Oscillation metering pump

Abstract

The invention relates to an oscillating metering pump. The invention relates to a metering pump for conveying a fluid, comprising: a metering head in which a metering chamber is arranged; a displacement element movable back and forth between a first position and a second position on a movement axis; and a drive which rotates about the axis of rotation, whereby a rotational movement of the drive about the axis of rotation is converted into a swinging movement of the connecting rod by means of the gear device. The connecting rod is connected to the displacement element in such a way that the displacement element moves back and forth along the axis of movement, whereby the actuator performs a turn angle [alpha] lt during operation of the metering pump; the invention relates to a gear arrangement for a connecting rod having a rotational axis and a swinging movement of 360 DEG and a frequency f, and comprising a cam drive which is arranged on the rotational axis and has a curved running surface which is offset at least in sections from a circular path around the rotational axis, on which running surface the connecting rod rolls via a roller, the travel length of the displacement element is determined by the angle alpha and the slope of the running surface, and the travel frequency of the displacement element is determined by the frequency f.

Description

[0001] The invention relates to a metering pump for delivering a metered volume of a fluid, the metering pump comprising: at least one metering head in which a metering chamber is arranged; a displacement element that is movable back and forth between a first position and a second position along a displacement axis, wherein the displacement element delimits the metering chamber and the volume of the metering chamber in the first position of the displacement element is greater than the volume of the metering chamber in the second position of the displacement element; and a drive that rotates about a rotation axis, wherein during operation of the metering pump, the rotational movement of the drive about the rotation axis is converted by a gear arrangement into an oscillating movement of a connecting rod. The connecting rod is connected to the displacement element in such a way that the displacement element moves back and forth along the displacement axis between the first position and the second position.

[0002] Furthermore, the invention relates to a metering method for delivering a metered volume of a fluid, in particular a method for operating a metering pump of the aforementioned type, in which a rotational movement of a drive is converted into a stroke movement of a displacement element by means of a gear mechanism.

[0003] Various designs of metering pumps are known from the prior art.A large part of the applications of metering pumps involves setting, controlling or regulating a specific metered volume of a fluid to be delivered, for example in order to supply a process with fluid in a temporally defined sequence.

[0004] Such metering pumps are typically used, for example, for metering chemical substances. In order to enable the fluid to be metered, the metering head is provided with a displacement element which can be moved back and forth between a first position and a second position and which defines a metering chamber.

[0005] Usually, the metering chamber of metering pump also has fluid outlet, by this fluid outlet, the fluid absorbed in the metering chamber is delivered to metering head.Realize delivering from metering head by reducing the volume of metering chamber, this is also referred to as pressure stroke (pressure stroke), and wherein displacement element moves to second position.

[0006] If the metering pump is operated with only one fluid outlet, the metering pump can be used as a pulsator, for example to drive an extraction column.

[0007] However, in most cases, the metering head also has a fluid inlet through which the fluid to be delivered is sucked into the metering chamber when the displacement element is moved to the first position, thereby increasing the volume of the metering chamber. This is also called the suction stroke.

[0008] In this way, a metering pump can be used to deliver a fluid, wherein the fluid is drawn in through the fluid inlet as the volume of the metering chamber increases, and delivered through the fluid outlet as the volume of the metering chamber decreases. Accidental backflow of the fluid is prevented by a suitably arranged check valve.

[0009] For example, a membrane can be used as the displacement element. Alternatively, the displacement element can also be a piston.

[0010] The displacement element is moved by a drive, which can be, for example, a motor or part of a motor. Rotary electric motors are often used as drives in metering pumps, where the rotational motion about an axis of rotation is converted into a linear motion of the displacement element between a first and a second position. For this purpose, a gear mechanism is provided, which is connected to the displacement element via a connecting rod. The connecting rod has a sinusoidal motion.

[0011] The metering volume of the fluid that can be delivered by the metering pump corresponds substantially to the volume change of the metering chamber between the first position and the second position of the displacement element. From the prior art, various solutions are known for regulating the metering volume of the fluid that can be delivered by the metering pump within a certain period of time.

