EP3663579B1 - Piston compressor - Google Patents

Description

The invention relates to a piston compressor for a double piston system, preferably for an air compressor in a vehicle application, in particular for a vehicle air suspension system, comprising a connecting rod for two pistons, the connecting rod having a section by means of a first connecting rod bearing on an eccentric extension of an eccentric shaft of a drive device is storable.

STATE OF THE ART

The invention is based on a piston compressor as part of an air compressor, which can preferably provide compressed air in a compact and low-vibration design when used in a vehicle. In particular, such air compressors are used in the operation of an air suspension system, in which the wheel suspensions are connected to a vehicle chassis in a damped manner via air springs. In such applications, low-noise and low-vibration operation of the air compressor, which is often arranged in the passenger compartment of a vehicle, is desirable.

Piston compressors with connecting rods which have different features are known from the prior art. From the DE 103 23 125 A1 For example, a connecting rod for the piston of a compressor is known which additionally has a vibration damping device which is arranged between the connecting rod bearing and a coupling point.

The WO 85/02232 discloses a reciprocating compressor with at least two pistons and a rotary drive, the two pistons being axially aligned with one another and firmly connected to one another with a rigid piston rod.

A reciprocating piston machine for, for example, a one, two or multi-stage piston compressor or a one, two or more cylinder compressor is from the WO 2018/082800 A1 or the DE 10 2016 001 595 A1 known.

The DE 19 46 149 A describes a compressor that delivers compressed air even when a single-cylinder compressor is used for air intake cannot expel air. This is achieved in that a piston rod is arranged between two opposing cylinders. The air emerging from both outlet valves flows into a common hose line. When the pistons move from right to left, the air combined in the left cylinder is led through the outlet valve into the hose line. Air is drawn in from the right piston through the inlet valve. This reciprocal way of working creates a constant flow of air in the hose line. The hose line is only arranged on one side next to the connecting rod, so that there is an asymmetrical mass distribution to the plane of oscillation of the piston. In the DE 101 25 420 C1 a piston compressor is shown, the check valves of which have a lower closing force and, at the same time, a high degree of tightness. A valve piston is arranged between a low-pressure piston with a low-pressure chamber and a high-pressure piston with a high-pressure chamber. The low-pressure chamber and the high-pressure chamber are connected to one another via an overflow channel. The overflow channel opens into at least two through bores.

The DE 103 23 125 A1 shows a connecting rod for the piston of a compressor, at least one vibration damper device being arranged between the connecting rod bearing and the coupling point. Here, too, the connecting rod is arranged axially offset to the oscillation plane behind the overflow channel and not in the oscillation plane of the connecting rod.

Furthermore, reciprocating compressors with connecting rods for pistons of a compressor are known, which have an air duct. This usually runs in such a way that it overlaps the connecting rod in the transverse direction or is arranged in front of the connecting rod. In other words, the air duct on the connecting rod runs in such a way that the air duct can be arranged, for example, on the side on which the connecting rod can be connected to a drive device, such as an electric motor, by means of a bearing with an eccentric shaft. For this purpose, the air duct is arranged between the connecting rod and the drive device.

So shows the U.S. 2,403,814 A a reciprocating compressor with a piston in which two channels are integrated. A low-pressure piston and a high-pressure piston are also shown. The two channels, which open into a common channel at both ends, run between the two pistons. The two channels are arranged inside the piston. The connecting rod is arranged in a plane offset to it, accordingly in front of the piston with the air ducts. The piston overlaps the connecting rod in the transverse direction or is here in front of or behind the connecting rod, depending on the plane of view. In such a design, a lot of installation space is required, since the connecting rod and the piston as well as the air ducts are arranged in different planes. This also results in an asymmetrical mass distribution of the moving parts in relation to the plane of movement of the piston. Thus, such a design must have sufficient stability of the individual connections and components, since the various levels in which the forces run cause moment loads with respect to individual levels or components.

