EP2161451A1 - Piston compressor - Google Patents

Abstract

The compressor has a piston (2) designed as a stepped piston, and a piston rod (3) for converting a rotary movement of the crankshaft into a linear movement for the piston. The piston rod directly connects the piston with a crankshaft (4), which drives the piston and the piston rod. The piston comprises two piston parts (5, 6) that are attached to working chambers (17, 18) and are received in cylinders (20, 21), respectively, where one of the piston parts exhibits a diameter smaller than another piston part.

Description

The invention relates to a particular oil-free piston compressor for compressing gaseous media in plunger compressor construction according to the preamble of claim 1. Such plunger compressors are characterized in that the piston and crankshaft are directly connected. The driven via the connecting rod, reciprocally movable guide piston of plunger compressors can simultaneously form pressure piston.

Plunger compressors have long been known and in use. A genre moderately comparable piston compressor is for example from the WO 02/068822 A1 known. This document describes an oil-free plunger compressor with a single acting plunger. Compaction takes place only on one side of the stroke (ic in the upstroke). A disadvantage of this design is that the delivery quantity per stroke is limited. In practice, several single-acting plungers are connected in parallel to increase the delivery quantity. A major disadvantage of this multi-cylinder design is the greater space requirement and the greater production costs.

It is therefore an object of the present invention to avoid the disadvantages of the known and in particular to provide a reciprocating compressor of the type mentioned, which is characterized by good performance data. Furthermore, the compressor should be easy and inexpensive to produce and can be performed in particular oil-free. The reciprocating compressor should be compact and suitable in particular for use in rail vehicles.

According to the invention, these objects are achieved with a reciprocating compressor having the features of claim 1. A piston compressor for compressing gaseous media in plunger compressor design has at least one piston, a crankshaft for driving the piston and a preferably substantially one-piece connecting rod, which connects the piston directly to the crankshaft. The piston compressor is preferably oil-free. With the connecting rod, the rotational movement of the crankshaft can be converted into a linear movement for the piston. The piston is designed as a stepped piston, which has at least two piston parts. The second piston part or the further piston parts have a smaller diameter than the first piston part. Each piston part is associated with a working space, wherein preferably one of the working spaces are cylindrical and the other working space or the other working spaces are annular. Preferably, the piston compressor according to the invention is designed as an oil-free plunger compressor. Through the use of a stepped piston, a two-stage compression can be achieved with one revolution of the crankshaft, whereby the compression efficiency can be significantly improved. Such a plunger compressor is particularly suitable for use in rail vehicles due to the small size. Of course, other applications are conceivable.

The reciprocating compressor can be designed as a single cylinder with a single stepped piston. Of course, it is also conceivable to drive with the one crankshaft two opposite or more juxtaposed stepped pistons. In the former case, for example, the piston compressor can thus be designed in a boxer design, in which the respective stepped pistons are arranged on opposite sides of the compressor.

In a first embodiment, the first piston part and the second piston part can each be accommodated in a cylinder, wherein for predetermining the working spaces at least one of the cylinders and preferably each of the cylinders is closed by a plate with a valve arrangement (also abbreviated to "valve plate" hereinafter) is. Such a plate is for example in the WO 2005/059362 been described.

The first piston part, i. the piston part with the largest diameter, can form the front end of the stepped piston. This results in a double-acting plunger compressor for compression in push-pull. Of course, it is also conceivable that the second piston part forms the front end of the stepped piston. In this case, there would be a compressor in which the compression in the work spaces would be done in common mode.

The adjoining the connecting rod piston part may have a first guide ring for guiding in the cylinder. The guide ring is slidably mounted in the cylinder and ensures a long life of the compressor. The guide ring may be made of a high temperature resistant plastic with a low coefficient of friction, for example, a plastic based on PTFE.

It can be particularly advantageous when the piston part adjoining the connecting rod has a second guide ring which extends into the working space and minimizes the so-called harmful volume there. As a result, the leadership and stability can be improved, and improve the compression efficiency. The guide ring should consist of a high temperature resistant plastic with a low coefficient of friction, for example, a plastic based on PTFE.

Furthermore, it may be advantageous if the first guide ring and the second guide ring are arranged at a distance from each other on the piston part. At least one piston ring, preferably two piston rings for sealing the respective working space, can be arranged between the two guide rings. Such piston rings may for example consist of a plastic based on PTFE.

