CN113446211A

CN113446211A - Hydraulic element and displacement pump having such an element

Info

Publication number: CN113446211A
Application number: CN202110290068.8A
Authority: CN
Inventors: J·马尔特里
Original assignee: Prominent GmbH
Current assignee: Prominent GmbH
Priority date: 2020-03-25
Filing date: 2021-03-18
Publication date: 2021-09-28
Also published as: US20210301810A1; DE102020108235A1

Abstract

The invention relates to a hydraulic component comprising a sleeve-shaped housing and a piston which is reciprocable in the sleeve-shaped housing in a longitudinal direction. In order to provide a hydraulic element for transporting small amounts of liquid for use in a displacement pump, in which the risk of the hydraulic element breaking or deflecting is reduced, it is proposed according to the invention that the piston has a chamber which extends in the longitudinal direction and has a chamber inlet, wherein a pin is provided which enters the chamber through the chamber inlet and is connected to the sleeve-shaped housing at the sleeve-shaped housing or by means of an intermediate element in such a way that a relative movement between the piston and the pin is produced during the reciprocating movement of the piston. The invention also relates to a displacement pump having a hydraulic component according to the invention.

Description

Hydraulic element and displacement pump having such an element

Technical Field

The invention relates to a hydraulic component comprising a sleeve-shaped housing and a piston which is reciprocable in the sleeve-shaped housing in the longitudinal direction. In addition, the invention relates to a displacement pump for transporting a liquid, comprising: a delivery chamber; a displacement element, preferably in the form of a diaphragm, wherein the displacement element is reciprocatable between a pressing position and a suction position, wherein a volume of the delivery chamber in the pressing position of the displacement element is smaller than a volume of the delivery chamber in the suction position of the displacement element; a hydraulic chamber, wherein a displacement element separates the delivery chamber from the hydraulic chamber, a hydraulic element, wherein the hydraulic element is connected to the hydraulic chamber, wherein the hydraulic element for applying a force to the displacement element has a hydraulic liquid arranged in the hydraulic chamber, wherein at least a part of the hydraulic element is reciprocatable between a first and a second hydraulic position; and a driver for driving the hydraulic element.

Background

Various forms of pumps are known from the prior art for the purpose of transporting liquid from a reservoir into a container or conduit. One frequently used form of pump is a displacement pump.

In the case of displacement pumps for conveying liquids, in most cases the volume of the delivery chamber increases and decreases in size alternately. During the volume increase, a reduced pressure is generated in the delivery chamber, whereby liquid is drawn into the delivery chamber by means of the suction connection. When the volume of the delivery chamber is subsequently reduced again, the liquid which has been drawn in is pushed out of the delivery chamber of the pump via the pressure connection.

In order to vary the volume of the delivery chamber, the displacement pump has a displacement element that is movable back and forth between a suction position and a pressure application position. The movement of the displacement element may be generated in a number of ways. The displacement element may be reciprocated, for example, by a mechanism directly fixed to the displacement element, or the displacement element may be reciprocated by an intermediate medium, such as a pressure change in a hydraulic liquid that applies a force to the displacement element. In that case, the pressure in the hydraulic chamber is usually changed by the movement of a movable piston of the hydraulic element. The hydraulic fluid causes a force coupling between the hydraulic element and the displacement element.

The amount of liquid transported depends directly on the size or effective area of the displacement element and the distance of movement, by which the delivery chamber alternately increases or decreases. Thus, as far as the additional hydraulic means for generating a movement of the displacement element are concerned, the volume of liquid transported also depends indirectly on the size or effective area of the hydraulic element and the distance of movement, which results in a change of the pressure in the hydraulic chamber.

If a very small amount of liquid is to be transported, the change in volume of the delivery chamber, and thus of the hydraulic chamber, must be correspondingly slight. This requires a correspondingly small displacement element in the delivery chamber or a hydraulic element in the hydraulic chamber.

A disadvantage of these very small hydraulic and displacement elements is that they are difficult to handle, since the piston breaks very quickly, for example when the elements in the displacement pump have to be replaced. The wear of such precision components is also higher, so that the service life of the respective displacement pump is reduced compared to those pumps having larger hydraulic and/or displacement components. Since these elements are easily bent, their production is also made more difficult.

In addition, the drives for such hydraulic and displacement elements require special, cost-intensive drive mechanisms, since small hydraulic or displacement elements cannot withstand the forces occurring in commercially customary drives without being destroyed.

