EP1242741B1 - Dual-stage, plunger-type piston compressor with minimal vibration - Google Patents

Abstract

The invention relates to a piston arrangement for a dual-stage piston compressor, comprising a cranksbaft and several cylinders which house the operating piston. Said arrangement allows two or more low-pressure stages and at least one high-pressure stage to be formed. The invention is characterized in that the two or more low-pressure cylinders are arranged in relation to the high-pressure stage in such a way that said two or more low-pressure cylinders are in phase or are offset by less than ±15° and compress in a position which is offset by 180°±20, in relation to one or more high-pressure cylinders.

Description

The invention relates to a piston arrangement for a two-stage Piston compressor with a crankshaft, several cylinders with it running Piston, wherein two or more low pressure stages and at least one High-pressure stage is formed and a reciprocating compressor for Rail vehicles with such a piston assembly.

The arrangement according to DE-PS 765 994 is characterized in that the Cylinder and the crank radii are designed so that the mass forces Balancing as well as possible.Gas as vibration-inducing components are not named. An assignment of the individual cylinders to a respective one Compaction level is not made in the citation.

A piston compressor with a crankshaft, several cylinders and in it running piston is for example from CH-A-200769 and DE-PS 765 994 and a 3-cylinder piston assembly with a high pressure cylinder and two low pressure cylinders from FR 1 239 385 become known.

In rail vehicle construction, lightweight construction is becoming increasingly popular Application. For example, modern lightweight car body structures Aluminum extrusion or support structures made of thin sheet metal Frequencies often close to the speed of the compressor Air system. The use of reciprocating compressors is such Constructions are often not possible, as often the permissible body noise level is exceeded.

This is due to the fact that piston engines design Massive forces and moments caused by the oscillating masses on the Crank drive and generate moments from the gas forces. Especially with the In the rail vehicle sector commonly used two-stage reciprocating compressors occurs a very non-uniform torque. Like the analysis of a typical Lastmomentes of such a compressor, corresponds to the overwhelming Proportion of the load torque of the rotational frequency of the reciprocating engine, often in the Range of 20 to 30 Hz. These frequencies are in turn for the im Passenger compartment very well felt, as for example the Natural frequency of legs with straight knees at about 20 Hz can be.

The load torque described above of a reciprocating compressor generates in the Interaction with the engine an excitation torque about the compressor rotation axis. The moment of inertia of a conventional reciprocating compressor unit is around the compressor rotation axis much lower than other axes. Since the Transmission mode of an elastic bearing around the compressor longitudinal axis in the rule is closer to the rotational frequency than, for example, the vertical mode, which plays a more important role in the transmission of inertia forces, this becomes Torsional vibration usually not as well insulated as others Pathogen components.

A generic reciprocating compressor with a piston assembly, a Crankshaft and a plurality of cylinders with pistons running therein, wherein two or formed a plurality of low pressure cylinder and at least one high pressure cylinder and the two or three or more low pressure cylinders with respect to High-pressure stage are arranged such that the two or more Low-pressure cylinder in phase or offset by less than ± 15 ° and around 180 ° ± 20 ° offset to one or more high pressure cylinders from CH-A-200 769 previously known. In this solution, the reciprocating compressor works however, with relatively high intake pressures in the low pressure stages to ensure appropriate fillings.

The object of the invention is to provide a reciprocating compressor machine, the avoids the disadvantages described above.

According to the invention, the problem is a drastic reduction of Part of the first order in the resulting mainly from the gas forces Lastmoment solved by two or by an unusual piston assembly several low-pressure stages are superimposed in phase and offset by about 180 ° to the high pressure stage act. This is achieved constructively in that at a Piston assembly for a two-stage reciprocating compressor with a crankshaft a plurality of cylinders having pistons therein, two or more Low-pressure cylinder and at least one high-pressure cylinder is formed, the two or three or more low pressure cylinders with respect to High-pressure cylinders are arranged such that the two or more Low-pressure cylinder in phase or offset by less than ± 15 ° and around 180 ° ± 20 ° offset to one or more high pressure cylinders.

