GB1563351A - Motor compressor unit - Google Patents

Description

(54) IMPROVEMENTS IN AND RELATING TO A MOTOR COMPRESSOR UNIT (71) We, DANFOSS A/S., A Danish Company, of DK-6430 Nordborg, Denmark, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following state ment : - This invention relates to a motor compress or unit especially for refrigerators.

The present invention provides a motor compresor unit comprising a motor having a stator the core of which has an axial bore, a rotor mounted in the bore, a motor drive shaft carrying the rotor, a compressor, and a bearing for the shaft; wherein, in operation of the unit the bore is substantially vertical, the stator having coils which pass through respective axial slots in the bore, which have end portions extending transversely across the upper end of the bore and which leave an opening through which the bearing extends; the unit further comprising an annular disc for supporting the said end portions, the disc being provided with means for fixing it in position relative to the stator core and having a diameter less than the diameter of the bore.

With this construction, use is made of the fact that the said coil end portions tend to sag under gravity during any oscillating movement of the unit. They therefore tend to lie against the annular disc to an ever increasing extent and in that way prevent movement of the disc that may give rise to noise. This also applies if the disc must initially be mounted with a certain play between the coil end portions and the stator core.

Further, the size of the disc can be chosen so that it does not cover the bore but leaves, radially outwards of it, a portion of the bore uncovered. In this way, an adequate flow cross-section is provided for the suction gases and the lubricating oil.

Furthermore, making the outer diameter of the disc smaller than that of the bore facilitates its assembly.

Surprisingly, it has been found that such an annular disc provides sufficient support because the main consideration is the support of the central and consequently longer coil end portions whereas the outer and thus shorter coil end portions have an adequate stiffness possibly even without any support.

It is a further advantage that end portions of the coils at the lower end of the stator core can form a winding head having a larger amount of conductor material and can be immersed in an oil sump, resulting in more intensive cooling. In addition, the motor is accessible from below, so that, during assembly, the annular disc will not hinder the introduction of centreing probes in the air gap between the rotor and stator.

With particular advantage, legs extend from the outer periphery of the annular disc in a direction substantially perpendicular to the end portions. These legs can provide support for the comparatively short outer coil end portions.

The means for fixing the disc in position may take several forms. For example, it may comprise two resiliently yieldable legs which extend radially from the annular disc and the ends of which are supported on one end of the stator core. Such legs are comparatively easily pressed together. They may also serve as a support for the outer coil end portions.

Desirably, the legs extend at an angle to the plane of the annular dise -- which is substantially at right angles, in use, to the motor axis - to facilitate the compresibility and to provide more stiffness when it is in position.

In addition, the legs may be provided with supporting feet which extend parallel to the periphery of the disc so as to increase the supporting surface of the disc on the stator core.

However, it is particularly preferred if the means for fixing the disc in position is secured to the main bearing. In this case a support for engagement with the stator core can be of comparatively weak construction or completely omitted.

To reduce still further the tendency of the coil end portions to oscillate, it is even possible to secure the annular disc to the main bearing such that it abuts against In particular, the collar may be substantially cylindrical and have an internal the coil end portions under pre-stress.

It is of particular advantage if the means for fixing the disc in position comprises a collar that can be pushed over the outer peripheral surface of the main bearing.

This results in a uniform circumferential engaging surface which ensures a particularly good hold.

Further, a groove may be provided at the outer peripheral surface of the main bearing in which part of the collar engages. This results in an extraordinarily secure attachment.

bead for resiliently snapping into the groove. To achieve this resilience, the cylindrical collar may be at least partially axially slotted.

With advantage the collar converges substantially conically towards the rotor and is radially slotted or toothed at its inner periphery. With such a construction, the securing forces increase with an increase in the load on the annular disc caused by the coil end portions.

Refrigerant motor compressor units constructed in accordance with the invention will now be described, with reference to the accompanying drawings, by way of example only, wherein: Fig. 1 is a diagrammatic longitudinal section through a first compressor unit; Fig. 2 is a side elevation of the supporting device used in the unit shown in Fig.

1; Figure 3 is a plan view of the stator of another compressor unit with a section taken through the main bearing; Fig. 4 is a plan view of the supporting element used in the unit shown in Fig. 3; Fig. 5 is a section through the supporting element used in Fig. 3; Fig. 6 is a partial section of a further compressor unit; Fig. 7 is a section through the unloaded supporting element of Fig. 6, and Fig. 8 is a plan view of the Fig. 6 supporting element.