[0012] For example, one solution is to vary the frequency with which the displacement element moves back and forth between the first and second positions. This changes the metered volume delivered per unit time. In the simplest case, the motor speed is varied accordingly. However, motor speed cannot be adjusted arbitrarily, making this approach unsuitable for every application. For example, processes requiring good mixing of the delivered fluid cannot be achieved with a low metering frequency.

[0013] Alternatively, the stroke length of the displacement element—that is, the distance between the first and second positions—can be varied to adjust the volume change in the metering chamber and, therefore, the metered volume. In metering pumps operating with a rotary drive, this is typically achieved through an additional stroke length adjustment provided independently of the drive. This type of stroke length adjustment is known in the prior art as a mechanical adjustment of the stroke length, for example, using a mechanically adjustable stroke adjustment spindle, which limits the backward movement of the connecting rod during the suction stroke. However, this additional mechanical adjustment option for stroke length makes the pump design more expensive and complex, and makes it more difficult for the metering pump user to adjust the metered volume. Furthermore, the aforementioned stroke adjustment spindle has the disadvantage that optimal metering of the fluid is achieved only at the full stroke length, where the connecting rod performs a sinusoidal motion. If the movement of the connecting rod is limited by mechanical means, the sinusoidal motion of the connecting rod is interrupted. This results in so-called phase cuts, which can cause pressure surges and pulsations in the metering pump and metering system. Furthermore, such metering pumps typically require an additional, expensive return spring to force the backward movement of the displacement element during the suction stroke.

[0014] Furthermore, the prior art discloses metering pumps operated with linear motors, whose starting and ending positions are linked to the first and second positions of a displacement element and are set according to the desired stroke length. Furthermore, the frequency of the linear motor can be adjusted. However, metering pumps with linear motors are associated with high costs.

[0015] The present invention is therefore based on the problem of providing a metering pump or a metering method for delivering a metered volume of a fluid, by which the metering volume can be controlled by simple means without requiring additional mechanical adjustments of the metering pump.

[0016] This problem is solved by a metering pump of the type described above, wherein, during operation of the metering pump, the drive executes a pendular movement with a twist angle α<360° and a frequency f, and wherein the gear arrangement comprises a cam gear which is arranged on the axis of rotation and has a curved running surface which deviates at least in sections from a circular path about the axis of rotation, the connecting rod rolling over a roller on the running surface so that the stroke length of the displacement element is determined by the twist angle α and the slope of the running surface, and the stroke frequency of the displacement element is determined by the frequency f.

[0017] An oscillating motion within the meaning of the present invention is a rotational motion around the axis of rotation with an angle of rotation of less than 360°. In other words, the drive of the metering pump according to the present invention does not perform a complete rotation, but rather changes the direction of rotation around the axis of rotation.

[0018] The slope of the running surface is defined as the quotient of the angle of rotation α and the stroke length "h" covered by the displacement element for the angle of rotation α, i.e. the starting angle α0 and the ending angle α on the axis of motion. 结束 In particular, the stroke length "h" corresponds to the deviation "e" of the curved running surface at the angle α from a circular path around the axis of rotation, the origin radius r0 of the circular path being defined by the distance between the running surface and the axis of rotation at the starting angle α0.

[0019] Due to the oscillating movement of the drive according to the invention, the movement frame of the displacement element on the movement axis, i.e. the stroke length, depends on the rotation angle of the drive about the axis of rotation and the slope of the curved running surface or the deviation of the curved running surface from a circular path about the axis of rotation.

[0020] The greater the deviation e of the curved running surface from the circular path with radius r0, the greater the displacement element's travel distance along the axis of movement. If the deviation e increases with the rotation angle—that is, if the curved running surface rises relative to the axis of rotation—then the displacement element's stroke length increases when a larger rotation angle is set. This also increases the metered volume to be delivered. Similarly, as the rotation angle decreases, the metered volume decreases.