A connecting rod of this type is usually arranged in a compressor between the output of a drive device and a piston or piston carrier of the compressor in order to convert the rotating, eccentric output movement of the drive device into a reciprocating movement of the piston via the connecting rod. The space in which the piston compressor or the connecting rod can be placed is limited.

More compressors are from the GB 507 798 A , DE 101 09 514 C1 , US 10 087 920 B2 , WO 2004/029476 A1 and US 2005/260080 A1 known.

The GB 507 798 A shows a compressor with two pistons. The two pistons are connected by cylindrical components. A transverse slot is formed between the two cylindrical components via a further cylindrical component. In this transverse slot a wave runs in a sliding block. The reciprocating motion of the slide block with the shaft and the motion of the drive shaft move the pistons back and forth.

In the DE 101 09 514 C1 a reciprocating compressor is shown which has multiple pistons having, each piston being connected to an eccentric extension via a connecting rod bearing.

The object of the invention is to propose a reciprocating compressor which requires only a small amount of installation space and experiences an optimized or reduced stress due to forces or torques and enables low-noise operation of an air compressor. Another object of the invention is to propose a reciprocating compressor that is lightweight.

This object is achieved by a reciprocating compressor according to independent claim 1. Advantageous further developments of the invention are the subject of the subclaims.

DISCLOSURE OF THE INVENTION

The invention relates to a piston compressor for a double piston system, with a connecting rod for two translationally oscillating pistons, the connecting rod being able to be supported with a section by means of a first connecting rod bearing on an eccentric extension of an eccentric shaft of a drive device and being arranged in a connecting rod movement plane. The connecting rod movement plane is defined as the mass balance plane of the connecting rod, which runs at right angles to the driving crankshaft.

It is proposed that at least one air duct, starting from a direction of view of a side surface of the connecting rod, is arranged next to the connecting rod and in a plane with the connecting rod so that it does not overlap the connecting rod in at least one transverse direction lying in the plane. The plane coincides with the plane of movement of the connecting rod, and a line of gravity of the translationally oscillating pistons, for which the connecting rod is designed, runs in this plane of movement of the connecting rod. The at least one air duct is arranged within a connecting element which runs from below the connecting rod to above the connecting rod. The connecting element is designed as a hollow structure with any cavity cross section and is connected at one end to the first piston and at a second end to the second piston.

In other words, a placement next to the connecting rod means the arrangement in such a position that is not in an intermediate space between the connecting rod and a drive device or a position opposite thereto with respect to the connecting rod. The at least one air duct is therefore preferably arranged in one plane with the connecting rod. In one plane means that the at least one air duct is arranged next to the connecting rod, starting from a direction of view of a side surface of the connecting rod. In a plane also means that the plane at least partially coincides with the plane of movement of the connecting rod.

The connecting rod preferably moves within the connecting rod movement plane at least along a longitudinal direction and preferably also along a transverse direction within the connecting rod movement plane. This can be achieved by means of a drive device and an eccentric shaft connected to it as a crankshaft, an eccentric extension being connected to a first connecting rod bearing. The eccentric shaft is usually aligned normal to the plane of movement of the connecting rod. The longitudinal direction as well as the transverse direction span the connecting rod movement plane. It is also possible to set a depth direction with respect to the plane of movement of the connecting rod define. This depth direction can be oriented orthogonally with respect to the connecting rod movement plane, which is defined by the longitudinal and transverse directions. Due to the definition of the directions within the connecting rod movement plane, as well as by defining the connecting rod movement plane itself, the position of the at least one air duct in a plane with respect to the connecting rod can advantageously be defined or described. In particular, a definition that delimits the known arrangements can thereby be achieved.

In a preferred embodiment, the plane of movement of the connecting rod and the plane of the air duct coincide completely. In other words, the at least one air duct is therefore arranged in the plane of movement of the connecting rod. Furthermore, the air duct preferably runs completely outside the connecting rod. The air duct can consequently be arranged outside the connecting rod, but in the connecting rod movement plane. In such an arrangement, the at least one air duct is arranged in such a way that it does not overlap the connecting rod in at least one transverse direction of the plane. As a result, the air duct runs next to the connecting rod in the plane of movement of the connecting rod. The air duct preferably runs over the entire length of the connecting rod. The at least one air duct can be arranged at a distance from the connecting rod. Such an arrangement of the air duct with respect to the connecting rod enables a space-saving design to be achieved. Furthermore, an optimized or reduced stress caused by forces or moments of the individual components can be achieved and a low-noise operation of an air compressor with such a piston compressor can be made possible. Furthermore, the vibrations can be reduced.

