COMPRESSOR

Abstract

A reciprocating compressor (10) comprises a casing (11), inside which two chambers are defined, respectively a first chamber (12) corresponding to the compression section, which, in turn, comprises at least one piston (16), a slider-crank mechanism (17) and an oil box, and a second chamber (13) for the motor (14) of the compressor. A transmission shaft (18) is provided, operatively connected to said motor and to said slider-crank mechanism. Said chambers are separated by means of a supporting portion (19) of said shaft, said supporting portion having a passage (20) for said shaft, wherein at least one anti-friction bushing (21) is provided in said passage for supporting said shaft. An oil supply duct (22) is provided at least partially inside said shaft, wherein the duct (22) has at least an end opening (23, 25) exiting in the space between said shaft and said passage so as to allow the lubrication of said at least one anti-friction bushing and said shaft. A niche (24, 26) is provided between the end of said passage (20) facing said second chamber (13) and said end opening (23, 25) of said duct. A discharge channel (27) is operatively connected to said niche and to said oil box, so that the oil lubricating the anti-friction bushing (21) and coming from the end opening is depressurized and adapted to come back into said oil box, thus eliminating or limiting the amount of oil reaching the second chamber with the motor.

Description

TECHNICAL FIELD

The present invention relates to compression systems for cooling systems and/or air conditioning systems and/or heat pumps or the like; more in particular, the object of the present invention is a compressor for cooling systems and/or air conditioning systems and/or heat pumps, of the reciprocating type, preferably of the semi-hermetic type.

STATE OF THE ART

As it is well known, refrigerating semi-hermetic compressors are characterized by a casing with two chambers, respectively a compression chamber (with oil box) and a chamber for the motor of the compressor. The chambers are separated by means of a central support with two bronze bushes for the shaft transmitting motion from the motor to the slider-crank mechanism of the compression section and the electric motor.

The oil pumped by a gear pump is conveyed to the central support through a duct inside the shaft. The oil is supplied to an annular recess provided between the two bronze bushes. Part of the oil is conveyed in the bronze bush on the side of the slider-crank mechanism and directly exits in the oil box. A similar quantity is conveyed towards the bronze bush motor side and then discharged motor side.

The flow of cooling fluid sucked by the compressor passes through the chamber of the motor and causes the oil to be drawn to the cylinders and then to the outside of the compressor.

The presence of oil downstream of the compressor is negative, as it reduces the exchange coefficient on the condensator and the evaporator.

SUMMARY

The object of the present invention is to provide a compressor for cooling systems and/or conditioning systems and/or heat pumps, of the reciprocating type, preferably of the semi-hermetic type, to reduce or eliminate the amount of oil lubricating the support of the transmission shaft exiting into the chamber where the compressor actuating motor is housed.

These and other objects, that will be more apparent below, are achieved through a compressor for cooling systems and/or air conditioning systems and/or heat pumps, of the reciprocating type, comprising a casing, inside which two chambers are defined, respectively a first chamber corresponding to the compression section, which, in turn, comprises at least one compression piston, a corresponding slider-crank mechanism for moving the piston and an oil box, and a second chamber for the motor of the compressor, a transmission shaft being provided, operatively connected to said motor and to said slider-crank mechanism, said chambers being separated by means of a support portion of said shaft, said support portion having a passage for said shaft, in said passage being provided at least one anti-friction bushing supporting said shaft, an oil supply duct being provided at least partially inside said shaft, the duct having an end opening exiting in the space between said shaft and said passage so as to allow the lubrication of said at least one anti-friction bushing and said shaft, characterized by comprising

a niche provided in a position comprised between the end of said passage facing said second chamber and said end opening of said duct and

a discharge channel operatively connected to said niche and to said oil box, so that the oil lubricating said at least one anti-friction bushing and coming from said end opening is depressurized and adapted to come back at least partially into said oil box, thus eliminating or limiting the amount of oil achieving said second chamber with the motor.

Practically, thanks to the configuration of the invention, it is possible to collect the oil lubricating the bronze bush motor side before it exits from the bronze bush, and to convey it to the oil box side.

This is achieved through a preferably annular oil discharging niche on the shaft or on the bronze bush, and, if necessary, a discharge hole on the motor side bronze bush in correspondence of said annular niche, and a discharge channel provided in the lower part of the support portion, bringing the oil to the oil box.

Alternatively, the niche can be provided on the surface, preferably the internal surface, of the anti-friction bushing.

The niche may be provided on the surface of said transmission shaft; the niche is preferably an annular recess or a niche extending all around the axis of the shaft.