The inventors have recognized that also the phase offset of all Low pressure cylinder to one or more high pressure cylinders a drastic Reduction of the 1st order as a result of the torque diagram m and thus a drastic Reduction of the vibration-inducing moment about the compressor rotation axis is reached.

In a first embodiment of the invention, the piston assembly is around an oil-lubricated piston assembly.

However, it is particularly preferred if the piston arrangement is an "oil-free", dry-running Piston assembly is. In a specific embodiment of the invention the piston assembly as a 3-cylinder arrangement with two low and one high-pressure cylinder executed, wherein a high-pressure cylinder, another low-pressure cylinder opposite. Such an arrangement is particularly space-saving. Of course, would be 4.5 or 6-cylinder arrangements, of the inventive Doctrine make use, conceivable.

By using heavy pistons, according to an advantageous embodiment the pressure peaks in the torque diagram are significantly reduced, as a increased kinetic energy of the piston is converted into compression work. In particular, the piston of the cylinder should have such a high mass that the pressure peaks are reduced in the tangential force diagram, with the in the Tangential force diagram of budding mass forces in the pressure peak in the for Piston compressor typical speed range from 1000 1 / min to 2000 1 / min, in particular 1500 1 / min are greater than 15% of the gas forces in the pressure peak. When Tangential force diagram is in the present application, the torque curve / crank radius Understood.

In an advantageous embodiment it is provided that, for example, in a 3-cylinder arrangement the masses of lying on the side of the high-pressure cylinder Low-pressure cylinder, namely the piston and / or connecting rod, so selected are that they are the opposite low-pressure piston and the high-pressure piston who are both sitting on the same crank sidewalk, compensate. The compensation This can be done both on the piston and on the connecting rod. By the increase the piston mass resulting from the mass balance decreases the Bearing load on the connecting rod.

In addition to the mass balance with the help of additional masses, it is also possible, the To balance oscillating mass with the help of moving dummy piston. Under a blind piston is understood in the present application, a piston that no Compacting work.

Advantageously, the pistons are arranged such that the low-pressure pistons suck in the same phase on the crankcase, wherein during the intake process the both low-pressure stages submerged in the crankcase, the air in the compression chamber bump. As a result, the intake vacuum in the low-pressure stage reduced and the filling improved. In a particularly advantageous embodiment This effect is achieved by the use of a check valve on the inlet port reinforced from air filter housing to crankcase. By the arrangement a check valve, the efficiency of a particular dry running Piston arrangement improved.

In addition to the piston arrangement, the invention also provides a piston compressor, in particular for rail vehicles comprising such a piston assembly available, which advantageously comprises an electric motor drive. The Piston assembly can also be used in compressed air generation systems in the industrial Be used area.

The invention will be explained with reference to the drawings.

Show it:

FIG. 1

the Tangentialkraftverlauf a conventional two-stage Piston compressor in boxer arrangement, such as DUBBEL, paperback for mechanical engineering 15th edition and 18th edition, pages P 32 - P 33 has become known

FIG. 2

the Tangentialkraftverlauf a piston compressor according to the invention

FIG. 3

a piston compressor according to the invention in section.

FIGS. 4a-4d

possible embodiments of Kolbenan orders carried out according to the invention as a boxer compactor

Figures 5a-5b

Embodiment of piston assemblies according to the Invention carried out as a series machine

FIG. 6

Embodiment of a piston assembly with a dummy piston

FIG. 7

Amplitudes of compressor vibration in vertical Direction for an embodiment according to the State of the art and the invention

In Figure 1, the Tangentialkraftdiagramm a piston assembly as known from the prior art, for example DUBBEL, paperback for engineering 15th edition and 18th edition pages P 32 - P 33, shown. The x-axis indicates the rotation angle in degrees, the y-axis the applied moment.
1 denotes the moment from the gas forces, 3 the total momentum from mass and gas forces, and 5 the moment from the mass forces.