The piston compressor can additionally have a vibration damping device which is arranged between the connecting rod bearing and a coupling point. This can be formed via a decoupling element, for example decoupling rings, by which impact forces are dampened and flexible and simple assembly of the connecting rod is ensured. The decoupling element consequently acts as a damper.

The course of the air channel can preferably be adapted at least in sections to the outer contour of the connecting rod and / or spaced apart from the outer contour be arranged. For this purpose, the air duct can run at least in sections along a curve and / or along a line. It is also possible here for the air duct to be arranged completely within the plane of movement of the connecting rod.

Such an arrangement of the at least one air duct with respect to the connecting rod makes it possible to form a slim piston compressor, by means of which installation space can be saved. This also has a positive effect on the compact design of a compressor.

The at least one air duct is arranged within a connecting element which runs from below the connecting rod to above the connecting rod. The connecting element is designed as a hollow structure with any cavity cross section and is connected at one end to a first piston and at a second end to a second piston.

In a preferred embodiment, the at least one air duct can be arranged next to the connecting rod in such a way that it overlaps the connecting rod in a depth direction with respect to the plane. In other words, the air duct can be arranged laterally next to the connecting rod in such a way that it overlaps the connecting rod when looking at the depth or thickness of the connecting rod. Such a viewing direction is consequently arranged within the plane of movement, wherein the viewing direction can correspond to the transverse direction of the plane. In this case, overlapping means that the air duct is arranged in front of the connecting rod when the viewing direction is oriented towards the depth or thickness of the connecting rod. The air duct or its cross section can be adapted to the depth or thickness of the connecting rod so that it does not protrude beyond the thickness or depth of the connecting rod, so that installation space can continue to be optimally used. This makes it possible to achieve a particularly advantageous delimitation from the known arrangements of air ducts from the prior art. In arrangements known from the prior art, the air duct runs on the connecting rod, for example, in such a way that the air duct is arranged on the side on which the connecting rod is connected to a drive device, such as an electric motor, by means of a bearing with an eccentric shaft. The air duct is between the connecting rod and the drive device arranged. This is not the case in the present embodiment. As a result, less installation space is required and a mass balance is achieved in the connecting rod movement plane. In this respect, undesired vibrations from the plane of the connecting rod movement can be prevented.

In a preferred embodiment, the air duct can have a cross section that is smaller than or equal to the smallest cross-sectional dimension of the connecting rod and / or the depth of the connecting rod, the air duct being arranged completely in the plane of movement of the connecting rod. A cross-sectional dimension of the connecting rod can be, for example, the thickness of the connecting rod. If the connecting rod has different thicknesses, the air duct can, for example, have a diameter that corresponds to this thickness. If the air duct is arranged next to the connecting rod, the air duct and the connecting rod lie in one plane, the air duct at least partially covering or overlapping the connecting rod in the thickness direction when the viewing direction is directed towards the thickness or depth of the connecting rod.

In a preferred embodiment, the air duct can have a round cross section. The air duct can have different diameters or a diameter that is constant over its length. The diameter can be adapted to the required volume flow.

In a preferred embodiment, the air duct can run at an angle along an outer contour of the connecting rod, this being preferably arranged at a distance from the outer contour. If the course of the air duct is adapted to the outer geometry of the connecting rod, installation space can still be optimally used and saved. The air duct is advantageously arranged at a distance from the outer contour of the connecting rod so that it does not touch the connecting rod even during operation.

In a preferred embodiment, there can be at least two air ducts. A second air duct can have the same construction as the first air duct and lie in a plane with the first air duct and with the connecting rod, ie likewise within the connecting rod movement plane or plane. Can be beneficial the at least two air ducts can be designed parallel to one another or also mirrored to one another with respect to at least one axis.

