EP1886024A1

EP1886024A1 - Scroll-type refrigerant compressor

Info

Publication number: EP1886024A1
Application number: EP06764668A
Authority: EP
Inventors: Pierre Ginies; David Genevois; Jean De Bernardi
Original assignee: Danfoss Commercial Compressors SA
Current assignee: Danfoss Commercial Compressors SA
Priority date: 2005-05-23
Filing date: 2006-05-23
Publication date: 2008-02-13
Anticipated expiration: 2026-05-23
Also published as: FR2885966B1; EP1886024B1; CN101223364A; WO2006125909A1; FR2885966A1; CN101223365A; US20090041602A1; KR20080011443A; CN101223364B; WO2006125908A1; CN100575706C; KR100938798B1; DE112006001283T5; US7708536B2; ATE437307T1; DE602006007987D1; DE112006001283B4; US20090035168A1; US7670120B2

Abstract

A scroll-type refrigerant compressor with a sealed enclosure defined by a shell and containing a suction volume and a compression volume at opposite ends of the enclosure. The shell has a gas inlet, an electric motor on the suction side having a stator and defining with the shell an annular volume. The stator is surrounded by a jacket defining an annular volume with the shell and a chamber which contains the motor winding and is directed towards the compression volume, an end of the intermediate jacket directed away from the compression volume being located at an end of the stator directed away from the compression volume. Structure is provided for conveying some of the gas arriving at the gas inlet into the chamber containing the motor winding, and gas conveyed by the structure is admitted into the chamber containing the winding through the gas intake orifice.

Description

Refrigeration compressor with spirals

The present invention relates to a scroll compressor.

A scroll compressor, also known as a Scroll compressor, comprises a tight enclosure delimited by a ferrule, containing a suction volume and a compression volume separated by a compression stage, and disposed respectively on the sides of the two ends of the compressor. the enclosure.

An electric motor is arranged in the suction volume, with a stator located on the outer side, mounted fixed relative to the shell, and a rotor disposed in a central position, integral with a drive shaft or crankshaft. The drive shaft comprises an off-axis lubrication duct extending over the entire length thereof, fed from oil contained in a casing located in the lower part of the enclosure by an oil pump arranged at a first end of the tree. The lubrication duct has lubrication holes at the various guide bearings of the shaft.

The compression stage contains a fixed volute equipped with a spiral engaged in a spiral of a moving volute, the two spirals delimiting at least one compression chamber of variable volume. The second end of the drive shaft is equipped with an eccentric driving the moving volute in an orbital motion, to achieve the compression of the refrigerant gas sucked.

The shell defining the sealed enclosure comprises a refrigerant gas inlet. This inlet opens into the annular volume between the engine and the ferrule. From a practical point of view, gas arrives from outside and enters this annular space. Part of the gas is sucked directly towards the compression stage, while the other part of the gas passes through the engine before flowing in the direction of the compression stage. All the incoming gas is directly to the compression stage, or after passing through the engine, is sucked by the compression stage, penetrating into at least one compression chamber defined by the two spirals, the inlet is forming at the periphery of the compression stage, and the gas being conveyed towards the center of the spirals as compression occurs by decreasing the volume of the compression chambers, resulting from the movement of the mobile scroll relative to the fixed scroll. The gas compressed leaves in central part in the direction of the compressed gas recovery chamber.

This structure has a certain number of drawbacks, and in particular the fact that, when the lubricating oil of the various bearings close to the compression zone returns towards the casing, this cascade flows through the interstices provided at the level of the casing. engine and thus comes into contact with the refrigerant gas passing through the engine, which can generate an excessive oil content in the refrigerant gas leaving the compressor. The direct consequence of this excessive rate of oil in the gas is a loss of efficiency of the heat exchange of the exchangers located downstream of the compressor, given the fact that the oil droplets contained in the gas tend to place on the exchangers and form a layer of oil on them.