The niche is preferably separated from the at least an end opening of the oil supply duct, i.e. the end opening is not inside the niche, i.e. it is outside the niche. Practically, the end opening exits outside the niche. Preferably, the niche is open directly on the discharge channel.

Preferably, the discharge channel is provided on the inner surface of the passage.

Preferably, the discharge channel is provided below the transmission shaft.

Preferably, the discharge channel and the niche are directly connected by means of a through hole provided through the at least one anti-friction bushing.

Preferably, the discharge channel is provided on the surface of the support portion; preferably, the discharge channel has three closing sides formed by the support portion and a fourth side closed by the at least one anti-friction bushing.

Preferably, the compressor comprises a ring for limiting the oil leakage, provided around said shaft in a position opposite to said at least one end opening of the oil duct and with respect to said niche.

Preferably, the oil leakage limiting ring is arranged in a seat provided at the end of said passage facing said second chamber.

Preferably, the compressor comprises two anti-friction bushings arranged in series after each other in the passage.

Preferably, the compressor comprises a further niche where said one said end opening exits, provided in the form of annular recess on the shaft, or a further niche extending all around the shaft.

Preferably, the compressor comprises a further end opening directly exiting on the surface of the shaft into contact with the at least one anti-friction bushing.

BRIEF DESCRIPTION OF THE DRAWING

The invention will be better understood by following the description below and the attached drawing, showing a non-limiting embodiment of the invention. More specifically, in the drawing:

FIG. 1 is a longitudinal cross section of the compressor of the invention;

FIG. 2 is an enlargement of a portion of FIG. 1 relating to the central support area of the transmission shaft;

FIG. 3 is a variant, according to the invention, of the central support area of the transmission shaft.

DETAILED DESCRIPTION OF EMBODIMENTS

With reference to the figures listed above, a compressor for cooling systems and/or conditioning systems and/or heat pumps of the reciprocating and semi-hermetic type, according to the invention is indicated as a whole with number 10.

The compressor 10 comprises a casing 11, inside which two chambers are defined, respectively a first chamber 12 corresponding to the compression section, and a second chamber 13 where the electric motor 14 is provided, actuating the compressor.

The compression section of the first chamber 12 comprises one or more cylinders 15 for corresponding one or more pistons 16 moved by means of respective one or more slider-crank mechanisms 17. The first chamber defines, in the inside thereof, a lubricating oil box 12A.

Each slider-crank mechanism 17 is operatively connected to a transmission shaft 18, which is in turn operatively connected to the electric motor 14.

The two chambers 12 and 13 are separated by means of a wall, i.e. a support portion 19 for the transmission shaft 18. The support portion 19 has a passage 20, i.e. a substantially cylindrical hole, to allow the shaft to be provided between the two chambers 12 and 13.

In the passage 20 a first and a second anti-friction bushings 21A and 21B are arranged in series, i.e. two bronze bushes of substantially equal diameter and thickness, supporting the shaft 18 and allowing the rotation thereof, in a known manner.

The compressor 10 comprises a lubricating system comprising, among the various components, an oil supply duct 22 provided at least partially inside the transmission shaft 18. The duct 22 has a first end opening 23 exiting in the space between the shaft 18 and the passage 20, and more in particular in a first niche 24 in the form of annular recess on the surface of the shaft 18, i.e. extending all around the shaft. The first niche 24 is provided in a position in correspondence of the two facing ends of the two anti-friction bushings 21. These ends are put over the first annular niche 24. The duct 22 allows lubricating the anti-friction bushings 21 and the shaft 18.

The oil supply duct 22 comprises a second end opening 25 directly exiting on the surface of the shaft 18, in contact with the first anti-friction bushing 21A.

A second annular niche 26 is provided on the surface of the shaft 18, in a position between the end of the passage 20 facing the second chamber 13 and the first end opening 23 of the duct 22. In this example, also the second niche 26 is an annular recess provided on the surface of the shaft 18 and extends all around the shaft.

It should be noted that the first end opening 23 of the duct 22 does not exit in the second niche, it directly exits outside the second niche 26.

On the surface of the support portion 19, below the transmission shaft, and in particular on the inner surface of the passage 20, a discharge channel 27 is provided for discharging the oil, operatively connected to the second niche 26 and the oil box 12A.

In particular, for example, the channel 27 has three closing sides formed by the body of the support portion (as provided thereon) and a fourth side closed by means of the second anti-friction bushing 21B and the first anti-friction bushing 21A.

The discharge channel 27 and the second niche 26 are directly connected by means of a through hole 30 provided through the second anti-friction bushing 21B.