By arranging at least two air ducts, the volume flow can be significantly increased and optimally adapted. By individually adapting the geometry of at least two air ducts to the existing installation space, a slim design of the piston compressor can still be achieved.

In a preferred embodiment, the second air duct can be arranged next to the connecting rod and in a plane with the connecting rod in such a way that it does not overlap the connecting rod at least in a transverse direction, the plane at least partially coinciding with the connecting rod movement plane, and a center of gravity of the at least one translationally oscillating piston runs in the plane of movement of the connecting rod. It is, for example, conceivable to have two air ducts arranged parallel to one another and directly adjacent to one another on one side of the connecting rod, i. H. in the transverse direction next to the connecting rod, which have the same geometry. It is also conceivable to arrange an air duct to the right of the connecting rod as seen from a viewing direction of a side surface of the connecting rod, and to provide a second air duct to the left of the connecting rod, both air ducts still being disposed in the connecting rod movement plane. The two air ducts can consequently run to the right and left of the connecting rod. Such a symmetrical configuration can particularly advantageously reduce vibrations, since the forces are balanced and the torque loads that occur are consequently reduced.

In a preferred embodiment, the second air duct can be arranged in such a way that it overlaps the connecting rod in at least one depth direction with respect to the plane. Overlapping means that the second air duct is arranged in front of the connecting rod, viewed from a direction of view of the thickness or depth of the connecting rod. Such a viewing direction is consequently arranged within the connecting rod movement plane, wherein the viewing direction can correspond to the transverse direction of the plane. The second air duct, like the first air duct, preferably lies in one plane with the connecting rod. The two air ducts can each be connected to one opposite side with respect to the connecting rod, or be arranged on the same side.

In a preferred embodiment, the two air ducts can be designed symmetrically with respect to a longitudinal axis of the connecting rod, the longitudinal axis in particular being a center of gravity of the at least one translationally oscillating piston. One air duct preferably runs to the right and another to the left of the connecting rod, seen from a viewing direction onto a side surface of the connecting rod. Both air channels are preferably arranged at a distance from the outer contour of the connecting rod, so that they do not touch the connecting rod. Both air channels consequently preferably run outside the connecting rod.

The center of gravity line of the at least one translationally oscillating piston can thus also form the center of gravity line between the two air ducts, so that a symmetrical arrangement and thus an equilibrium of forces is created. Consequently, the longitudinal axis of the connecting rod can coincide with the center of gravity of the at least one piston. If the center of gravity also lies within the plane of movement of the connecting rod, the arrangement of the air ducts and the connecting rod with respect to the at least one piston, in particular between two pistons, can be achieved in a particularly space-saving manner.

In a preferred embodiment, the two air channels can open into a common channel. The common channel is preferably above the connecting rod or below the connecting rod. In this way, both pistons can be reached, especially with a double piston system. The common channel can be arranged in the center of gravity of the piston.

In a preferred embodiment, at least one balancing disk can be arranged at the level of the first connecting rod bearing. The balancing disk is preferably arranged particularly close to the piston.

In a preferred embodiment, at least two balancing disks can be arranged at the level of the first connecting rod bearing. The two balancing disks can be of the same type. The two balancing disks can be designed symmetrically to one another. It is also conceivable more than two balancing letters to be arranged, for example, two balancing disks can be arranged parallel to each other. A tilting moment that occurs can be reduced by arranging two balancing discs. The resulting reduced inertia forces also reduce the dynamic effects, which means that the functioning of the reciprocating compressor can be optimized.

In a preferred embodiment, a first balancing disk can be arranged on one side of the connecting rod, which can be aligned in the direction of an eccentric shaft, and the second balancing disk on an opposite side of the connecting rod. In other words, the two balancing disks can be arranged on two opposite sides of the connecting rod, wherein the first balancing disk can be arranged, for example, in front of the connecting rod, viewed from a direction of view of the side surface of the connecting rod, and the second balancing disk can be arranged behind the connecting rod. This allows the weight distribution to be optimized and possible overturning moments to be reduced.