Disclosure of Invention

It is therefore an object of the present invention to provide a hydraulic or displacement element for use in a displacement pump carrying small amounts of liquid, wherein the risk of breakage or deflection of the hydraulic or displacement element is reduced.

According to the invention, this object is achieved by a hydraulic component comprising: a sleeve-shaped housing and a piston which is reciprocable in the sleeve-shaped housing in a longitudinal direction, wherein the piston has a chamber which extends in the longitudinal direction and has a chamber inlet, wherein a pin is provided which extends through the chamber inlet into the chamber and is connected to the sleeve-shaped housing at the sleeve-shaped housing or by means of an intermediate element such that a relative movement is produced between the piston and the pin during the reciprocating movement of the piston.

The hydraulic component according to the invention can be used to exert a force on a hydraulic liquid arranged in a hydraulic chamber. The hydraulic element, which is thus capable of exerting a force, usually comprises two components, namely a sleeve-shaped housing and a piston guided therein in the longitudinal direction. The movement of the piston then causes a greater or lesser force to be exerted on the hydraulic liquid. In this case, the force is decisively determined by the product of the cross section of the piston and the distance of movement, i.e. the stroke, of the piston in the longitudinal direction.

According to the invention, the cross-sectional area of the piston is reduced by the cross-sectional area of a pin extending in the chamber of the piston. After subtracting the cross-sectional area of the pin, the remaining cross-sectional area of the piston is referred to as the effective piston surface according to the invention.

The term cross-sectional area of the piston in the present invention is used to denote the surface perpendicular to the longitudinal direction of the piston and within the outer edge of the piston, in contrast to the effective piston surface. In the hydraulic components known from the prior art, the total cross-sectional area of the piston corresponds to the effective piston surface.

The advantage of reducing the effective piston surface by introducing a pin in the chamber of the piston according to the invention is that the effective piston surface, i.e. the cross-sectional area of the piston minus the cross-sectional area of the pin, is critical for the change in volume and can therefore reduce the amount of liquid that can be transported without any modification in the outer dimensions of the piston or the inner dimensions of the sleeve-shaped housing. With regard to the consideration of the normally acting forces, it is neither desirable for the piston to break nor for the piston to deflect, but at the same time a piston with such outer dimensions can reduce the amount of liquid transported compared to a piston with the same outer dimensions, but without the chamber and the pin extending therein, and a piston with such outer dimensions would therefore be employed.

For this purpose, the piston and the pin are arranged relative to each other such that the pin is at least partially arranged in a chamber of the piston and a relative movement is achieved between the piston and the pin by movement of the piston. In this case, it is mainly the piston that moves, while the pin remains in its position.

In order to achieve a relative movement between the piston and the pin, the pin is either directly fixed to the sleeve-shaped housing of the hydraulic element or the pin is fixed to an intermediate element which is itself connected to the sleeve-shaped housing. In any case, the fixing of the pin in the hydraulic element is preferably achieved in this way.

There are many possible ways of fixing the pin to the sleeve-shaped housing or the intermediate element. In one embodiment, the pin has a corresponding contact surface at its end facing the piston, which can engage with a corresponding contact surface of the sleeve-shaped housing or the intermediate element. In that case, it is conceivable to use both a screw connection and a positive-locking connection shaped like a bayonet connection.

In one embodiment, the piston of the hydraulic component is cylindrical and the sleeve-shaped housing is hollow-cylindrical, wherein the outer diameter of the piston substantially corresponds to the inner diameter of the sleeve-shaped housing. The piston thus fills the sleeve-shaped housing almost completely, at least in the radial direction. It will be appreciated that there must be some difference between the inner diameter of the sleeve-like housing and the outer diameter of the piston to allow the piston to move in the sleeve-like housing. However, in a preferred embodiment, the clearance between the outer surface of the piston and the inner surface of the housing is so small that only a negligible amount of hydraulic fluid can pass through in operation.

Additionally, a sealing element may be provided in the gap to prevent or at least reduce the hydraulic liquid flow therethrough.

This configuration of the hydraulic element gives the following advantages: both the sleeve-shaped housing and the piston are easy to manufacture.

In a further embodiment, the hydraulic element is designed such that the chambers and/or the pins in the longitudinal direction have a circular cross section. This provides the advantage that on the one hand the cavity can be manufactured, for example by simple drilling, and on the other hand the pin can be selected from readily available, but highly accurate, standard components which do not have to be produced specifically for the hydraulic element according to the invention, but which are available inexpensively in large quantities.

