DRIVE UNIT FOR MOTOR DOSING PUMP

Abstract

A drive unit for a motor metering pump and a metering pump, including a drive chamber and a drive shaft arranged in the drive chamber. The drive shaft is rotated about a longitudinal axis in a direction of rotation during operation of the drive unit, the drive unit includes a bearing in which the drive shaft is mounted. The drive chamber is filled with a lubricant up to a filling level during operation of the drive unit, and the bearing is arranged above the filling level in the direction of the longitudinal axis. The drive shaft has a conveying channel for the lubricant, which extends from a first point below the filling level to a second point above the filling level and is arranged in such a way that, during operation of the drive unit, lubricant is transported from the first point to the second point.

Claims

1-14. (canceled)

15. A drive unit for a motor metering pump, comprising a drive chamber and a drive shaft arranged in the drive chamber, wherein the drive shaft is rotated in a direction of rotation about a longitudinal axis during operation of the drive unit, wherein the drive unit comprises a bearing in which the drive shaft is mounted, wherein the drive chamber is filled with a lubricant up to a filling level during operation of the drive unit, wherein the bearing is arranged above the filling level in the direction of the longitudinal axis, wherein the drive shaft comprises a conveying channel for the lubricant which extends from a first point below the filling level to a second point above the filling level and is arranged such that during operation of the drive unit lubricant is transported from the first point to the second point, characterized in that the conveying channel is formed as a recess in an lateral surface of the drive shaft.

16. The drive unit according to claim 15, wherein the conveying channel has a first boundary wall which delimits at least a section of the conveying channel in the radial direction, wherein preferably the conveying channel comprises a channel guide wall extending along the longitudinal axis or a channel guide wall inclined with respect to the longitudinal axis, and the first and a second boundary wall, wherein the first and the second boundary wall extend along the longitudinal axis and do not lie in a plane with the channel guide wall.

17. The drive unit according to claim 15, wherein the drive shaft has a conveying section and a bearing section arranged in the direction of the longitudinal axis next to the conveying section and above the filling level, the conveying section projecting at least in sections in a radial direction with respect to the longitudinal axis beyond the bearing section, so that the conveying section has an upper surface and a lateral surface, wherein the upper surface forms an end of the conveying section facing the bearing section and is arranged above the filling level, wherein the conveying channel has an opening in the upper surface and an opening in the lateral surface, wherein the conveying section is configured such that when the drive shaft rotates in the direction of rotation, lubricant enters the conveying channel via the opening in the lateral surface and exits the conveying channel via the opening in the upper surface.

18. The drive unit according to claim 16, wherein the channel guide wall is inclined relative to the longitudinal axis by a maximum of 85, the inclination being such that, when the drive shaft is rotated in the direction of rotation, lubricant is lifted from the channel guide wall above the filling level.

19. The drive unit according to claim 18, wherein the channel guide wall is delimited by the upper surface.

20. The drive unit according to claim 16, wherein a first connecting section extending along the longitudinal axis is provided between the channel guide wall and the lateral boundary walls, wherein the first connecting section is curved with a radius of curvature, wherein preferably the lateral boundary walls are delimited by the lateral surface, and between the lateral boundary walls and the lateral surface a second connecting portion is provided which is curved with a radius of curvature.

21. The drive unit according to claim 16, wherein the channel guide wall comprises at least two portions which enclose a different angle with the longitudinal axis, wherein preferably a portion of the channel guide wall spaced from the upper surface encloses a larger angle with the longitudinal axis than a portion of the channel guide wall (6a) adjacent to the upper surface.

22. The drive unit according to claim 16, wherein the channel guide wall is convexly curved at least in sections.

23. The drive unit according to claim 17, wherein the conveying section is cylindrical.

24. The drive unit according to claim 15, wherein the drive shaft comprises two or more conveying channels, wherein a number N of conveying channels is preferably arranged around the longitudinal axis such that the drive shaft has an N-fold rotational symmetry.

25. The drive unit according to claim 15, wherein the second point is arranged at most 50 mm above the filling level.

26. The drive unit according to claim 15, wherein the bearing comprises a lower boundary surface arranged at an angle to the longitudinal axis, wherein the conveying channel ends at the lower boundary surface.

27. The drive unit according to claim 15, wherein the drive shaft comprises an actuating member engaged with an eccentric for converting a rotational movement of the drive shaft into a translational movement, wherein the drive shaft further comprises a conveying section, wherein the conveying section is arranged along the longitudinal axis above the actuating member, wherein the conveying section comprises the conveying channel.

28. A metering pump for conveying a fluid, comprising a displacement element and a metering chamber, wherein the displacement element delimits the metering chamber and is movable back and forth between a pressure position and a suction position, wherein a volume of the metering chamber in the pressure position of the displacement element is smaller than a volume of the metering chamber in the suction position of the displacement element, wherein a drive unit according to claim 15 is provided, with which a drive force is applied to the displacement element during operation of the metering pump.

Description

[0031] Further advantages, features and possible applications of the present invention will become clear from the following description of an embodiment and the accompanying figures. Identical components are described by the same reference signs.

[0032] FIG. 1 shows a schematic representation of an embodiment of the drive unit according to the invention.

[0033] FIG. 2 shows a three-dimensional schematic representation of the drive shaft of the embodiment shown in FIG. 1.

[0034] FIG. 3a shows a drive shaft of a further embodiment of the drive unit according to the invention.

[0035] FIG. 3b shows a drive shaft of a further embodiment of the drive unit according to the invention.