An advantageous sealing and guiding can result if the length of the first guide ring and optionally of the second guide ring measured in the axial direction of the piston is a multiple compared to the length of the at least one piston ring. A multiple means that the guide rings are at least twice as long as the piston rings. It is particularly advantageous if the length of the first guide ring and optionally of the second guide ring is in each case at least five times, and particularly preferably approximately ten times, compared to the length of the piston ring.

Further, it may be advantageous if the second guide ring arranged on the side facing away from the connecting rod of the piston part consists of plastic and in a starting position after a first mounting against the inner diameter of the respective cylinder and / or with respect to the plate with the valve assembly, through which the respective Piston part performed or feasible, has an undersize. As a result, after a first startup (running-in process), the second guide ring can be adapted precisely to the inside diameter of the cylinder and / or the plate by wear. This embodiment can lead to a further optimization of the guiding properties of the stepped piston in the cylinders and reduce the harmful volume.

On a top valve plate, which closes the working space at the end of the stepped piston, can connect a cylinder head, which is provided with channels for supplying and discharging the medium from the associated working space.

It may then be advantageous if at least one of the valve plates and preferably each of the valve plates is or are designed as a lamella valve. In this case, the lamella valve can essentially be made up of two disk bodies and a lamella part arranged sandwiched between them. The fin part may have fixed and movable for a suction sections. The movable portions may be formed, for example, as tongue-shaped lamellar portions ("tongue portions") which may be predetermined by correspondingly shaped cuts in the lamella portion.

For a simple and inexpensive manufacturability and handling during assembly or disassembly, it may finally be advantageous if the crankshaft, the stepped piston and connecting rod at least in the end position (in this end position, the compressor is ready) form a unit that as a whole from outside to End position by targeted movement after at least one predetermined sequence of movements in a preferably one-piece housing part can be introduced. The crankshaft can be rotatably supported via shaft bearings in the housing part in an end position. For disassembly, the unit can be removed as a whole, starting from the end position of the housing part. Preferably, no additional cover parts or other crankcase parts are necessary for the rotatable mounting of the crankshaft. An advantage of this arrangement is that the number of interfaces requiring high accuracy of fit can be significantly reduced. Replacing the crank drive unit can also be done by a mechanic without special knowledge easy and fast. Due to the advantageous compactness of the reciprocating compressor, this is also particularly suitable for use in rail vehicles.

When the first piston part forms the front end of the stepped piston, it may be advantageous if the first piston part is fastened to the adjacent second piston part by means of a screw (for example a countersunk screw). Thanks to the detachable connection arrangement, the first piston part can be removed from the aforementioned unit, whereby disassembly of the valve plate and cylinder can be made, and then remove the entire crank mechanism unit via the opening on the crankcase.

Figur 1:

Einen Querschnitt durch einen erfindungsgemässen Tauchkolbenkompressor,

Figur 2:

Eine Kurbeltrieb-Einheit mit Stufenkolben, Pleuel und Kurbelwelle des Tauchkolbenkompressors gemäss Figur 1,

Figur 3:

Ein Kurbelgehäuse mit ausgebautem Deckelteil des Tauchkolbenkompressors gemäss Figur 1

Figur 4:

Das Kurbelgehäuse mit einer darin angeordneten Kurbelwelle in einer Ruhestellung (Schnittlinie B-B gemäss Figur 1), und

Figur 5:

Das Kurbelgehäuse mit der Kurbelwelle in einer Entnahmestellung.

Further individual features and advantages of the invention will become apparent from the following description of an embodiment and from the drawings. Show it:

FIG. 1:

A cross section through a plunger compressor according to the invention,

FIG. 2:

A crank drive unit with stepped piston, connecting rod and crankshaft of the plunger compressor according to FIG. 1 .

FIG. 3:

A crankcase with removed lid part of the plunger compressor according FIG. 1

FIG. 4:

The crankcase with a crankshaft arranged therein in a rest position (section line BB according to FIG FIG. 1 ), and

FIG. 5:

The crankcase with the crankshaft in a removal position.