In a preferred embodiment, the two balancing disks can be designed symmetrically with respect to a longitudinal axis of the connecting rod. If the two balancing disks are designed symmetrically to one another, then there is also a symmetrical weight distribution, which further reduces a tilting moment. Overall, forces and moments can consequently be optimally compensated for by two balancing plates, since the center of mass lies on the longitudinal axis.

In a preferred embodiment, at least one piston, which is constructed in one piece or in several parts, can be arranged above the connecting rod as a high-pressure piston which is connected to the at least one air duct. The at least one air duct can perform the function of connecting a first and a second compressor unit between a low-pressure and a high-pressure stage.

In a preferred embodiment, at least one piston, which is constructed in one piece or in several parts, can be arranged below the connecting rod as a low-pressure piston which is connected to the at least one air duct. The at least one air duct can also function as the connection between a first and a second compressor unit.

The low-pressure and high-pressure stage is connected via the air duct or ducts and a valve system which provides a controlled guiding of compressed air from the low-pressure stage to the high-pressure stage. The valves required for this can be arranged in the base of the respective pistons of the compressor stages and / or in the air duct or ducts.

DRAWINGS

Further advantages emerge from the present drawings and description of the drawings. Exemplary embodiments of the invention are shown in the drawings. The drawing, the description and the claims contain numerous features in combination. The person skilled in the art will expediently also consider the features individually and combine them into meaningful further combinations.

Fig. 1

eine isometrische Darstellung einer Ausführungsform eines erfindungsgemäßen Kolbenverdichters;

Fig. 2

einen Längsschnitt der Ausführungsform nach Fig. 1;

Fig. 3

einen Querschnitt der Ausführungsform nach Fig. 1;

Fig. 4

eine Seitenansicht einer weiteren Ausführungsform eines erfindungsgemäßen Kolbenverdichters;

Fig. 5

eine isometrische Darstellung der Ausführungsform nach Fig. 4;

Fig. 6

einen Längsschnitt der Ausführungsform nach Fig. 4;

Fig. 7

einen Querschnitt der Ausführungsform nach Fig. 4.

It shows:

Fig. 1

an isometric view of an embodiment of a reciprocating compressor according to the invention;

Fig. 2

a longitudinal section of the embodiment according to Fig. 1 ;

Fig. 3

a cross section of the embodiment according to Fig. 1 ;

Fig. 4

a side view of a further embodiment of a reciprocating compressor according to the invention;

Fig. 5

an isometric view of the embodiment according to FIG Fig. 4 ;

Fig. 6

a longitudinal section of the embodiment according to Fig. 4 ;

Fig. 7

a cross section of the embodiment according to Fig. 4 .

In the figures, the same or similar components are numbered with the same reference symbols.

Fig. 1 shows an isometric view of an embodiment of a piston compressor 10 according to the invention. The piston compressor 10 is designed as a double piston system 12 and has a connecting rod 14 that is connected to a drive device 22 (not shown) via a connecting rod bearing 18 with an eccentric extension 12 of an eccentric shaft 20. The drive device 22 can be designed, for example, as an electric motor that drives the eccentric shaft 20, with an eccentric extension 21 attached to an end face of the eccentric shaft 20 rotatably supporting the connecting rod 14, and translating the rotational movement of the eccentric shaft 20 into a translational oscillating movement of the double piston system with the connecting rod 14 . The lower bearing 13, which supports a low-pressure piston 16a on the connecting rod 14, has one or more decoupling elements 40, by means of which impact forces can be dampened and flexible and simple assembly of the connecting rod 14 is ensured. The decoupling element 40 is used for a mechanically resilient decoupling to suppress the vibration of the connecting rod 14 and the lower low-pressure piston 16a and can, for example, be designed as a rubber ring or similar resilient decoupling element, and consequently acts as a damper. In this embodiment, a high-pressure piston 16b is arranged above the connecting rod 14. The connecting rod 14 is consequently arranged between the low-pressure piston 16a and the high-pressure piston 16b. The connecting rod 14 moves within the connecting rod movement plane PE. The connecting rod movement plane PE can be described by the transverse direction Q and the longitudinal direction or longitudinal axis L. The connecting rod 14 is consequently arranged within the connecting rod movement plane PE. In this embodiment, the connecting rod movement plane PE also coincides with the plane E1, the plane E1 describing the plane in which the two air ducts 24 are arranged.

