WO2022167502A1

WO2022167502A1 - Compressor, in particular refrigerant compressor, refrigeration machine, and method for producing a compressor

Info

Publication number: WO2022167502A1
Application number: PCT/EP2022/052513
Authority: WO
Inventors: Sören GELKE; Sebastian Krause
Original assignee: thyssenkrupp Presta Ilsenburg GmbH; Thyssenkrupp Ag
Priority date: 2021-02-05
Filing date: 2022-02-02
Publication date: 2022-08-11
Also published as: DE102021201091A1; CN117242262A; EP4288665A1; US20240110734A1

Abstract

The invention relates to a compressor (V), in particular a refrigerant compressor, comprising a low-pressure region (1) and a high-pressure region (2), wherein: a lubricant (S) is provided in the low-pressure region (1) for lubricating the compressor; a fluid (F) is conducted out of the low-pressure region (1) into the high-pressure region (2) and compressed, some of the lubricant (S) passing into the high-pressure region (2) together with the fluid (F) from the low-pressure region (1); a lubricant separator (21) for separating the lubricant (S) out of the fluid-lubricant mixture is provided in the high-pressure region (2); a lubricant return channel (3) for transporting the separated lubricant (S) from the high-pressure region (2) to the low-pressure region (1) is provided; and the lubricant return channel (3) comprises a fluid diode (31). The invention also relates to a refrigeration machine, comprising a compressor (V), a gas cooler (G), an expansion valve (E) and an evaporator (D), which are fluidically connected to one another, characterised by a compressor (V) according to at least one of the preceding claims. The invention further relates to a method for producing a compressor (V) according to at least one of the preceding claims, wherein the channel geometry definitive for the fluid diode (31), in particular the design of the inner wall of the lubricant return channel (3), is created by stamping, etching or eroding.

Description

Compressors, in particular refrigerant compressors, refrigeration machines, and methods for producing a compressor

The present invention relates to a compressor according to the preamble of claim 1, a refrigerating machine according to the preamble of claim 10, and a method for producing a compressor according to the preamble of claim 11.

A compressor, also called a compressor, is a machine, in particular a fluid energy machine, which supplies mechanical work to an enclosed gas. Compressors are typically used to compress gases. They preferentially increase the pressure and density of the gas.

The compressor or the moving components of the compressor are usually lubricated with a lubricant such as oil. Mixing, in particular as an aerosol, of the fluid to be compressed and the lubricant is usually unavoidable. The atomization of the lubricant can be caused, for example, by components moved by the lubricant (eccentrics/connecting rods, etc.). The lubricant is distributed as a fluid/lubricant aerosol in the fluid circuit, in particular in the high-pressure area HD and in the low-pressure area ND, and is no longer available, for example, for lubricating compressor components. The lubricant reservoir may become exhausted.

This can be remedied by separating the lubricant from the fluid-lubricant aerosol, especially in both the HP and LP areas. Lubricant separated in the HP area must then be returned to the LP area. However, this always means a fluid "short circuit" between HP and ND and thus a loss/loss of power for the compressor.

To remedy this problem, a compressor has become known, for example from DE102015224071, which comprises a lubrication system for lubricating components of the compressor with a lubricant. The compressor has a low-pressure area, in particular in the form of an engine room, and a high-pressure area with a compressor outlet. During operation of the compressor, the lubricant comes into contact with the fluid in the low-pressure area, so that a fluid mixture of fluid and lubricant is formed. Next includes the compressor a compression device for compressing the fluid mixture. In order to ensure a reliable recirculation of the lubricant in the compressor, the compressor includes a lubricant return which fluidly connects the HP with the LP area and enables a lubricant return. The lubricant return thus represents a kind of bypass of the compressor unit or the piston arrangement. For this purpose, a first lubricant return is arranged in the high-pressure area and the second lubricant return in the low-pressure area. Both lubricant returns are fluidly connected to one another in a controllable manner by means of a valve arrangement. The valve arrangement thus regulates the separation/connection of the high-pressure and low-pressure areas of the compressor. The valve arrangement can automatically adjust a flow cross section at least as a function of a flow force. The flow force is created by the fluid mixture flowing through the valve assembly.

