FR3043148A1 - SPIRAL COMPRESSOR - Google Patents

Abstract

This scroll compressor comprises: - a fixed part carrying a spiral called fixed spiral (1) - a movable part relative to the fixed spiral (1) carrying a so-called spiral spiral mobile (2), - drive means of the mobile spiral (2) in an orbital translation movement relative to the fixed spiral (1), - balls (6) arranged between the fixed spiral (1) and the movable spiral (2), said balls (6) being arranged each in a housing made both in the fixed spiral (1) and in the mobile spiral (2), - axial prestressing means (9) tending to bring the moving spiral (2) of the fixed spiral (1) and - Radial prestressing means tending to move the center of the moving spiral away from the center of the fixed spiral.

Description

The present invention relates to a scroll compressor, also known as a scroll type compressor.

Such a compressor comprises two parts on each of which is formed a labyrinth spiral. The pieces are placed facing each other so that the spirals interpenetrate. By then maintaining a fixed part and giving the other an orbital translation movement, a chamber can be formed whose volume decreases during the movement of the moving part.

Many compressors of this type exist. The present invention relates more particularly to compressors of this type having a reduced size, for example the largest dimension of which is of the order of ten centimeters.

The technical problem at the origin of the present invention is to produce a scroll compressor, of relatively small size, not lubricated. It is therefore necessary to carry out a guide, without lubrication of the moving part, called moving spiral, with respect to the fixed part, called fixed spiral. Advantageously, the solution provided will be compact and will not weigh down the compressor made. For this purpose, the present invention proposes a scroll compressor comprising a fixed part carrying a so-called fixed spiral spiral and a part movable with respect to the fixed spiral bearing a so-called mobile spiral, and means for driving the mobile spiral. in an orbital translation movement relative to the fixed spiral.

According to the present invention, balls are disposed between the fixed scroll and the moving scroll; said balls are each arranged in a housing made both in the fixed scroll and in the moving spiral, and the compressor further comprises, on the one hand, axial prestressing means tending to bring the moving spiral of the fixed spiral and on the other hand, radial prestressing means tending to move the center of the moving spiral away from the center of the fixed spiral.

Such a structure with a guide with balls and the prestressing means making it possible to compensate for wear and guiding games makes it possible to dispense with the use of a lubricant.

One embodiment provides that the housing for each of the balls is formed by a circular bore formed in the face of the fixed spiral facing the mobile spiral and by another bore formed in the face of the spiral mobile facing the spiral. fixed.

In a scroll compressor according to the invention, the mobile spiral is mounted for example on an eccentric, and then the axial prestressing means may comprise a spring bearing on the eccentric to exert a force on the moving spiral towards the fixed spiral.

To achieve the radial prestressing it is for example proposed to use a flexible element acting on the mobile spiral.

If the driving means of the mobile spiral comprise an eccentric, then the flexible element can be arranged between the eccentric and the moving spiral.

It can also be provided that the flexible element is disposed between a housing and the fixed spiral, the fixed spiral being mounted on said housing. The flexible element used as radial prestressing means is for example a sheet having corrugations. The invention also relates to a scroll compressor in which the fixed scroll has a wall defining a labyrinth; the movable scroll comprises a wall defining a labyrinth and wherein a sealing device is disposed between each labyrinth bottom and each free edge of the wall. This embodiment avoids axial leakage in the compressor between the fixed spiral and the moving spiral.

Each sealing device may for example be in the form of a spiral flat seal. The material used to make these joints can be a composite material based on graphite-filled polymer.

In an alternative embodiment, each sealing device is formed by a coating. The latter can be made on one and / or the other of the spirals but in a preferred embodiment, the coating is made at the bottom of the labyrinth of the fixed spiral and on the free edge of a wall defining the labyrinth of the fixed spiral.

In a conventional manner in a scroll compressor, the fixed scroll has a wall defining a labyrinth and the moving scroll comprises another wall defining a labyrinth, each wall having a free edge and two lateral faces. To better match the fixed spiral with the moving coil, it is proposed that the two side faces of a wall are coated with a coating sensitive to abrasion. The pairing can then be achieved by implementing a coin lapping process.

Advantageously, the same coating is used on the one hand for pairing the spirals and for sealing and, on the other hand, only one spiral, preferably the fixed spiral, is coated. Thus, the lateral faces of the wall of the fixed spiral are advantageously coated with a coating of the same nature as the labyrinth bottom and the free edge of the wall.

The coating used for pairing the spirals and / or for sealing the compressor is for example a coating based on aluminum and silicon.