In addition, excessive oil in the gas can also cause emptying of the crankcase oil reservoir, which could lead to the destruction of the compressor.

To overcome these disadvantages, a separation of gas and oil flows is often used.

A known gas and oil flow separation solution is to provide deflectors in the flow path of the refrigerant gas. Due to the changes of direction and speed differences due to the presence of the deflectors, the oil is separated from the gas flow and falls by gravity into the housing.

However, the effectiveness of this solution is directly related to gas velocities. Indeed, when the gas speeds are too high, the separation time of oil and gas is greatly reduced, which can cause an excessive oil content in the gas and therefore a decrease in the efficiency of the compressor see a destruction of the latter.

Thus, this solution for separating gas and oil flows is not sufficiently effective and safe under all compressor application conditions.

Another problem encountered in this type of compressor is related to the degassing of the refrigerant gas contained in the lubricating oil when the latter flows into the lubrication duct. This degassing of the gas in the lubrication duct is a consequence of the centrifugation generated by the rotation of the drive shaft. Under certain operating conditions of the compressor, the degassing of the refrigerant gas limits the oil supply flow of the bearings, which can generate a risk of deterioration of the compressor.

In order to avoid this situation, various evacuation solutions for these gases are proposed.

A known solution is to provide radial vent holes in the drive shaft at the different bearings, these vent holes opening on the one hand in the lubrication conduit and on the other hand in the wall of the shaft opposite the lubrication ports. This solution involves providing, by construction, a pressure gradient favoring the expulsion of gas from the lubrication duct through the vent holes, however the pressure gradient is limited so as not to disturb the flow of oil in the duct. In fact, a pressure gradient that is too high could lead to an expulsion of oil through the vent holes. The conditions of use of the compressor over its application range involve pressure gradients at the terminals of the vent holes which vary in large proportions and therefore greatly modify the venting efficiency of the vent holes. In addition, in some cases, the pressure gradient can be reversed and create a vacuum in the lubrication duct, which prevents expulsion of the gas through the vent holes, this even reduces or limits the flow of oil out of the pump to the bearings.

The present invention therefore aims to remedy these drawbacks. The technical problem at the base of the invention is the production of a scroll compressor with refrigeration making it possible to control the oil content in the gas leaving the compressor under all the operating conditions of the compressor, while ensuring effective lubrication of the compressor. different guide bearings of the drive shaft.

For this purpose, the present invention relates to a scroll compressor comprising:

a sealed enclosure containing a suction volume and a compression volume respectively disposed on the side of the two ends of the enclosure on either side of a body, the enclosure comprising a refrigerant gas inlet, an engine electric device arranged on the suction side having a stator, and a rotor secured to a drive shaft, in the form of a crankshaft, - The drive shaft having an off-axis lubrication duct extending over the entire length thereof, fed from oil contained in a casing located in the lower part of the enclosure by an oil pump arranged at a first end of the shaft, the lubrication duct having lubrication ports at different bearings of the shaft,

the second end of the drive shaft being equipped with a device for driving the mobile spiral of the compressor in an orbital motion, characterized in that the drive shaft comprises a return duct parallel or inclined by relative to the axis of the shaft and extending over at least a part of the length of the shaft, one end of the return duct opening into the wall of the shaft, in the zone thereof beyond the rotor, on the side of the oil sump, means for fluid communication between the lubrication and return ducts being provided.

The lubrication duct allows an oil flow from the oil sump to the compression stage to ensure lubrication of the various bearings of the shaft. After the oil supply of all the bearings, if there is residual oil, it can be discharged into the return conduit through the communication means. Due to the rotation of the shaft, the centrifugally pressed oil on the outer part is forced to flow towards the housing. This residual oil is conveyed directly to the oil sump without passing through the engine, thus limiting its contact with the refrigerant gas. As a result, the structure of the compressor according to the invention makes it possible to ensure a separation of the oil and gas flows which is not linked to the gas velocities and therefore to the operating conditions of the compressor. Thus, the structure of the compressor makes it possible to control the rate of oil in the gas leaving the compressor under all the operating conditions of the latter.