A particular disadvantage of this solution for returning lubricant from the high-pressure area to the low-pressure area is that many moving parts are used, so that high wear and tear but also high production costs are to be expected. Furthermore, the valve arrangement must be adjusted, which in turn can lead to uncertainties during operation. There is also the risk of the valve arrangement becoming clogged, with the result that in fact there is no longer any return of lubricant. Also, an uncontrolled loss of pressure across the valve assembly can occur, so that a lot of fluid would flow back through the valve.

This is where the present invention comes in and sets itself the task of proposing an improved compressor, in particular proposing a compressor, in which at least some, preferably all, of the problems outlined above can be overcome, or at least reduced. In particular, a compressor is to be proposed in which few or no moving parts are used, at least for the lubricant return, which requires little or no adjustment with regard to the lubricant return, and in which a blockage of the lubricant return can be largely ruled out. According to the invention, this object is achieved by a compressor having the characterizing features of claim 1. Because the lubricant return channel includes a fluid diode, a regulated or switched valve, possibly a sensor system for determining the fluid in front of the valve and the required electronic control, can be dispensed with. In addition, there are no moving parts, which means that wear and tear is fundamentally excluded. With an advantageous structural design, hardly any fluid is allowed to pass through from the high-pressure area to the low-pressure area, but mainly lubricant. A risk of clogging by particles is reduced by an open geometry. In principle, there is also no need to adjust the fluid diode. The blocking behavior is preferably determined structurally by means of the length and/or the geometry of the throttle point, ie the fluid diode.

The basic idea is that there is less resistance to flow in one direction than in the opposite direction. This is to ensure that the flow has a preferred direction or that the fluid only flows in one direction. This should be achieved by structures that allow a more laminar flow in one direction, but cause turbulence in the opposite direction through turbulence and thus increase the flow resistance. For every point inside such a valve, the flow resistance is low towards the outlet and very high towards the inlet. Therefore, this device is also referred to as a "fluid diode". According to the invention, such a fluid diode is operated here as a connection or in the connection (lubricant return channel) of the high-pressure and low-pressure areas of the refrigerant compressor in the blocking direction. This means that the fluid flowing from the high-pressure area into the low-pressure area is met with a resistance that depends on the respective fluid and thus on the respective material properties/physical properties. This means that there is less resistance to the lubricant than to the refrigerant.

Further advantageous refinements of the proposed invention result in particular from the features of the dependent claims. The objects or features of the various claims can in principle be combined with one another as desired. In an advantageous embodiment of the invention, it can be provided that the lubricant return channel has a heart-shaped or offset heart-shaped inner wall to form a fluid diode. Such a structure is advantageously suitable for designing a fluid diode, in particular with the properties outlined above.

In a further advantageous embodiment of the invention, it can be provided that the lubricant return channel is introduced into a metal sheet. The plate can be integrated into the compressor in a simple manner, for example as an intermediate plate in the housing of the compressor.

In a further advantageous embodiment of the invention, it can be provided that the lubricant return channel is designed in the shape of a semicircle. In this way, for example, integration can take place in a simple manner in a circular-cylindrical housing, with the inlet and outlet of the lubricant return channel being offset by 180°, for example, in the circumferential direction.

In a further advantageous embodiment of the invention, it can be provided that the lubricant return channel is formed in a flat parting surface in a housing, a sealing surface and/or in a seal of the compressor. In this way, the lubricant return channel can advantageously be integrated into the compressor housing.

In a further advantageous embodiment of the invention, it can be provided that the fluid is a refrigerant, in particular supercritical CO2.

In a further advantageous embodiment of the invention, it can be provided that the lubricant is oil.

In a further advantageous embodiment of the invention, it can be provided that the channel geometry that is decisive for the fluid diode, in particular the design of the inner wall of the lubricant return channel, is produced by stamping, etching or eroding. The aforementioned measures represent advantageous manufacturing processes for the design of the lubricant return channel. In a further advantageous embodiment of the invention it can be provided that the lubricant return channel has a fluid diode as a separate component and/or the lubricant return channel is configured as a fluid diode at least in sections.

Another object of the present invention is to propose an improved refrigerator.

According to the invention, this object is achieved by a refrigerating machine having the characterizing features of claim 10 . As a result, the advantages of the compressor according to the invention can be utilized for a refrigerating machine, for example an air conditioning system in a motor vehicle.

Another object of the present invention is to propose an advantageous method for manufacturing a compressor according to the invention.

According to the invention, this object is achieved by a method for producing a compressor with the characterizing features of claim 11.

