Reciprocating compressor, in particular of the semi-hermetic type

Abstract

 The compressor (1) comprises: an electric motor (4), a drive shaft (7) driven by said electric motor (4); at least one piston (9) to compress the refrigerating fluid (R) driven by said shaft (7); and an oil lubrication circuit supplied by an oil slinger (2). To make operation of the compressor more regular even at a low number of revolutions, the oil slinger (2) is dimensioned to act also as a flywheel.

Description

Technical field

[0001] The present invention relates to a reciprocating compressor, in particular but not exclusively a hermetic or semi-hermetic compressor for refrigeration and air conditioning. More in particular, the present invention relates to improvements to make this type of compressors more efficient and versatile.

Prior art

[0002] In the field of refrigeration machines and refrigerators, and refrigeration and air conditioning systems in general the use is known of hermetic or semi-hermetic reciprocating compressors, comprising - in the basic characteristics thereof - a body inside which an electric motor is housed, which is used to rotate a drive shaft connected to a plurality of pistons sliding in compression cylinders. In this manner a refrigerating fluid is compressed to then carry out the refrigeration cycle.

[0003] There are known in particular reciprocating compressors that utilize an oil slinger rotating inside a hermetic, i.e. non-disasseblable, or semi-hermetic, i.e. at least partly disasseblable, sealed body, to supply - through centrifugation - oil to the lubrication system, in order to produce compact compressors that are simple to manufacture and use.

[0004] Reciprocating compressors of the aforesaid type are described, for example, in EP-A-0.524.552, EP-B-1.344.933, EP-A-0.046.585, EP-A-0.952.347 and EP-A-0.978.655.

[0005] Fig. 1 shows a vertical section of a semi-hermetic compressor 101 of known type, comprising a motor compartment 103, inside which there is positioned an electric motor 104 with a stator 104A and a rotor 104B connected mechanically through a key 106 to a drive shaft 107. In a second compartment 105, adjacent to the motor compartment 103 and separated therefrom by a dividing wall 110, two pistons 109 are arranged, which are associated with the shaft 107 by means of respective connecting rods 111. Said pistons 109 are used to compress the refrigerating fluid R of the refrigeration machine with which the compressor 101 is associated inside respective compression cylinders 113.

[0006] A compression chamber 129 is in fluid communication with the compression cylinders 113 by means of respective output valves or jumpers 131 and of respective input valves or jumpers, the latter not shown in the figure for simplicity.

[0007] A connection duct (Figure 1 only shows the through hole 121 of said duct) is used to allow the refrigerating fluid R to flow from the compartment 103 into the compression chamber 129.

[0008] A further inlet hole 119, arranged in a transverse position with respect to the shaft 107 on a wall of the motor compartment 103, is used to supply the refrigerating fluid R to the compressor 101, to be compressed by said compressor and which is also used as coolant for the motor 104.

[0009] The second compartment 105 has, moreover, a lower sump 115, to contain the lubricating oil L, in connection with the lower part of the motor compartment 103 by means of a through hole 117 provided in the dividing wall 110.

[0010] The oil L is loaded into the compressor 101 during assembly according to the technical specifications of the compressor and of the refrigeration system in which it is to be installed.

[0011] The lubrication system of this type of compressor comprises an axial hole 112 in the drive shaft 107, with a plurality of radial holes 114 at the surfaces of the components to be lubricated, in order to supply oil L to said surfaces by means of centrifugal force during rotation of the drive shaft 107.

[0012] To supply oil L to the aforesaid lubrication system, in place of a feed pump there is provided an oil slinger 102 mounted integral with the shaft 107 and partly immersed in the oil L contained in the sump 115. During rotation the slinger 102 picks up oil from the sump 115 and throws it through centrifugal force. Part of the oil thrown by the oil slinger 102 by centrifugal force is collected in a reservoir 108 in fluid communication with the axial hole 112 provided in the shaft 107.

[0013] The compressor schematically shown in Fig. 1 also comprises a box 240 with the electrical contacts for a control unit of the motor 104, not represented in the figure for simplicity.

