FR2998339A1 - REFRIGERATION COMPRESSOR AND METHOD FOR ASSEMBLING SUCH A REFRIGERATION COMPRESSOR - Google Patents

Abstract

This refrigeration compressor (2) comprises an electric motor having a stator (23) and a rotor (21) provided with an axial through passage (22), a compression unit (8) arranged to compress a refrigerant, and a drive shaft (24) arranged to drive the compression unit (8), the drive shaft (24) extending into the axial through passage (22) of the rotor. The rotor (21) is slidably fitted to the drive shaft (24).

Description

Field of the Invention The present invention relates to a refrigeration compressor, and in particular a scroll type refrigeration compressor.

Background of the Invention As known, a scroll-type refrigeration compressor comprises: - an electric motor having a stator and a rotor, the rotor being provided with an axial through passage, - a scroll compression unit arranged for compressing a refrigerant and comprising an orbiting scroll member and a fixed scroll member, and - a drive shaft arranged to drive the orbital scroll member of the compression unit, the spindle The drive extends into the axial through-passage of the rotor and is tightly attached to the rotor, for example by press fitting or hot-pressing the rotor onto the drive shaft. During the starting of the compressor electric motor, the rotor tends to move slightly axially towards the compression unit, causing a corresponding axial displacement of the drive shaft and the scroll element to orbital motion, since the rotor is attached to the drive shaft. Such displacement of the orbital scroll member could create excessive forces between the fixed and orbital scroll members and thereby damage the fixed and orbital scroll members or the sealing member disposed between the spiral winding of the orbital scroll member and the end plate of the fixed scroll member. In addition, during operation of such a refrigeration compressor, deformations of the drive shaft, and more particularly bends of the drive shaft, can be transferred to the rotor and then damage the latter. In addition, during the operation of such a refrigeration compressor, torque variations occurring in the motor generate vibrations which are transmitted to the shaft and the scroll compression unit, which could damage certain elements of the compressor. the scroll compression unit.

SUMMARY OF THE INVENTION An object of the present invention is to provide an improved refrigeration compressor that can overcome the disadvantages encountered in conventional refrigeration compressors.

Another object of the present invention is to provide a refrigeration compressor which is reliable. According to the invention, such a refrigeration compressor comprises: - an electric motor comprising a stator and a rotor, the rotor being provided with an axial through passage, - a compression unit arranged to compress a refrigerant, and - a shaft drive unit arranged to drive the compression unit, the drive shaft extending into the axial through passage of the rotor and being connected to the rotor, characterized in that the connection between the rotor and the drive shaft is arranged to allow limited relative movements between the rotor and the drive shaft during startup and normal operation of the refrigeration compressor. Such a rotor arrangement permits, during the operation of the refrigeration compressor, small angular displacements of the rotor relative to the stator, which avoids a transfer of the mechanical tensions from the drive shaft to the rotor and dampens the vibrations generated by the rotor. the torque variations appearing in the engine. Such vibration damping leads to a reduction in the noise level of the compressor and a reduction of the vibrations transmitted to the piping connected to the compressor. In addition, such a rotor arrangement permits small axial displacements of the rotor relative to the drive shaft during startup of the compressor electric motor, thereby reducing the impact of the orbital scroll element on the rotor. fixed scroll element. Therefore, any damage to the rotor and the compression unit can be avoided during the operation of the refrigerant compressor according to the invention. According to one embodiment of the invention, the clamping interference between the rotor and the drive shaft is less than 0.0003, said clamping interference being calculated by the following formula: FI = (Dps - DR ) / DR, where FI is the interference interference between the rotor and the drive shaft, Dps is the outside diameter of the portion of the drive shaft extending through the axial through passage of the rotor, and DR is the inside diameter of the rotor. Clamping interference may be negative, in which case there is clearance between the rotor and the drive shaft. For example, the interference may range from -0.005 to +0.0003. According to one embodiment of the invention, the rotor is slidably assembled on the drive shaft, which means that the maximum clamping interference is zero. Such an assembly of the rotor, that is to say without the application of stress to the rotor, allows small angular and axial displacements of the rotor relative to the stator. In addition, such mounting of the rotor avoids attaching the rotor to the drive shaft by hot fitting and thus exposing the rotor to high temperatures. Therefore, the present invention allows the use of an IPM rotor (permanent indoor magnet) comprising permanent magnets which lose their magnetic properties when exposed to high temperatures. According to one embodiment of the invention, the rotor is slidably fitted to the drive shaft in a sliding fit relationship arranged to allow limited angular and / or axial sliding displacements between the rotor and the rotor. drive shaft. In other words, the rotor is assembled on the drive shaft with axial and / or angular play. The refrigeration compressor may further include a locking member arranged to rotatably couple the drive shaft to the rotor. For example, the locking member may be made of a non-magnetic material. According to one embodiment of the invention, the locking element is arranged to allow limited relative angular sliding displacements between the rotor and the drive shaft. According to one embodiment of the invention, an outer surface of the drive shaft has a first longitudinal recess, and an inner surface of the rotor has a second longitudinal recess, the first and second longitudinal recesses being circumferentially aligned and locking member extending into the first and second longitudinal recesses.