In a further embodiment of the hydraulic component according to the invention, the chamber has a constant cross section in the longitudinal direction at least in the part of the chamber in which the pin is arranged almost completely at the moment of the relative movement, and the pin fills the chamber substantially completely in cross section, so that the effective piston surface is formed substantially by the cross-sectional area of the piston minus the cross-sectional area of the chamber.

In case the cross-section of the cavity and the pin is circular, the inner diameter of the cavity thus substantially corresponds to the outer diameter of the pin, such that the pin substantially completely fills the cavity at least in radial direction.

It should also be understood here that there must be some difference between the cross-sectional area of the chamber and the cross-sectional area of the pin so that the chamber can move relative to the outer surface of the pin. Nevertheless, the chamber of the piston is sealed by the pin, which allows almost no further substances, such as hydraulic liquid or impurities, to penetrate into the chamber by means of the outer surface of the pin.

The object of the invention is also achieved by a displacement pump for transporting a liquid, comprising: a delivery chamber; a displacement element, preferably in the form of a diaphragm, wherein the displacement element is reciprocatable between a pressing position and a suction position, wherein a volume of the delivery chamber in the pressing position of the displacement element is smaller than a volume of the delivery chamber in the suction position of the displacement element; a hydraulic chamber, wherein the displacement element separates the delivery chamber from the hydraulic chamber; a hydraulic element, wherein the hydraulic element is connected to the hydraulic chamber, wherein the hydraulic element for applying a force to the displacement element has a hydraulic liquid arranged in the hydraulic chamber, wherein a portion of the hydraulic element is reciprocatable between a first and a second hydraulic position; and a driver for driving the hydraulic element, wherein the hydraulic element is a hydraulic element as described above.

As mentioned in the opening part of the description, the displacement element may be moved by mechanical means directly fixed to the displacement element, or, as claimed in one embodiment of the invention, the displacement element may be moved indirectly by interposed hydraulic means. In this case, the displacement element is preferably in the form of a diaphragm. In addition to the displacement element, in this exemplary embodiment the displacement pump according to the invention additionally has a hydraulic element, wherein the hydraulic element produces a movement of the displacement element by means of a force coupling between the hydraulic element and the displacement element.

The force coupling between the displacement element and the hydraulic element is achieved by means of a hydraulic liquid arranged in a hydraulic chamber. By the movement of the piston of the hydraulic element, the volume of the hydraulic chamber and thus the pressure in the hydraulic chamber acting on the diaphragm, i.e. the displacement element, is alternately increased and decreased. As a result, the volume of the delivery chamber also alternately increases and decreases, so that liquid is alternately drawn into and discharged from the displacement pump.

The volume of liquid transported depends on the change in pressure or volume in the hydraulic chamber, which occurs by means of the movement of the piston in the sleeve-shaped housing of the hydraulic element. The change in pressure or volume in the hydraulic chamber is then mainly dependent on the product of the effective piston surface and the piston stroke, as described above.

By having a piston with a chamber into which the pin extends, the effective piston surface is reduced by the cross-section of the pin. Thus, the term effective piston surface as used in accordance with this patent is used to denote the surface of the piston cross-sectional area that remains after subtracting the cross-sectional area of the pin. The piston according to the invention therefore has a small effective piston surface for conveying small amounts of liquid, despite its relatively large outer dimensions.

Preferably, the cross-section of the pin is adapted to the cross-section of the chamber such that the pin substantially completely fills the cavity in terms of cross-section, wherein preferably the chamber is constant in cross-section along the longitudinal direction at least in the portion of the pin arranged in the pressing position. The volume of liquid that can be transported by the displacement pump according to the invention is thus essentially determined by the extent of the chamber in a direction perpendicular to the longitudinal direction of the sleeve-shaped housing or piston.

This has the advantage that, for the displacement pump according to the invention, it is possible to use a piston which is easier to manufacture in terms of production engineering than a very thin piston with a correspondingly small cross section. The larger size of the piston is less prone to cracking and less severe distortion during manufacture.