[0021] At the same time, the metered volume delivered per unit time can be adjusted by the frequency f of the driver's oscillating motion. Therefore, the metered volume, determined by the stroke length and stroke frequency, can be controlled solely by the driver. Mechanical adjustment of the stroke length independently of the motor control is no longer necessary. Both stroke length and stroke frequency are influenced solely by the motor control. This simplifies pump design and reduces manufacturing costs.

[0022] Individual metering profiles can be created using curved shapes of any complexity, even with varying slopes, depending on the selected curve for the running surface and the section of the curved running surface in which the roller rolls. In one embodiment, the curved running surface thus has varying slopes. This allows the curved running surface to follow a freely selectable curved shape. The slope of the running surface section in which the roller rolls, depending on the set rotation angle α, determines the stroke length. Optimizing the curved profile of the running surface can influence the metering speed and pulsation of the fluid, as well as the acceleration of the drive, the drive torque, and the roller load. This also has a positive impact on the service life of the drive.

[0023] This individual setting ensures a particularly uniform metering process for all adjustable stroke lengths. There is no phase interruption at reduced stroke lengths. A uniform, sinusoidal connecting rod movement is ensured for all stroke lengths.

[0024] In one embodiment, the rotation angle is α ≤ 180°, and preferably α ≤ 120°. A smaller rotation angle has the advantage that, depending on the application, a less powerful and therefore more cost-effective drive can be used. The larger the maximum possible rotation angle, the higher the motor speed must be. However, the motor torque no longer behaves linearly with increasing speed and decreases as speed increases. Therefore, for larger rotation angles, a motor must be selected that still has sufficiently constant torque at high speeds to provide the desired delivery rate.

[0025] The advantage of a larger rotation angle is that the roller load is more favorable, because a larger rotation is performed and the roller is therefore not only subjected to forces in a smaller area. In addition, the full suction stroke and full pressure stroke of the displacement element or connecting rod can be performed during the rotation of the drive in only one direction, thereby reducing energy consumption, the load on the drive, and the number of direction changes. For this purpose, the curved running surface is preferably designed to be mirror-symmetrical about a mirror axis perpendicular to the rotation axis, so that for the starting rotation angle α0 and the ending rotation angle α 结束 For example, a curved running surface deviates from a circular path by the same amount.

[0026] In another embodiment, the slope of the curved running surface is constant, wherein the running surface is particularly defined by a circular path around a center, wherein the center is different from the rotation axis. In other words, the running surface is arranged eccentrically with respect to the rotation axis.

[0027] In another embodiment, the cam drive is designed as a disc having a groove with a curved running surface, so that the connecting rod is guided in the groove via rollers, the groove being preferably closed. Guiding the connecting rod via rollers in the curved, preferably closed groove offers the advantage that both the force for pushing the connecting rod during the pressure stroke and the force for pulling the connecting rod during the suction stroke can be transmitted via the disc. Consequently, no additional pretensioning device is required to push the connecting rod back during the suction stroke.

[0028] During the pressure stroke, the connecting rod is pushed by the roller from the inner running surface of the groove in the direction of the second position, which is closer to the rotation axis than the outer running surface of the groove, while during the suction stroke, the connecting rod is pulled by the roller from the outer running surface in the direction of the first position. In other words, both the suction stroke and the pressure stroke are force-controlled by the groove of the driver.

[0029] Furthermore, the rollers are guided on both sides between the two running surfaces of the groove. Since there is only linear contact, power transmission is limited. If low-maintenance roller bearings are used, lubrication can be omitted.

[0030] Another advantage of a flat disk is that it requires less installation space. In addition, the disk is characterized by a low weight and a low mass moment of inertia, which is advantageous for the oscillating motion of the drive.