[0014] This type of compressor rotates at a nominal rotation speed, such as 1200 or 1800 rpm, which depends on the power supply frequency. A higher or lower number of revolutions can cause problems.

[0015] In particular, a disadvantage at low rotation speeds is given by the fact that vibrations occur, determined by the rotating kinematic mechanism and in particular by the stroke of the compression pistons.

[0016] Another disadvantage is given by the fact that insufficient lubrication of the rotating elements, in particular the main bearings of the drive shaft, can occur at low speeds, as decreased rotation of the oil slinger in the oil causes a decrease in lubricating oil flow rate.

[0017] A further disadvantage is given by the fact that the electric motor can overheat at low speeds causing risks during operation.

[0018] A disadvantage at high rotation speeds is given by the fact that the displaced volume of compressed gas increases and consequently the volume in the compression chamber is insufficient, causing pulsations in the flow and excessive power input of the motor due to overpressures generated in the compression chamber.

[0019] Currently therefore, notwithstanding the developments in technology, problems remain and there is felt the need to produce reciprocating compressors, in particular of the hermetic or semi-hermetic type for refrigeration and air conditioning, which are of simple construction and more efficient and versatile to use and, in particular, which allow the current possibilities offered by inverters to control variable speed electric motors to be used, outside the range of speeds currently possible (due to the aforesaid reasons), by known compressors.

Objects and summary of the invention

[0020] The object of the present invention is to provide some improvements to a reciprocating compressor, in particular but not exclusively a semi-hermetic compressor, without a feed pump to supply oil to the lubrication system, overcoming or alleviating at least some of the aforesaid disadvantages.

[0021] In particular, an object of the present invention is to provide some improvements to a compressor of the aforesaid type, so that it is efficient and effective within a variable rotation speed of the motor.

[0022] According to a first aspect, the invention provides for a reciprocating compressor, in particular of the hermetic or semi-hermetic type, for refrigeration and air conditioning or the like, comprising an oil lubrication circuit supplied by at least one oil slinger flywheel, i.e. by an element having the dual function of oil slinger and flywheel.

[0023] Oil slinger flywheel is intended as a rotating element capable of supplying oil to the lubrication circuit and of simultaneously balancing the rotating crank mechanism during operation of the compressor.

[0024] In the preferred embodiment of the present invention, this oil slinger flywheel is designed-with a shape suitable to pick up lubrication oil from a lower sump, throw it upward through centrifugal force and allow it to collect at least partly in a collection area or conveyer in fluid communication with the lubrication circuit.

[0025] The oil slinger flywheel is also designed with an increased mass suitable to obtain a suitable polar moment of inertia about the rotation axis thereof, in order to statically and/or dynamically balance the crank mechanism, as a function of the number of pistons and of the crank shaft used.

[0026] In one embodiment of the invention, the oil slinger flywheel is suitable to limit the maximum acceleration modulus during adjustment to steady state speed during the startup and shutdown transients and to provide, in the compressor at periodic speed, a driving torque in periods in which it is absent or less than the resisting torque.

[0027] In particular, the oil slinger flywheel is produced with an increased mass suitable to make the angular velocity of the drive shaft in the reciprocating compressor at periodic speed uniform in time, making the rotating during operation of the crank mechanism uniform.

[0028] More in particular, the oil slinger flywheel is designed with an increased mass suitable to dampen the flow pulsations generated against the head of the compression pistons both at low and at high rotation speeds during operation of the crank mechanism.

[0029] In this manner it is possible to obtain greater balancing of the rotating kinematic mechanism, a decrease in the vibrations and noise of the reciprocating compressor and an improvement in the performance of the machine, both at low and at high rotation speeds.

[0030] Said mass can be distributed evenly around the axis of the oil slinger flywheel and/or concentrated in one or more areas of said flywheel, and in particular can be primarily distributed on the periphery thereof.

[0031] In a particularly advantageous embodiment, the oil slinger flywheel is made of metal and is advantageously and preferably circular with a concentric concavity facing the aforesaid collection area.

[0032] The inner surface of the concavity is shaped so that the oil is directed towards the collection area.

