WO2005059362A1

WO2005059362A1 - Piston compressor for compressing gaseous media in at least two working chambers

Info

Publication number: WO2005059362A1
Application number: PCT/EP2004/014024
Authority: WO
Inventors: Beat Frefel
Original assignee: Fritz Haug Ag
Priority date: 2003-12-09
Filing date: 2004-12-09
Publication date: 2005-06-30
Also published as: DE502004005581D1; US20070116588A1; EP1702162A1; EP1702162B1; EP1541867A1

Abstract

The invention relates to a piston compressor (15) which is used to compress gaseous media and which contains a differential piston (1) provided with a first piston part (16) and a second piston part (17) which are arranged on an axis. Two cylinders (7, 8) having internal holes with different diameters form two working chambers (21, 22). The cylinders are closed by plates (2, 9) comprising valve arrangements. The piston part (17) with the smaller diameter is guided through an opening (20) in the plate (2). The valves are more particularly lamella valves, reed valves or values with a spring return position.

Description

Piston compressor for compressing gaseous media in at least two work rooms

The invention relates to a piston compressor for compressing gaseous media in at least two work spaces with the features of the independent claim.

Numerous piston compressors with several work rooms are already known and in use. For example, US 4,889,039 describes a piston compressor in which the valves are each arranged in the cylinder jacket. Such compressors are relatively complex to manufacture and correspondingly expensive. A major disadvantage of a valve arrangement in the cylinder jacket is the relatively large volume of the displacement, which, particularly in the case of smaller compressors with a small stroke volume, results in poor compression efficiency.

It is therefore an object of the present invention to avoid the disadvantages of the known, in particular to provide a compressor of the type mentioned, which is simple and. inexpensive to manufacture and at the same time characterized by good performance data. In particular, easy assembly in a modular design should be possible. The compressor should continue to have a long service life.

According to the invention, this object is achieved with a piston compressor with the features of the independent claim.

A piston compressor for compressing gaseous media has a stepped piston with a first piston part and at least a second coaxially arranged piston part. The piston compressor has a first cylinder with an inner bore for receiving the first piston part to form a first workspace. The second cylinder also has an inner bore for receiving the second piston part to form a second working space. The second piston part has a smaller diameter than the first piston part. Each of the at least two cylinders is closed by a plate with valve arrangements, the second piston part with the smaller diameter being guided through an opening in one of the plates with valve arrangements. The stepped piston can move back and forth in the compressor, whereby gaseous medium is sucked in and then compressed. With the help of the stepped piston, compression in at least two separate work rooms is possible. One work area is ring-shaped (annular gap), while the other work area is cylindrical. The stroke movements of the stepped piston can take place, for example, via a connecting rod system with a drive via a crank mechanism. For this purpose, the stepped piston is connected to the drive via a piston rod or a guide piston. In particular, the stepped piston could therefore be built on a crosshead of a compressor engine.

The plates with valve arrangements close the cylinders and serve to control the inlet and outlet of the gaseous medium to be compressed. Such a valve arrangement has several advantages. So the plates with the valve arrangements can be easily assembled and disassembled. A modular design is also made possible because the necessary valves can be attached to the plates in a simple manner. The advantages of this design are the good utilization of the cylinder cross-section and the smoothly moving valve plates. The damage space, wear and flow losses are therefore small with this valve arrangement and it is therefore particularly suitable for smaller and high-speed compressors. In a first embodiment, the first piston part is arranged at one end of the second piston part. The piston part with the larger diameter thus forms the front end of the step piston. The first piston part forms a cylindrical working space and the second smaller piston part forms an annular working space. The piston parts and the two cylinders are thus arranged in such a way that compression takes place in push-pull. The gaseous medium is compressed in one direction of movement in each work area and sucked in the other work area (and vice versa).

Since the gas forces, which act on the entire piston surface on the one hand and only on the annular gap on the other hand, partially cancel each other out in the workrooms, the forces on the drive are relieved. Another effect of this arrangement is a balanced torque curve and thus better smooth running.

In an alternative embodiment, the second piston part is arranged at the end of the first piston part. The second piston part, the diameter of which is smaller than the diameter of the first piston part, thus forms the front end of the stepped piston. The second smaller piston part forms a cylindrical working space and the first larger piston part forms an annular working space. The piston parts and the two cylinders are arranged such that compression takes place in the “same cycle ^λ- . In this arrangement, one direction of movement has the same effect for both workspaces. A compression takes place simultaneously in the two work rooms. However, the compression takes place in two stages. In a first stage, compression takes place via the annular gap (formed by the second working space). The compression in the second Step takes place over the piston surface of the second piston part, which forms the front end of the step piston.

