Metering pump with temporary reversal of direction of the displacement element

Abstract

The present invention relates to a method for moving a fluid comprising the steps a. providing a metering head comprising a metering chamber and a displacement element which delimits said metering chamber, b. moving the displacement element in a suction direction from a first position to a second position, wherein a volume of the metering chamber in the second position of the displacement element is greater than a volume of the metering chamber in the first position of the displacement element such that fluid is drawn into the metering chamber via a fluid inlet during a suction stroke, c. moving the displacement element in a pressure direction from the second position to the first position such that fluid is forced out of the metering chamber via a fluid outlet during a pressure stroke. In order to provide a method for moving a fluid or a corresponding metering pump with which a number of the aforementioned disadvantages are prevented without the need for additional components, it is proposed according to the invention that the movement of the displacement element in suction direction during the suction stroke involve at least two changes of direction before the displacement element reaches the second position and/or that the movement of the displacement element in pressure direction during the pressure stroke involve at least two changes of direction before the displacement element reaches the first position.

Claims

1. Method for moving a fluid comprising the steps of (a). providing a metering head (2) having a metering chamber (3) and a displacement element (4) which delimits said metering chamber (3), (b). moving the displacement element (4) in a suction direction (10) from a first position (12) to a second position (13), wherein a volume of the metering chamber (3) in the second position (13) of the displacement element (4) is greater than a volume of the metering chamber (3) in the first position (12) of the displacement element (4) such that fluid is drawn into the metering chamber (3) via a fluid inlet (8) during a suction stroke, (c). moving the displacement element (4) in a pressure direction (11) from the second position (13) to the first position (12) such that fluid is forced out of the metering chamber (3) via a fluid outlet (9) during a pressure stroke, characterized in that the movement of the displacement element (4) in pressure direction (11) during the pressure stroke involves at least two changes of direction (16, 17) before the displacement element (4) reaches the first position (12).

2. The method according to claim 1, wherein the displacement element (4) is moved by means of a drive (6), wherein the drive (6) is a linear motor.

3. The method according to claim 1, wherein the displacement element (4) is moved at a speed of at least 1 m/s.

4. The method according to claim 1, wherein the displacement element (4) travels a distance x between the first position (12) and the second position (13) when the displacement element (4) is moved without a change of direction from the first position (12) to the second position (13) or vice versa, wherein the displacement element (4) travels a distance (1+2a)x when the movement of the displacement element (4) in suction direction (10) or pressure direction (11) involves two changes of direction (16, 17), wherein a is at least 0.1.

5. The method according to claim 1, wherein the displacement element (4) is periodically accelerated with an acceleration of at least 100 m/s.sup.2 and at most 400 m/s.sup.2.

6. The method according to claim 5, wherein the displacement element (4) is periodically accelerated at the beginning or at the end of the suction or pressure stroke or before or after the change of direction of the movement.

7. Metering pump (1) for moving a fluid, comprising: a metering head (2), a metering chamber (3) disposed in said metering head, and a displacement element (4) which can be moved back and forth between a first position (12) and a second position (13), wherein the displacement element (4) delimits the metering chamber (3), and a volume of the metering chamber (3) in the second position (13) of the displacement element (4) is greater than a volume of the metering chamber (3) in the first position (12) of the displacement element (4), wherein the displacement element (4) is coupled to a drive (6) via a movable element (5) such that, in an operation of the drive (6), in a housing, the movable element (5) carries out a forward stroke and a return stroke in the direction of an axis of movement having a stroke length h between a first end position and a second end position and the displacement element (4) is moved back and forth between the first position (12) and the second position (13), wherein the drive (6) further comprises a control device (7), characterised in that the control device (7) is configured to carry out a method according to claim 1.

8. The metering pump (1) according to claim 7, wherein the movable element (5) and the displacement element (4) are integrally formed.

9. The metering pump (1) according to claim 7, wherein the control device (7) is further configured such that an acceleration of the movable element (5) at the beginning of the forward and/or return stroke is greater than an acceleration of the movable element (5) at the end of the forward and/or return stroke, or vice versa.

10. The metering pump (1) according to claim 7, wherein the displacement element (4) divides the metering head (2) into the metering chamber (3) and a hydraulic chamber, wherein the hydraulic chamber is or can be filled with a hydraulic fluid, wherein a stroke element is disposed in the hydraulic chamber and connected to the movable element (5) such that a movement of the movable element (5) during operation of the drive (6) causes a force exerted by the stroke element on the hydraulic fluid to be transferred to the displacement element (4).

11. Method for moving a fluid comprising the steps of (a). providing a metering head (2) having a metering chamber (3) and a displacement element (4) which delimits said metering chamber (3), (b). moving the displacement element (4) in a suction direction (10) from a first position (12) to a second position (13), wherein a volume of the metering chamber (3) in the second position (13) of the displacement element (4) is greater than a volume of the metering chamber (3) in the first position (12) of the displacement element (4) such that fluid is drawn into the metering chamber (3) via a fluid inlet (8) during a suction stroke, (c). moving the displacement element (4) in a pressure direction (11) from the second position (13) to the first position (12) such that fluid is forced out of the metering chamber (3) via a fluid outlet (9) during a pressure stroke, characterized in that the movement of the displacement element (4) in suction direction (10) during the suction stroke involves at least two changes of direction (16, 17) before the displacement element (4) reaches the second position (13) and that the movement of the displacement element (4) in pressure direction (11) during the pressure stroke involves at least two changes of direction (16, 17) before the displacement element (4) reaches the first position (12).