In addition, the communication means allow a passage of the gas from the degassing of the lubrication duct in the return duct to its lower end regardless of the flow rate and the speed of rotation of the shaft and the speed of the gas flowing in the compressor. Thus, the evacuation of gases from degassing is effective in all operating conditions of the compressor. In addition, considering that the residual oil is pressed by centrifugation in the outer portion of the return duct, it leaves a free passage for the gas to the lower end of the return duct. This free passage allows to evacuate the gas from degassing in excellent conditions even if there is surplus oil for the supply of bearings.

Advantageously, the second end of the return duct opens at the end of the shaft located on the side of the moving spiral, the means for placing in fluid communication having a space delimited by the end of the shaft located on the side of the mobile spiral and the bottom of a housing receiving this end of the tree.

According to another characteristic of the invention, the fluidic communication means comprise at least one transverse orifice formed in the shaft, the two ends of which respectively open into the lubrication and return ducts.

Advantageously, the transverse orifice extends radially with respect to the shaft.

According to yet another characteristic of the invention, the end of the return duct opening at the end of the shaft located on the side of the mobile spiral opens near the center of the shaft.

Advantageously, the end of the return duct opening, on the side of the housing, in the wall of the shaft is located substantially at the second end of the shaft.

According to another characteristic of the invention, the end of the return duct opening on the housing side comprises a vacuum pump for accelerating the flow of fluid in the return duct.

Preferably, the diameter of the return duct is less than or equal to the diameter of the lubrication duct.

According to another characteristic of the invention, the lubrication duct is inclined relative to the axis of the shaft.

According to yet another characteristic of the invention, the body of the compressor forms an oil collector intended to collect the leakage rates of the bearings situated on the side of the mobile spiral, recirculation means being provided for conveying the oil collected by the collector in the return duct. Advantageously, the recirculation means comprise a duct formed in the drive shaft opening on the one hand in the return duct and on the other hand in an annular groove formed in the shaft or in the body of the compressor, a duct fed oil from the manifold by an oil pump opening into the annular groove.

In any case the invention will be better understood with the aid of the description which follows, with reference to the appended schematic drawing, showing, by way of nonlimiting examples, several embodiments of this compressor. Figure 1 is a longitudinal sectional view of a first compressor.

Figure 2 is a longitudinal sectional view of a second compressor.

Figure 3 is an enlarged partial view, in cross section, of a third compressor.

Figure 4 is a partial sectional view along the line IV-IV of Figure 3.

Figure 5 is a partial view in longitudinal section of a fourth compressor. Figure 6 is a sectional view along the line B-B of Figure 5.

Figure 7 is a sectional view along the line C-C of Figure 6.

Figure 1 depicts a scroll compressor with a vertical position. However, the compressor according to the invention could occupy an inclined position, or a horizontal position, without its structure being modified.

The compressor shown in FIG. 1 comprises a sealed enclosure delimited by a shell 2 whose upper and lower ends are respectively closed by a cover 3 and a base 4. The intermediate part of the compressor is occupied by a body 5 which delimits two volumes, a suction volume located below the body 5, and a compression volume disposed above it. On the body is fixed a tube 6 inside which is mounted an electric motor comprising a stator 7 at the center of which is disposed a rotor 8. The tube 6 is for example crimped on the stator so as to carry the motor. At its lower end, the tube 6 rests on a centering piece 9 itself attached to the shell 2. In the shell 2 is provided an orifice 10 which is associated with a connector 12 to achieve reduced gas to the compressor. This connector 12 opens into an annular volume 13 formed between the shell 2 and the tube 6 containing the motor, at the top of the engine.