FIG. 1 shows a designated with 1 plunger compressor with a cylinder 20, 21 movably arranged step piston 2. The stepped piston is guided in the cylinder 21. For this construction, the stepped piston 2 is connected via a connecting rod 3 directly to the crankshaft 4. On the piston side, a piston pin 28 and a piston pin bearing 29 are used for the connection of the stepped piston 2 with the crankshaft 4. The stepped piston 2 consists of two piston parts, namely a first piston part 5 and a second piston part 6. The piston part 5 is fastened to the lower piston part 6 by means of a countersunk screw. Both connecting rods 3 and crankshaft 4 are made in one piece. The second piston part 6, which forms a guide piston, evidently has a smaller diameter than the first piston part 5, which forms the front end of the stepped piston. Thus, the compression takes place in the respective working spaces 17, 18 of the double-acting plunger compressor in push-pull.

The first piston part 5 and the second piston part 6 are each received in a cylinder 20, 21. The working axis of the stepped piston is designated A. For specifying work spaces 17 and 18, each of the cylinders 20, 21 by an in FIG. 1 only schematically illustrated plate 22, 23 closed with a valve assembly. Such a valve plate 22, 23 includes valves (not shown) for the supply and removal of air or other gaseous medium. At the uppermost valve plate 22, a cylinder head 10 connects, which is provided with channels for supplying and discharging air or other gaseous medium from the associated working space 17 (the air supply and removal is indicated by arrows). The valve plate 23 is clamped between the cylinders 20, 21. The cylinder 21 is with channels provided for the supply and removal of air from the working space 18 (see arrows).

Out FIG. 1 is further apparent that the crankshaft 4 is mounted in a one-piece housing part 7. The longitudinal direction in which the crankshaft 4 extends is indicated by an arrow x. The crankcase further has an opening 15 and a lid formed as a cover part 16 which is detachably mounted on the opposite side of the stepped piston 7 of the housing part.

FIG. 2 shows a developed crank mechanism for the plunger compressor. The crank mechanism forms a unit, which - as described below with reference to FIGS. 4 to 6 explained - as a whole in the crankcase can be installed or removed. The unit basically consists of the three components: stepped piston 2, connecting rod 3 and crankshaft 4. In FIG. 2 are further two attached to the piston member 6 guide rings 24 and 25 can be seen, which consist of a plastic based on PTFE. Between these spaced guide rings 24 and 25 is a piston ring pair 26 which serves to seal the lower, annular working space. The piston rings are also made of a PTFE-based plastic. The length L1 and L2 of the first guide ring 24 and the second guide ring 25 measured in the axial direction A of the stepped piston is compared to the length designated L3 of the piston rings 26 in about ten times, whereby an optimal guiding and sealing effect can be achieved. The second guide ring 25 has in a starting position after a first mounting against the inner diameter of the valve plate 23 an undersize, whereby after a first startup (inlet) of the guide ring 25 exactly adapted to the inner diameter of the valve plate 23 by wear is. The upper piston part 5 is equipped with two piston rings 27 for sealing the cylindrical working space.

As FIG. 3 shows, the crankcase is configured substantially rectangular in a plan view. The housing part 7 thus has two approximately cuboid cavities, which are separated by a wall portion. In the respective cavities respectively the (not visible here) crankshaft and clutch are added to a drive.

From the FIGS. 4 and 5 shows how the unit of stepped piston, connecting rod and crankshaft can be dismantled, with the sake of simplicity in the FIGS. 4 and 5 in each case only the crankshaft 4 is shown. FIG. 4 shows the piston compressor in a prepared for disassembly position (or vice versa: mounting position), in which the drive-side components (in particular the clutch) and the cylinders were removed with cylinder head and valve plates. Furthermore, the in FIG. 1 With 16 designated cover plate of the crankcase removed, creating a mounting hole is formed. The mounting hole is in the FIGS. 4 and 5 indicated by a rectangle marked 15. The working axis A is located in the cavity in the middle. FIG. 4 shows further that the housing part 7 basically basically rectangular and in particular the respective cavities for the crankshaft 4 on the one hand and for a coupling for connection to a drive on the other hand are designed rectangular. The expansion of the shaft bearings creates openings 8 and 9. The distance E between diagonally opposite edges 11 and 12 at the housing openings 8 and 9 is 2R. Upon rotation of the crankshaft 4 about the axis A, the shaft ends 13 and 14 of the crankshaft 4 define a circle. This circle is indicated by a dot-dash line (circle center: A, circle radius: E / 2). The crankshaft and the housing part are designed such that the diameter of this circle (2R) is slightly smaller than the mentioned distance E (eg E - 2R = 0.5 ... 5mm). Out FIG. 4 further reveals that the housing part 7 is configured approximately cuboid.