[0031] In another embodiment, the arc length of the groove is defined by an opening angle β around the axis of rotation, where α≤β. Preferably, β≈α applies max +Δ, where Δ is in the range of 2° to 5°, and α maxDescribes the maximum rotation angle that the drive's oscillating motion can execute. This ensures that the drive's change of direction of rotation is electronically controlled and that the roller does not hit the end of the groove, which could damage the drive.

[0032] In another embodiment, the curved running surface has at least two sections, preferably three sections, wherein at least two sections of the curved running surface have different slopes. The different slopes can be used to set a specific metering profile.

[0033] In particular, the first and third sections of the curved running surface have a smaller slope than the second section, with the second section being arranged circumferentially between the first and third sections relative to the axis of rotation. Preferably, the slope in the first and / or third sections is substantially zero. This results in stable sections with little or no slope at the beginning and end of the pump stroke, as well as a wide operating range with a large slope for delivering the majority of the metered volume. This allows for particularly smooth fluid delivery by avoiding surge pressures and pulsations.

[0034] In another embodiment, the slope of the running surface is selected so that for a movement of the connecting rod along the movement axis h1=1 mm, the inclination angle Between 5° and 360°, and preferably 8°≤α h1 ≤90°. The metering speed and volume are influenced, on the one hand, by the slope of the curved running surface, on the other hand by the acceleration of the drive, the drive torque, and the roller load. The angle of inclination determines the force or torque increase in the drive. A larger inclination angle reduces the force increase, thus reducing the load on the drive and, at the same time, lowering the fluid velocity in the metering chamber and metering system.

[0035] In another embodiment, the disk has a plurality N of preferably closed grooves, each groove comprising a curved running surface which deviates at least in sections from a circular path about the axis of rotation, wherein N={2, 3, 4} is particularly preferred, and wherein the grooves are particularly preferably arranged in a mirror-inverted manner around 360° / N with respect to the axis of rotation.

[0036] In particular, in another embodiment, the metering pump has a plurality of metering heads, each metering head having a metering chamber and a displacement element, wherein a plurality of M (a plurality M of) connecting rods are provided, wherein, in each case, a displacement element is connected to one of the grooves via a connecting rod, and in particular, M=N is applied in one embodiment. Utilize the drive according to the present invention, therefore several metering heads can be operated simultaneously. The metering heads preferably work in opposite cycles. That is to say, for example, if one of the displacement elements is performing a pressure stroke, another displacement element can perform a suction stroke at the same time so that the fluid is delivered when there is no pulsation.

[0037] In another embodiment, the drive is a controllable drive, preferably an electronically controllable drive, and particularly preferably a stepper motor or a brushless DC motor. These types of motors are particularly suitable for the required changes of direction and for performing partial circular motions during the oscillating motion of the drive according to the invention.

[0038] In another embodiment, the gear arrangement has a reduction gear arranged between the driver and the cam transmission. This allows the torque of the driver to be increased or the rotational speed to be reduced.

[0039] In another embodiment, the running surface of the cam transmission is coated with a sliding coating. This further reduces the friction between the connecting rod and the running surface to minimize wear.

[0040] The problem underlying the invention is also solved by a metering method of the type described above, wherein the rotational movement of the drive is an oscillating movement with an angle of rotation α<360° and a frequency f, and the gear arrangement comprises a cam drive which is arranged on the axis of rotation of the drive and has a curved running surface which deviates at least in sections from a circular path around the axis of rotation, wherein a connecting rod rolls on the running surface via a roller, wherein the connecting rod is connected to a displacement element such that the stroke length of the displacement element is determined by the angle of rotation α and the slope of the running surface, and the stroke frequency of the displacement element is determined by the frequency f.

[0041] In summary, the invention makes it possible to control the metering volume by varying the stroke length and by varying the stroke frequency solely through motor control. No additional means such as for adjusting the stroke length are required.

[0042] Further advantages, features and possible applications of the invention will become apparent from the following description of embodiments and the associated drawings.

[0043] Figure 1 A schematic diagram of an embodiment of a metering pump according to the invention is shown.