The connector 12 is extended, at the annular volume 13 by a sleeve 14 passing through this annular space and opening into a high chamber 11 defined by the tube 6, containing the motor coil head. In the annular volume 13, the sleeve 14 has a bypass opening 15.

The body 5 serves for mounting a compression stage 16 of the gas. This compression stage comprises a fixed volute 17 equipped with a fixed spiral 18 facing downwards, and a mobile scroll 19 equipped with a spiral 20 facing upwards. The two spirals 18 and 20 of the two volutes interpenetrate to provide compression chambers 22 of variable volume. The admission of the gas is from outside, the compression chambers 22 having a variable volume which decreases from the outside towards the inside, during the movement of the mobile scroll 19 relative to the fixed scroll 17, the gas compressed escaping at the center of the scrolls through an opening 23 towards a chamber 24 from which it is discharged by a connector 25. On the rotor 8 is wedged a shaft 26 whose upper end is off-center in the manner of a crankshaft. This upper part is engaged in a housing delimited by a portion 27 in the form of a sleeve, which comprises the mobile volute 19. During its driving in rotation by the motor, the shaft 26 drives the moving volute which is guided through a connecting member 28 vis-à-vis the fixed scroll 17, in an orbital motion.

The shaft 26 is guided relative to the other parts by means of a lower bearing 29 formed in the centering part 9, an intermediate bearing 30 formed in the body 5 and an upper bearing 32 formed between the 26 and the sleeve 27. The volume containing the upper bearing 32 communicates with the chamber 11 through openings 21 formed in the body 5.

The base 4 delimits a casing 31 containing oil, the oil level being marked by the reference 33. In the bath of oil bathes the end of the intake duct of the pump 34, which supplies oil lubricating the different bearings, via a lubrication conduit 35 inclined relative to the axis of the shaft, opening into the end thereof located from side of the movable scroll 19, as well as by lubrication holes 36 at the bearings, to perform the lubrication thereof.

In the upper part, the lubricating oil can return to the housing passing through the openings 21 formed in the body 5, as well as in interstices provided at the motor, allowing the leakage flow of the bearings 30,32 and mobile scroll 19 to flow towards the engine.

In Figure 1, the fat arrows represent the flow of gas and the fine arrows represent the oil flow. According to an important characteristic of the invention, the shaft 26 also comprises a return line 37 of the oil, inclined relative to the axis of the shaft, one end of which opens at the end of the rotated shaft on the side of the mobile scroll 19 and in the center of the shaft, and the other end of which opens into the peripheral wall of the shaft, in the zone of the latter located at the end of the engine opposite to the compression volume .

Means for placing in fluid communication between the lubrication and return ducts 37 are provided. These communication means comprises a space 38 delimited by the end of the shaft located on the side of the mobile spiral and the bottom of the housing receiving this end of the shaft.

The fluidic communication means further comprise transverse orifices 39 formed in the shaft, the two ends of each orifice opening respectively into the lubrication and return ducts 37. The tube 6 serving as support for the motor comprises in its lower part, one or more radial orifices 40 each being able to be equipped with a diffuser such as a grid 41.

The operation of this compressor is as follows: refrigerant gas loaded with oil and potentially liquid particles arrives through the connector 12. A significant portion of the flow of gas passes through the sleeve 14 in the volume defined by the tube 6 , lying above the engine. Another part of the flow passes the bypass duct 15 in the annular volume 13 to flow directly towards the compression stage 16. The gas arriving in the volume above the engine is mixed with the lubricating oil which flows towards the lower bearing 29, in particular from the upper bearing 32 and the intermediate bearing 30. The mixture of gas and lubricating oil flows through the engine downwards, evacuating heat losses from the engine. This passage is made in particular by a space 42 located between the rotor and the stator, as well as by a space 43 situated between the stator and the tube 6. The mixed flow flowing through the motor arrives in the lower part of the engine where In addition, there is the flow of oil from the lower bearing. The gas-oil mixture then passes through the radial orifices 40 through the diffusers 41 constituted for example by a wire mesh forming a grid. This mesh allows a diffusion of the gas flow all around the motor tube, in the annular volume 13. Due to the changes of direction and differences in speed, the oil is separated from the gas flow and falls back into the housing 31. The flow gaseous then travels through the annular volume 13 to the compression stage 16. The separation of gas and oil continues during the path in the annular volume due to gravity and / or controlled gas velocities and a suitable separation time.