1. Ordnung: 40 Nm

2. Ordnung: 20 Nm

3. Ordnung: 7 Nm

The Fourier analysis of the load torque shown in FIG. 1 from mass and gas forces of a compressor according to the prior art can be split into the following proportions:

1st order: 40 Nm

2nd order: 20 Nm

3rd order: 7 Nm

The majority of the load torque corresponds to the rotational frequency of the piston engine, which is often 20, 25 or 30 Hz. These frequencies are for the People, for example, in the passenger compartment of a rail vehicle, easy to feel. Thus, the natural frequency of legs with straight knees about 20 Hz be.

The load torque of a reciprocating compressor generates in interaction with the engine an excitation torque about the compressor longitudinal axis, wherein the moment of inertia a conventional piston compressor unit around the compressor longitudinal axis is much lower than other axes. The transmission mode of an elastic Storage around the compressor's longitudinal axis is usually closer to the rotational frequency as, for example, the vertical mode used for the transmission of inertial forces plays a bigger role. This torsional vibration is usually not like that well isolated like other exciter components.

According to the invention, the vibration problem of conventional reciprocating compressor by drastically reducing the proportion of the first order in the predominantly released from the gas forces resulting load moment. This reduction of first order can be achieved by a piston assembly in which two or several low-pressure stages are superimposed in phase and about 180 offset to the high-pressure stage act.

The tangential force diagram of such an arrangement is shown in FIG. As In Fig. 1, reference numeral 1 denotes the moment of gas forces, 3 the moment from mass and gas forces and 5 the moment of inertial forces.

1. Ordnung: 19 Nm

2. Ordnung: 28 Nm

3. Ordnung: 7 Nm

The Fourier analysis of the curve according to FIG. 2 leads to the following result:

1st order: 19 Nm

2nd order: 28 Nm

3rd order: 7 Nm

The proportion of the first order is drastically reduced, resulting in a reduced Vibration excitation around the compressor longitudinal axis precipitates. The unwanted Vibration in the passenger compartment can be significantly reduced or almost completely avoided.

FIG. 3 shows a reciprocating compressor with a piston arrangement according to the invention exemplified. The embodiment shown in FIG. 3 is without limitation, to a 3-cylinder boxer arrangement with two low-pressure cylinders 20, 22, which form the low pressure stage and a high pressure cylinder 24 upstream of one of the low pressure stages.

The pistons 40, 42, 44 of the three cylinders are on a common crankshaft via connecting rods 32 by means of ball or roller bearings 34 stored.

For cooling the arrangement is on the front side of the crankshaft 30, a fan 36th provided for air cooling of the housing 38 in which the two low pressure stages and the high-pressure stage are arranged, with rotating crankshaft 30 provides.

In the position shown in Figure 3, the pistons 40, 42 are the low-pressure cylinder in the highest position. The high pressure piston 44 is located on upper end of the cylinder. If the crankshaft 30 is moved, so move the two pistons 40, 42 of the low-pressure cylinder in-phase and offset by 180 opposite the piston 44 of the high-pressure stage.

In the embodiment shown in Figure 3 is an oil-free Compressive piston compressor with intake air duct over the crankcase.

The individual pistons 40, 42, 44 are relative to the cylinder by means of sealing elements 50 sealed. The drive of the crankshaft is 30 by means of an electric motor 60th

The following is the operation of the piston compressor shown in Figure 3 be described in more detail:

During the compression process in the low pressure stages increases through the in phase from the crankcase 38 diving large low-pressure piston 40, 42, the air volume in the crankcase 38. Air is sucked into the crankcase. When the air is sucked into the compression chamber, the low-pressure pistons dip 40, 42 in the crankcase 38. The volume in the crankcase 38 decreases in the moment in which air from the crankcase 38 in the compression space of the Low pressure stages is sucked, i. the piston underside of the low-pressure pistons 40, 42 pushes air from the crankcase 38 in the compression chambers of the low pressure stages. This will increase the intake vacuum in the low pressure stages reduced compared to the embodiments according to the prior art. supports This effect can occur when using a check valve on the inlet port of Air filter housing to the crankcase 38, in particular the efficiency is improved.