[0044] Figure 2 Shown Figure 1Three-dimensional representation of the drive unit of the embodiment of the metering pump shown in .

[0045] Figure 3 Shown Figure 2 Schematic cross section of the drive unit shown in FIG. 1 in a plane spanned by the axis of movement and the axis of rotation.

[0046] Figure 4a Shown Figure 2 Schematic side view of the drive unit shown in FIG in the starting position of the cam mechanism during a pressure stroke.

[0047] Figure 4b Shown Figure 2 Schematic side view of the drive unit shown in FIG in the center position of the cam mechanism during a pressure stroke.

[0048] Figure 4c Shown Figure 2 Schematic side view of the drive unit shown in FIG. 1 in the end position of the cam mechanism during a pressure stroke.

[0049] Figure 5a A schematic diagram of a cam transmission of a first embodiment of a metering pump according to the present invention is shown.

[0050] Figure 5b A schematic diagram of a cam transmission of a second embodiment of a metering pump according to the present invention is shown.

[0051] Figure 6a A schematic diagram of a cam transmission of a third embodiment of a metering pump according to the present invention is shown.

[0052] Figure 6b A schematic diagram of a cam transmission of a fourth embodiment of a metering pump according to the present invention is shown.

[0053] Figure 7 A schematic diagram of a cam transmission of a fifth embodiment of a metering pump according to the present invention is shown.

[0054] Figure 8 A schematic top view of a drive unit of a sixth exemplary embodiment of a metering pump according to the invention is shown.

[0055] like Figure 1 As shown, an embodiment of a metering pump according to the present invention has a metering head 10 for delivering a metered volume of a fluid, in which a metering chamber 11 is arranged. The metering chamber 11 is delimited by a displacement element 12, which can be moved back and forth between a first position and a second position on a displacement axis 100. The volume of the metering chamber 11 in the first position of the displacement element 12 is greater than the volume of the metering chamber 11 in the second position of the displacement element 12, wherein Figure 1The second position of the displacement element 12 is shown in FIG.

[0056] The metering chamber 11 further comprises a fluid inlet 13 and a fluid outlet 14. The fluid to be conveyed is sucked into the metering chamber 11 via the fluid inlet 13 and forced out of the metering chamber 11 via the fluid outlet 14. To this end, the displacement element 12 moves back and forth between a first position and a second position on the movement axis 100.

[0057] A rotary drive 20 is provided for moving the displacement element 12 back and forth between the first position and the second position, which rotates about an axis of rotation 200. During operation of the metering pump 1, the rotary motion of the shaft of the drive 20 about the axis of rotation 200 is converted via a gear arrangement 21 into an oscillating motion of a connecting rod 22, which is connected to the displacement element 12.

[0058] The rotary drive 20 is designed so that it performs an oscillating motion at a rotational angle α, thereby moving the connecting rod 22 back and forth. Therefore, the reciprocating motion of the displacement element 12 depends on the oscillating motion of the drive 20 and the design of the gear arrangement 21. The stroke length of the displacement element 12 is determined by the rotational angle α and the design of the running surfaces 230 and 231 of the gear arrangement 21, while the stroke frequency of the displacement element 12 is determined by the frequency f of the oscillating motion of the drive 20.

[0059] The design details of the drive unit of the metering pump according to the invention can be found in Figures 2 to 8 In particular, from Figure 2 It can be seen that, in addition to the reduction gear 26, the gear arrangement 21 also includes a cam drive 23 in the form of a disk arranged on the axis of rotation 200. The disk has a groove 25 comprising curved running surfaces 230, 231, on which the connecting rod 22 is guided via the roller 24. The curved running surfaces 230, 231 deviate from a circular path 300 about the axis of rotation 200, at least in some sections.