It can consequently be seen that the plane E1 coincides with the connecting rod movement plane PE, and a center of gravity line SE of the translationally oscillating pistons 16a, 16b runs in the connecting rod movement plane PE. It can also be seen in the illustration that the center of gravity line SE coincides with a longitudinal axis L of the reciprocating compressor 10 or of the connecting rod 14.

In this embodiment, an air duct 24a, 24b is arranged next to the connecting rod 14 to the right and left with respect to the transverse direction Q in the plane E1 or the connecting rod movement plane PE in such a way that it does not overlap the connecting rod 14 in the transverse direction Q. This means that the air channels 24a, 24b are arranged completely outside of the connecting rod 14. The air channels 24a, 24b follow the outer contour 36 of the connecting rod 14 at least in sections. The air channels 24a, 24b are arranged at a distance from this outer contour 36 so that the connecting rod 14 does not touch the air channels 24a, 24b. The air channels 24a, 24b form a connection between a first and a second unit and can be arranged, for example, in connecting webs. A piston 16, a lower low pressure piston 16a for generating a low pressure of up to approx. 5-8 bar and an upper high pressure piston 16b for generating a high pressure of approx multi-part pistons can also be formed. The lower low-pressure piston 16a sucks in air via an inlet valve (not shown) and compresses it to a low pressure. A further valve (not shown) in the low-pressure piston 16a directs the pre-compressed air over the longitudinal extension of the connecting rod 14 via the air duct (s) 24 to the upper high-pressure piston 16b and compresses it to a desired high-pressure level in a second compressor stage. The valve arrangements integrated in the piston head of the low-pressure and high-pressure piston 16a, 16b are not shown.

In the area of the upper high-pressure piston 16b, the two air channels 24a, 24b merge into a common channel 30. In this embodiment, two balancing disks 32a, 32b are arranged at the level of the connecting rod bearing 18. One balancing disk 32b is arranged on the side of the connecting rod 14 which is oriented in the direction of the eccentric shaft 20. Another balancing disk 32a is arranged on the opposite side of the connecting rod 14 in the depth direction T. By arranging the balancing disks 32a, 32b so close to the connecting rod bearing 18, tilting moments can be reduced, since a mass balance takes place and the center of gravity lies on the longitudinal axis L. Ideally, the balancing disks 32a, 32b set a center of mass of the piston seal 10, which lies both in the longitudinal axis L and in the axis of the eccentric extension 21.

A longitudinal section through the plane E1, ie through the plane LQ, ie through the connecting rod movement plane PE shows Fig. 2 . It can be seen that the two air ducts 24a, 24b are arranged symmetrically to one another. Along the entire course of each air channel 24a, 24b, the latter is arranged at a distance from the outer contour 36 of the connecting rod 14. The air channels 24a, 24b run in a straight line in sections. Due to the additionally angled shape, the air channels 24a, 24b can be adapted to the outer contour 36 of the connecting rod 14. In this embodiment, the connecting rod bearing 18 is formed by a ball bearing 42. The second, lower bearing 13 for mounting the lower low-pressure piston 16a on the connecting rod 14 has a bushing 44, a needle roller and cage assembly 46 and a cylinder pin 48 and in this embodiment is designed as a needle bearing. In the lower area of the illustration, a cup seal 50 and a clamping ring 52 for a first pressure stage can also be seen. In this plane LQ it can be seen that the air ducts 24a, 24b do not overlap the connecting rod 14 in the transverse direction Q, since they are spaced apart in the transverse direction Q and are arranged next to one another. If the air channels 24a, 24b overlap the connecting rod 14, they would be arranged at least partially in front of or behind the connecting rod 14 from this viewing direction, and consequently not within the connecting rod movement plane PE.

