US20090301293A1

US20090301293A1 - Compressor

Info

Publication number: US20090301293A1
Application number: US12/084,733
Authority: US
Inventors: Mario Bechtold; Bernd Gromoll; Stefan Nunninger
Original assignee: BSH Bosch und Siemens Hausgeraete GmbH
Current assignee: BSH Hausgeraete GmbH
Priority date: 2005-11-09
Filing date: 2006-10-26
Publication date: 2009-12-10
Also published as: ATE503111T1; RU2008119085A; DE102005053836A1; CN101305186B; RU2411394C2; EP1948928A1; ES2360729T3; WO2007054437A1; DE502006009174D1; CN101305186A; EP1948928B1

Abstract

Known compressors are equipped with gas bearings, in which the bearing nozzles are continuously supplied with a stream of gas. According to the invention, the gas bearing is a self-sufficient bearing, in which the supply pressure is independent of the delivery pressure. To achieve this, the compressor is equipped with a gas reservoir with a bearing supply pressure.

Description

The invention relates to a compressor according to the preamble of claim 1.
The piston of a compressor is to be mounted by means of a gas bearing. To this end, part of the gas compressed by the compressor is tapped off from the useful stream of gas and conveyed into the gas bearing by way of nozzles. The problem with this arrangement is the loss of useful gas, particularly as the gas loss depends on the thermodynamic working point of the compressor. In other words, more gas is lost with a high final pressure of the gas than with a low final pressure. The gas loss and the load bearing capacity of the gas bearing are therefore dependent on the compressor working point.
A number of bearing nozzles are accordingly to be provided with a suitable cross-section in order to ensure the load bearing capacity of the bearing also in the case of a low final pressure of the compressor. High final pressure of the compressor results in significant gas losses and thus in poor compressor efficiency.
The structure of a gas bearing known from the prior art is shown schematically below in FIG. 1 and is described in detail. The bearing nozzles must be continuously provided with a stream of gas to ensure that the gas bearing functions. This is achieved in that the supply is fed directly from the high pressure chamber of the compressor.
On the other hand, the object of the invention is to create an improved compressor.
The object is achieved according to the invention by the features of the claim. Developments are specified in the subclaims.
The subject matter of the invention is a compressor with a self-sufficient gas bearing, in which the supply pressure is independent of the delivery pressure. The gas bearing is thus optimized in terms of its design and function.

Further details and advantages result from the description of the figures of the exemplary embodiments below with reference to the drawings in conjunction with the claims, in which:

FIG. 1 shows an arrangement of a linear compressor according to the prior art,

FIG. 2 shows a compressor according to FIG. 1 with an optimized gas bearing

FIG. 3 shows a first connection of the gas reservoir and compression chamber and

FIG. 4 shows a second connection of the gas reservoir and compression chamber.