The piston parts are each preferably sealed against the inner bore of the cylinder parts by means of piston rings. The advantage of this embodiment is that the losses via the piston rings emerge from the second stage into the first stage and do not reach the outside. As a result, gas losses can be minimized considerably. The loads on the piston rings are also reduced.

For example, the diameter of the second smaller piston part is preferably selected in comparison to the diameter of the first larger piston part such that the annular gap volume of the first stage has a volume three to four times greater than the working space at the front end of the step piston.

It is advantageous if the plates are disc-shaped and delimit the work areas on the end face, as a result of which the work rooms are closed in a simple manner. This also enables a simple and compact design of compressors.

It is advantageous if the plates with valve arrangements have at least one inlet valve and at least one outlet valve. This ensures that air or other gaseous media is drawn in via an inlet valve in one direction of movement and that the compressed air is expelled through the outlet valves during the opposite movement. For this purpose, the plates advantageously have bores for the valve arrangements. The corresponding valves can be arranged on these holes. Such holes can be wall on the plates, which are preferably made of metal such as steel or aluminum, are introduced.

It is particularly advantageous if the inlet valves and outlet valves are designed as lamellar valves, as tongue valves, or individual valves with spring return. A slat closes (respectively opens) the passage through a hole for the passage of the media. A tongue closes (or opens) the passage through several holes for the passage of the media at the same time. A single valve closes (or opens) the passage through one or more holes for the passage of the media. Such valves are particularly suitable for use in a compression unit with a small stroke volume. These valve types are characterized by the fact that they are easy and inexpensive to manufacture or obtain. They can also be easily arranged in the plate.

The plates are sealed off from the cylinder parts by seals, for example flat seals, O-ring seals or, if necessary, metallic seals.

Further individual features and advantages of the invention result from the following description of the exemplary embodiments and from the drawings. Show it:

FIG. 1: cross section through a first exemplary embodiment of a piston compressor according to the invention,

FIG. 2: cross section through an alternative exemplary embodiment of a piston compressor according to the invention, Figure 3 ^' : enlarged view of a section through the upper part of a piston compressor with lamellar valves and

Figure 4: enlarged representation of a partial cross section through a further piston compressor with valves which have a spring return.

In Figure 1, a piston compressor designated 15 with a step piston 1 is shown. The stepped piston 1 consists of two piston parts: a first piston part 16 and a second piston part 17. The pistons are of course basically arranged symmetrically and coaxially in an axis A. The stepped piston 1 can move back and forth in the x-direction along the axis A. The first piston part 16, which defines the front end of the stepped piston, is arranged in a first cylinder 7. The diameter of the first piston part 16 is larger than the diameter of the second piston part 17. Above a piston surface 30 of the first cylinder 7 there is a working space 21 formed by the first cylinder 7, closed off by the valve plate 9. Another working space 22 is in the region of the second cylinder 8 and the second piston part 17 are arranged. Obviously, this working space 22 is configured in a ring shape.

In Figure 1, the compressor 15 also has a cylinder head 29. In this case, the plate 9 is located between the cylinder head 29 and the first cylinder 7. At best, it is conceivable to dispense with the cylinder head 29 shown and only one plate 2 with valve arrangement as Insert the end of cylinder 7. The other plate 9 with the valve arrangements, which closes the annular gap or working space 22, is arranged between the first cylinder 7 and the second cylinder 8. In the middle, the plate 2 has a circular opening 20, the diameter of which preferably corresponds to the diameter of the inner bore 19 of the second cylinder 8. The opening 20 can, however, also be designed in such a way that there is a seal with the piston part 17. At least one inlet valve 3 and 13 and one outlet valve 4 and 14 are arranged on the plates 2 and 9, respectively. For example, in FIG. 1, the inlet valves 3 and 13 and the outlet valves 4 and 14 are designed as lamella valves 31. Of course, other types of valves can also be used. The piston parts 16 and 17 have piston rings 5 on their outer surfaces for sealing the respective working spaces 21 and 22, respectively. Other seals such as labyrinth seals or rod packs are also conceivable. The front piston part 16 also has guide elements 6, on the one hand to increase the stability of the stepped piston 1 and on the other hand to minimize the distance between the stepped piston 1 and the cylinder (here only the cylinder part 7). As a result, the efficiency of the piston compressor 15 can be improved.