Details and advantages of the present invention will become more apparent from the description which follows, given with reference to the appended schematic drawing in which:

FIG. 1 is a longitudinal sectional view of a compressor according to the present invention,

FIG. 2 is a schematic view illustrating an embodiment of radial stressing means implemented in the compressor of FIG. 1,

FIG. 3 is a schematic view illustrating another embodiment of radial constraint means that can be implemented a compressor according to the invention,

FIGS. 4A and 4B are schematic diagrams corresponding to sectional views in two different section planes illustrating a seal of the prior art, and

Figure 5 is a schematic view corresponding to the view of Figure 4A for a compressor according to the invention. Those skilled in the art knowing the technique of scroll compressors recognize immediately in Figure 1 on the left a room commonly called and then fixed spiral 1 and another piece facing it and commonly called and subsequently mobile spiral 2.

The compressor in question here as a purely illustrative and non-limiting example can be called micro-compressor because of its small size. The fixed spiral 1 and the mobile spiral 2 have for example a diameter of less than 10 cm and preferably less than 5 cm.

The fixed spiral 1 faces the moving spiral 2 and each has a face vis-à-vis the other piece. The face of the stationary spiral 1 has in a hollow recess a wall (projecting from the bottom of this hollow recess) defining a labyrinth in the form of a spiral while the movable spiral 2 has a projection on its face in the form of a spiral. a wall defining a corresponding maze with respect to the fixed spiral 1, the wall of a spiral coming into place in the labyrinth of the spiral facing it in a manner known to those skilled in the art. In the embodiment shown, the fixed spiral 1 forms the "female" spiral while the mobile spiral 2 forms the "male" spiral. The present invention can also be applied to a male fixed scroll and a female movable scroll.

The fixed spiral 1 is held on a casing which because of its shape is called bell and bears the reference 14. Indeed, the side of the fixed spiral 1, the casing is flared reminding and the shape of a bell. The inner surface of the latter serves as a bearing for two ball bearings 10 and 11 carrying an eccentric 8. A motor 16 drives the eccentric 8 in rotation about an axis considered as a longitudinal axis. It is mounted on a motor plate 15, itself fixed on the bell 14 on the opposite side to the fixed spiral 1. The eccentric 8 generally has a circular cylindrical shape (tubular) but the axis, called the eccentric axis, of this cylindrical shape is parallel but offset from an eccentricity RO with respect to the longitudinal axis of the motor 16. The eccentric 8 is mounted in the bell 14 as well as its bearings 10 and 11 is made using a nut 13 braked by a lock washer 12. Shoulders on the eccentric 8 and on the inner face of the bell 14 allow perfect assembly of the bearings 10 and 11 and guide the eccentric 8 during its rotation about the axis longitudinal. The eccentric 8 carries the movable scroll 2 by means of a third bearing 7. When the eccentric is rotated by the motor 16, the mobile scroll 2 has a circular translational movement known as orbital motion of the a person skilled in the art and who is not detailed further here.

For the guidance of this orbital movement without the use of lubricant, it is proposed here to carry out guidance with balls 6. FIG. 2 schematically illustrates the guidance proposed here. As can be seen better in this FIG. 2, on which the ladders are not respected at all, each ball 6 is housed, on the one hand, in a bore made in the fixed spiral 1 and, on the other hand, in a similar bore made in the mobile spiral 2. The bores made in the fixed spiral 1 and the mobile spiral 2 are circular bores whose diameter is substantially equal to the diameter of the ball 6 it receives increased eccentricity RO illustrated on Figure 2 shows the longitudinal axis and the eccentric axis.

In order to limit the chain of dimensions at the level of the guide between the fixed spiral 1 and the mobile spiral 2, the balls 6 are assembled by a direct connection between the two parts. They thus come directly into contact with the fixed spiral 1 and the mobile spiral 2.

To ensure good contact of the balls 6 with the fixed spiral 1 and the moving spiral 2, an axial prestressing is performed so as to press the mobile spiral 2 against the fixed spiral 1. This axial prestress is provided by an axial spring 9 (FIG. 1) which bears on a shoulder of the eccentric 8 to push (indirectly) the mobile spiral 2 in the direction of the fixed spiral 1.

Radial preload is also exerted to eliminate any radial clearance in the orbital displacement of the mobile spiral 2. The idea here is to exert a prestress so as to tend to move the eccentric axis (mobile with the moving spiral 2) away from the longitudinal axis.

A first way of producing a radial stress on the moving spiral 2 is illustrated in FIGS. 1 and 2. It is a matter here of arranging a linear expander 5 between the eccentric 8 and the moving spiral 2. In the embodiment of FIG. 1, this linear expander 5 is placed between the third bearing 7 and the mobile spiral 2. It is an elastic piece which is for example in the form of a sheet (very thin, less than millimeter) arranged around the eccentric 8. The corrugations of the linear expander 5 (when it is of course a corrugated sheet) are for example oriented in the peripheral direction (Figure 2) but they can also extend longitudinally, that is to say be parallel to the longitudinal and eccentric axes. The deformation of the corrugations ensures radial prestressing because they tend to return to their neutral position.