[0033] According to another aspect of the invention, the reciprocating compressor comprises a refrigerating fluid-supply inlet positioned axially with respect to the drive shaft and at the side of the motor. In this manner, it is possible to produce a particularly effective and efficient flow of refrigerating fluid, as heat exchange is increased both with the outer surface of the motor and through the gap between stator and rotor, improving refrigeration of said motor.

[0034] A fluid outlet is also provided in an appropriate position, as explained in greater detail below.

[0035] The main drawback of this type of positioning of the supply inlet is given by the fact that the high number of revolutions attainable by the motor causes an increased flow of refrigerating fluid from the inlet, and therefore a thrust is produced on the motor and on the drive shaft shim that causes abnormal wear of the contact surfaces and of the axial bearing surfaces of the main bearing.

[0036] To solve this drawback, according to an advantageous embodiment of the invention, there is provided a diaphragm element positioned in front of the supply inlet and suitable to break and divert the flow of refrigerating fluid, preventing said flow from striking the motor directly. Said diaphragm element can be designed with a shape that further facilitates creation of the flow of current that laps the outer surface of the motor.

[0037] It is clear that use of the supply inlet of the aforesaid type is particularly advantageous in combination with a compressor like the one of the present invention, capable of reaching a high number of motor revolutions and which therefore requires increased cooling.

[0038] However, it would also be possible to use this configuration of the supply inlet for compressors of different type, such as conventional semi-hermetic reciprocating compressors.

[0039] According to a further aspect, the reciprocating compressor according to an embodiment of the invention comprises self-lubricating friction bearings at the large end of each piston and of the main bearing of the drive shaft. This allows the compressor also to function at very limited rotation speeds, at which the oil picked up by the oil slinger flywheel might not be sufficient to lubricate bearings of another type, not self-lubricating.

[0040] According to another aspect, the compressor comprises a compression chamber in fluid connection with the compression cylinders inside which the compression pistons slide. Said compression chambers have a variable or adjustable volume, in particular a volume that can be increased with respect to the rated or basic volume, as will be explained in greater detail below.

[0041] In this manner, it is possible to avoid vibrations and excessive power input of the motor caused by the increase in the displaced volume of the fluid in the compression chamber, in particular at high rotation speeds.

[0042] According to yet another aspect of the invention, it is possible to modify a conventional compressor by providing appropriate spacers or spacer rings, in order to create the space required to position both the oil slinger flywheel on the drive shaft and the diaphragm element in front of the supply inlet, as described below.

[0043] All in all, the (semi)hermetic reciprocating compressor according to the invention can operate within a wider rotation speed range with respect to conventional compressors, simultaneously reducing vibrations and noise caused in particular by the masses in reciprocating motion of the rotating crank mechanism.

[0044] In this manner, the motor can be controlled by an inverter and made to operate at variable speed, even at a number of rpm significantly below or above the rated rpm.

[0045] An advantage of the present invention is given by the fact that operation of the compressor is extremely versatile, as it can operate at different speeds, also having a more balanced rotating crank mechanism that allows vibrations and noise to be eliminated or decreased significantly.

[0046] Yet another advantage is that it is extremely easy to modify conventional compressors in a simple and inexpensive manner, without the need for complex machining operations.

[0047] Further advantageous characteristics and embodiments of the device according to the invention are indicated in the appended dependent claims and will be described in more detail below with reference to some non-limiting examples of embodiment.

Brief description of the drawings

[0048] The present invention can be better understood and its numerous objects and advantages will be apparent to those skilled in the art with reference to the description below and to the accompanying schematic drawings, which show a practical non-limiting example of the invention. In the drawing:

Figure 1 shows a vertical schematic section of a semi-hermetic reciprocating compressor without lubrication oil feed pump according to the state of the art;

Figure 2 shows a vertical schematic section of a modified version according to the invention of the compressor in Fig. 1.

Detailed description of the preferred embodiment of the invention

[0049] In the drawing, a compressor according to an embodiment of the invention is indicated with 1 and comprises a casing or body 1A, in which there is formed a motor compartment 3, inside which an electric motor 4 positioned, including a stator 4A and a rotor 4B mechanically connected to a drive shaft 7 by means of a key 6.