[0060] The movement sequence of the metering pump 1 according to the invention is as follows: Figure 4a 、 Figure 4b and Figure 4c Shown. Figure 4a In the starting position shown, the roller 24 is located at the first end of the groove 25 , in which position the connecting rod 22 is retracted to the right in the direction of the image. This position of the connecting rod 22 corresponds to the first position of the displacement element 12 . Figure 4b The central position of the cam drive 23 is shown, wherein the roller 24 is located in the center of the groove 25 and the connecting rod 22 has been moved to the left in the direction of the drawing. Figure 4c The end position of the cam drive 23 is shown, in which the connecting rod 22 is fully deflected to the left in the direction of the drawing. This representation corresponds to the second position of the displacement element 12.

[0061] therefore, Figures 4a to 4c The time sequence of the cam drive 23, i.e. the rotation in the counterclockwise direction, represents the pressure stroke in the sense of the present invention. In order to draw the fluid into the chamber, the movement sequence is in the opposite direction, i.e. according to Figure 4c to Figure 4a sequence, or by rotating the cam drive 23 clockwise.

[0062] Figure 5a 、 Figure 5b 、 Figure 6a 、 Figure 6b 、 Figure 7 and Figure 8 Various embodiments of the cam drive 23 of the metering pump 1 according to the invention are shown. Figure 5a Shows that already Figures 1 to 4c The cam transmission member 23 is depicted in FIG.

[0063] Figure 5a The cam transmission member 23 has a groove 25 with an arc length of β. Figure 5a The inner running surface 230 of the groove 25 shown is described by a circular path of radius r, the center 201 of which is offset by a deviation e from the center of the circular path 300 (i.e., the axis of rotation 200). The radius r0 of the circular path 300 is defined for the starting angle α0. The outer running surface 231 of the groove 25 is described by a circular path of radius R, the center of which is also offset by a deviation e from the center of the circular path 300. The oscillating movement of the driver 20 is limited by the cam drive 23 to an adjustable angle α≤β, where Figure 5a The arc length for β=90° is shown in FIG.

[0064] During the pressure stroke, i.e., when the cam drive 23 rotates counterclockwise about the axis of rotation 200, the force is transmitted via the inner running surface 230 of the groove 25, which is marked with a radius r. Conversely, during the suction stroke, i.e., during the clockwise movement about the axis of rotation 200, the outer running surface 231 with the larger radius R pulls the roller 24 back to the starting position. This means that no additional return spring is required for the connecting rod 22.

[0065] Figure 5b The embodiment of the cam drive 23 shown in FIG. Figure 5aThe embodiment shown in FIG differs primarily in the arc length β of the groove 25, which allows for a rotation angle α greater than 180°. The groove 25 is also designed to be mirror-symmetrical about the mirror axis 400, so that the running surfaces 230, 231 at both ends of the groove 25 deviate from the circular path 300 by the same amount. The advantage of this longer groove 25 is that the roller 24 is more evenly loaded due to the greater rotation about the rotation axis 200. Furthermore, the deviation at the groove ends allows the entire suction and pressure stroke of the displacement element 12 or connecting rod 22 to be performed during only one direction of rotation of the drive, thereby reducing energy consumption, load on the drive, and the number of direction changes.

[0066] Figure 6a , another embodiment of a cam transmission 23 is shown in FIG. , in which groove 25 features different slopes. Groove 25 has three sections 25a, 25b, and 25c. First section 25a and third section 25c have a slope of, for example, zero, i.e., the radius r of inner running surface 230 corresponds to radius r0 of circular path 300. Second section 25b, arranged circumferentially between first section 25a and third section 25c in the rotation axis 200, has a slope greater than zero. Inner running surface 230 of section 25b is described by a circular path of radius r1, with center 201 of circular path r1 offset from the center of circular path 300 by an amount e. Similarly, outer running surface 231 is described by a circular path of radius R1 around center 201.

[0067] Figure 6b Another embodiment of the cam drive 23 is shown, in which the groove 25 has a free curved shape. Compared to the previously described embodiment, Figure 6b The running surfaces 230, 231 of the groove 25 shown in FIG are not described by a circular path, but rather follow a freely curved shape. For a rotation angle α, there is a deviation e from the circular path 300 about the axis of rotation 200, which ultimately corresponds to the stroke length of the displacement element 12. The freely curved shape serves to individually specify the motion profile of the displacement element 12, namely the speed, acceleration, and deceleration during the suction and pressure strokes.