In other examples, the oil discharge channel 27 may be provided laterally to the shaft, or, in less preferred embodiments, above the shaft.

FIG. 3 shows a variant of the central area of the compressor according to the invention, where both the first niche, now indicated with number 124, and the second niche, now indicated with number 126, are provided on the second anti-friction bushing 21B, thus avoiding to excessively working the surface of the shaft 18.

Moreover, in this example, the first niche 124 is closed only by means of the second bushing 21B. In other examples, the first niche 124 may be closed only by means of the first bushing 21A.

Obviously, examples may be also provided, wherein the first niche is provided on the first or the second bushing and the second niche is provided on the shaft, or vice versa.

At the end of the passage 20 facing the second chamber 13, a seat 31 is provided for positioning a ring 32 limiting the oil leakage towards the second chamber 13, i.e. the ring is provided in opposite position to the first end opening of the oil duct with respect to the second niche 26.

From an operational viewpoint, the lubricating oil is supplied, under pressure, in the oil supply duct 22. The oil achieves the first and the second end opening, and is distributed between the bushings 21 and the inner surface of the passage 20 and the shaft 18. When the oil achieves the second niche 26, it loses pressure and passes into the discharge channel 27, for being discharged into the oil box 12A.

With this configuration of the area where the bushings/bronze bushes supporting the transmission shaft of the compressor are housed, the leakage of oil towards the second chamber, i.e. towards the electric motor, is greatly reduced, with great advantage of the efficiency of the system.

It is understood that what is illustrated purely represents possible non-limiting embodiments of the invention, which may vary in forms and arrangements without departing from the scope of the concept on which the invention is based. Any reference numerals in the appended claims are provided for the sole purpose of facilitating the reading thereof in the light of the description hereinbefore and the accompanying drawings and do not in any way limit the scope of protection.

Claims

1. A compressor for cooling systems and/or air conditioning systems and/or heat pumps, of the reciprocating type, the compressor comprising a casing, inside which two chambers are defined, respectively a first chamber and a second chambera compression section, the first chamber corresponding to the compression section, which compression section comprises at least one compression piston, a corresponding slider-crank mechanism for moving the piston and an oil box;a motor of the compressor, wherein the second chamber is for the motor of the compressor;a transmission shaft operatively connected to said motor and to said slider-crank mechanism;a support portion of said transmission shaft, said chambers being separated by means of the support portion of said transmission shaft, said support portion having a passage for said shaft;at least one anti-friction bushing supporting said shaft, said at least one anti-friction bushing supporting said transmission shaft;an oil supply duct provided at least partially inside said transmission shaft, the oil supply duct having an end opening exiting in the space between said shaft and said passage so as to allow lubrication of said at least one anti-friction bushing and said shaft;a niche provided in a position comprised between the end of said passage facing said second chamber and said end opening of said oil supply duct; anda discharge channel operatively connected to said niche and to said oil box, so that oil lubricating said at least one anti-friction bushing and coming from said end opening is depressurized and adapted to come back at least partially into said oil box, thus eliminating or limiting an amount of oil achieving said second chamber with the motor.

2. The compressor of claim 1, wherein said niche is provided on a surface of said transmission shaft or on a surface of said at least one anti-friction bushing, facing said shaft; and said niche comprises an annular recess or a niche extending all around an axis of said shaft.

3. The compressor of claim 1, wherein said discharge channel is provided on an inner surface of said passage.

4. The compressor of claim 1, wherein said discharge channel and said niche are directly connected by means of a through hole provided through said at least one anti-friction bushing.

5. The compressor of claim 1, wherein said discharge channel is provided on a surface of said support portion and has three closing sides formed by said support portion and a fourth side closed by said at least one anti-friction bushing.

6. The compressor of claim 1, wherein said at least one end opening of the oil supply duct exits outside said niche operatively connected to said discharge channel; said niche being preferably open on said discharge channel.

7. The compressor of claim 1, further comprising a ring for limiting the oil leakage, provided around said shaft in a position opposite to said at least one end opening of the oil duct and with respect to said niche.

8. The compressor of claim 7, wherein said oil leakage limiting ring is arranged in a seat provided at the end of said passage facing said second chamber.

9. The compressor of claim 1, comprising two said anti-friction bushings arranged in series after each other in said passage.

10. The compressor of claim 1, comprising a further niche where a said end opening exits, provided in the form of annular recess on said shaft, or a further niche extending all around said shaft.

11. The compressor of claim 1, further comprising a further end opening directly exiting on a surface of said shaft into contact with said at least one anti-friction bushing.