In addition, the displacement pump according to the invention has the advantage that it is not necessary to change the inner diameter or the inner shape of the sleeve-shaped housing itself in order to carry different volumes of liquid. In order to vary the volume which can be transported by the displacement pump according to the invention, it is provided that only the chamber in the piston and the pin extending in the chamber are adapted in terms of their shape in order in this way to vary the effective piston surface and thus the volume of liquid transported. This gives the following advantages: the displacement pump according to the invention can be easily adapted to different quantities to be transported without the need to replace expensive parts of the displacement pump, such as a sleeve-shaped housing, which is usually cast in one piece with other pump parts.

In addition, the hydraulic element according to the invention in the displacement pump according to the invention can be operated with a conventional drive, since the piston of the hydraulic element is sufficiently stable to withstand the forces of a conventional drive. A drive element which may be considered is, for example, a linear motor which essentially comprises a stationary element and an element which moves relative to the stationary element.

In one embodiment of the displacement pump, the piston is acted upon by hydraulic liquid only on the side facing the pin, and preferably the drive for moving the piston has a crankshaft and a connecting rod, wherein the connecting rod is connected to the piston and the crankshaft such that a rotary motion of the crankshaft is converted into an oscillating linear motion of the piston by the connecting rod. Both linear and rotary motors are well known in the art and may be inexpensively incorporated into a displacement pump according to the present invention. In this respect, the motor does not have to meet any specific requirements regarding the transmission of force, since the piston to be moved has sufficient stability.

In a further embodiment of the invention, the ratio of the cross-sectional area of the piston to the cross-sectional area of the part of the pin extending into the chamber is at most three, preferably at most two. In this way, as little liquid as possible can be transported despite the relatively large size of the piston. This arrangement also ensures, by virtue of the claimed relationship, that the piston still has a sufficiently high stability, that is to say that it neither breaks nor deflects under the usual forces.

In another embodiment, the chamber has a chamber outlet at its end remote from the chamber inlet through which fluid can leave the chamber, wherein the chamber outlet is preferably connected to the reservoir. This is advantageous because when the piston moves, fluid can escape or flow in through the chamber outlet.

The object of the invention is also achieved by a displacement pump for transporting a liquid, comprising: a delivery chamber and a displacement element, wherein a portion of the displacement element is reciprocatable between a pressing position and a suction position, wherein a volume of the delivery chamber in the pressing position of the displacement element is smaller than a volume of the delivery chamber in the suction position of the delivery element, wherein the displacement element is a hydraulic element according to the preceding description, and wherein the pin is arranged in the delivery chamber.

In displacement pumps known from the prior art, the entire displacement element is usually moved. However, as in the case of the present invention, the displacement element is replaced by a hydraulic element according to the invention, which consists of a non-moving part and a moving part, this embodiment of the invention provides that only a part of the displacement part is moved.

Thus, in this embodiment of the displacement pump according to the invention, the liquid is transported directly by the hydraulic element, and not indirectly by a force acting on the displacement element and generated by the hydraulic element in the hydraulic chamber.

This embodiment is particularly suitable for transporting liquids where contact with the hydraulic components is not an issue. They comprise, inter alia, non-etching substances which do not lead to surface degradation of the hydraulic components. In addition, this embodiment of the displacement pump has the same advantages for carrying small amounts of liquid as the embodiments described above.

The hydraulic component according to the invention can also be used as a pneumatic cylinder.

Drawings

Other advantages, features and possible uses of the invention will become apparent from the following description of preferred embodiments and the accompanying drawings. Like parts are denoted by like reference numerals.

Figure 1 shows a schematic view of an embodiment of a displacement pump according to the invention,

fig. 2 shows a perspective view of an embodiment of a hydraulic component according to the invention, an

Fig. 3 shows a schematic view of a further embodiment of a displacement pump according to the present invention.

Detailed Description

Fig. 1 shows a displacement pump 1 for conveying a liquid, which displacement pump 1 comprises a delivery chamber 20, a displacement element 21 and a hydraulic element 10 driven by a drive (not shown). The hydraulic component 10 is connected to a hydraulic chamber 16 filled with hydraulic liquid. The hydraulic liquid causes a force coupling between the hydraulic element 10 and the displacement element 21. The hydraulic chamber 16 is separated from the delivery chamber by a diaphragm as a displacement element 21.

During operation of the displacement pump 1, the piston 12 of the hydraulic element 10 is moved back and forth in the box sleeve 11 by the drive. The force acting on the displacement element 21 by means of the hydraulic liquid is varied by the movement of the piston 12.