The lubrication duct 35 allows an oil flow from the oil sump 31 to the compression stage to ensure lubrication of the different bearings for guiding the shaft. After the oil supply of all the bearings, the residual oil is discharged into the return duct 37 through the space 38. Due to the rotation of the shaft 26, the oil is plated by centrifugation. on the outside of the return duct is forced to flow towards the housing. This residual oil is conveyed directly to the oil sump without passing through the engine, thus limiting its contact with the refrigerant gas. In addition, the transverse holes 39 allow a passage of the gas from the degassing in the return duct 37 to its lower end regardless of the flow rate and the speed of rotation of the shaft and the speed of the gas flowing in the compressor . The flow of gas in the return duct is possible taking into account that the oil plated by centrifugation allows free passage of gas from the bearing of the mobile scroll to the other end of the return duct. This free passage makes it possible to evacuate the gas coming from the degassing of the various bearings under excellent conditions even if there is surplus oil for feeding the bearings. FIG. 2 represents an alternative embodiment of the compressor of FIG. 1 in which the same elements are designated by the same references than previously. In this compressor, the end of the return duct 37 opening, on the housing side 31, in the wall of the shaft 26 is located substantially at the second end of the shaft and beyond the lower bearing 29. In this case, the return duct 37 makes it possible to evacuate a large oil flow, while being ensured of the return thereof to the casing, whatever the flow rate brought by the pump and the speed of rotation of the pump. 'tree.

FIGS. 3 and 4 show an alternative embodiment of the compressor of FIG. 2. In this compressor, the end of the return duct 37 located on the housing side 31 opens into a transverse orifice 39 formed in the shaft whose two ends respectively open into the lubrication duct 35 and into the wall of the shaft.

In addition, this end of the return duct 37 is equipped with a vacuum pump 44 intended to accelerate the flow of fluid in the return duct. The vacuum pump is formed by a tube comprising a first portion 45 disposed longitudinally in the return duct, a second portion 46 perpendicular to the first portion and extending in the transverse orifice 39 radially outwardly from the first portion and a third portion 47 perpendicular to the plane defined by the first and second portions and extending from the second portion in a direction opposite to the direction of rotation of the shaft.

It should be noted that the first and second portions have sections respectively lower than those of the return duct and the transverse orifice 39, to allow free passage to a certain amount of fluid flowing in the return duct and in the transverse orifice.

During the rotation of the shaft 26, the direction of rotation is represented by the arrow ω in Figure 4, the structure of this tube creates a vacuum in the return duct and therefore a suction effect in the latter. This results in an acceleration of the fluid located near the opening of the tube disposed in the return duct, and thus, step by step, the flow of the fluid flowing in the return duct.

The presence of this vacuum pump thus promotes the return of oil to the crankcase.

Figures 5 to 7 show a fourth embodiment of the compressor of Figure 1. According to this alternative embodiment, the body 5 of the compressor has no openings 21 and thus forms an oil collector for collecting the leakage rates of the upper bearing 32 and intermediate 30.

Recirculation means are provided for conveying the oil collected by the collector into the return duct 37. The recirculation means comprise a duct 50 formed in the drive shaft 26 and opening on the one hand in the return duct 37 and secondly in an annular groove 51 formed in the body 5 of the compressor. The recirculation means also comprise a conduit 52 formed in the body 5 and opening into the annular groove 51. The conduit 52 is supplied with oil from the manifold by an oil pump 53 disposed in a housing 54 formed in the body 5.