[0050] In a second compartment 5, adjacent to the motor compartment 3 and separated therefrom by means of a dividing wall 10, two compression pistons 9 are housed, which are connected to the shaft 7 by means of respective connecting rods 11. Said pistons 9 are used to compress a refrigerating fluid R of the refrigerating machine inside respective compression chambers 13.

[0051] The second compartment 5 also has a lower sump 15 to contain the lubrication oil L, in fluid communication with the lower part of the motor compartment 3 by means of a through hole 17 provided in the dividing wall 10. The oil L flows from the sump 15 of the compartment 5 through the hole 17 into the motor compartment 3, to lubricate the motor 4.

[0052] According to the invention, a rotating element 2 is provided, which is suitable to operate both as an oil slinger and as a flywheel and which is mounted integral with the shaft 7 and partly immersed in the oil L contained in the sump 15.

[0053] In the particular embodiment shown in Figure 2, the oil slinger flywheel 2 is provided with a cup shape capable of picking up the oil L from the sump 15, throwing it upward through centrifugal force and collecting it through gravity in a collection area or reservoir 8, in fluid communication with the lubrication circuit, as described below. Said oil slinger flywheel 2 has a concavity 2A concentric with the axis of the shaft and cup-shaped, and a perimeter portion of increased thickness, to balance the crank mechanism and constituting the mass of the flywheel.

[0054] Moreover, balancing elements 23, such as cavities, holes, weights or the like, can be easily provided on the rotating element 2.

[0055] Furthermore, drawing elements, such as paddles or projections on the periphery of this rotating element 2, or suitable surface machining of the rotating element (not shown in the figure for simplicity) can be provided to facilitate picking up and throwing of the oil through centrifugal force.

[0056] It is clear that the shape and the dimensions of the rotating element 2 can vary as a function of specific constructional requirements, as described above.

[0057] In the embodiment shown in the drawing, the collection area 8 is structured with a reservoir having raised edges 8A to collect the falling oil L. In an advantageous embodiment, the reservoir 8 is produced in one piece in a side cover 27 of the second compartment 5 and projects inwardly from said cover. A different embodiment or shape for the collection area 8 would also be possible. The reservoir is in fluid communication with a seat for a bearing of the compressor drive shaft, as described below in greater detail.

[0058] In an embodiment of the invention, the compressor 1 has a lubrication circuit comprising an axial hole 12 on the drive shaft 7 in fluid communication with the collection area or reservoir 8 and also comprising radial holes 14 at the elements of the kinematic mechanism to be lubricated, in order to supply lubrication oil L thereto. In particular, respective radial holes 14 are provided both at the large end 11A of each connecting rod 11 and at a first main bearing 7B of the drive shaft 7.

[0059] An appropriate friction bearing 7A can be provided on the large end 11A of each connecting rod 11.

[0060] Moreover, in the embodiment shown in Figure 2, there is provided a first spacer ring 25A to be fitted on the periphery of the side cover 27 of the second compartment 5, between said cover and the body of the compressor and at least partly surrounding the oil slinger flywheel 2. An optional second spacer element 25B can be associated with the end of the drive shaft 7, in order to increase the dimension of the compartment 5 and position the oil slinger flywheel 2 therein. Said second spacer element 25B is appropriately positioned in the seat provided in the projecting portion of the cover 27, where the oil collection area 8 is provided, and the end of the shaft 7 is bored axially for fluid communication between the collection area 8 and the axial hole 12 of the shaft 7. In the second spacer element 25B there is appropriately arranged a second main bearing 7C of the drive shaft 7, which is lubricated directly by the oil that collects in the area 8.

[0061] Both the first bearing 7B and the second bearing 7C can advantageously be self-lubricating, and made, for example, of PTFE.

[0062] Analogous self-lubricating material can be used for the bearings 7A fitted on each large end 11A of the connecting rods 11.

[0063] This allows the compressor also to operate at very limited rotation speeds, at which the oil picked up by the oil slinger 2 might not be sufficient to lubricate a bearing 7A, 7B and 7C of other type, not self-lubricating.