The presence of the linear expander 5 tends to increase the eccentricity of the moving coil 2. If the nominal eccentricity given by the distance separating the longitudinal axis from the eccentric axis is equal to e, the real eccentricity due to the presence the linear expander 5 will be RO + x.

In the assembly, the linear expander 5 is integrated between the eccentric 8 and the mobile spiral 2. More precisely, as is apparent from FIG. 1, the linear expander 5 is placed between the bearing 7 and the mobile spiral 2. The latter is thus linked to the eccentric 8 by said linear expander 5 which collapses below the value of the real eccentricity and comes to prestress the assembly made. In the proposed arrangement, if wear occurs in the guiding system of the moving coil 2, it is directly caught by the linear expander 5.

It is proposed in a variant embodiment (FIG. 3) to perform radial prestressing in a different manner. It is also intended here to give the moving coil 2 a real eccentricity greater than the nominal eccentricity RO. Here we find a real eccentricity RO + x.

In this embodiment, it is proposed to have a flexible element between the bell 14 and the fixed spiral 1. This flexible element can for example be placed on the bell 14. The fixed spiral 1 is then directly connected to the bell 14 by said flexible element. The latter is elastically deformed because of the real value of the eccentricity and thus preload the assembly made here. The eccentricity is applied in a given direction that moves 360 ° when the eccentric 8 is rotated. The flexible element, integrated in the bell 14 in the preferred embodiment described herein, undergoes the rotational movement and its deformation allows it to adapt to the displacement of the eccentricity over 360 °.

In the two embodiments proposed here (FIGS. 2 and 3), the flexible element (called linear expander in the embodiment of FIG. 2) makes it possible to compensate for any play related to wear and / or assembly. compressor parts. The efficiency of the compressor realized being related to the precision of the assembly, this control of the radial clearances makes it possible to guarantee a good performance of the compressor.

The compressor shown in Figure 1 also allows to have a good performance through a good axial seal.

Figure 4A and Figure 4B illustrate a known solution of the prior art. In this solution of the prior art, a seal taking the form of labyrinths (spiral) extends the wall defining the labyrinth to come into contact with the piece arranged vis-à-vis. This solution makes it possible to delimit compression chambers, but leaves axial leakage paths 20 that are proposed here to be eliminated.

It is proposed here to have at the bottom of each labyrinth a seal. There is thus a fixed spiral seal 3 and a movable spiral seal 4. In this way, the free edge of the wall defining a labyrinth bears on the seal (3 or 4) with respect to the solutions of the prior art where the seal extending the free edge of the wall defining a labyrinth comes as a wiper seal ensure the bottom of the labyrinth of the opposite piece. The joints proposed here are each a flat seal which has a spiral shape adapted to the bottom of the labyrinth in which it comes to take place.

For the assembly of these joints 3 and 4, it is proposed to proceed as described below as illustrative and not limiting.

To reduce the friction on the joints 3 and 4, the axial prestressing is reduced. The axial spring 9 is then mounted with the interposition of a wedge. By reducing the thickness of this wedge, the axial force is reduced.

After placing the seals, they are new, it is expected that a game exists between the ball 6 and the bottom of the bores in which they are housed. A break-in is then performed until the balls 6 come into contact with the bottom of the bores.

The shim (at the axial spring 9) can then be replaced to obtain the nominal and desired axial prestressing force for prestressing the balls 6.

The seals 3 and 4 then prevent axial leakage without creating radial leaks. They can be made for example in a composite material such as a polymer material loaded with graphite.

In an alternative embodiment, it is possible to replace the joints 3 and 4 by a coating which would be arranged in the same place as the joints 3 and 4. However, rather than to make a coating at the bottom of the labyrinth on the fixed spiral 1 and another coating at the bottom of the labyrinth of the mobile spiral 2, it is proposed in a preferred embodiment to make the coating only on the fixed spiral 1, on the one hand, at the bottom of the labyrinth of the fixed spiral 1 and, d on the other hand, in front of the fixed spiral 1, on the free edge of the wall defining the labyrinth of the fixed spiral 1, that is to say facing the bottom of the labyrinth of the mobile spiral 2. The coating is advantageously a coating sensitive to abrasion and it is for example a coating of aluminum / silicon type. The assembly of the compressor is done here as with the joints 3 and 4, making a break-in with a reduced axial stress and then adapting the radial stress.

