FR2998340A1 - SPIRAL COMPRESSOR WITH VARIABLE SPEED. - Google Patents

Abstract

The present variable speed scroll compressor (2) comprises a closed housing (3) comprising a low pressure volume and a high pressure volume, and an electric motor placed in the low pressure volume and comprising a rotor (21) and a stator ( 22), the rotor (21) including permanent magnets, the stator (22) comprising a stator core (26) having a plurality of radially extending tooth portions (28) and a plurality of formed slots between the radially extending tooth portions (28), and stator windings (27) each wound on the radially extending tooth portions (28). Each stator winding (27) is wound around a respective tooth portion (28) and includes winding portions respectively extending into the slots formed on each side of said respective tooth portion (28).

Description

Field of the Invention The present invention relates to a variable speed scroll compressor. BACKGROUND OF THE INVENTION As we know, a scroll-type compressor can comprise: - a closed housing including a low pressure volume and a high pressure volume, and - a variable speed electric motor disposed in the low pressure volume , the electric motor comprising a rotor and a stator, the rotor comprising permanent magnets, the stator comprising a stator core having a plurality of radially extending tooth portions and a plurality of slots formed between the portions of radially extending tooth, and stator windings wound on the radially extending tooth portions.

In such a scroll-type compressor, the stator windings almost completely fill the slots provided in the stator core. Therefore, in operation, the low pressure, low temperature refrigerant entering the low pressure volume substantially flows through a small annular space defined between the rotor core and the stator core. As a result, the cooling of the stator windings and permanent magnets disposed in the rotor core could be insufficient. This could lead to demagnetization of the permanent magnets due to excessive heating of the permanent magnets by the hot windings of the stator. This problem is more critical at low rotational speeds when the flow of refrigerant is low. In addition, due to the flow of the refrigerant through the small annular space defined between the rotor core and the stator core, the pressure drop of the refrigerant is important, which reduces the efficiency of the compressor, particularly at a high rotational speed when the refrigerant flow is important.

SUMMARY OF THE INVENTION An object of the present invention is to provide a variable speed scroll compressor capable of overcoming the disadvantages encountered in conventional scroll compressors.