[0064] The compressor 1 thus designed is capable of operating at variable speed within a wider interval of rotation speeds with respect to that within which a conventional compressor can operate and can be controlled by an external inverter, indicated schematically with 22. The inverter 22 is connected to the motor 4 through electrical contacts 24A housed in a conventional box 24 and is interfaced with a microprocessor of a central control unit (not shown in the figure for simplicity) of the refrigeration machine with which the compressor 1 is associated. Fig. 2 shows the electrical contacts 24A, which extend inside the compartment 3. The electrical connections with the motor 4 are omitted to simplify representation.

[0065] Through the inverter 22, the control unit can control the compressor 1 to operate at variable speed according to the requirements of the refrigeration machine or of the environment to be cooled. In particular, the compressor according to the invention can reach a rotation speed ranging from approximately 600 to over 3000 rpm. Thanks to the oil slinger flywheel, the compressor operates in acceptable conditions in the entire interval of rotation speeds mentioned.

[0066] According to a particular aspect of a preferred embodiment of the invention, the refrigerating fluid R of the circuit of the refrigeration machine, which is compressed by the compressor 1, is also used as refrigerating fluid for the motor 4. For this purpose the refrigerating fluid R is sucked into the compressor 1 through a supply inlet 19 coaxial or at the head with respect to the drive shaft 7 and the motor 4 and is positioned on a side cover 37 of the motor compartment 3.

[0067] To prevent the refrigerating fluid R from striking the motor 4 directly; a diaphragm 38 is mounted in front of the suction inlet 19. This diaphragm 38 is schematically represented in the figure as a flat metal plate, but it could also be of other type, such as a conical plate or the like, in order to help the refrigerating fluid R to lap both the outer surface and the gap between stator 4A and rotor 4B of the motor 4.

[0068] To form sufficient space to contain the diaphragm 38, a spacer ring 25C is positioned between the side cover 37 and the body housing the motor 4 and the pistons 9. In this manner, it is unnecessary to modify the shape of the compressor casing.

[0069] The refrigerating fluid R flows from the motor compartment 3 and is conveyed to the compression chamber 29 through at least one outlet duct, not shown in the Figure for simplicity. The compression chamber 29 is in turn in fluid communication with the compression cylinders 13 through conventional valves or jumpers 31.

[0070] Advantageously, a further spacer ring 29A is provided on the compression chamber 29 to increase the volume thereof, in particular to double this volume. The spacer ring 29A can be fastened between the compression chamber 29 and the body 1A of the compressor 1 by means of studs 30 or the like, without the need for modifications or complex machining operations. The spacer ring 29A is thus easily interchangeable or replaceable, to allow the volume in the compression chamber 29 to be adjusted in a simple manner according to specific requirements.

[0071] In this manner, it is possible to prevent vibrations and excessive power input of the motor 4 caused by the increase in displaced volume of the refrigerating fluid R in the compression chamber 29 at high rotation speeds.

[0072] The compressor 1 described above is of the two-cylinder type. However, it is clear that it can also be of a type comprising one or more cylinders and a crank mechanism with a different articulated system, as a function of specific technical requirements and of the refrigeration machine with which it is to be associated.

[0073] It is understood that the description above merely represents a possible non-limiting embodiment of the invention, which can vary in forms and arrangements without departing from the scope of the concept underlying the invention. Any reference numbers in the appended claims are provided purely to facilitate reading thereof in the light of the preceding description and of the accompanying drawings and do not in any way limit the scope of protection.

Claims

1. Compressor (1) for refrigeration and air conditioning or the like comprising: an electric motor (4), a drive shaft (7) driven by said electric motor (4); at least one piston (9) to compress the refrigerating fluid (R) driven by said shaft (7); and an oil lubrication circuit supplied by an oil slinger (2); characterized in that said oil slinger (2) is dimensioned to act also as a flywheel.

2. Compressor according to claim 1, characterized in that it is a hermetic or semi-hermetic compressor.

3. Compressor according to claim 1 or 2, characterized in that said oil slinger flywheel (2) has a shape suitable to pick up lubrication oil (L) from a lower sump (15), throw it upward through centrifugal force and collect it at least partly in a collection area (8) in fluid communication with said lubrication circuit.

