body 3 and the system 2. Said presser members 7 are moved along a closed loop path as described below. This closed loop path includes a portion directed towards the side of the pump body 3 and that allows the presser members 7 passing along this portion to press the duct against the plane surface 32 of the pump body 3.

(5) Preferably, said pump is used for pumping blood in a dialysis machine. In this event, said tube 5 forms a bloodline.

(6) Said plane surface 32 is directed towards said force application system 2 in order to make it possible for said system to apply a pressure force to the peripheral wall of said flexible tube 5 positioned against the pump body 3.

(7) Said pump body 3 is mounted to move relative to the force application system 2 between a position spaced apart from said force application system (see FIG. 4), and a position close to said force application system 2 (see FIG. 5). Said pump body 3 and the force application system 2 thus define between them a space for inserting the substantially straight flexible tube since it extends along the plane surface 32 of the pump body.

(8) When said force application system 2 is in a position spaced apart from the pump housing, the space left free between the force application system 2 and the pump body is sufficient for freely inserting the tube 5 between the force application system 2 and the pump body 3. Once the tube 5 is positioned against the plane face 32 of the pump body 3, the pump body 3 and the system 2 are brought into the close position in order to make it possible for the system 2 to apply force to the peripheral wall of the tube 5 from one end of the space for inserting the tube towards the other end.

(9) A force is applied to the peripheral wall of the tube 5 by said presser members 7 pressing against the peripheral wall of said tube so as to gradually deform it along its portion pressing against the plane face 32 of the pump body 3 and thus causing the fluid contained in the tube 5 to flow from one end of the surface 32 towards its other end. Said pump body 3 is mounted to move in translation along a (preferably orthogonal) direction D31 that is transverse to said plane surface 32 of the pump body.

(10) Said pump includes motor means 31 for moving said pump body 3 between said closer position and said spaced apart position.

(11) Said pump 1 also includes means 35 for determining a magnitude that is representative of the force applied to the peripheral wall of the tube 5, when said tube 5 is in its state positioned between the force application system 2 and the pump body 3. Said means 35 for determining a magnitude representative of the force applied to the tube 5 include at least one strain gauge. Advantageously, said at least one strain gauge is positioned on a plate arranged so as to become deformed as a function of the relative position between system 2 and said pump body 3. Preferably, said means 35 include two or four strain gauges.

(12) Said pump 1 further comprises governor means 36 for governing the movement of the pump body 3 relative to the system 2 as a function of said determined magnitude.

(13) Said governor means are formed by an electronic and computer unit for processing and calculation. Said unit may be embodied in the form of an electronic circuit provided with a microcontroller or a microprocessor associated with a memory for storing data. Thus, in the description below, when it is specified that given means are configured to perform a given operation, it should be understood that the electronic and computer system forming said means, includes computer instructions making it possible to perform said operation.

(14) Said governor means 36 include means 360 for defining a setpoint value for said magnitude. This setpoint value corresponds to the force desired for pinching the tube 5 between the system 2 and the pump body 3. Said governor means 36 further include regulator means 361 that are configured to regulate the movement of the pump body 3 in the direction moving the force application system 2 closer or further apart as a function of the determined value of said magnitude in order to reach said setpoint value.

(15) Thus, using the determination means 35, said regulation means 36 are configured to acquire the value of said magnitude representative of the force applied to the peripheral wall of the tube 5, and to compare this acquired value with the stored setpoint value. Depending on the result of this comparison the governor means 36 control the motor 31 so that it moves the pump body 3 towards or away from the system 2 until a value is reached that is close to the setpoint value or that is located in a given range relative to the setpoint value.

(16) Said drive means for moving the presser members 7 include a loop element 6 that connects the presser members 7 to one another, and two rotary cylinders 8, positioned inside and at opposite ends of said loop element 6. At least one of the cylinders 8 is motor-driven in order to cause the loop element 6 to move around said cylinders 8. Advantageously, the presser members 7 are rollers.

(17) The loop element 6 comprises a drive belt arranged in a loop around the cylinders 8. One of the cylinders 8 is driven by a motor 81 so that said cylinder forms a cylinder suitable for driving the belt around said cylinders. The other cylinder forms a support for guiding movement of the belt.

(18) The rollers 7 are mounted to be constrained to move with the belt 6 and they project from the outer face of said belt so that the tube is pressed when said rollers move along the tube.

(19) As explained above, the loop element includes at least one substantially straight portion that extends substantially parallel to the plane surface 32 of the pump body 3, so that the rollers that are moved along said straight portion press the tube from one end of the portion towards the other end.

(20) Said pump includes a housing 10 in which the system 2 and the pump body 3 are housed, and the pump body 3 is mounted to move relative to said housing 10.

(21) As shown more particularly in FIG. 3, said pump 1 includes a diaphragm 9 that, when said tube is in the state positioned between the force application system and the pump body plate extends around the peripheral wall of said tube 5 in order to form a protective casing around said tube 5 in cooperation with a wall of the housing 10, opposite the bottom of the diaphragm.

(22) Said diaphragm 9 is made out of a liquid-proof flexible material.

(23) Advantageously, provision may be made for the space left free between the system 2 and the pump body 3 to be located in the top portion of the pump so as to be easily accessible by the operator.

(24) The present invention is not limited in any way to the embodiments described and shown, and the person skilled in the art can make any variation thereto in accordance with its spirit.