Referring to the accompanying drawings, the refrigerant motor compressor unit illustrated in Fig. 1 comprises a motor compressor suspended in a hermetically closed capsule 1 by means of springs 2 (only one of which is shown). The springs engage a supporting member 3 at the top of which there is a refrigerant compressor 4. The latter comprises a cylinder 5, a cylinder head 6 and a piston 8 driven through a connecting rod 7. At the bottom of the supporting member 3 there is the stator 9 of the electric motor drive. It comprises a core or a packet 10 of stator laminations having an axial bore 13 and a stator winding 11. The latter comprises two windings - the main and auxiliary each having a plurality of coils passing through a respective axial slot in the wall of the bore and having transverse end portions; electrical connections for the motor being made with the upper end portions. The transverse end portions at the lower end of the stator core 10 form a normal winding head 12 disposed completely radially outwards of the bore 13 and dipping into the oil sump 14. The transverse end portions 15 of the main winding of the coils at the upper end of the stator core extend - when viewed as in Fig. 3 - like chords across the bore 13 of the core. The transverse end portions 16 of the auxiliary resistance winding, however, are placed around and outside the bore 13 of the stator core.

The supporting member 3 further comprises a central main bearing 17 in which a motor shaft 18 is mounted. This bearing is integral at the top with a crank 19 on which the connecting rod 7 is mounted.

Beneath the main bearing 17, the motor shaft 18 carries a packet 20 of rotor laminations, the short-circuiting rings 21 and 22 of its conductor cage being visible. An oil supply tube 23 projects into the oil sump 14. The remainder of the oil distribution system by means of which oil is fed to the lubricating points in the main bearing 17 at the crank pin 19 and in the cylinder 5 and with which oil is also circulated for cooling purposes is not shown in more detail. Only holes 24 in the supporting member 3 indicate that oil flowing off from the top can reach the motor chamber located thereunder.

The transverse end coil portions 15 are supported by a supporting device 25. This consists of an annular disc 26 on which at least the portions 15 of longer length are supported, and a collar 28 which is provided with axial slots 27 and, at the top end, with an internal bead 29 which is engaged in a groove 30 at the outer peripheral surface of the main bearing 17. If outer and consequently shorter transverse end portions 15, receive no support, this is generally of no consequence because they are stiffer by reason of their shorter length.

During assembly, the motor shaft 18 is first of all inserted in the main bearing 17 and its crank pin 19 is connected to the connecting rod 7. The stator 9 is then provisionally attached to the supporting member 3. The supporting device 25 is now pushed onto the main bearing 17 through bore 13 of the core or packet 10 of stator laminations until the bead 29 engages in the groove 30. The packet 20 of rotor laminations is thereafter shrunk onto the motor shaft 18 and the stator core 10 is centred with respect to the rotor 20 and in this position secured to the supporting member 3. Finally, the assembled unit is secured to the capsule 1 by way of the springs 2 and the capsule is closed.

During transport and operation, oscillations of the transverse coil end portions 15 are unavoidable. They cannot, however, come into contact with the short-circuiting ring 21 of the rotor 20 because they are supported by the supporting device 25.

Because of gravitational forces, deformation of the end portions 15 is also unavoidable. Such deformation leads to a more intensive abutment against the supporting device 25 and the resultant pre-stress reduces subsequent oscillations. One can even ensure during assembly that the annular disc 26 lies against the end portions 15 under a certain amount of pre-stress so as to reduce their tendency to oscillate.

Particularly when the supporting device 25 consists of an elastically yielding material such as plastics, slight deformation can be used to apply a correspondingly large amount of pre-stress to this annular disc 26.

In Fig. 3, a supporting device 31 is used comprising a planar annular disc 32 surrounding the main bearing 17 and two radial legs 33 serving as holding means which extend at an angle to the annular disc 32 and are provided with supporting feet 34 extended in the peripheral direction. These supporting feet rest on the end face 35 of the packet 10 of stator laminations.

This supporting device 31 can be built into the stator before the latter is secured to the supporting member 3. For this purpopse it is merely necessary slightly to compress the two inclined legs 33 so that the supporting device 31 can be introduced through the bore 13 of the stator core 10.