A cross section along the plane TL is shown in FIG Figs. 3rd shown. It can be seen that in this embodiment the two balancing disks 32a, 32b are designed symmetrically with respect to the longitudinal axis L. The balancing disks 32a, 32b are arranged at a distance from the side surfaces 34 of the connecting rod 14. It can also be seen that the illustrated air duct 24b overlaps the thickness of the connecting rod 14 in the depth direction T, so that it is arranged with the connecting rod 14 in a plane E1, ie in the connecting rod movement plane PE. In other words, it can be seen in this sectional illustration that the air duct 24b is at least partially covered by the connecting rod. The air duct 24b has a cross section 26 which is smaller than the cross section of the connecting rod 14, that is to say smaller than the minimum depth t of the connecting rod 14. With such an arrangement, a reciprocating compressor 10 can have a compact design, since it requires only little installation space.

Another embodiment of a reciprocating compressor 10 is in a side view in Fig. 4 shown. The embodiment is designed without a decoupling element 40. In this illustration, the two pistons 16 are as in FIG Fig. 3 shown in section, so that only one air duct 24b is visible. The piston compressor 10 is connected via an eccentric extension 21 of an eccentric shaft 20 of a drive device 22, with at least one further bearing 54 for supporting the eccentric shaft 20 being present in the connection area. In the lower area, the piston compressor 10 is designed for a first pressure stage with a larger diameter via a cup collar 50 and a clamping ring 52, which form the lower low-pressure piston 16a. In the upper, opposite area, however, the high-pressure piston 16b is designed with a smaller diameter for a second high-pressure stage. The piston compressor 10 is therefore designed in two stages with a low-pressure piston 16a and a high-pressure piston 16 at the respective ends of the connecting rod 14, both piston stages being connected via a valve system (not shown) and the air ducts 24 extending over the longitudinal extension of the connecting rod 14. The valves used are usually mechanically self-resetting one-way valves that open and close automatically at a preset pressure in order to direct the compressed air into the low-pressure piston 16a and from this to the high-pressure piston 16b when the pre-compression pressure in the low-pressure stage is reached.

In the Figs. 4 to 7 are the same components with the same reference numerals as in Figs. 1 to 3 so it will not be discussed further.

Fig. 5 FIG. 11 shows an isometric view of the embodiment of the reciprocating compressor 10 from FIG Fig. 4 . A corresponding cross-sectional view along the QL plane is shown in Fig. 6 , a further cross-sectional view along the plane TL in Fig. 7 shown.

The reciprocating compressor 10 according to the invention is not restricted to the embodiments shown here, but is defined by the appended claims.

List of reference symbols

10

Reciprocating compressors

12th

Double piston system

13th

warehouse

14th

Connecting rod

16

piston

16a

Low pressure piston

16b

High pressure piston

18th

Connecting rod bearings

20th

Eccentric shaft

21

Eccentric process

22nd

Drive device

24

Air duct

24a

first air duct

24b

second air duct

26th

cross-section

30th

common channel

32

Balancing disc

32a

first balancing disc

32b

second balancing disc

34

Side face of the connecting rod

36

Outer contour of the connecting rod

38

Connecting element

40

Decoupling element

42

ball-bearing

44

Liner

46

Needle ring

48

Straight pin

50

Cup seal

52

Clamping ring

54

warehouse

Q

Transverse direction

T

Depth direction

L.

