EP0389414B1 - Piston compressor - Google Patents

Description

The invention relates to a reciprocating compressor with at least two cylinders, each with a piston guided therein, which pistons are arranged in pairs, opposite one another on a common axis, and are coupled via a yoke connecting two piston rods to a slider which is located between two parallel guide surfaces formed on the yoke is movably guided transversely to the common axis and in which a crank pin of a drive shaft engages.

In a known from EP patent application 0 269 082 (P.6073), designed for high pressure four-stage small compressor of the type mentioned, with two piston pairs arranged offset by 90 °, the yokes are each made in one piece and provided with a longitudinal slot in which the relevant slide in the form of a square is guided over linear needle bearing arrangements. The exact guidance of the sliding piece, which is important for the safe and low-maintenance operation of such compressors, requires, in the known designs, in particular in the case of compressors for high pressure, in which correspondingly large bearing forces occur, very precise machining of a roller bearing arrangement or of Parts interacting sliding surfaces and thus a correspondingly high manufacturing cost for the yoke and the slider.

The invention has for its object to provide a particularly in this regard, reciprocating compressor of the type mentioned in a construction which ensures low backlash, an essentially backlash-free, precise parallel guidance of the slider connected to the crank pin in the yoke.

This object is achieved by the features specified in the characterizing part of claim 1. The embodiment according to the invention achieves in a simple, inexpensive manner that the sliding shoes are pressed against the sliding piece under a predetermined prestressing - via rolling elements or via interacting sliding surfaces. Accordingly, a bumpless transmission of the drive forces to be introduced into the pistons via the slide and the slide shoes is achieved.

Embodiments of the inventions are specified in the dependent claims.

Fig. 1

einen erfindungsgemäss ausgeführten Hubkolbenkompressor in einem durch zwei Horizontalebenen geführten Schnitt;

Fig. 2

eine Einzelheit eines Hubkolbenkompressors in einer abgewandelten Ausführungsform in einem der Fig. 1 entsprechenden Teilschnitt;

Fig. 3

den Schnitt III-III aus der Fig. 2.

Further details and features emerge from the following description of exemplary embodiments of the invention shown schematically in the drawing. Show it:

Fig. 1

a reciprocating compressor designed according to the invention in a section made through two horizontal planes;

Fig. 2

a detail of a reciprocating compressor in a modified embodiment in a partial section corresponding to FIG. 1;

Fig. 3

the section III-III of FIG. 2nd

The compressor shown, a small compressor, has four cylinders 1, 2, 3 and 4, in which pistons 5, 6, 7 and 8 are guided. The cylinders 1 and 3 each have a common horizontal axis 10 lying in the plane of the drawing, while the cylinders 2 and 4 are arranged on a common horizontal axis 11 set back from the plane of the drawing. The pistons 5 and 7 are coupled via a yoke 14 connecting their piston rods 12 and 13, respectively, to a square-shaped sliding piece 15 which, via a sliding bearing arrangement or, as indicated in FIG. 1, via a roller bearing arrangement (needle bearing) 9 on a crank pin 16 one vertically arranged crankshaft 17 is mounted. The crankshaft 17 is equipped with an engine, not shown, e.g. an electric motor. The slider 15 is guided transversely to the axis 10 between two guide surfaces 18 formed in the yoke 14 and parallel to one another. The pistons 6 and 8 are coupled via a second yoke 22 connecting their piston rods 20 and 21 to a second slider, not shown, mounted on the crank pin 16, which can be displaced transversely to the axis 11 in the yoke 22 offset by 90 ° relative to the yoke 14 is led.

The guide surfaces 18 are formed on slide shoes 23, which are connected in any way, as shown by means of a screw 25, to one of the piston rods 12, 13, 20 and 21 and which each have a cylindrical support surface 24 on the side facing the piston concerned are executed. Yokes 14 and 22 each contain two of these sliding shoes 23 and a holder connecting them in the form of a connecting part which can be braced against the sliding shoes and which, according to the embodiment shown, can be formed by a resiliently deformable clamping ring 26 which can be placed on the supporting surfaces 24. The slide shoes 23 can interact with the slide 15 via slide bearing arrangements or, as indicated in FIG. 1, via roller bearing arrangements 27, linear needle bearings as shown.