According to one aspect of the invention, the locking member is slidably fitted into 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 relative axial sliding displacements between the rotor and the drive shaft. 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 relative angular sliding displacements between the rotor and the drive shaft. The second longitudinal recess provided on the rotor may extend substantially over the entire length of the rotor. According to one embodiment of the invention, the refrigeration compressor comprises a positioning element fixed on the drive shaft, the positioning element having an axial abutment surface arranged to slidably cooperate with a part of the engine. end of the rotor opposite the compression unit. According to one embodiment of the invention, the positioning element 20 is a positioning ring fixed to the drive shaft. According to one embodiment of the invention, the positioning element is assembled by heat-fitting to the drive shaft. For example, the positioning element may be made of a non-magnetic material. According to one aspect of the invention, under conditions of 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. According to one aspect of the invention, the refrigeration compressor further comprises a first axial abutment surface provided on the rotor and a second axial abutment surface provided on the drive shaft, a predetermined axial space being provided between the first and second axial abutment surfaces to permit limited relative axial displacements between the drive shaft and the rotor. For example, the predetermined axial space is between 0.005 and 1 mm, and preferably between 0.5 and 1 mm. According to one embodiment of the invention, the drive shaft comprises a radial shoulder delimiting the second axial abutment surface.

According to one embodiment of the invention, the first and second axial abutment surfaces are arranged to prevent axial displacement of the rotor beyond a predetermined position toward the compression unit. The first axial abutment surface may be provided on an end face of the rotor facing the compression unit.

According to one embodiment of the invention, the refrigeration compressor is a scroll type refrigeration compressor. According to one aspect of the invention, the drive shaft has a first end arranged to drive a moving part of the compression unit. According to one embodiment of the invention, the rotor is an IPM rotor.

The present invention also relates to a method for assembling a refrigeration compressor according to the invention, comprising the step of assembly by sliding fit of the rotor on the drive shaft. The method may further comprise the steps of: - pushing the rotor along the drive shaft towards the compression unit until the first annular abutment surface provided on the rotor bears against the second annular abutment surface provided on the drive shaft, - fixing the positioning element to the drive shaft at an axial distance from the rotor corresponding to the predetermined axial space. According to another aspect of the invention, the method may further comprise the steps of: - pushing the rotor along the drive shaft to the compression unit until the first annular abutment surface provided on the rotor bears against the second annular abutment surface provided on the drive shaft, - for fixing the positioning element to the drive shaft so that the axial abutment surface of the positioning element is in abutment against the end portion of the rotor opposite to the compression unit. According to one aspect of the invention, the fixing step comprises the hot-fitting step of the positioning element on the drive shaft.

The method may further comprise the steps of: - aligning the first and second longitudinal recesses, - inserting the locking element in the first and second longitudinal recesses.

According to one aspect of the invention, the insertion step comprises the steps of sliding fit assembly of the locking member in at least one of the first and second longitudinal recesses. These and other advantages will become apparent upon reading the following description with the accompanying drawings showing, as a non-limiting example, one embodiment of the refrigeration compressor according to the invention. BRIEF DESCRIPTION OF THE DRAWINGS The following detailed description of an embodiment of the invention will be better understood when read in conjunction with the accompanying drawings, although the invention is not limited to the embodiment of the invention. specific realization presented. Figure 1 is a longitudinal sectional view of a scroll type refrigeration compressor according to 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. FIG. 5 is a perspective view of the various elements shown in FIG. 4. FIG. 5 is an exploded perspective view of a detail of the refrigeration compressor of FIG. 1. DETAILED DESCRIPTION OF THE FIG. Figure 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 a 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 casing 3, the closed casing 3 and the support frame 7 defining a low pressure volume below the support frame 7 and a high pressure volume at above the support frame 7.