After a rotation about the A-axis by 90 °, the crankshaft 4 (together with the connecting rods and pistons, not shown) is in a removal position. This position is in FIG. 5 shown. From the removal position, the crankshaft 4 is moved without further change in its angular position with respect to the axis A as a function of the (not shown) form of the mounting hole so far that it can be pulled out without resistance through the mounting hole 15.

Claims (12)

Piston compressor (1) for compressing gaseous media in a plunger compressor design, in particular an oil-free piston compressor with at least one piston (2), a crankshaft (4) for driving the piston (2) and a connecting rod (3) connecting the piston (2) connects directly to the crankshaft (4) and with which the rotational movement of the crankshaft in a linear movement for the piston is convertible, characterized in that the piston (2) as a stepped piston containing a first piston part (5) and at least one second piston part (6 ), wherein the second piston part (6) has a smaller diameter than the first piston part (5) and wherein each piston part (5, 6) is associated with a working space (17, 18). Piston compressor according to claim 1, characterized in that the first piston part (5) and the second piston part (6) in each case in a cylinder (20, 21) are received, wherein for prescribing the working spaces (17, 18) at least one of the cylinders and preferably each of the cylinders (17, 18) is each closed by a plate (22, 23) with a valve arrangement. Piston compressor according to claim 1 or 2, characterized in that the first piston part (5) forms the front end of the stepped piston (2). Piston compressor according to one of claims 1 to 3, characterized in that the connecting rod (3) adjoining the piston part (6) for guiding in the cylinder (21) has a first guide ring (24). Piston compressor according to Claim 4, characterized in that the piston part (6) adjoining the connecting rod (3) has a second guide ring (25). Piston compressor according to claim 5, characterized in that the first guide ring (24) and the second guide ring (25) are arranged at a distance from each other on the piston part (6) and that between the two guide rings (24, 25) at least one piston ring (26 ) is arranged for sealing the respective working space (18). Piston compressor according to one of claims 4 to 6, characterized in that the length (L1, L2) of the first guide ring (24) and optionally the second guide ring (25) measured in the axial direction of the piston compared to the length of the at least one piston ring (26 ) is a multiple. Piston compressor according to one of claims 4 to 7, characterized in that on the conrod (3) facing away from the piston part (6) arranged, second guide ring (25) consists of plastic and in a starting position after a first assembly relative to the inner diameter of respective cylinder (21) and / or with respect to the plate (23) with the valve assembly through which the respective piston part (6) is performed, an undersize, whereby after a first startup (run-in) the second guide ring (25) exactly on the Inner diameter of the cylinder (21) and / or the plate (23) is adaptable by wear. Piston compressor according to one of claims 2 to 8, characterized in that on a top plate (22) having a Valve arrangement, which closes the working space (17) at the end of the stepped piston (2), a cylinder head (10) connects, which is provided with channels for supplying and discharging the medium from the associated working space (17). Piston compressor according to one of claims 2 to 9, characterized in that at least one of the plates (22, 23) with a valve arrangement and preferably each of the plates (22, 23) is formed with a valve arrangement as lamella valves or are. Piston compressor according to one of claims 1 to 10, characterized in that the crankshaft (4), stepped piston (2) and connecting rods (3) form a unit and that the crankshaft (4) via shaft bearings in a preferably one-piece housing part (7) in an end position is rotatably mounted, wherein the housing part (7) is formed such that the unit of crankshaft (4), stepped piston (2) and connecting rod (3) as a whole from the outside to the end position in the housing part (7) can be introduced or starting from the end position of the housing part (7) is removable by targeted movement after at least one predetermined movement of the unit. Piston compressor according to claim 11, characterized in that the housing part (7) has two mutually opposite openings (8, 9), in the shaft bearing (5, 6) can be installed or installed, wherein the openings (8, 9) and the crankshaft ( 4) are dimensioned such that the crankshaft (4) about a perpendicular to the longitudinal direction extending central axis (z) in the housing part (7) by a rotation angle up to 90 ° in a removal position is rotatable.

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