Due to the tension ring 26 placed on the support surfaces 24 under a predetermined preload, the sliding shoes 23 of the yoke 14 are clamped with a corresponding, predetermined pressing force via the roller bearing arrangements 27 against the guide surfaces 19 of the sliding piece 15 which can be inserted between the sliding shoes 23. In a corresponding manner, the sliding shoes 23 of the second yoke 22 are braced against the guide surfaces 19 of the second sliding piece, not shown, which run parallel to the axis 10. With this arrangement, there is a coupling of the pistons 5 and 7 that is free of play in the direction of the axis 10 and a coupling of the pistons 6 and 8 that is free of play in the direction of the axis 11, and thus a correspondingly bumpless drive connection between the crank pin 16 and the pistons 5, 6, 7 and 8 guaranteed. The connection between the clamping ring 26 and the sliding blocks 23 is secured by the piston rods 12 and 13 or 20 and 21, which are each brought together with the relevant sliding block 23 through a passage opening 28 provided on the circumference of the clamping ring 26.

The piston 5 shown in its top dead center position is provided with a plurality of suction valves 35, each associated with a passage opening 30, of which only one is shown. A connection between a compression chamber 31 of the cylinder 1 forming the first compression stage and the central crank chamber 36 of the compressor is established by the suction valves 35 during the suction stroke of the piston 5. The crank chamber 36 is connected to a feed line, not shown, for the gas to be compressed, for example natural gas, which is fed to the crank chamber 36 at a pressure of, for example, 10 mbar and is sucked into the compression chamber 31. During the pressure stroke, the gas is compressed to a pressure of, for example, 5 bar and is supplied to the second compression stage formed by the cylinder 2 by means of pressure valves 37 arranged in the cylinder head of the cylinder 1, of which only one is also shown, via a connecting channel 38.

In the cylinder 2, the gas is drawn into a compression chamber 32 by suction valves 35 arranged in the cylinder head during the suction stroke of the piston 6, during the subsequent pressure stroke to a pressure of e.g. Compressed 20 bar and fed through a centrally arranged pressure valve 37 via a connecting channel 39 to the third compression stage formed by the cylinder 3, the piston 7 of which is shown in its bottom dead center position. In the cylinder 3, the gas sucked into the compression chamber 33 during the suction stroke of the piston 7 is correspondingly reduced to a pressure of e.g. 60 bar compressed and supplied via a connecting channel 40 to the final pressure stage formed by the cylinder 4.

In the cylinder 4, the gas drawn into the compression chamber 34 during the suction stroke of the piston 8 is compressed to a pressure of, for example, 200 bar during the pressure stroke and is conveyed through the pressure valve 37 into a pressure line 41, which is connected to a pressure container (not shown) for the compressed gas can be connected. The pressure vessel can be designed, for example, as a gas fuel tank of a motor vehicle.

The suction valves 35 and pressure valves 37 can be of any design. Corresponding valves, the arrangement and design of which is not the subject of the present invention, are e.g. in the CH patent application 02 209 / 88-9 (P.6196) described in more detail.

1, the sliding shoes 23 can be designed with lateral stops 43 which limit the range of motion of the roller bearing arrangements 27.

In the embodiment shown in FIG. 2, the yokes 14 and 22 each contain two bow-like clamping parts 44 that can be inserted into the clamping ring 26, each of which is designed with two bent ends that can be resiliently clamped against the facing sides of the two sliding shoes 23, on each of which in the direction of the common axis 10 or 11 of the yoke 14 or 22 opposite stops 43 for the roller bearing arrangements 27 are formed. 2, the roller bearing arrangements 27 each contain a number of needle-shaped roller bodies 45, which are arranged in a cage 46 movable between the stops 43.

As can further be seen from FIG. 2, the sliding shoes 43 can each be provided with a support 47, which consists of a wear-resistant material, for example hardened steel. The supports 47 can each be provided by a plate which can be fastened on the slide shoe 23 in any manner, for example by means of a soldered connection, or by a correspondingly applicable layer made of a corresponding bearing material, for example ceramic material be educated. The slider 15 can also be provided with a corresponding pad or be made of a wear-resistant material.