Another object of the present invention is to provide a variable speed scroll compressor which is reliable and has improved efficiency. According to the invention, such a variable speed scroll compressor comprises: a closed casing comprising a low pressure volume and a high pressure volume, and a variable speed electric motor arranged in the low pressure volume and comprising a rotor and a stator, the rotor comprising permanent magnets, the stator comprising a stator core having a plurality of radially extending tooth portions and a plurality of slots formed between the radially extending tooth portions, and windings stator coiled on the radially extending tooth portions, characterized in that each stator winding is wound around a respective tooth portion and in that at least one slot formed between a first and a second tooth portion extending radially adjacent comprises a first slot portion in which extends a winding portion of a first stator winding wound around the first wherein a radially extending tooth portion has a second slot portion in which extends a winding portion of a second stator winding wound around the second radially extending tooth portion and a third slot portion. disposed between the first and second slot portions and defining a refrigerant flow passage. Such winding of the stator windings on the tooth portions of the stator core allows a large free flow section to be maintained within the stator slots for the flow of refrigerant through said stator slots. This leads on the one hand to reduce the pressure drop of the refrigerant, which improves the efficiency of the compressor, and on the other hand to improve the cooling of the stator windings, even at a slow speed of rotation of the engine. Consequently, the stator and rotor cores and in particular the permanent magnets are effectively protected against any deterioration whatever the operating conditions of the compressor according to the invention. According to one embodiment of the invention, each slot formed between first and second radially extending tooth portions 5 adjacent comprises a first slot portion in which extends a winding portion of a first winding of stator wound around the first radially extending tooth portion, a second slot portion in which extends a winding portion of a second stator winding wound around the second radially extending tooth portion and a third slot portion disposed between the first and second slot portions and defining a refrigerant flow passage. According to one embodiment of the invention, the variable speed scroll compressor further comprises a refrigerant suction inlet opening into the low pressure volume. According to one embodiment of the invention, the variable speed scroll compressor is configured to force at least a portion of the refrigerant entering the refrigerant suction inlet to pass through the refrigerant flow passages. slots to cool the stator windings and permanent magnets. According to one embodiment of the invention, the ratio of the sum of the cross-sectional areas of the refrigerant flow passages to the cross-sectional area of the stator is between 3 and 14%, preferably between 5 and 14%. and 10% and for example, between 6 and 8%. The cross sectional area of the stator does not include the central opening 25 to accommodate the rotor. According to one embodiment of the invention, the electric motor is a variable speed electric motor. The variable speed scroll compressor may further comprise an intermediate liner surrounding the stator, the intermediate liner 30 defining an annular external volume with the closed housing and at least one first internal chamber which contains a first stator winding head directed to the high pressure volume. According to one embodiment of the invention, the variable speed scroll compressor may further comprise a fastener for securing the stator core to the closed housing, the intermediate jacket being formed by a cap covering a portion of the stator core. end of the stator core directed to the high pressure volume. The variable speed scroll compressor may further include conveying means for conveying at least a portion of the refrigerant penetrating through the refrigerant suction inlet into the inner chamber. According to one embodiment of the invention, the conveying means comprise an intake orifice provided in the cap and oriented towards the refrigerant suction inlet. According to one embodiment of the invention, the electric motor is entirely arranged in the intermediate liner, the intermediate liner being mounted on a support frame separating the low and high pressure volumes. According to one embodiment of the invention, the variable speed scroll compressor further comprises a centering element fixed to the closed housing and on which is fixed an end portion of the intermediate liner opposite the high pressure volume, the centering element and the intermediate liner defining a second internal chamber which contains a second winding head of the stator opposite to the first winding head, the centering element being further provided with at least one fluid passage opening refrigerant opening into the second internal chamber. According to one embodiment of the invention, the variable speed scroll compressor further comprises: - a compression unit arranged to compress the refrigerant, - a drive shaft arranged to drive the compression unit, the driving shaft being rotatably coupled to the rotor. According to one embodiment of the invention, the rotor is slidably mounted on the drive shaft in a sliding fit relation designed to allow limited angular and / or axial sliding motions between the rotor and the drive shaft. In other words, the rotor is fitted to the drive shaft with axial and / or angular play. According to one embodiment of the invention, the centering member is provided with a guide bearing designed to guide an end portion of the drive shaft opposite to the compression unit. and According to one embodiment of the invention, the variable speed scroll compressor further comprises a locking member arranged to rotatably couple the drive shaft to the rotor. For example, the locking member may be made from non-magnetic material. For example, an outer surface of the drive shaft includes a first longitudinal recess and an inner surface of the rotor includes a second longitudinal recess, the first and second longitudinal recesses being circumferentially aligned and the locking member extending in the first and second longitudinal recesses. first and second longitudinal recesses. The locking member may be arranged to allow limited relative angular sliding movements between the rotor and the drive shaft. According to one aspect of the invention, the locking member is slidably mounted in at least one of the first and second longitudinal recesses. According to one aspect of the invention, the sectional dimensions of the locking member and the first and second longitudinal recesses are adapted to allow limited axial and / or angular sliding movements between the rotor and the drive shaft. .

According to one embodiment of the invention, the variable speed scroll compressor further comprises a positioning element fixed on the drive shaft, the positioning element having an axial abutment surface arranged to cooperate by sliding with an end portion of the rotor opposed to the compression unit. The positioning element may be a positioning ring attached to the drive shaft. According to one embodiment of the invention, the positioning element is mounted by heat-fitting on the drive shaft. For example, the positioning member may be made from a non-magnetic material.

According to one aspect of the invention, in use, the drive shaft extends substantially vertically. According to one embodiment of the invention, a lower end portion of the rotor rests on the axial abutment surface of the positioning element.