FIG. 1 shows a linear compressor, in which a linearly guided compressor piston 2 acts upon a gas volume 1. A connecting hollow cylindrical element 10 forms a gas bearing between the piston 2 and inner wall of the hollow cylinder 10.
Four gas inlet nozzles 11 to 11′″ with a longitudinal passage 12 are indicated by way of example, by way of which a stream of gas reaches the gas bearing. Suitable lines are available for this.
A low pressure chamber 15 and a high pressure chamber 20 are assigned to the gas chamber 1. The low pressure chamber 15 has a gas inlet 16 and an inlet valve 17. The high pressure chamber 20 has a gas outlet 21 and an outlet valve 22.
FIG. 2 shows an improved embodiment of the gas bearing. The bearing nozzles 11 are fed from a separate gas reservoir 25, in which a sufficient quantity of gas at suitable pressure is located. The stream of gas through the bearing and thus the number of nozzles, nozzle diameter and gas pressure can be selected here such that the bearing provides reliable support.
To adjust the pressure in the gas bearing reservoir 25 independently of the working point of the main gas circuit, a second gas outlet 33 with channel 30 is attached in the compression chamber 1. The pressure in the gas reservoir 25 is determined by way of the position A of the gas outlet 33 in the compression chamber and the drop in pressure in the connecting line and lies below the compression final pressure. The channel 30 is ideally designed such that the drop in pressure is minimal.
Alternatively, the gas bearing can be directly fed from the high pressure, with the stream of gas being restricted to the minimal bearing pressure required by means of a pressure reducer.
The combination of a pressure reducing element and second gas outlet allows for minimal losses of the gas bearing, since the gas mass flow and the necessary compression work for the bearing supply become minimal.
The connection between the compression chamber 1 and gas bearing reservoir 25 is established by way of a channel 30 which can be sealed by valve 31 in accordance with FIG. 3 or a channel 40 without a valve, but however with an anisotropic flow resistor 41 according to FIG. 4. Both cases ensure that gas reaches the gas reservoir 25 from the compression chamber 1. By contrast, no gas or only minimal gas can however leave the reservoir 25 and flow back into the compression chamber I through the valve 31 or through the anisotropic flow resistor 41.
The volume of the gas reservoir 25 is selected such that with a repetitive operation, particularly when the gas bearing is reliably fed from the reservoir 25 during the part of the compression cycle and/or intake cycle in which the reservoir is not fed from the high pressure chamber 20.
The gas reservoir 25 can be provided with an outlet valve 26 particularly for the start-up of the compressor. The pressure in the reservoir 25 can herewith be continuously maintained or at least for longer, as a result of which the length of time in which the compressor can remain switched off without the gas bearing losing the load bearing capacity, can be lengthened. Prior to the start-up of the piston 2, the outlet valve 26 of the gas reservoir is reopened, in order first to re-establish the load bearing capacity of the gas bearing and only then to move the piston 2.
One alternative to the start-up consists in moving the piston 2 first with a reduced stroke when the gas reservoir 25 is empty, in order to pressurize the gas reservoir 25. Once the load bearing capacity of the gas bearing is provided, the stroke can be increased to a normal stroke and the normal compressor operation begins.
One further alternative would be an outlet valve of the compression chamber, which only opens from a certain pressure irrespective of the pressure behind the outlet valve. This allows the gas reservoir 25 to be filled up at the start-up of the compressor and only then the useful gas flow to be used.

Claims

1-10. (canceled)

11. A compressor comprising:

a gas bearing, the gas bearing having a cylinder;

a piston movable within the cylinder, the gas bearing providing a gas interface between the piston and the cylinder to thereby assist in supporting the piston for movement within the cylinder and the gas cylinder being configured as a self-sufficient gas bearing in which the supply pressure of gas forming the gas interface is independent of the delivery pressure of the gas.

12. The compressor as claimed in claim 11, wherein a gas reservoir with bearing supply pressure is provided.

13. The compressor as claimed in claim 12, wherein the supply of the gas bearing is taken at a lower pressure than a compression final pressure.

14. The compressor as claimed in claim 11, wherein the compressor includes a pressure reducer and the supply of the gas bearing is fed from a high pressure source via the pressure reducer.

15. The compressor as claimed in claim 14, wherein the compressor includes a compression chamber and the pressure reducer is fed from a separate tap in the compression chamber.

16. The compressor as claimed in claim 11, wherein the compressor includes a device for ensuring the gas bearing load bearing capacity to assist in a repetitive operation of the gas bearing.

17. The compressor as claimed in claim 12, wherein the compressor includes a gas reservoir and the gas reservoir is continuously under pressure.

18. The compressor as claimed in claim 15, wherein the compressor includes a gas reservoir and at least one channel with a valve located between the compression chamber and the gas reservoir.

19. The compressor as claimed in claim 15, wherein the compressor includes a gas reservoir and a channel with an anisotropic flow resistor that is located between the compression chamber and the gas reservoir.