According to the illustration according to FIGS. 2 and 3, the two clamping rings 26 can each be provided with two cap-like cover parts 48, which consist of a plastic and each with an end wall 50 that laterally delimits the interior of the clamping ring 26 and one on a shoulder part of the clamping ring 26 in question attachable flange section 51 can be performed. The end walls 50 are each provided with an elongated hole-like passage opening 52 for the crank pin 16 which is adapted to the range of movement of the sliding piece 15. The inner parts of the yokes 14 and 22 containing the bearing arrangements 9 and 27 are protected from contamination by the ingress of dust by the cover parts 48, in connection with cover disks 53 attached to the crank pin 16 and covering the passage openings 52.

The clamping ring 26, the sliding shoes 23 connected to the piston rods 12 and 13 or 20 and 21 and the sliding block 15 each form a self-supporting, stable installation unit which is guided in the corresponding, opposing cylinders 1 and 3 or 2 and 4. The screwless, resilient connection between the slide shoes 23 enables compensation of inaccuracies of the interacting parts, in particular a limited displacement of the slide shoes 23 in the circumferential direction of the clamping ring 26. Accordingly, the sliding shoes 23 can each - with a substantially constant pretensioning force of the clamping ring 26 - exactly Set parallel to the guide surfaces 19 of the slider 15. The clamping ring 26 also ensures a uniform distribution of the contact pressure on the slider 15.

In a modified, not shown embodiment, the holder for two interacting sliding shoes 23 can contain two supporting clamping rings, which, axially offset from one another, can be placed on both sides of the piston rods 12, 13 or 20, 21 under prestress on the opposite shoulder parts of the sliding shoes 23 . When fitting and removing these clamping rings, the sliding shoes can therefore remain connected to the piston rods. Instead of clamping rings, other mounts can be provided with connecting parts that can be detached from the sliding shoes and braced against them.

The invention is not limited to compressors of the type described and illustrated above, but also for two-stage or multi-stage designs as well as for other applications, e.g. suitable as breathing air compressors, compressors for low-temperature technology and the like.

Claims (7)

1. A reciprocating compressor comprising at least two cylinders (1, 2, 3, 4) each containing a piston (5, 6, 7, 8), which pistons (5. 7, and 6, 8) are disposed in pairs one opposite the other on a common axis (10; 11) and are coupled to a sliding block (15) via a yoke (14; 22) connecting two piston rods (12, 13; 20, 21), the said block being guided for movement transversely of the common axis (10; 11) between two parallel guide surfaces (18) formed on the yoke (14; 22), a crankpin (16) of a drive shaft (17) engaging in said block, characterised in that the yoke (14, 22) is formed basically by two separate shoes (23) each having one of the guide surfaces (18) and each connected to one of the piston rods (12, 13, 20, 21) and at least one elastically deformable, supporting clamping ring (26) which surrounds said shoes (23) and said block (15) and which is fitted with pre-stressing on to the two shoes (23) and braced via said shoes (23) against the block (15) in the direction of the common axis (10; 12).
2. A compressor according to claim 1, characterised in that the shoes (23) are each constructed with a cylindrical support surface (24) for the clamp ring (26) on the side facing the piston (5, 6, 7, 8).
3. A compressor according to claim 1 or 2, characterised by at least one cover member (48) in the form of a cap laterally defining a shoulder part of the clamp ring (26), said cover member having an aperture (52) for the passage of the crank pin (16), such aperture being adapted to the range of movement of block (15).
4. A compressor according to any one of the preceding claims, characterised in that the guide surfaces (18) of the shoes (23) and/or the corresponding guide surfaces (19) of the block (15) are each formed on a lining (47) applied to the associated shoe (23) or block (15), said lining consisting of a wear-resistant material.
5. A compressor according to any one of the preceding claims, with linear rolling bearing systems (27) provided between the block (15) and the shoes (23), characterised in that two lateral stops (43) limiting the range of installation of the rolling bearing system (27) are provided on each shoe (23).
6. A compressor according to claim 5, characterised in that the lateral stops (43) disposed in each case opposite one another in the direction of the common axis (10; 11) on the co-operating pair of shoes are formed on a common clamping member (44) which is adapted to be braced against the shoes (23).
7. Use of a compressor according to any one of the preceding claims in a device for filling the tank of a motor vehicle with a gaseous fuel, more particularly natural gas, for storage therein.

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