The refrigeration compressor 2 further comprises a scroll compression unit 8 disposed above the support frame 7, i.e. in the high-pressure volume. The scroll compression unit 8 has a fixed scroll member 9 and an orbiting scroll member 11 cooperating with each other. In particular, the orbiting scroll member 11 is supported by and is in sliding contact with an upper face of the support frame 7, and the fixed scroll member 11 is stationary relative to the closed housing 3. The fixed scroll member 11 could for example be attached to the support frame 7. As is known, the fixed scroll member 9 has an end plate 12 and a spiral winding 13 projecting from the plate. 12 to the orbital scroll member 11, and the orbital scroll member 11 has an end plate 14 and a spiral winding 15 projecting from the end plate 14 to the fixed scroll member 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 orbital motion relative to the fixed scroll member 25. compressed refrigerant in the compression chambers 16 escapes from the center of the fixed and orbital scroll elements 9, 11 through an opening 17 in the fixed scroll member 9 leading to a high-pressure chamber 18, from wherein the compressed refrigerant is discharged through a discharge port 19. The refrigeration compressor 2 further comprises an electric motor disposed below the support frame 7. The electric motor comprises a rotor 21 provided with an axial through passage 22, and a stator 23 disposed around the rotor 21. For example, the electric motor may be a variable speed electric motor, and the rotor 21 may be an IPM rotor. In addition, the refrigeration compressor 2 comprises a drive shaft 24 arranged to drive the orbiting scroll member 11 in an orbital motion. The drive shaft 24 extends into the axial through passage 22 of the rotor 21 and is rotatably coupled to the rotor 21 so that the drive shaft 24 is rotated by the rotor 21 about an axis. of rotation.

The drive shaft 24 comprises, at its upper end, an eccentric pin 25 which is eccentric to the center of the drive shaft 24, and which is inserted into a connecting sleeve portion 26 of the element. orbiting volute 11 to cause the orbital scroll member 11 to be driven in orbital motion relative to the fixed scroll member 9 when the electric motor is operating. The lower end of the drive shaft 24 drives an oil pump 27 which supplies oil to a lubrication passage 30 formed within the central portion of the drive shaft 24, from a oil pan defined by the closed housing 3. According to the invention, the rotor 21 is assembled by sliding fit on the drive shaft 24. As shown in Figure 2, the refrigeration compressor 2 comprises a first surface of annular axial stop 28 provided on the rotor 21 and a second axial axial abutment surface 29 provided on the drive shaft 24. As shown in particular in FIG. 3, a predetermined axial space is provided between the first and second axial abutment 28, 29 to allow relative axial sliding displacements between the rotor 21 and the drive shaft 24. For example, the predetermined axial space is between 0.5 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 24 has a radial shoulder delimiting the second annular axial abutment surface 29. The first and second Axial axial abutment surfaces 28, 29 are arranged to prevent the rotor 21 from moving axially with respect to the drive shaft 24 beyond a predetermined position towards the compression unit 8. The compressor of FIG. Refrigeration 2 further comprises a locating ring 31 attached to the drive shaft 24. For example, the locating ring 31 is heat-joined to the drive shaft 24. Advantageously, the locating ring 31 is made of a non-magnetic material. The locating ring 31 has an axial abutment surface 32 on which a lower end portion of the rotor 21 rests, and more precisely a radial abutment surface 33 provided on the lower end portion of the rotor 21. The positioning ring 31 is arranged to axially position the rotor 21. The refrigeration compressor 2 further comprises a locking key 34 arranged to couple the drive shaft 24 to the rotor 21 in rotation. For example, the locking key 34 is made of a non-magnetic material. The locking key 34 extends respectively into a first longitudinal recess 35 provided on the outer surface of the drive shaft 24 and in a second longitudinal recess 36 provided on the inner surface of the rotor 21, the first and second recesses longitudinal members 35, 36 being circumferentially aligned. The sectional dimensions of the locking key 34 and the first and second longitudinal recesses 35, 36 are adapted to allow relative axial and angular sliding displacements between the rotor 21 and the drive shaft 24. According to the embodiment shown in the figures, the locking key 34 is slightly larger than the first longitudinal recesses 35 so that the locking key 34 is force-fitted into the first longitudinal recess 35, and the locking key 34 is assembled by adjustment sliding in the second longitudinal recess 36. However, the locking key 34 can be slidably fitted in the first and second longitudinal recesses 35, 36. The second longitudinal recess 36 provided on the rotor 21 can extend over the entire rotor length 21. Advantageously, the first longitudinal recess 35 extends along a partial length of the drive shaft 24 and defines an axial abutment surface 37 for the upper end of the locking key 34. In addition, the axial abutment surface 32 provided on the locking ring positioning 31 also forms an axial abutment for the lower end of the locking key 34.