4. Compressor according to claim 1, 2 or 3, characterized in that said oil slinger flywheel (2) has a shape suitable to obtain a suitable polar moment of inertia about the rotation axis thereof.

5. Compressor according to one or more of the preceding claims, characterized in that said oil slinger flywheel (2) comprises an increased mass suitable to reduce the vibrations and noise caused by the rotating kinematic mechanism during operation of said compressor (1).

6. Compressor according to one or more of the preceding claims, characterized in that said oil slinger flywheel (2) comprises an increased mass suitable to make the angular velocity of said drive shaft (7) more uniform in time.

7. Compressor according to one or more of the preceding claims, characterized in that said oil slinger flywheel (2) comprises an increased mass suitable to dampen the pulsations of the flow generated against the head of said compression pistons (9).

8. Compressor according to one or more of claims 5 to 7, characterized in that said mass is distributed uniformly about the axis of said flywheel (2).

9. Compressor according to one or more of claims 5 to 7, characterized in that said mass is concentrated in one or more areas of said oil slinger flywheel (2).

10. Compressor according to one or more of claims 5 to 9, characterized in that said mass is distributed in a substantially uniform manner on the periphery of said flywheel (2).

11. Compressor according to one or more of the preceding claims, characterized in that said oil slinger flywheel (2) is substantially circular in shape.

12. Compressor according to one or more of the preceding claims, characterized in that said oil slinger flywheel (2) has a concavity (2A) concentric with the axis of rotation of said flywheel and facing said collection area (8).

13. Compressor according to claim 12, characterized in that the inner surface of said concavity (2A) is shaped so that the oil (L) is directed towards said collection area (8) after it has been thrown upward by centrifugal force from the oil slinger flywheel.

14. Compressor according to one or more of the preceding claims, characterized in that said oil slinger flywheel (2) is cup-shaped.

15. Compressor according to one or more of the preceding claims, characterized in that said oil slinger flywheel (2) comprises balancing elements (23).

16. Compressor according to one or more of the preceding claims, characterized in that said oil slinger flywheel (2) comprises drawing elements for the oil (L).

17. Compressor according to one or more of the preceding claims, characterized in that said oil slinger flywheel (2) is made of metal.

18. Compressor according to one or more of the preceding claims, characterized in that said oil slinger flywheel (2) is splined onto said drive shaft (7).

19. Compressor according to one or more of the preceding claims, characterized in that said collection area (8) of the oil (L) comprises a reservoir having raised edges (8A) to collect the oil (L) falling from said oil slinger flywheel (2).

20. Compressor according to claim 19, characterized in that said collection area (8) is made in one piece with and projects from a first side cover (27) of the body (1A) of the compressor.

21. Compressor according to one or more of the preceding claims, characterized in that said lubrication system comprises an axial hole (12) provided in said drive shaft (7) and in fluid communication with said collection area (8) and comprising radial holes (14) at the elements of the kinematic mechanism to be lubricated, in order to supply lubrication oil (L) thereto.

22. Compressor according to one or more of the preceding claims, characterized in that it comprises a system to control the motor (4) at variable speed.

23. Compressor according to one or more of the preceding claims, characterized in that said motor (4) has an operating speed ranging from approximately 600 to 3000 rpm or greater.

24. Compressor according to one or more of the preceding claims, characterized in that it comprises an inverter (22) to control said motor (4).

25. Compressor according to one or more of the preceding claims, characterized in that it comprises an inlet (19) for the refrigerating fluid positioned at the head with respect to said motor (4).

26. Compressor according to claim 25, characterized in that said inlet (19) is approximately coaxial with respect to said drive shaft (7) and to said motor (4).

27. Compressor according to claim 25 or 26, characterized in that said inlet (19) is provided in a side cover (37) of the body (1A) of the compressor (1).

28. Compressor according to claim 25, 26 or 27, characterized in that it comprises a diaphragm element (38) in front of said inlet (19) suitable to break and divert the flow of refrigerating fluid.

29. Compressor according to claim 28, characterized in that said diaphragm element (38) is has a shape that helps the refrigerating fluid (R) to lap the outer surface of said motor (4) and/or the gap between stator (4A) and rotor (4B).