In the final position, the supporting feet 34 elastically increase their diameter and lie on the packet 10 of stator laminations. The play necessary for this is automatically reduced during transport or operation when the end connection conductors 15 sag under their own weight.

Fig. 3 indicates that the transverse coil end portions 15 at the centre are spread apart -- and/or arranged on top of each other - to such an extent that they form a passage 36 for the main bearing 17. In any case, a comparatively narrow annular disc 32 will suffice. The arms 33 are orientated so that they can also serve as a support for the shorter outer transverse end portions 15.

Figs. 6 to 8 illustrate a supporting device 37 which is shown to a larger scale in Figs. 7 and 8 than in Fig. 6. Again, an annular disc 38 is provided. It comprises an arm 39 at each of two opposed sides.

The holding means are formed by a collar 40 which conically converges towards the motor. Serrations produced by radial incisions 41 or teeth 42 are provided at its inner radius. Partly because of this configuration and partly because of the inherent elasticity of the material which may be a plastics material, this supporting device 37 can be pushed onto the main bearing 17 until the internal periphery of the collar 40 engages in the groove 30.

In this embodiment, this takes place under pre-stress, so that the annular disc 38 bends downwardly adjacent to the arms 39, whereby its secure engagement in the groove 30 is increased further. The arms 39 do not here serve as holding means but merely for supporting the shorter outer transverse end portions 15.

Fig. 3 shows that the breadth of the annular disc can be kept so small that, radially outwards of t, a considerable cross-section of the bore 13 is left uncovered. Consequently there can be free circulation of suction gases from the motor chamber and lubricating oil can return to the sump 14. It will also be evident that for such a supporting device a very small amount of material is necessary.

WHAT WE CLAIM IS: 1. A motor compressor unit comprising a motor having a stator the core of which has an axial bore, a rotor mounted in the bore, a motor drive shaft carrying the rotor, a compressor, and a bearing for the shaft; wherein, in operation of the unit the bore is substantially vertical, the stator having coils which pass through respective axial slots in the bore, which have end portions extending transversely across the upper end of the bore and which leave an opening through which the bearing extends; the unit further comprising an annular disc for supporting the said end portions, the disc being provided with means for fixing it in position relative to the stator core and having a diameter less than the diameter of the bore.

2. A compressor unit as claimed in claim 1, in which legs extend from

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (15)

1. **WARNING** start of CLMS field may overlap end of DESC **.

   generally of no consequence because they are stiffer by reason of their shorter length.

   During assembly, the motor shaft 18 is first of all inserted in the main bearing

   17 and its crank pin 19 is connected to the connecting rod 7. The stator 9 is then provisionally attached to the supporting member 3. The supporting device 25 is now pushed onto the main bearing 17 through bore 13 of the core or packet 10 of stator laminations until the bead 29 engages in the groove 30. The packet 20 of rotor laminations is thereafter shrunk onto the motor shaft 18 and the stator core 10 is centred with respect to the rotor 20 and in this position secured to the supporting member 3. Finally, the assembled unit is secured to the capsule 1 by way of the springs 2 and the capsule is closed.

   During transport and operation, oscillations of the transverse coil end portions 15 are unavoidable. They cannot, however, come into contact with the short-circuiting ring 21 of the rotor 20 because they are supported by the supporting device 25.

   Because of gravitational forces, deformation of the end portions 15 is also unavoidable. Such deformation leads to a more intensive abutment against the supporting device 25 and the resultant pre-stress reduces subsequent oscillations. One can even ensure during assembly that the annular disc 26 lies against the end portions 15 under a certain amount of pre-stress so as to reduce their tendency to oscillate.

   Particularly when the supporting device 25 consists of an elastically yielding material such as plastics, slight deformation can be used to apply a correspondingly large amount of pre-stress to this annular disc 26.

   In Fig. 3, a supporting device 31 is used comprising a planar annular disc 32 surrounding the main bearing 17 and two radial legs 33 serving as holding means which extend at an angle to the annular disc 32 and are provided with supporting feet 34 extended in the peripheral direction. These supporting feet rest on the end face 35 of the packet 10 of stator laminations.

   This supporting device 31 can be built into the stator before the latter is secured to the supporting member 3. For this purpopse it is merely necessary slightly to compress the two inclined legs 33 so that the supporting device 31 can be introduced through the bore 13 of the stator core 10.