The oil pump 53 comprises a first gear 55 disposed around the shaft 26 and meshing with a second idler gear 56. During the rotation of the shaft 26, and thus the gear wheels 55 and 56, the oil collected in the body 5 is sucked into the housing 54, then compressed in the spaces formed between the toothed wheels and the body 5, before being discharged into the conduit 52. Then, the compressed oil flows into the annular groove 51 to finally be fed into the return duct 37 using the duct 50.

As goes without saying, the invention is not limited to the embodiments of this compressor, described above as examples, it encompasses, on the contrary, all variants. Thus, in particular, that the end of the return duct facing the compression stage could be closed for specific needs of use. In addition, the connection 12 could lead into the annular volume 13 at the bottom of the engine. In addition, this arrangement could be associated with compressor structures different from those described, including compressors with different gas circuits without departing from the scope of the invention.

Claims

1 - Spiral compressor, comprising:

a sealed enclosure containing a suction volume and a compression volume respectively disposed on the side of the two ends of the enclosure on either side of a body, the enclosure comprising a refrigerant gas inlet (10),

an electric motor arranged on the suction side having a stator (7), and a rotor (8) integral with a crankshaft-shaped drive shaft (26),

- The drive shaft comprising a lubrication conduit (35) off-axis extending over the entire length thereof, fed from oil contained in a housing (31) located in the lower part of the enclosure by an oil pump (34) disposed at a first end of the shaft, the lubrication line having lubrication holes (36) at different shaft guide bearings,

the second end of the drive shaft being equipped with a device for driving the mobile spiral of the compressor in an orbital motion, characterized in that the drive shaft comprises a parallel return duct (37) or inclined relative to the axis of the shaft and extending over at least a portion of the length of the shaft, one end of the return duct opening into the wall of the shaft, in the area of the it is located beyond the rotor, on the side of the oil sump, fluidic communication means (38, 39) between the lubrication and return ducts being provided.

2 - A compressor according to claim 1, characterized in that the second end of the return duct (37) opens at the end of the shaft located on the side of the moving spiral, the fluidic communication means having a space ( 38) delimited by the end of the shaft located on the side of the moving spiral and the bottom of a housing receiving this end of the shaft.

3 - Compressor according to one of claims 1 and 2, characterized in that the fluidic communication means comprise at least one transverse orifice (39) formed in the shaft whose two ends open respectively into the lubrication ducts and back. 4 - Compressor according to claim 3, characterized in that the transverse orifice extends radially relative to the shaft.

5 - Compressor according to one of claims 2 and 4, characterized in that the end of the return duct (37) opening at the end of the shaft located on the side of the movable spiral opens near the center of the 'tree.

6 - Compressor according to one of claims 1 to 5, characterized in that the end of the return duct opening, on the housing side, in the wall of the shaft is located substantially at the second end of the tree.

7 - Compressor according to one of claims 1 to 6, characterized in that the end of the return duct opening on the housing side comprises a vacuum pump (44) for accelerating the flow of fluid in the return duct . 8 - Compressor according to one of claims 1 to 7, characterized in that the diameter of the return duct is less than or equal to the diameter of the lubrication duct.

9 - Compressor according to one of claims 1 to 8, characterized in that the lubrication duct is inclined relative to the axis of the shaft. 10 - Compressor according to one of claims 1 to 9, characterized in that the compressor body forms an oil collector for collecting the leak rates of the bearings located on the side of the moving coil, recirculation means (50). to 53) being provided for conveying the oil collected by the collector into the return duct. 11 - Compressor according to claim 10, characterized in that the recirculation means comprise a conduit (50) formed in the drive shaft opening on the one hand in the return duct (37) and on the other hand in a annular groove (51) formed in the shaft or in the body (5) of the compressor, a conduit (52) supplied with oil from the manifold by an oil pump (53) opening into the annular groove.