Because the channel geometry that is decisive for the fluid diode, in particular the configuration of the inner wall of the lubricant return channel, has been produced by stamping, etching or eroding, a method that is simple in terms of production technology can be proposed.

Further features and advantages of the present invention become clear from the following description of preferred exemplary embodiments with reference to the attached figures. show in it

1 shows a schematic representation of a refrigerating machine with a compressor according to the invention;

2 shows a fluid diode in a sectional view;

3a shows an exemplary surface structure of a fluid diode of a compressor according to the invention with an indicated movement profile of the fluid; 3b shows an exemplary surface structure of a fluid diode of a compressor according to the invention with an indicated movement profile of the lubricant;

4 shows a housing component of a compressor according to the invention with a milled fluid diode;

Fig. 5 shows a detail "X" according to Fig. 4;

6 shows part of a housing for a compressor according to the invention

(Parting surfaces in the housing);

7 shows a compressor according to the invention in a sectional schematic representation.

The following reference symbols are used in the figures:

V Compressor

G gas cooler

E expansion valve

D evaporator

S Lubricants, especially oil

F Fluid, especially refrigerant

1 low pressure area

2 high pressure area

3 lubricant return channel compressor housing

E-motor (drive)

Lubricant reservoir

low pressure inlet

Piston cap with inlet valve

Pistons

eccentric shaft

cylinder body

working space

Lubricant separator

high pressure outlet

outlet valve

channel

fluid diode

Gasket/Seal

Part of the compressor housing

Part of the compressor housing First, reference is made to FIG.

A compressor V according to the invention, in particular a refrigerant compressor, is, for example, part of a refrigeration machine, such as an air conditioning system. In addition to the compressor V, such a refrigeration machine usually includes a gas cooler G, an expansion valve E and an evaporator D. The aforementioned components are fluidically connected to one another, i.e. a fluid F, such as preferably a cooling fluid, is compressed in the compressor V, passes through the High-pressure outlet 22 of the compressor V into the gas cooler G and from the gas cooler G to the expansion valve E and from there into the evaporator D. From the evaporator D, the fluid is again introduced via the low-pressure inlet 12 of the compressor V. Such a refrigerating machine is sufficiently known to the person skilled in the art, so that no further explanation is required here.

The compressor V can be, for example, a piston compressor, in particular an axial piston compressor, radial piston compressor or scroll compressor.

The compressor has a low-pressure area 1 and a high-pressure area 2 . In the compressor V, in particular in its low-pressure area 1 , a lubricant S, such as oil, is used to lubricate the moving components of the low-pressure area 1 .

The low-pressure area 1 of the compressor V includes, for example, a low-pressure inlet 12 for the fluid or refrigerant to be fed into the compressor. The compressor V also includes, in particular, a driving electric machine 5 or a shaft for connecting an external drive. The compressor shown by way of example in FIG. 7 comprises two housing parts 41, 42. A cylinder housing 16 forms cylinders in which pistons 14 are movably arranged. These pistons 14 can be driven by an eccentric shaft. The cylinders and thus also the pistons 14 that can be moved therein run radially or are arranged radially with respect to the eccentric shaft. A cover with an inlet valve 13, the pistons 14 and the cylinders form the working chamber 17 and the compression chamber. Fluid is drawn in from the low-pressure area 1 via the inlet valves, compressed in the working chamber 17 and discharged through the outlet valves 23 into a duct 24, and thus ejected into the high pressure area of the compressor. The condensed or compressed fluid can contain lubricant S, which can be separated, for example, at edges or when there is a change in the direction of flow of the fluid. This usually also takes place in a lubricant separator 21 . The lubricant separator 21 does not have to be a separate component. Rather, any geometry in which lubricant can be separated, for example, at edges or deflections, in particular geometries for flow deflection or changing the flow speed, etc., can be used as a lubricant separator 21. The separated lubricant S then collects in the channel 24. The compressed fluid can be routed out of the compressor to the other components of the refrigeration circuit via a high-pressure connection 22 . A lubricant separator 21 is preferably connected upstream of the high-pressure connection 22, so that the fluid can be routed out of the compressor via the lubricant separator 21 and the high-pressure outlet. In order to be able to guide the lubricant S from the high-pressure area 2 into the low-pressure area 1 of the compressor, at least one lubricant return channel 3 is provided. Such a lubricant return channel 3 can be designed as a fluid diode 31 or have such a fluid diode 31 as a separate component, as indicated in FIG. 7 . A plurality of fluid diodes 31 can also be arranged in a lubricant return channel 3 in order to achieve the desired properties. A lubricant return channel 3 can also be formed between two housing parts of the compressor V, for example in a seal. Such a seal 32 is arranged or formed, for example, between a part of the compressor housing 42 and the cylinder housing 16, as shown in FIGS. The geometry of the fluid diode is formed in the seal 32, for example. In the installed state, the seal 32 forms the lubricant return channel 3 with the adjacent components, such as the housing part 42 and the cylinder housing 16 .