   In the final position, the supporting feet 34 elastically increase their diameter and lie on the packet 10 of stator laminations. The play necessary for this is automatically reduced during transport or operation when the end connection conductors 15 sag under their own weight.

   Fig. 3 indicates that the transverse coil end portions 15 at the centre are spread apart -- and/or arranged on top of each other - to such an extent that they form a passage 36 for the main bearing 17. In any case, a comparatively narrow annular disc 32 will suffice. The arms 33 are orientated so that they can also serve as a support for the shorter outer transverse end portions 15.

   Figs. 6 to 8 illustrate a supporting device 37 which is shown to a larger scale in Figs. 7 and 8 than in Fig. 6. Again, an annular disc 38 is provided. It comprises an arm 39 at each of two opposed sides.

   The holding means are formed by a collar 40 which conically converges towards the motor. Serrations produced by radial incisions 41 or teeth 42 are provided at its inner radius. Partly because of this configuration and partly because of the inherent elasticity of the material which may be a plastics material, this supporting device 37 can be pushed onto the main bearing 17 until the internal periphery of the collar 40 engages in the groove 30.

   In this embodiment, this takes place under pre-stress, so that the annular disc 38 bends downwardly adjacent to the arms 39, whereby its secure engagement in the groove 30 is increased further. The arms 39 do not here serve as holding means but merely for supporting the shorter outer transverse end portions 15.

   Fig. 3 shows that the breadth of the annular disc can be kept so small that, radially outwards of t, a considerable cross-section of the bore 13 is left uncovered. Consequently there can be free circulation of suction gases from the motor chamber and lubricating oil can return to the sump 14. It will also be evident that for such a supporting device a very small amount of material is necessary.

   WHAT WE CLAIM IS: 1. A motor compressor unit comprising a motor having a stator the core of which has an axial bore, a rotor mounted in the bore, a motor drive shaft carrying the rotor, a compressor, and a bearing for the shaft; wherein, in operation of the unit the bore is substantially vertical, the stator having coils which pass through respective axial slots in the bore, which have end portions extending transversely across the upper end of the bore and which leave an opening through which the bearing extends; the unit further comprising an annular disc for supporting the said end portions, the disc being provided with means for fixing it in position relative to the stator core and having a diameter less than the diameter of the bore.
2. 2. A compressor unit as claimed in claim 1, in which legs extend from

   the outer periphery of the annular disc in a direction substantially perpendicular to the end portions.
3. 3. A compressor unit as claimed in claim 1 or claim 2, in which the means for fixing the disc in position comprises two resiliently yieldable legs which extend radially from the annular disc and the ends of which are supported on one end of the stator core.
4. 4. A compressor unit as claimed in claim 3, in which the legs extend at an angle to the plane of the annular disc.
5. 5. A compressor unit as claimed in claim 3 or claim 4, in which the legs are provided with supporting feet which extend perallel to the periphery of the disc.
6. 6. A compressor unit as claimed in any one of claims 1 to 5, in which the means for fixing the disc in position are secured to the bearing.
7. 7. A compressor unit as claimed in claim 6, in which the annular disc is secured to the bearing so that it abuts against the said coil end portions under pre-stress.
8. 8. A compressor unit as claimed in claim 6 or claim 7, in which the means for fixing the disc in position comprises a collar that can be forced over the outer peripheral surface of the bearing.
9. 9. A compressor unit as claimed in claim 8, in which a groove is provided at the outer peripheral surface of the main bearing in which part of the collar engages.
10. 10. A compressor as claimed in claim 9, in which the collar is substantially cylindrical and has an internal bead for resiliently snapping into the groove.
11. 11. A compressor unit as claimed in claim 10, in which the cylindrical collar is at least partly axially slotted.
12. 12. A compressor unit as claimed in claim 8 or claim 9, in which the collar converges substantially conically towards the rotor and is radially slotted or toothed at its inner periphery.
13. 13. A compressor unit as claimed in any one of claims 1 to 12, in which the disc is made of resilient material.
14. 14. A compressor unit as claimed in claim 13, in which the disc is made of plastics material.
15. 15. A motor compressor unit substantially as hereinbefore described with reference to, and as illustrated by, the accompanying drawings.