These and other advantages will become apparent from reading the following description with reference to the accompanying drawing showing, by way of non-limiting examples, two embodiments of the variable speed scroll compressor according to the invention. BRIEF DESCRIPTION OF THE DRAWINGS The following detailed description of the embodiments of the invention is more understandable when read in conjunction with the accompanying drawings, it being understood, however, that the invention is not limited to the described embodiments. . Figure 1 is a longitudinal sectional view of a scroll type refrigeration compressor according to a first embodiment of the invention. Fig. 2 is an enlarged view of a detail of Fig. 1. Fig. 3 is an enlarged view of a detail of Fig. 2. Fig. 4 is an exploded perspective view of a detail of the refrigeration compressor of Fig. FIG. 5 is a perspective view of the various elements shown in FIG. 4. FIG. 6 is a cross-sectional view of the spiral type refrigeration compressor according to FIG.

FIG. 7 is a top view of a stator core and a rotor core of the scroll-type refrigeration compressor according to FIG. 1. FIG. 8 is a longitudinal sectional view of a refrigeration compressor of FIG. spiral type according to a second embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION FIG. 1 shows a scroll-type refrigeration compressor 2 occupying a vertical position. However, the refrigeration compressor 2 according to the invention could occupy an inclined position or a horizontal position, without significant modification of its structure. The refrigeration compressor 2 shown in FIG. 1 comprises a closed casing 3 defined by a shell 4 whose upper and lower ends are respectively closed by a cover 5 and a base 6. The refrigeration compressor 2 also comprises a support frame 7 fixed in the closed housing 3, the closed housing 3 and the support frame 7 defining a low pressure volume.

The refrigeration compressor 2 further comprises a scroll compression unit 8 disposed above the support frame 7. The scroll compression unit 8 comprises a fixed scroll element 9 and an orbital movement scroll element 11 that can be adjusted. one on the other. In particular, the orbiting volute element 11 is supported by an upper face of the support frame 7 and is in sliding contact therewith, and the fixed volute element 11 is fixed relative to the closed housing 3. The fixed scroll element 11 could, for example, be fixed to the support frame 7. As is known, the fixed scroll element 9 comprises an end plate 12 and a spiral winding 13 projecting from the plate. end 12 to the orbiting scroll member 11, and the orbiting scroll member 11 includes an end plate 14 and a spiral winding 15 projecting from the end plate 14 to the Fixed scroll 9. The spiral winding 15 of the orbiting scroll member 11 cooperates with the spiral winding 13 of the fixed scroll member 9 to form a plurality of compression chambers 16 therebetween. The compression chambers 16 have a variable volume which decreases from the outside to the inside, when the orbiting scroll member 11 is driven in an orbital motion relative to the fixed scroll member 9. end 12 of the fixed scroll element 9 comprises, in its central part, a discharge opening 17 opening into the central compression chamber 16 and leading to a high pressure delivery chamber 18. The refrigeration compressor 2 also comprises a refrigerant suction inlet 19 opening into the low pressure volume to supply the refrigerant to the compressor, and a discharge outlet 20 which opens into the discharge chamber 18. The refrigeration compressor 2 further comprises a electric variable speed motor disposed under the support frame 7, i.e. in the low pressure volume. The electric motor comprises a rotor 21 and a stator 22 disposed around the rotor 21. As shown in FIG. 7, the rotor 21 comprises a rotor core or rotor stack 23 having an axial through passage 24 and permanent magnets. 25 are inserted in longitudinal slots provided in the rotor core 23. The permanent magnets 25 are for example arranged in a regular manner around the axial through passage 24.