30. Compressor according to claim 28 or 29, characterized in that said diaphragm element (38) is produced with a flat plate or with a conical plate.

31. Compressor according to one or more of the preceding claims, characterized in that it comprises a compression chamber (29) in fluid communication with the compression cylinders (13), said compression chamber (29) having a variable or adjustable volume.

32. Compressor according to claim 31, characterized in that the volume of said compression chamber (29) is increasable with respect to the rated or basic value.

33. Compressor according to claim 31 or 32, characterized in that it comprises a spacer element (29A) to increase the volume of said compression chamber (29), in particular doubling said volume.

34. Compressor according to claim 33, characterized in that said spacer element (29A) is a spacer ring fastened between said compression chamber (29) and said body (1A) by means of studs (30) or the like.

35. Compressor according to one or more of the preceding claims, characterized in that it comprises two compression pistons (9).

36. Compressor according to one or more of the preceding claims, characterized in that said drive shaft (7) is supported by friction bearings (7A; 7B; 7C), at least some of which are self-lubricating.

37. Compressor according to one or more of the preceding claims, characterized in that it comprises a body (1A), inside which there are provided a motor compartment (3) for said motor (4) and a compartment (5) to house the piston(s) (9), a first front cover (37) to close said motor compartment (3), and a second front cover (27) to close said compartment (5) to house the piston(s) (9).

38. Compressor according to claim 37, characterized in that between said body (1A) and said front cover (27) there is positioned a first annular spacer element (25A), at least partly surrounding said oil slinger flywheel (2).

39. Compressor according to claim 37 or 38, characterized in that said second cover (27) is produced in one piece with a collection area (8) of the oil thrown through centrifugal force by said oil slinger flywheel (2).

40. Compressor according to claim 39, characterized in that it comprises a second spacer element (25B) associated with an end of said drive shaft (7), said second spacer element (25B) being positioned between said collection area (8) and the end of said shaft (7) and axially bored for fluid communication between said collection area (8) and said axial hole (12).

41. Compressor according to one or more of claims 37 to 40, characterized in that between said body (1A) and said first cover (37) there is positioned a third annular spacer element (25C).

42. Hermetic or semi-hermetic reciprocating compressor for refrigeration and air conditioning or the like, comprising a drive shaft (7) to drive at least one piston (9) and an electric motor (4), housed in a motor compartment (3), comprising a supply inlet (19) for the refrigerating fluid (R) that laps said motor (4), characterized in that said supply inlet (19) is positioned axially with respect to said drive shaft (7) and at the side of said motor (4).

43. Compressor according to claim 42, characterized in that said supply inlet (19) is positioned on a first side cover (37) of said compressor (1).

44. Compressor according to claim 42 or 43, characterized in that it comprises a diaphragm element (38) positioned in front of said supply inlet (19) suitable to break and divert the flow of refrigerating fluid (R).

45. Compressor according to claim 44, characterized in that said diaphragm element (38) is produced with a shape that helps the refrigerating fluid (R) to lap the outer surface of said motor (4) and/or the gap between stator (4A) and rotor (4B) of the electric motor (4).

46. Compressor according to claim 44 or 45, characterized in that said diaphragm element (38) is produced with a flat or conical plate.

47. Hermetic or semi-hermetic reciprocating compressor for refrigeration and air conditioning or the like, comprising a drive shaft (7) to drive at least one piston (9) sliding in a compression cylinder (13) and an electric motor (4), housed in a motor compartment (3), comprising a supply inlet (19) for the refrigerating fluid that laps said motor (4), characterized in that it comprises a compression chamber (29) in fluid connection with said compression chamber (13), said compression chamber (29) having a variable or adjustable volume.

48. Compressor according to claim 47, characterized in that the volume of said compression chamber (29) is increasable with respect to the rated or basic volume.

49. Compressor according to claim 47 or 48, characterized in that it comprises a spacer element (29A) to increase the volume of said compression chamber (29), in particular to double this volume.

50. Compressor according to at least one of claims 47 to 49, characterized in that said spacer element (29A) is a spacer ring fastened between said compression chamber (29) and a body (1A) housing said at least one piston.

Drawing