Another advantage of the piston compressor according to the invention consists in the following:

Due to the strongly fluctuating load torque of the reciprocating compressor Rotational irregularity generated. This is amplified by the electric motor 60 because of Motor 60 reacts to the load peak out of phase and that when the Torque requirement of the compressor is low. The resulting speed fluctuation over a revolution can in piston compressors according to the state The technology, for example, be ± 14%. This effect has so far only by the use of large flywheel masses are reduced, but for weight reasons was not wanted. Furthermore, the electric motor 60 has a clear increased power consumption and a drastic reduction of the power factor - until to 0.6 - and must therefore in embodiments according to the prior art oversized. Due to the inventive strong reduction of first order in the load moment this effect is reduced. The rotation uniformity becomes lower, it becomes according to the invention of for example 0,15 to 0,08 reduced. The current consumption of the motor decreases. The power factor increases considerably, for example from Lf = 0.7 to 0.8 in an arrangement according to the Invention.

By using heavy pistons, in a further developed embodiment the pressure peaks in the torque diagram are significantly reduced, as a increased kinetic energy of the piston is converted into compaction work, It is particularly preferred if the pistons of the cylinder have such a high mass have that the pressure peaks are reduced in Tangentialkraftdiagramm wherein the incoming in the tangential force mass forces in the pressure peak in the speed range between 1000 1 / min and 2000 1 / min greater than 15% of Gas forces are in the pressure peak.

In this way it is possible the excitation moments in all orders still continue to reduce.

In order to achieve a mass balance of the oscillating and rotating masses, are the masses of lying on the side of the high pressure cylinder low pressure cylinder chosen so that they are the opposite low-pressure piston and equalize the high pressure piston. The compensation can be both on the piston as also done on the connecting rod. By increasing the piston mass resulting from The mass balance reduces the bearing load on the connecting rod. This is cheap for the load on the piston pin bearing on the side of the high-pressure cylinder lying low pressure stage, because this caused by the adjacent high-pressure stage is cooled worse.

FIGS. 4a-4d show arrangements according to the invention with opposite ones Cylinders shown. Figure 4a shows a 3-cylinder arrangement, as detailed previously described. FIG. 4b is a 6-cylinder arrangement, in FIG. 4c a 4-cylinder arrangement and in Figure 4d, a 5-cylinder arrangement according to the invention shown. The high-pressure pistons are designated by the reference numerals 44, 46 and the low-pressure pistons with the Bezugsziffem 40, 41, 42, 43 occupied. The high pressure cylinder with the reference numerals 24, 26 and the low pressure cylinder with the reference numerals 20, 21, 22, 23. In addition to 180 V piston arrangements and series machines are conceivable.

FIG. 5a shows a 4-cylinder in-line machine according to the invention, and FIG. 5b shows a 3-cylinder inline engine.

In Figure 6 is a 3-cylinder inline engine with a, running dummy piston 50, which does no compression work and serves only as a mass balance shown. As in FIGS. 4a-4d, the high pressure pistons are 44 and the low pressure pistons with 40, 42, the high pressure cylinder with 24 and the low pressure cylinder with 20, 22 characterized.

The invention thus becomes the first time a piston assembly and a reciprocating compressor provided with the unwanted vibrations first Order, as in piston compressors according to the prior art from the Compressive forces result, can be reduced.

This can be seen particularly well in FIGS. 7a-7c. In Figure 7a is schematic a compressor with two low pressure cylinders 20, 22 and a high pressure cylinder 24 shown according to the invention. Furthermore, there are four possible suspensions 70, 72, 74, 76, for example, shown on a rail vehicle. The Cylinders are in the x-y plane, the z-axis is perpendicular to the cylinder axis in the direction of the suspensions 70, 72, 74, 76.