The stepped piston 1 compresses, for example, a gaseous medium, in particular air, during the downward movement in the x direction, the compressed medium being able to be expelled via the outlet valve 14. With the same downward movement, the gaseous medium is sucked into the first working space 21. If the stepped piston 1 moves in the opposite direction, the process takes place in the opposite way. The arrows shown in Figure 1 illustrate the inflowing or outflowing air. An alternative embodiment of a piston compressor 15 is shown in FIG. This piston compressor 15 compresses air or other gaseous media in unison. If, for example, a stepped piston 1 is moved forward, that is, approximately in the direction of the cylinder head 29, the air in the working spaces 21 and 22 is compressed. If the pressure in the workrooms exceeds a certain level, the compressed air escapes via the respective outlet valves 4 or 14.

The compression takes place in two stages. In a first stage, the medium is compressed via the annular gap 28 in the lower working space 21. In the second stage, the medium in the front working chamber 22 is compressed via the piston surface 30 of the front piston 17. Due to the relatively small piston area 30, higher final pressures can be achieved here. The arrangement is characterized, inter alia, in that the losses emerge from the second stage into the first stage via the piston rings 5 and thus do not escape into the open. In this way, gas losses can be minimized considerably. In addition, the loads on the piston rings 5 are minimized since, due to the high support pressure in the lower working chamber 21, the differential pressure acting on the piston rings 5 is smaller with respect to the front working chamber 22. In addition to piston rings 5, the second piston part 16 has additional guide elements 6. Depending on the dimensioning and application, several such sealing elements and / or guide elements can be arranged.

The actual drive of the stepped piston 1 is not shown in FIGS. 1 and 2. A stepped piston 1 is moved by an oscillating drive, for example via a crank drive. The stepped piston 1 is preferably connected to the drive via a piston rod. The guide of the stepped piston 1 can be done in particular by a crosshead (also not shown).

FIG. 3 shows a section through an upper plate 9 with the representation of an inlet valve 3 in the form of a lamellar valve 31. A hole 23 in the form of a through hole is provided in the plate 9 for an inlet valve 3, which is covered by a respective lamella , The lamella valves 31 are attached off-center. A total of at least one lamella is to be provided as the inlet and outlet valve. The number of slats essentially depends on the size and the intended performance data. Of course, the piston parts 16 and 17 must have recesses at locations where components of the valves 3 and 4 protrude into the displacement. The position of the stepped piston 1 around the longitudinal axis A must be fixed.

The inlet valves 3 and outlet valves 4 can, according to the design with lamellar valves 31, also each be designed as a tongue valve, in which case a tongue would cover several bores 23 at the same time (not shown).

FIG. 4 shows an example of a valve arrangement on a plate 9, which also applies analogously to the valve arrangement of the plate

2 of the annular gap 28 apply. The valves 3 and 4 are designed as individual valves with spring return 33, which are arranged centrally above the bores 23.

Of course, the remaining plates (each not shown in FIGS. 3 or 4) can have similar valve arrangements. The individual valve constructions of lamellar, tongue or individual valves are not the subject of the invention. These have been described in detail in many specialist publications and are assumed to be known.

Claims

claims

1. Piston compressor (5) for compressing gaseous media in at least two working spaces with a step piston (1) containing a first piston part (16) and at least one coaxially arranged second piston part (17), a first cylinder (7) for receiving the first piston part (16) and to form a first working space (21) and at least one second cylinder (8) for receiving the second piston part (17) and to form a second working space (22), the second piston part (17) having a smaller diameter than the first piston part (16), each of the at least two cylinders (16, 17) being closed by a plate (2, 9) with valve arrangements and the second piston part (17) by an opening (20) in one of the plates (2) is guided, the second piston part (17) being arranged at one end (27) of the first piston part (16), the second piston part (17) forming the front end of the stepped piston (1) and the second piston nteil (17) forms a cylindrical working space (22) and the first piston part (16) forms an annular working space (21).

2. Piston compressor according to claim 1, characterized in that the plates (2, 9) are disc-shaped and limit the working spaces on the end face.

3. Piston compressor claim 1 or 2, characterized in that the plates (2, 9) with inlet valves (3, 13) and outlet valves (4, 14) are provided.

4. Piston compressor according to one of claims 1 to 3, characterized in that the valves (3, 4, 13, 14) are lamellar valves (31).

5. Piston compressor according to one of claims 1 to 4, characterized in that the valves (3, 4, 13, 14) are tongue valves (32).

6. Piston compressor according to one of claims 1 to 5, characterized in that the valves (3, 4, 13, 14) are individual valves with spring return (33).