12. The method according to claim 11 wherein the displacement element (4) is moved by means of a drive (6), wherein the drive (6) is a linear motor.

13. The method according to claim 11, wherein the displacement element (4) is moved at a speed of at least 1 m/s.

14. The method according to claim 11, wherein the displacement element (4) is periodically accelerated with an acceleration of at least 100 m/s.sup.2 and at most 400 m/s.sup.2.

15. The method according to claim 14, wherein the displacement element (4) is periodically accelerated at the beginning or at the end of the suction or pressure stroke or before or after the change of direction of the movement.

16. The method according to claim 11, wherein the displacement element (4) travels a distance x between the first position (12) and the second position (13) when the displacement element (4) is moved without a change of direction from the first position (12) to the second position (13) or vice versa, wherein the displacement element (4) travels a distance (1+2a)x when the movement of the displacement element (4) in suction direction (10) or pressure direction (11) involves two changes of direction (16, 17), wherein a is at least 0.1.

17. Metering pump (1) for moving a fluid, comprising: a metering head (2), a metering chamber (3) disposed in said metering head, and a displacement element (4) which can be moved back and forth between a first position (12) and a second position (13), wherein the displacement element (4) delimits the metering chamber (3), and a volume of the metering chamber (3) in the second position (13) of the displacement element (4) is greater than a volume of the metering chamber (3) in the first position (12) of the displacement element (4), wherein the displacement element (4) is coupled to a drive (6) via a movable element (5) such that, in an operation of the drive (6), in a housing, the movable element (5) carries out a forward stroke and a return stroke in the direction of an axis of movement having a stroke length h between a first end position and a second end position and the displacement element (4) is moved back and forth between the first position (12) and the second position (13), wherein the drive (6) further comprises a control device (7), characterised in that the control device (7) is configured to carry out a method according to claim 11.

18. The metering pump (1) according to claim 17, wherein the movable element (5) and the displacement element (4) are integrally formed.

19. The metering pump (1) according to claim 17, wherein the control device (7) is further configured such that an acceleration of the movable element (5) at the beginning of the forward and/or return stroke is greater than an acceleration of the movable element (5) at the end of the forward and/or return stroke, or vice versa.

20. The metering pump (1) according to claim 17, wherein the displacement element (4) divides the metering head (2) into the metering chamber (3) and a hydraulic chamber, wherein the hydraulic chamber is or can be filled with a hydraulic fluid, wherein a stroke element is disposed in the hydraulic chamber and connected to the movable element (5) such that a movement of the movable element (5) during operation of the drive (6) causes a force exerted by the stroke element on the hydraulic fluid to be transferred to the displacement element (4).

Description

(1) Further advantages, features, and possible applications of the present invention will become apparent from the following description of an embodiment and the associated figures.

(2) FIG. 1 shows a schematic illustration of a metering pump known from the state of the art.

(3) FIG. 2 schematically shows the position of the displacement element as a function of time for the method according to the invention during a pressure stroke.

(4) FIG. 3 is a schematic view of a metering pump according to the present invention, including a hydraulic chamber 20, a stroke element 21, and a movable element 5.

(5) The metering pump 1 shown in FIG. 1 comprises a metering head 2, in which a metering chamber 3 and a displacement element 4 are disposed. The displacement element 4 can be moved back and forth between a first position 12 and a second position 13 (see FIG. 2) and delimits the metering chamber 3. When the displacement element 4 is moved back and forth between the first position 12 and the second position 13 with the aid of a movable element 5 of a drive 6, a volume of the metering chamber 3 changes and with it the pressure conditions inside the metering chamber 3.

(6) When the displacement element 4 is moved from the first position 12 to the second position 13 during a suction stroke in suction direction 10, the volume of the metering chamber 3 increases, underpressure is created in the metering chamber 3 and fluid is drawn into the metering chamber 3 via a fluid inlet 8.

(7) When the displacement element is moved from the second position 13 to the first position 12 during a pressure stroke in pressure direction 11, the volume of the metering chamber 3 decreases, overpressure is created and fluid is forced out of the metering chamber 3 via a fluid outlet 9.

(8) The metering pump shown in FIG. 1 further comprises a control device 7 which controls the drive 6. According to the invention, the drive 6 is controlled by the control device 7 such that, during the pressure stroke, i.e. a movement from the second position 13 to the first position 12 in pressure direction 11, the displacement element 4 carries out two changes of direction 16, 17.

(9) FIG. 2 shows the position 14 of the displacement element 4 as a function of time for the pressure stroke. In Section A, the displacement element 4 moves from the second position 13 in pressure direction 11 toward the first position 12. Before the displacement element 4 reaches the first position 12, however, a first change of direction 16 takes place so that the displacement element now periodically moves in the opposite direction, i.e. in suction direction 10 (Section B). A second change of direction 17 takes place at the end of Section B, so that the displacement element 4 moves in pressure direction 11 again until the displacement element 4 has reached the first position 12 (Section C).

LIST OF REFERENCE SIGNS

(10) 1 Metering pump 2 Metering head 3 Metering chamber 4 Displacement element 5 Movable element 6 Drive 7 Control device 8 Fluid inlet 9 Fluid outlet 10 Suction direction 11 Pressure direction 12 First position 13 Second position 14 Position of the displacement element 16 First change of direction 17 Second change of direction 20 hydraulic chamber 21 stroke element