In order to collect or store this lubricant S in the compressor V, in particular in the low-pressure area 1 , the low-pressure area 1 can be equipped with a lubricant reservoir 11 . In the course of the compression of the fluid F to be compressed, part of the lubricant S reaches the high-pressure area 2 together with the fluid F. A lubricant separator 21 can be provided in order to separate the lubricant S from the fluid-lubricant mixture. In principle, lubricant S in the compressor V can be separated at every deflection or change in cross section of the fluid-lubricant mixture.

In order to transport the lubricant S from the high-pressure area 2 back to the low-pressure area 1, a lubricant return channel 3 is provided between the high-pressure area 2, in particular the lubricant separator 3 in the high-pressure area, and the low-pressure area 1, in particular the lubricant reservoir 11 in the low-pressure area. The compressor V can be equipped with a compressor housing 4 for accommodating or forming the aforementioned components.

According to the invention, it is provided that the lubricant return channel 3 includes a fluid diode 31 . In principle, the fluid diode 31 comprises a geometry that offers a medium flowing through resistance to flow that varies depending on the direction. A fluid diode has also become known under the name Tesla valve. In other words, the lubricant return channel 3 is designed, at least in sections, to be media-selective or as a media-selective throttle, i.e. differences in the material properties are exploited, whereby the, in particular gaseous, fluid F, preferably refrigerant, and the, in particular liquid, lubricant S , Different flow resistances act when passing through the lubricant return channel 3 from the high-pressure area 2 to the low-pressure area 1 . In particular, there is a high resistance for the fluid F, in particular for the gaseous fluid, as a result of which little fluid F passes from the high-pressure area 2 into the low-pressure area 1 via the lubricant return channel. The fluid F is preferably a refrigerant, such as supercritical CO2. Compared to the fluid F, the lubricant S, which is present in liquid form downstream of the separator 3 in particular, experiences a lower flow resistance when passing through the fluid diode 31 .

Examples of fluid diodes and flow patterns are shown in FIGS. 2, 3a and 3b. The fluid diode 31 or the section of the lubricant return channel 3 designed as a fluid diode can be characterized in particular by the following details.

For the selective formation of the flow resistance, a lubricant return channel 3 is introduced, for example, into a metal sheet. The flow guidance takes place in particular with a non-constant cross-section and preferably has a repetitive basic contour along an arbitrary development curve. The fluid F, in particular the refrigerant, and the lubricant S are thus forced into a meandering main flow with circulating secondary flows.

The lubricant return channel 3 has a similar geometry to the "Tesla valve" or fluid diode and is operated here in the "blocking direction", so to speak, resulting in a particularly high resistance in the direction of flow from the high-pressure area 2 to the low-pressure area 1 . In addition, differences in the material properties are exploited. The material properties or the different physical properties can be, for example, density, viscosity or compressibility. With a given pressure drop, these different physical properties result in different flow properties such as flow velocity and degree of turbulence for the respective medium.

The gaseous fluid F, in particular the refrigerant, is strongly deflected in the fluid diode 31, it goes more strongly into the "contour corners" of the section of the lubricant return channel 3 designed as a fluid diode 31. The kinetic energy of the fluid F, in particular the gaseous fluid, is partially dissipated during the deflection. In particular, the degree of turbulence in gas flow is greater, resulting in greater flow resistance. The gaseous fluid F has a high speed, which is due in particular to its density. An expanding gas has significantly higher flow velocities.

The lubricant S present in a liquid state is not deflected as much as the fluid F present in gaseous form, in particular the refrigerant present in gaseous form. The fluid diode 31, in particular the contour of the fluid diode, can almost constant speed and a lower degree of turbulence. The flow resistance acting here is therefore lower.