Longitudinal axis

t

depth

E1

level

PE

Connecting rod plane of motion

SE

Center of gravity

Claims (16)

1. Piston compressor (10) for a double-piston system (12), with a connecting rod (14) for two translationally oscillating pistons (16, 16a, 16b), said connecting rod (14) being mountable with one section on an eccentric extension (21) of an eccentric shaft (20) of a drive device (22) by means of a first connecting rod bearing (18) and arranged in a connecting rod movement plane (PE), characterized in that at least one air duct (24) is, from a direction looking onto a lateral surface of the connecting rod (14), arranged next to the connecting rod (14) and in a plane (E1) with said connecting rod (14) such that it does not overlap the connecting rod (14) in at least a transverse direction (Q) in the plane (E1), said plane (E1) corresponding to the connecting rod movement plane (PE), and a centre-of-gravity line (SE) of the translationally oscillating pistons (16, 16a, 16b) extending in the connecting rod movement plane (PE), the at least one air duct (24) being arranged inside a connecting element that extends from below the connecting rod (14) to above the connecting rod (14) and said connecting element being designed as a hollow structure with any cavity cross-section and connected at one end to the first piston (16a) and at a second end to the second piston (16b).
2. Piston compressor (10) according to claim 1, characterized in that the at least one air duct (24) is arranged next to the connecting rod (14) such that it overlaps said connecting rod (14) in a depth direction (T) relative to the plane (E1).
3. Piston compressor (10) according to one of the preceding claims, characterized in that the air duct (24) has a cross-section (26) designed smaller than or equal to the lowest cross-sectional dimension of the connecting rod (14) and/or to the depth (t) of said connecting rod (14), the air duct (24) being arranged completely inside the connecting rod movement plane (PE).
4. Piston compressor (10) according to one of the preceding claims, characterized in that the air duct (24) has a round cross-section.
5. Piston compressor (10) according to one of the preceding claims, characterized in that the air duct (24) extends with an angle along an outer contour (36) of the connecting rod (14), being arranged preferably at a distance to said outer contour (36).
6. Piston compressor (10) according to one of claims 1 to 5, characterized in that at least two air ducts (24, 24a, 24b) are provided.
7. Piston compressor (10) according to claim 6, characterized in that the second air duct (24b) is arranged next to the connecting rod (14) and in the plane (E1) with said connecting rod (14) such that it does not overlap the connecting rod (14) in at least a transverse direction (Q) in the plane (E1), said plane (E1) at least partly corresponding to the connecting rod movement plane (PE), and a centre-of-gravity line (SE) of the at least one translationally oscillating piston (16, 16a, 16b) extending in the connecting rod movement plane (PE).
8. Piston compressor (10) according to claim 6 or 7, characterized in that the second air duct (24b) is arranged such that it overlaps the connecting rod (14) in a depth direction (T) relative to the plane (E1).
9. Piston compressor (10) according to one of claims 6 to 8, characterized in that the two air ducts (24a, 24b) are designed symmetrical relative to a longitudinal axis (L) of the connecting rod (14), said longitudinal axis (L) in particular being a centre-of-gravity line (SE) of the at least one translationally oscillating piston (16, 16a, 16b).
10. Piston compressor (10) according to one of claims 6 to 9, characterized in that the two air ducts (24a, 24b) merge into a common duct (30).
11. Piston compressor (10) according to one of the preceding claims, characterized in that at least one balancing disc (32) is arranged at the level of the first connecting rod bearing (18).
12. Piston compressor (10) according to one of the preceding claims, characterized in that at least two balancing discs (32, 32a, 32b) are arranged at the level of the first connecting rod bearing (18).
13. Piston compressor (10) according to claim 12, characterized in that a first balancing disc (32a) is arranged on a side of the connecting rod (14) which is alignable in the direction of an eccentric shaft (20), and the second balancing disc (32b) on an opposite side of the connecting rod (14).
14. Piston compressor (10) according to claim 12 or 13, characterized in that the two balancing discs (32a, 32b) are designed symmetrical relative to a longitudinal axis (L) of the connecting rod (14).
15. Piston compressor (10) according to one of the preceding claims, characterized in that at least one piston (16), which is designed with one or more parts, is arranged above the connecting rod (14) as a high-pressure piston (16a) which is connected to the at least one air duct (24).
16. Piston compressor (10) according to one of the preceding claims, characterized in that at least one piston (16), which is designed with one or more parts, is arranged below the connecting rod (14) as a low-pressure piston (16b) which is connected to the at least one air duct (24).

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