If the piston 12 is moved to the left in fig. 1 to a first hydraulic position, the force on the displacement element 21 increases. This in turn causes the displacement element 21 to move to a pressing position in which the volume of the delivery chamber 20 is smaller than the volume of the delivery chamber 20 in the suction position. Conversely, if the piston 12 is moved to the right in fig. 1 to the second hydraulic position, the force on the displacement element 21 is reduced and the element moves to the suction position.

The drive of the hydraulic element 10 comprises a crankshaft and a connecting rod which is directly fixed to the piston 12, so that the rotational movement of the crankshaft is converted by the connecting rod into an oscillating linear movement of the piston 12.

During operation of displacement pump 1, the driver alternately reciprocates piston 12 of hydraulic component 10 between first and second hydraulic positions, such that displacement component 21 also reciprocates between a pressing position and a suction position. In the suction position, liquid is sucked into the delivery chamber 20 by means of the suction line 22. In the pressure position, the liquid sucked in is discharged from the delivery chamber 20 by means of the pressure line 23.

The volume of liquid delivered by the displacement pump 1 depends on the distance between the effective piston surface 18 of the piston 12 and the first and second hydraulic positions of the piston 12 in the longitudinal direction 40, wherein the effective piston surface 18 is formed by the cross-sectional area of the piston 12 minus the cross-sectional area 19 of the pin 15, as shown in fig. 2.

Fig. 2 shows the structure of a hydraulic element 10 according to the invention fitted in a displacement pump 1. The hydraulic component 10 itself has a sleeve-shaped housing and a piston 12 which reciprocates in the sleeve-shaped housing in the longitudinal direction. The housing 11 has a cylindrical chamber for guiding the piston 12. The piston 12 itself is cylindrical, so that the inner diameter of the sleeve-shaped housing 11 substantially corresponds to the outer diameter of the piston 12.

The piston 12 has a chamber 13 extending in a longitudinal direction 40. The chamber 13 has a chamber inlet 14 at one end. The pin 15 extends through the chamber inlet 14 into the chamber 13 of the piston 12. The chamber 13 of the piston 12 and the pin 15 are also cylindrical, so that the pin 15 substantially completely fills the chamber 13 in the radial direction.

The outer diameter of the piston 12 is 16mm and the outer diameter of the pin 15 is 11mm so that a maximum volume of 1.7ml can be delivered in each stroke of the displacement element 21. Thus, the relationship between the cross-sectional area of the piston and the cross-sectional area 19 of the pin 15 is about 1.45.

The pin 15 is fixed at the sleeve-shaped housing 11 of the hydraulic component 10 by means of a fastening ring 30 (see fig. 1) such that, when the piston 12 is moved by the drive, the piston 12 performs a relative movement with respect to the pin 15, while the pin 15 is substantially maintained in a fixed position.

In the suction position or the second hydraulic position, the pin 15 fills the chamber 13 of the piston 12 to a lesser extent in the axial direction than in the pressure-applying position shown in fig. 1. Thus, the filling degree of the chamber 13 of the piston 12 is greater when the pin 15 is in the pressing position or first hydraulic position in the axial direction than when the pin 15 is in the suction position.

Fig. 3 shows a displacement pump 1' according to another embodiment of the invention, in which the hydraulic element 10 itself is used as displacement element 21. Here, the piston 12 has exactly the same configuration as in the previous embodiment. The drive of the piston 12 is effected by means of a linear motor which moves the piston 12 in the longitudinal direction 40 relative to the sleeve-shaped housing 11 and the pin 15 accommodated in the chamber 13.

In this embodiment, the movement of the piston 12 directly results in a change in the volume of the delivery chamber 20, whereby liquid is alternately drawn into and pushed out of the displacement pump 1'. In this case, the pin 15 is arranged in the delivery chamber 20 and is fixedly connected to the sleeve-shaped housing 11.

For the purposes of this original disclosure, it is pointed out that all features which would be apparent to a person skilled in the art from the present specification, drawings and claims, even if they were described only in terms associated with certain other features, can be combined individually or with other features or groups of features or technical aspects disclosed so far, as such features are not explicitly excluded and do not make such combinations impossible or meaningless. A full and clear representation of all conceivable combinations of features has been omitted here, merely for the sake of brevity and readability of the description.

While the application has been illustrated and described in detail in the drawings and foregoing description, the illustration and description are to be considered exemplary only and are not intended to limit the scope of protection defined by the claims. The invention is not limited to the disclosed embodiments.