As shown in Figures 6 and 7, the stator 22 comprises a stator core or stator stack 26, and stator windings 27 wound on the stator core 26. The stator core 26 is provided on its inner periphery with a plurality of radially extending tooth portions 28, and a plurality of longitudinal slots 29 formed between the radially extending tooth portions 28. According to the invention, each stator winding 27 is wound directly around a respective tooth portion 28 and extends into the longitudinal slots 29 formed on each side of said respective tooth portion 28. Each slot 29 comprises a first slot portion in which extends a winding portion of a first winding adjacent stator 27, a second slot portion in which a portion of a second adjacent stator winding 27 and a third slot portion extending between the first and second portions of the slot extend. e and defining a refrigerant flow passage 30.

The stator core 26 may for example comprise six tooth portions 28 and six longitudinal slots 29, and the stator 22 may therefore comprise six stator windings 27. In addition, the refrigeration compressor 2 comprises a drive shaft 31 arranged for driving the orbiting scroll element 11 in an orbital motion. The drive shaft 31 extends in the axial through passage 24 of the rotor 21 and is rotatably coupled to the rotor 21 so that the drive shaft 31 is rotated by the rotor 21 around the rotor. an axis of rotation. The drive shaft 21 comprises, at its upper end, an eccentric pin 32 which is eccentric to the center of the drive shaft 31 and which is inserted into a connecting sleeve portion 33 of the orbiting scroll member 11 so that the orbiting scroll member 11 is orbited in motion relative to a fixed scroll member 9 when the electric motor is actuated. The lower end of the drive shaft 31 drives an oil pump 34 which supplies oil from an oil pan defined by the closed housing 3 to a lubrication passage 35 formed therein of the central part of the drive shaft 31.