As configurations of the fluid diode 31 or configuration of the inner wall of the lubricant return channel 3, for example, a heart-shaped structure, particularly preferably an offset heart-shaped structure, comes into consideration. However, other shapes of the contour are conceivable and known in principle from “fluid diodes”. The length of the lubricant return channel 3 is preferably a matter of individual design. In principle, any number of such units can be connected in series. The lubricant return channel 3 as such can be designed in various geometries, in particular as a semicircle (cf., for example, FIGS. 4 and 5). The lubricant return channel 3, in particular the part designed as a fluid diode 31, can also be designed as a fold or other arrangement, in particular due to the respective space conditions in the compressor.

The lubricant return channel 3 is preferably formed in planar dividing surfaces in the housing, a sealing surface and/or in a seal 32 of the compressor V. Such a configuration is structurally simple to integrate in the compressor and requires less installation space. Such a configuration is shown in particular in FIG.

The channel geometry that is decisive for the fluid diode, in particular the configuration of the inner wall, can be produced in planar parting surfaces by stamping, etching or eroding.

The number of repetitions of the basic contour of the inner wall of the lubricant return channel 3, in particular of the fluid diode 31, and the height of the contour or the sheet metal thickness can be adapted to the requirements of the respective throttling task.

Features and details that are described in connection with a method also apply in connection with the device according to the invention and vice versa, so that the disclosure of the individual aspects of the invention is or can always be referred to reciprocally. In addition, an optionally described method according to the invention can be carried out with the device according to the invention. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. As used herein, the singular forms "a" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will also be understood that the terms "comprises" and/or "comprising" when used in this specification specify the presence, but not the presence, of the recited features, integers, steps, operations, elements and/or components or exclude the addition of one or more other features, integers, steps, operations, elements, components and/or groups thereof. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

A refrigerant, for example, can be considered as the fluid to be compressed. In this respect, the compressor can preferably be designed as a refrigerant compressor.

Claims

Claims Compressor (V), in particular refrigerant compressor, comprising

- A low-pressure area (1) and

- A high-pressure area (2), wherein

- A lubricant (S) in the low-pressure area (1) is provided for lubricating the compressor, wherein

- A fluid (F) is conveyed from the low-pressure area (1) to the high-pressure area (2) and compressed, with part of the lubricant (S) being conveyed with the fluid (F) from the low-pressure area (1) to the high-pressure area (2). , whereby

- A lubricant separator (21) for separating the lubricant (S) from the fluid-lubricant mixture in the high-pressure region (2) is provided, wherein

- A lubricant return channel (3) for transporting the separated lubricant (S) from the high-pressure area (2) into the low-pressure area (1) is provided, characterized in that the lubricant return channel (3) comprises a fluid diode (31). Compressor according to claim 1, characterized in that the lubricant return channel (3) to form a fluid diode (31) has a heart-shaped or offset heart-shaped inner wall. Compressor according to at least one of the preceding claims, characterized in that the lubricant return channel (3) is made in a metal sheet. Compressor according to at least one of the preceding claims, characterized in that the lubricant return channel (3) is designed in the shape of a semicircle. Compressor according to at least one of the preceding claims, characterized in that the lubricant return channel (3) is formed in a flat dividing surface in a housing (4), a sealing surface and/or in a seal (32) of the compressor (V). Compressor according to at least one of the preceding claims, characterized in that the fluid (F) is a refrigerant, in particular supercritical CO2. Compressor according to at least one of the preceding claims, characterized in that the lubricant (S) is oil. Compressor according to at least one of the preceding claims, characterized in that the fluid diode (31) decisive channel geometry, in particular the design of the inner wall of the lubricant return channel (3), has been produced by stamping, etching or eroding. Compressor according to at least one of the preceding claims, characterized in that the lubricant return channel (3) has a fluid diode (31) as a separate component and/or the lubricant return channel (3) is designed at least in sections as a fluid diode (31). Refrigeration machine comprising a compressor (V), a gas cooler (G), an expansion valve (E) and an evaporator (D) which are fluidically connected to one another, characterized by a compressor (V) according to at least one of the preceding claims. Method for producing a compressor (V) according to at least one of the preceding claims, characterized in that the channel geometry relevant for the fluid diode (31), in particular the design of the inner wall of the lubricant return channel (3), is produced by stamping, etching or eroding.