Modifications to the disclosed embodiments will be apparent to those skilled in the art from the accompanying drawings, description, and appended claims. In the claims, the word "having" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. Reference to the claims is not to be construed as limiting the scope.

List of reference numerals

1,1' displacement pump

10 Hydraulic element

11 Sleeve-shaped housing

12 piston

13 chamber

14 chamber inlet

15 pin

16 hydraulic chamber

18 effective piston surface

Cross sectional area of 19 pins

20 conveying chamber

21 displacement element

22 suction line

23 pressure line

30 fastening ring

40 longitudinal direction.

Claims

1. A hydraulic component (10) comprising a sleeve-shaped housing (11) and a piston which is reciprocable in the sleeve-shaped housing (11) in a longitudinal direction (40), characterized in that the piston (12) has a chamber (13) which extends in the longitudinal direction (40) and has a chamber inlet (14), wherein a pin (15) is provided, which pin (15) extends through the chamber inlet (14) into the chamber (13) and is connected with the sleeve-shaped housing (11) at the sleeve-shaped housing (11) or by means of an intermediate element, such that in the reciprocating movement of the piston (12) a relative movement occurs between the piston (12) and the pin (15).

2. A hydraulic component (10) according to claim 1, characterized in that the piston (12) is cylindrical and the sleeve-shaped housing (11) is hollow-cylindrical, wherein the outer diameter of the piston (12) substantially corresponds to the inner diameter of the sleeve-shaped housing (11).

3. A hydraulic component (10) according to claim 1 or 2, characterized in that the chamber (13) is circular in cross-section in the longitudinal direction (40) and/or the pin (15).

4. A hydraulic component (10) according to any one of claims 1-3, characterised in that the chamber (13) has a constant cross-section in the longitudinal direction (40) and the pin (15) assumes a cross-section that substantially completely fills the chamber (13) so that an effective piston surface (18) is formed substantially by the cross-sectional area of the piston (12) minus the cross-sectional area (19) of the chamber (13).

5. A displacement pump (1) for conveying a liquid, comprising: a transport chamber (20); a displacement element (21), preferably in the form of a diaphragm, wherein the displacement element (21) is reciprocally movable between a pressing position and a suction position, wherein the volume of the delivery chamber (20) in the pressing position of the displacement element (21) is smaller than the volume of the delivery chamber (20) in the suction position of the displacement element (21); a hydraulic chamber (16), wherein the displacement element (21) separates the delivery chamber (20) from the hydraulic chamber (16); a hydraulic element (10), wherein the hydraulic element (10) is connected to the hydraulic chamber (16), wherein the hydraulic element (10) for applying a force to the displacement element (21) has a hydraulic liquid arranged in the hydraulic chamber (16), wherein a portion of the hydraulic element (10) is reciprocatable between a first hydraulic position and a second hydraulic position; and a drive for driving the hydraulic element (10), characterized in that the hydraulic element (10) is a hydraulic element (10) according to any one of claims 1 to 4.

6. The displacement pump (1) of claim 5, wherein the ratio of the cross-sectional area of the piston (12) to the cross-sectional area (19) of a portion of the pin (15) extending into the chamber (13) is no more than 3, preferably no more than 2.

7. The displacement pump (1) according to any one of claims 5 and 6, characterized in that the piston (12) is acted upon by hydraulic liquid only on the side facing the pin (15), wherein the drive preferably has a crankshaft and a connecting rod, wherein the connecting rod is connected to the piston (12) and the crankshaft, such that a rotary motion of the crankshaft is converted into an oscillating linear motion of the piston (12) by means of the connecting rod.

8. The displacement pump (1) of any one of claims 5 to 7, characterized in that the chamber (13) has a chamber outlet at its end remote from the chamber inlet (14), through which fluid can leave the chamber, wherein the chamber outlet is preferably connected to a reservoir, wherein fluid can flow from the reservoir through the chamber outlet into the chamber.

9. A displacement pump (1') for transporting a liquid, comprising: a transport chamber (20); a displacement element (10), wherein a portion of the displacement element (10) is reciprocally movable between a pressing position and a suction position, wherein a volume of the delivery chamber (20) in the pressing position of the displacement element (10) is smaller than a volume of the delivery chamber (20) in the suction position of the displacement element (10), characterized in that the displacement element (10) is a hydraulic element (10) according to any one of claims 1 to 4, wherein the pin (15) is arranged in the delivery chamber (20).