Figure 7b shows the time course of the compressor vibration 1st order in the z direction in a compressor according to the prior art. FIG. 7c shows the temporal course of the compressor oscillation 1st order in z-direction at a Compressor according to the invention. As from the comparison of the amplitudes of Vibrations in Figures 7b and 7c, is the amplitude of the oscillation the compressor according to the invention over the prior art at least halved. In a particularly preferred embodiment of the invention the amplitude of a compressor according to the invention is only one third of the Amplitude of a compressor according to the prior art.

LIST OF REFERENCE NUMBERS

1

Moment from gas forces

3

Moment of mass and gas forces

5

Moment of mass forces

20, 22, 23

Low-pressure cylinder

24, 26, 28

High pressure cylinder

30

crankshaft

32

connecting rod

34

ball-bearing

36

fan

38

casing

40, 42, 43

Low-pressure piston

44, 46, 48

High pressure piston

49

sealing element

50

blind piston

60

electric motor

70, 72, 74, 76

suspensions

Claims (11)

1. Piston compressor, in particular for rail vehicles comprising a piston arrangement for a dual-stage piston compressor, comprising a crankshaft (30) in a crankshaft case (38), a plurality of cylinders (20, 22, 24) with pistons (40, 42, 43, 44, 46, 48) operating therein, wherein two or more low-pressure cylinders (20, 22, 23) of a low-pressure stage and at least one high-pressure cylinder (24, 26, 28) of a high-pressure stage are formed, and the two or three or more low-pressure cylinders (20, 22, 23) are arranged with respect to the high-pressure stage such that the two or more low-pressure cylinders (20, 22, 23) compress co-phasally or offset by less than ± 15° and offset by 180° ± 20° with respect to one or more high-pressure cylinders (24, 26, 28), characterised in that the piston-cylinder arrangement of the low-pressure stage is constructed such that, in an intake process, the pistons of the low-pressure stage move in the direction of the crankshaft (30) and in the process compress the air in the interior of the crankshaft case (38), and the air is taken in the process into the piston displacement of the low-pressure cylinders (20, 22, 23) from the interior of the crankshaft case (38).
2. Piston compressor according to claim 1, characterised in that the piston arrangement is an oil-lubricated piston arrangement.
3. Piston compressor according to claim 1, characterised in that the piston arrangement is a dry-running piston arrangement.
4. Piston compressor according to any one of claims 1 to 3, characterised in that the piston arrangement is constructed as a 6-cylinder, 5-cylinder, 4-cylinder or 3-cylinder arrangement with two or more low-pressure cylinders (40, 42, 43) and one or more high-pressure cylinders (44, 46, 48).
5. Piston compressor according to any one of claims 1 to 4, characterised in that the piston arrangement is constructed as a 3-cylinder arrangement, comprising two low-pressure cylinders (20, 22) and one high-pressure cylinder (24), a further low-pressure cylinder (20) being situated opposite a high-pressure (24) and a low-pressure cylinder (22).
6. Piston compressor according to any one of claims 1 to 5, characterised in that the pistons (40, 42, 43, 44, 46, 48) of the cylinders (20, 22, 23, 24, 26, 28) have such a large mass that the inertial forces in the pressure peak of a compression process, in the rotational speed range between 1,500 1/min and 2,000 1/min are greater than 15% of the gas forces in the pressure peak.
7. Piston compressor according to any one of claims 1 to 6, characterised in that a balancing of the oscillating masses (piston, connecting rod) is carried out with the aid of additional masses at at least one of the pistons (20, 22, 23, 24, 26, 28) and/or at a connecting rod.
8. Piston compressor according to any one of claims 1 to 7, characterised in that the balancing of the oscillating mass is carried out with the aid of a dummy piston (50) also running along.
9. Piston compressor according to any one of claims 1 to 8, characterised in that the balancing of masses is carried out with the aid of additional masses on the crankshaft (30).
10. Piston compressor according to any one of claims 1 to 9, characterised in that a return valve is arranged at the inlet opening to the crankcase (38).
11. Piston compressor according to any one of claims 1 to 10, characterised in that the piston compressor comprises an electric motor drive (60).

Images