[0068] exist Figure 7 and Figure 8 In FIG. 2 , a cam drive 23 is shown having a plurality of grooves 25 , 25 ′, 25 ″, 25 ′″. All grooves have the same arc length β and a running surface with the same curved shape, ie the same deviation from the circular path 300 .

[0069] Figure 7 The drive unit shown can be used to operate two metering heads simultaneously. Figure 7Also shown are rollers 24, 24' arranged in each groove 25, 25', the rollers 24, 24' being connected to the connecting rods 22, 22'. The connecting rods 22, 22' are in turn connected to the connecting rods 22, 22'. Figure 1 The displacement element shown hereby generates a suction stroke in the other metering chamber while the connecting rod 22 generates a pressure stroke in the one metering head. To this end, the grooves 25, 25' of the cam member 23 are arranged 180° in mirror-image with respect to the axis of rotation 200, i.e., mirror-symmetrically with respect to the mirror axis 400, so that the connecting rods 22, 22' run in opposite cycles. This enables the metering pump 1 according to the present invention to achieve particularly low-pulsation delivery characteristics.

[0070] Although Figure 7 Two grooves are provided in the Figure 8 There are four grooves 25, 25', 25", 25'' provided, wherein Figure 8 The four grooves in the embodiment are arranged in a mirror-inverted manner at 90° about the axis of rotation 200. This results in mirror symmetry about the mirror axis 400, with the connecting rods guided by the rollers in the adjacent grooves 25, 25', 25", 25"' running in opposite cycles. The four metering heads can be connected to the Figure 8 The drive units shown operate simultaneously.

[0071] The advantage of the design of the metering pump 1 according to the invention is that both the stroke length of the displacement element 12 and the stroke frequency of the displacement element 12 can be set independently via the motor control, thereby influencing the metering volume of the metering pump 1 according to the invention by means of two control variables. By deviating the running surfaces 230, 231 from the circular path 300 or by a variable curvature of the running surfaces 230, 231 of the cam drive 23, any metering sequence can be set with the metering pump 1 according to the invention.

[0072] Reference Signs List

[0073] 1 metering pump

[0074] 10 Metering head

[0075] 11. Measuring Room

[0076] 12 Displacement element

[0077] 13 Fluid inlet

[0078] 14 Fluid outlet

[0079] 20 Driver

[0080] 21 Gear

[0081] 22, 22' connecting rod

[0082] 23 Cam transmission parts

[0083] 24, 24' roller

[0084] 25, 25', 25", 25"' grooves

[0085] 25a First section of the groove

[0086] 25b Second section of the groove

[0087] 25c The third section of the groove

[0088] 26 reduction gear

[0089] 100 Moving axis

[0090] 200 Rotation axis

[0091] 201 Center of curved running surface

[0092] 230 inner running surface

[0093] 231 External running surface

[0094] 300 Circular Path

[0095] 400 Mirror axis.

Claims

1. A metering pump (1) for delivering a measured volume of a fluid, the metering pump (1) comprising: at least one metering head (10), in which a metering chamber (11) is arranged; a displacement element (12), which is movable back and forth between a first position and a second position on a displacement axis (100), wherein: The displacement element (12) defines the metering chamber (11), and the volume of the metering chamber (11) when the displacement element (12) is in the first position is greater than the volume of the metering chamber (11) when the displacement element (12) is in the second position; and a drive (20) rotating about an axis of rotation (200), wherein, during operation of the metering pump (1), the rotational movement of the drive (20) about the axis of rotation (200) is converted by a gearing (21) into an oscillating movement of a connecting rod (22), the connecting rod (22) being connected to the displacement element (12) so that the displacement element (12) moves back and forth along the movement axis (100) between the first position and the second position, characterised in that, during operation of the metering pump (1), the drive (20) performs an oscillating movement with an angle of rotation α<360° and a frequency f, and the gearing The wheel arrangement (21) comprises a cam transmission (23), which is arranged on the rotation axis (200) and has a curved running surface (230, 231), which deviates at least in sections from a circular path (300) around the rotation axis (200), wherein the connecting rod (22) rolls on the running surface (230, 231) via a roller (24), so that the stroke length of the displacement element (12) is determined by the rotation angle α and the slope of the running surface (230, 231), and the stroke frequency of the displacement element is determined by the frequency f.