In a preferred embodiment, it is intended to cover the entire surface of the fixed scroll 1 which is located opposite the moving coil 2 with an abrasion-sensitive coating (aluminum / silicon or other), including the flanks of the spiral proper, that is to say the lateral faces of the wall defining the labyrinth. It is thus possible to optimize the radial games. To do this, a break-in step is performed before the final assembly of the compressor. The break-in is carried out progressively so as to perfectly match the fixed spiral 1 on the mobile spiral 2.

The foregoing description makes it possible to produce a compressor more particularly adapted for compressing a gaseous fluid. Despite limited dimensions (length less than 100 mm, width and height each less than 50 mm), it allows a differential pressure of up to 7 bar. Its weight is for example of the order of 600 g. Thanks to its optimization, its power consumption is limited and its motor can be a 12 V motor.

A major advantage of this compressor is the absence of solid or liquid lubrication that allows it to operate and guaranteeing the absence of pollution of the compressed fluid.

It can be envisaged to seal between the fixed scroll and the moving spiral as described above, using labyrinth seals or using a suitable coating even in a scroll compressor. having no radial prestressing means and / or guide balls. The means for sealing between the fixed spiral and the moving spiral to prevent axial leakage can be used a priori on any type of scroll compressor.

Of course, the present invention is not limited to the embodiment described by way of illustrative and non-limiting example and variants mentioned but it also relates to any embodiment within the reach of the skilled person in the context of claims below.

Claims (15)

1. Spiral compressor comprising a fixed part carrying a spiral called fixed spiral (1) and a movable part relative to the fixed spiral (1) carrying a spiral called mobile spiral (2), as well as drive means of the spiral mobile spiral (2) in an orbital translation movement with respect to the fixed scroll (1), characterized in that balls (6) are arranged between the fixed scroll (1) and the movable scroll (2), in that said balls (6) are each arranged in a housing made both in the fixed scroll (1) and in the moving spiral (2), and in that the compressor further comprises, on the one hand, prestressing means axial (9) tending to bring the moving spiral (2) of the fixed spiral (1) and, on the other hand, radial prestressing means tending to move the center of the moving spiral away from the center of the fixed spiral. 2. Spiral compressor according to claim 1, characterized in that the housing for each of the balls (6) is formed by a circular bore formed in the face of the fixed spiral (1) opposite the moving spiral (2) and by another bore formed in the face of the mobile spiral (2) facing the fixed spiral (1). 3. Spiral compressor according to one of claims 1 or 2, characterized in that the movable scroll (2) is mounted on an eccentric (8), and in that the axial prestressing means comprise a spring (9) taking pressing on the eccentric (8) to exert a force on the moving spiral (2) in the direction of the fixed spiral (1). 4. Spiral compressor according to one of claims 1 to 3, characterized in that the radial prestressing means comprise a flexible element (5) acting on the moving spiral (2). 5. Spiral compressor according to claim 4, characterized in that the driving means of the mobile spiral (2) comprise an eccentric (8), and in that the flexible element (5) is arranged between the eccentric (8) and the mobile spiral (2). Spiral compressor according to Claim 4, characterized in that the fixed spiral (1) is mounted on a casing (14), and in that the flexible element is arranged between the casing (14) and the fixed spiral ( 1). 7. scroll compressor according to one of claims 4 to 6, characterized in that the flexible element (5) is a sheet having corrugations. 8. Spiral compressor according to one of claims 1 to 7, characterized in that the fixed spiral (1) comprises a wall defining a labyrinth, in that the movable spiral (2) comprises a wall defining a labyrinth, and a sealing device (3, 4) is arranged between each labyrinth bottom and each free edge of the wall. 9. Spiral compressor according to claim 8, characterized in that each sealing device is in the form of a flat spiral-shaped seal (3, 4). 10. Spiral compressor according to claim 9, characterized in that each joint is made of a composite material based on graphite-filled polymer. 11. Spiral compressor according to claim 8, characterized in that each sealing device is formed by a coating. 12. Spiral compressor according to claim 8, characterized in that the coating is made at the bottom of the labyrinth of the fixed spiral (1) and on the free edge of a wall defining the labyrinth of the fixed spiral (1). 13. Spiral compressor according to one of claims 1 to 12, characterized in that the fixed spiral (1) comprises a wall defining a labyrinth, in that the mobile spiral (2) comprises a wall defining a labyrinth, in that each wall has a free edge and two lateral faces, and in that the two lateral faces of a wall are coated with an abrasion-sensitive coating. 14. Spiral compressor according to claims 12 and 13, characterized in that the side faces of the wall of the fixed spiral (1) are coated with a coating of the same nature as the labyrinth bottom and the free edge of the wall. 15. Spiral compressor according to one of claims 11 to 14, characterized in that the coating is a coating based on aluminum and silicon.