The refrigeration compressor 2 further comprises a locating ring 36 attached to the drive shaft 31. For example, the locating ring 36 is heat-fitted on the drive shaft 31. The locating ring 36 can be made from non-magnetic material. The positioning ring 36 comprises an axial abutment surface 37 on which rests a lower end portion of the rotor 21 and more precisely a radial abutment surface 38 placed on the lower end portion of the rotor 21. Positioning 36 is arranged to axially position the rotor 21. As shown in Figures 2 and 3, the refrigeration compressor 2 comprises a first annular axial abutment surface 39 provided on the rotor 21 and a second annular axial abutment surface 41 provided on the drive shaft 31. As shown in particular in FIG. 3, a predetermined axial space can be provided between the first and second axial abutment surfaces 39, 41 in order to allow limited relative axial sliding movements between the rotor 21 and the drive shaft 31. For example, the predetermined axial space is between a few micrometers and 1 mm. In particular, the first annular axial abutment surface 28 is provided on the upper end face of the rotor 21 and the drive shaft 28 comprises a radial shoulder delimiting the second annular axial abutment surface 29. The first and second Annular axial abutment surfaces 28, 29 are arranged to prevent the rotor 21 from moving axially relative to the drive shaft 24 beyond a predetermined position to the compression unit 8. The refrigeration compressor 2 further comprises a lock key 42 arranged to rotatably couple the drive shaft 31 to the rotor 21. For example, the lock key 42 is made from non-magnetic material. The locking key 42 extends respectively in a first longitudinal recess 43 provided on the outer surface of the drive shaft 31 and in a second longitudinal recess 44 provided on the inner surface of the rotor core 23, the first and second longitudinal recesses 43, 44 being circumferentially aligned. The sectional dimensions of the locking key 42 and the first and second longitudinal recesses 43, 44 are adapted to allow limited relative axial and angular sliding movements between the rotor 21 and the drive shaft 31. The latch 42 may be slightly larger than the first longitudinal recesses 43 so that the locking key 42 is force-fitted into the first longitudinal recess 43, and the locking key 42 can be slidably fitted into the second longitudinal recess 44. However, alternatively, the locking key 42 may be slidably fitted in the first and second longitudinal recesses 43, 44. The second longitudinal recess 44 provided on the rotor 21 may extend the entire length of the rotor core 23 Advantageously, the first longitudinal recess 43 extends only over a partial length of the drive shaft. t 31 and defines an axial abutment surface 45 for the upper end of the locking key 42. In addition, the axial abutment surface 37 placed on the positioning ring 36 also forms an axial abutment for the lower end of the The refrigeration compressor 2 also comprises an annular fixing element 46 for fixing the stator 22 to the closed housing, and a centering element 47 fixed to the closed housing 3 and provided with a guide bearing 40 arranged to guiding the lower end portion of the drive shaft 31. The refrigeration compressor 2 further comprises an intermediate liner 48 surrounding the stator 22 and covering the upper end of the electric motor. The intermediate liner 48 and the closed casing 3 delimit an annular external volume 49 into which the refrigerant suction inlet opens. The intermediate liner 48 defines, with the electric motor, an internal chamber 50 containing the winding head. 27a of the stator 22 facing the scroll compression unit 8. The winding head 27a is formed by the portions of the stator windings 27 extending outwardly from the end face 26a of the stator core. 26. The intermediate liner 48 is provided with an inlet opening 51 opening into the proximal chamber 50 and facing the suction inlet 30 of the refrigerant 19 to enable the liner admitting refrigerant into the proximal chamber 49. In addition, the support frame 7 comprises one or more opening (s) refrigerant passage 52 opening into the low pressure volume and into the In operation, a first portion of the refrigerant penetrating through the refrigerant suction inlet 19 flows into the annular outer volume 49 and then flows upwardly directly to the compression unit. 8, through the refrigerant passage apertures 52. In addition, a second portion of the refrigerant entering the refrigerant suction inlet 19 flows into the inner chamber 50 through the inlet port. 51 of the intermediate liner 48 and then flows downward towards the centering element 47 through the refrigerant flow passages 30 (shown in FIG. 6) delimited by the stator core 26 and the stator 27. It should be noted that a portion of the refrigerant which has entered the inner chamber 50 can also flow down towards the element The refrigerant flowing through the refrigerant flow passages 30 cools the stator windings 27, while the refrigerant flowing through the refrigerant passages passes through the spaces 54 delimited between the stator core 26 and the rotor core 23. Spaces 54 cools the stator core 26 and the rotor core 23, which protects the stator core, the rotor core and the permanent magnets of the rotor from damage. Then, the refrigerant moves upwardly through the low pressure volume to the scroll compression unit 8 and enters the compression chambers 16 through the refrigerant fluid passage apertures 52. refrigerant entering the scroll compression unit 8 is compressed in the compression chambers 16 and escapes from the center of the fixed and orbital scroll elements 9, 11 through the discharge opening 17 leading to the chamber delivery 18, from which the compressed refrigerant is discharged through the discharge outlet 20. Fig. 8 shows a scroll-type refrigeration compressor 2 according to a second embodiment of the invention which differs from that described in FIGS. 1 to 7 essentially in that the electric motor is entirely placed in the intermediate liner 48, and in that the intermediate liner 48 and the motor electrical define a proximal chamber 55a containing the winding head 27a of the stator 22 facing the scroll compression unit 8 and a distal chamber 55b containing the winding head 27b of the stator 22 opposite the first winding head 27a the winding heads 27b being formed by the portions of the stator windings 27 extending outwardly from the end face 26b of the stator core 26 opposite the end face 26a. According to a second embodiment, the upper end of the intermediate liner 48 is fixed to the support frame 7 and the lower end 5 of the intermediate liner 48 is fixed to the centering element 47, so that the liner intermediate 48 serves to fix the stator core 26. It should be noted that an annular connection member 56 can be placed between the intermediate liner 48 and the stator 22. In addition, according to the second embodiment, the element of FIG. centering 47 is further provided with at least one refrigerant passage opening 57 opening into the distal chamber 54b. In operation, the refrigerant penetrating through the refrigerant suction inlet 19 flows downward into the annular outer volume 49 to the centering element 47. Thereafter, the refrigerant flows through the passage opening. refrigerant 57 provided in the centering element 47 and enters the distal chamber 55b. The refrigerant that has entered the distal chamber 55b flows upward toward the scroll compression unit 8 through the refrigerant flow passages 30 defined by the stator core 26 and the stator windings. 27, the proximal chamber 55a and the refrigerant passage openings (not shown in FIG. 8) provided in the support frame 7. It should be noted that a portion of the refrigerant which has entered the distal chamber 55b can move upwards towards the scroll compression unit 8 through the spaces (not shown in Figure 8) delimited by the intermediate sleeve 48 and the outer periphery of the stator 22. Then the refrigerant entering the The scroll compression unit 8 is compressed in the compression chambers 16 and escapes from the center of the fixed and orbital scroll elements 9, 11 through the opening of the delivery 17 leading to the delivery chamber 18, from which the compressed refrigerant is discharged through the discharge outlet 20. Of course, the invention is not limited to the embodiments described above as a non-limiting examples, but on the contrary covers all of its embodiments.