2. The metering pump (1) according to the preceding claim, wherein the following applies to the rotation angle: α≤180°, preferably α≤120°.

3. The metering pump (1) according to claim 1, wherein The curved running surfaces (230, 231) have different slopes.

4. The metering pump according to claim 1, wherein The slope of the curved running surface is constant, wherein the curved running surface is preferably defined by a circular path around a center, wherein the center is different from the rotation axis.

5. The metering pump (1) according to one of the preceding claims, wherein The cam drive (23) is designed as a disk, wherein the disk has a groove (25) comprising the curved running surfaces (230, 231), so that the connecting rod (22) is guided in the groove (25) via the roller (24), and the groove (25) is preferably closed.

6. Metering pump according to the preceding claim, wherein The arc length of the groove is defined by the opening angle β about the axis of rotation, where α≤β.

7. The metering pump (1) according to one of the preceding claims, wherein The curved running surface (230, 231) has at least two sections (25a, 25b), preferably three sections (25a, 25b, 25c), wherein in each case at least two sections of the curved running surface (230, 231) have different slopes.

8. Metering pump according to the preceding claim, wherein The first section (25a) and the third section (25c) of the curved running surface have a smaller slope than the second section (25b), and the second section (25b) is arranged between the first section and the third section in the circumferential direction relative to the rotation axis (200).

9. The metering pump according to claim 1, wherein The slope of the running surface is chosen so that for a movement of the connecting rod along the movement axis h1 = 1 mm, the inclination angle Between 5° and 360°, and preferably 8°≤α h1 ≤90°.

10. The metering pump according to claim 5, wherein: The disk has a plurality N of preferably closed grooves (25, 25', 25", 25'", each groove comprising a curved running surface which deviates at least in sections from a circular path about the axis of rotation, wherein particularly preferably N={2, 3, 4}, and wherein the grooves are particularly preferably arranged in a mirror-inverted manner around 360° / N with respect to the axis of rotation.

11. The metering pump according to claim 1, comprising a plurality of metering heads, each having a metering chamber and a displacement element, wherein M connecting rods (22, 22') are provided, wherein: In each case, one displacement element is connected to one of the grooves via a connecting rod.

12. The metering pump according to claim 1, wherein The drive is a controllable drive, preferably an electronically controllable drive, and particularly preferably a stepper motor or a brushless DC motor.

13. The metering pump according to claim 1, wherein The gear arrangement has a reduction gear (26) which is arranged between the driver and the cam transmission.

14. The metering pump according to claim 1, wherein At least one running surface (230, 231) of the cam transmission is coated with a sliding coating.

15. A metering method for delivering a metered volume of a fluid, in particular a method for operating a metering pump according to one of claims 1 to 14, wherein the rotational movement of the drive is converted into a stroke movement of the displacement element by means of a gear mechanism, characterized in that The rotational movement of the drive is an oscillating movement with an angle of rotation α<360° and a frequency f, and the gear device includes a cam transmission, which is arranged on the rotation axis of the drive and has a curved running surface that deviates at least in sections from a circular path around the rotation axis, wherein a connecting rod rolls on the running surface via a roller, wherein the connecting rod is connected to the displacement element so that the stroke length of the displacement element is determined by the rotation angle α and the slope of the running surface, and the stroke frequency of the displacement element is determined by the frequency f.

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