The method for assembling the refrigeration compressor 2 according to the invention comprises at least the following steps: - tight fitting assembly of the locking key 34 in the first longitudinal recess 35 so that the upper end face of the the locking key 34 is in abutment against the axial abutment surface 37 provided on the drive shaft 24, - the engagement of the rotor 21 around the drive shaft 24 from the lower end portion of the drive shaft 24, - alignment of the second longitudinal recess 36 with the locking key 34, - thrust of the rotor 21 along the drive shaft 24 to the compression unit 10 8 up that the first annular abutment surface 28 provided on the rotor 21 bears against the second annular abutment surface 29 provided on the drive shaft 24, for heating the positioning ring 31, commitment of the positioning ring 31 around the drive shaft 24 from the lower end portion of the drive shaft 24, - positioning the support surface 32 of the positioning ring 31 to an axial distance from the radial abutment surface 33 provided on the rotor 21 corresponding to the predetermined axial space, and 20 - cooling of the positioning ring 31. When assembled, the refrigeration compressor 2 is positioned vertically. As a result, the rotor 21 slides axially by gravity along the drive shaft 24 until the radial abutment surface 33 provided on the rotor 21 bears against the support surface 32 of the bushing 25. positioning 31, and that the predetermined axial space between the first and second axial abutment surfaces 28, 29 is introduced. It should be noted that the positioning step may consist of the positioning of the support surface 32 of the positioning ring 31 against the radial abutment surface 33 provided on the rotor 21. In such a case, a very high axial space small (a few microns) is finally obtained between the first and second axial abutment surfaces 28, 29 because of the cooling of the positioning ring 31. Of course, the invention is not limited to the embodiment described above. by way of nonlimiting example, but on the contrary it encompasses all the embodiments thereof.

Claims (14)

REVENDICATIONS1. Refrigeration compressor (2) comprising: - an electric motor having a stator (23) and a rotor (21), the rotor (21) being provided with an axial through passage (22), - a compressor unit (8) arranged to compress a refrigerant, and - a drive shaft (24) arranged to drive the compression unit (8), the drive shaft (24) extending into the axial through passage (22) of the rotor and being connected to the rotor (21), characterized in that the connection between the rotor (21) and the drive shaft (24) is arranged to allow limited relative movements between the rotor (21) and the shaft drive (24) during startup and normal operation of the refrigeration compressor. The refrigeration compressor of claim 1, wherein the rotor (21) is slidably mounted on the drive shaft (24). The refrigeration compressor of claim 1 or 2, further comprising a locking member (34) arranged to rotatably couple the drive shaft (24) to the rotor (21). The refrigeration compressor according to claim 3, wherein an outer surface of the drive shaft (24) has a first longitudinal recess (35), and an inner surface of the rotor (21) has a second longitudinal recess ( 36), the first and second longitudinal recesses (35,36) being circumferentially aligned and the locking member (34) extending into the first and second longitudinal recesses (35,36). 30 5. Refrigeration compressor according to claim 3 or 4, wherein the locking element is arranged to allow limited relative angular sliding movements between the rotor and the drive shaft. 35 The refrigeration compressor according to any one of claims 1 to 5, further comprising a positioning element (31) fixed on the drive shaft (24), the positioning element (31). having an axial abutment surface arranged to slidably cooperate with an end portion of the rotor opposed to the compression unit (8). 5 The refrigeration compressor of claim 6, wherein the positioning member (31) is a positioning ring attached to the drive shaft. 10 The refrigeration compressor of claim 6 or 7, wherein the positioning member (31) is heat-joined to the drive shaft (24). 9. Refrigeration compressor according to any one of claims 1 to 8, wherein, under use conditions, the drive shaft (24) extends substantially vertically. The refrigeration compressor according to claim 9 and any one of claims 6 to 8, wherein a lower end portion of the rotor (21) rests on the axial abutment surface of the positioning member (31). . The refrigeration compressor according to any one of claims 1 to 10, further comprising a first axial abutment surface (28) provided on the rotor (21) and a second axial abutment surface (29) provided on the shaft a predetermined axial space is provided between the first and second axial abutment surfaces (28, 29) to permit limited relative axial displacements between the drive shaft (24) and the rotor (21). ). The refrigeration compressor according to claim 11, wherein the first and second axial abutment surfaces (28, 29) are arranged to prevent the rotor (21) from moving axially beyond a predetermined position to the compression unit (8). 2 9 9 83 3 9 13 13. A method for assembling a refrigeration compressor (2) according to any one of claims 1 to 12, comprising the step of connecting the rotor (21) to the drive shaft (24) so as to allow displacements relative limitations between the rotor (21) and the drive shaft (24) during startup and normal operation of the refrigeration compressor. The method of claim 13, wherein the bonding step comprises slidably assembling the rotor (21) to the drive shaft (24).