Claims (10)

CLAIMS1 Variable speed scroll compressor (2) comprising: - a closed housing (3) comprising a low pressure volume and a high pressure volume, and - an electric motor disposed in the low pressure volume and comprising a rotor (21) and a stator (22), the rotor (21) including permanent magnets (25), the stator (22) comprising a stator core (26) having a plurality of radially extending tooth portions (28) and a plurality of slots (29) formed between the radially extending tooth portions (28), and stator windings (27) wound on the radially extending tooth portions (28), characterized in that each stator winding (27) is wound around a respective tooth portion (28) and in that at least one slot (29) formed between first and second radially extending tooth portions (28) adjacent thereto comprises a first slot portion in which extends a winding portion of a n first stator winding (27) wound around the first radially extending tooth portion (28), a second slot portion in which extends a winding portion 20 of a second stator winding (27) wound around the second radially extending tooth portion (28) and a third slot portion disposed between the first and second slot portions and defining a refrigerant flow passage (30). 25 The variable speed scroll compressor (2) according to claim 1, wherein the ratio of the sum of the cross-sectional areas of the refrigerant flow passages to the cross-sectional area of the stator is between 3 and 14 %. 30 The variable speed scroll compressor (2) according to claim 1 or 2, wherein the variable speed scroll compressor is configured to force at least a portion of the refrigerant entering the refrigerant suction inlet to passing through the refrigerant flow passages (30) of the slots (29). 35 A variable speed scroll compressor (2) according to any one of claims 1 to 3, further comprising an intermediate liner (48) surrounding the stator (22), the intermediate liner (48) defining an annular external volume ( 49) with the closed housing (3) and at least one inner chamber (50, 55a), which contains a first winding head (27a) of the stator (22) facing the high pressure volume. The variable speed scroll compressor (2) according to any one of claims 1 to 4, further comprising: - a compression unit (8) arranged to compress the refrigerant, and - a drive shaft (31). ) arranged to drive the compression unit (8), the drive shaft (31) being rotatably coupled to the rotor (21). The variable speed scroll compressor according to claim 5, further comprising a locking member (42) arranged to rotatably couple the drive shaft (31) to the rotor (21). The variable speed scroll compressor according to claim 6, wherein an outer surface of the drive shaft (31) comprises a first longitudinal recess (43) and an inner surface of the rotor (21) comprises a second longitudinal recess. (44), the first and second longitudinal recesses (43,44) being circumferentially aligned and the locking member (42) extending into the first and second longitudinal recesses (43,44). A variable speed scroll compressor according to claim 6 or 7, wherein the locking element (42) is arranged to allow limited relative angular sliding movements between the rotor (21) and the drive shaft ( 31). The variable speed scroll compressor according to any one of claims 5 to 8, further comprising a positioning member (36) attached to the drive shaft (31), the positioning member (36) having an axial abutment surface (37) arranged to slidably cooperate with an end portion of the rotor (21) opposite the compression unit (8). The variable speed scroll compressor according to claim 9, wherein the positioning member (36) is a positioning ring attached to the drive shaft.