[0036] FIG. 4 shows a schematic representation of a metering pump with the drive unit according to the invention.

[0037] The drive unit 1 shown in FIGS. 1, 2 and 4 has a drive chamber 2 in which a bearing section 8 of the drive shaft 3 is supported in a bearing 4. The drive shaft 3 extends along a longitudinal axis 101 and is rotated about the longitudinal axis 101 in a direction of rotation 100 during operation of the drive unit 1.

[0038] The drive chamber 2 is filled with a lubricant up to a filling level 5 for lubricating the drive shaft 3. In order to also supply the bearing 4, which is arranged above the filling level 5, with lubricant, the drive shaft 3 has a conveying section 7 with a conveying channel 6 which extends from a first point below the filling level 5 to a second point above the filling level 5.

[0039] The arrangement of the conveying channel 6 in the conveying section 7 according to the embodiment shown in FIGS. 1, 2 and 4 becomes particularly clear from FIG. 2. Due to the arrangement of an opening of the conveying channel 6 in the lateral surface 7b of the conveying section 7, which extends into an area below the filling level 5, lubricant can enter into the conveying channel 6. Due to the rotation of the drive shaft 3 in the direction of rotation 100 and the centrifugal forces acting therewith, the lubricant is conveyed to an opening of the conveying channel 6 in an upper surface 7a of the conveying section 7, which is located above the filling level 5.

[0040] The lubricant thus exits in an area of the drive shaft 3 where the bearing section 8 and the conveying section 7 are in contact with the bearing 4. In particular, there is contact between the upper surface 7a of the conveying section and a lower boundary surface 4a of the bearing 4. These contact surfaces, which are formed by rolling elements of the bearing 4 and are subject to a high level of friction during rotation of the drive shaft 3, are thus sufficiently supplied with lubricant without the need to raise the filling level 5. Further lubricant supply to other bearing components, such as the rolling element cage in which the rolling elements are held, is then ensured via the rolling elements which are supplied with the lubricant.

[0041] Various options are available for the design of the conveying channel 6. The conveying channel 6 of the embodiment shown in FIGS. 1, 2 and 4 has a channel guide wall 6a comprising two portions 6a, 6a, wherein a portion 6a adjacent to the upper surface 7a of the conveying section 7 extends along the longitudinal axis 101, while a portion 6a spaced from the upper surface 7a encloses an angle with the longitudinal axis 101. Further, the portion 6a spaced from the upper surface 7a is convex, thus curving outwardly into the conveying section 7 as viewed from the conveying channel 6.

[0042] Further, the conveying channel 6 is delimited in the radial direction by two boundary walls 6b, which connect at an angle to the portions 6a, 6a of the channel guide wall 6a.

[0043] FIGS. 3a and 3b show alternative embodiments for the design of the conveying channel 6. In the embodiment shown in FIG. 3a, the conveying channel 6 has a channel guide wall 6a that extends along the longitudinal axis 101 and is connected to the boundary walls 6b via a first curved connecting section 6c. The boundary walls 6b in turn merge with the lateral surface 7b of the conveying section 7 via a second curved connecting section 6d.

[0044] In contrast, the conveying channel 6 shown in FIG. 3b has only one lateral boundary wall 6b, whereas the channel guide wall 6a consists of two portions 6a and 6a which are inclined with respect to the longitudinal axis 101 and wherein the portion 6a spaced from the upper surface 7a forms a larger angle with the longitudinal axis 101 than the portion 6a adjacent to the upper surface 7a, which is additionally convex, i.e. curves into the body of the conveying section 7 as viewed from the conveying channel 6.

[0045] The conveying section 7 of the drive shaft 3 shown in FIGS. 3a and 3b each has two conveying channels 6 arranged rotationally symmetrically with respect to the longitudinal axis 101.

[0046] FIG. 4 illustrates the mode of operation of the drive unit 1 according to the invention in a metering pump 10. The drive unit 1 moves a displacement element 11 back and forth between a pressure position and a suction position, whereby a fluid to be conveyed is sucked into a metering chamber 12 or pressed out again. For this purpose, the rotational movement of the drive shaft 3 is converted into a translational movement via an actuating member 9 and an eccentric, which moves the displacement element 11 back and forth along a movement axis.

[0047] Despite the economical supply of lubricant to the bearing 4 by the design of the drive unit 1 according to the invention, the metering pump 10 can be used in areas where, for example, explosive substances are used. Due to the continuous supply of lubricant to the bearing 4 in accordance with the invention, there is no risk of lubricants leaking out or of the bearing 4 not being sufficiently lubricated, resulting in increased friction and heat generation. Any requirements for a level of ignition protection can thus be met despite lower lubricant use. This not only saves costs for lubricants, but also increases the service life of the metering pump 10.

LIST OF REFERENCES

[0048] 1 Drive unit [0049] 2 Drive chamber [0050] 3 Drive shaft [0051] 4 Bearing [0052] 4a Lower boundary surface of the bearing [0053] 5 Filling level [0054] 6 Conveying channel [0055] 6a Channel guide wall [0056] 6a, 6a Sections of the channel guide wall [0057] 6b Lateral boundary wall [0058] 6c First connecting section [0059] 6d Second connecting section [0060] 7 Conveying section [0061] 7a Upper surface [0062] 7b Lateral surface [0063] 8 Bearing section [0064] 9 Actuating member [0065] 10 Metering pump [0066] 11 Displacement element [0067] 12 Metering chamber [0068] 100 Direction of rotation [0069] 101 Longitudinal axis