Patent Description:
More specifically, the present invention refers to the arrangement of the bearings necessary for the implementation of an axial flux electric motor in a hermetic reciprocating compressor and the arrangement of the rotor, in relation to the block and stator. The present invention also relates to the electric motor support arrangement for reciprocating compressor, said arrangement supports an axial flux electric motor within the hermetic housing of a compressor. In addition, the present invention also relates to the mounting of the extender element (which integrates the lubricating oil pump) between the lower end of the rotating shaft and the rotor of said axial flux electric motor.

The current state of the art comprises a wide range of reciprocating compressor constructions, which are widely used in refrigeration fluid compressors. In general, a reciprocating compressor has the main objective of achieving alternating suction and discharge cycles of any working fluid, and in the case of refrigeration fluid compressors, the reciprocating compressor cooperates with valves that, acting in sync with the alternating suction and discharge cycles of said reciprocating compressor, allow the discharge fluid to reach a pressure higher than the pressure of the suction fluid.

The functional principle of refrigeration compressors based on reciprocating compressors is widely known in the state of the art.

As a rule, the driving force element capable of moving the movable piston comprises an electric motor with radial flux, which is schematically illustrated in <FIG> of the state of the art.

In this sense, an electric motor with radial flux is fundamentally integrated by a rotor and a stator, which are built in order to establish electromagnetic interaction. Topologies in which the rotor is circularly surrounded by the stator and topologies in which the stator is circularly surrounded by the rotor are known, and in both, the rotating magnetic field between the rotor and the stator (see illustrative arrows in <FIG>) is generated between the physical radial spacing (clearance) between said rotor and said stator.

Naturally, an electric motor with radial fluw can be easily associated with a reciprocating compressor.

On the other hand, recent technological advances in the area of motors have been able to optimize electric motors with axial flux, so that they have become more energy efficient than those with radial fluw. A basic construction of an axial flux electric motor can be seen in <FIG> of the state of the art.

In general, an axial flux electric motor is fundamentally integrated by a rotor and a stator, which are built in order to establish electromagnetic interaction. Topologies are known in which the rotor is disposed above the stator and topologies in which the stator is disposed above the rotor, and in both, the rotating magnetic field between the rotor and the stator (see illustrative arrows in <FIG>) is generated between the axial physical spacing (clearance) between said rotor and said stator.

The document <CIT>, discloses a motor-compressor unit, and more specifically to a hermetic motor-compressor unit for use in a refrigeration system wherein the motor is of the axial air-gap type.

The document <CIT>, discloses an apparatus generating distributed x-ray, in particular to an external thermionic cathode distributed x-ray apparatus generating x-ray altering the position of focus in a predetermined order in a x-ray light source device by arranging a plurality of independent thermionic cathode electron transmitting units via an external approach and by cathode control or grid control and a CT device having the external thermionic cathode distributed x-ray apparatus.

The document <CIT>, discloses a motor-compressor for a refrigerator including a housing containing a lubricant and a reciprocating compressor driven by a direct-current electric motor having a disc-shaped rotor and stator. The stator is located between magnetic flux closing discs of the rotor and carries electronically commutated drive coils. Goniometric indicators detect the position of the rotor and cause signals to be applied to an alternating current generator which modulates a bridge circuit to provide current flux for driving the rotor.

A problem of the state of the art is the fact that because they comprise topologies essentially different from the radial flux electric motor topologies, the axial flux electric motors are not used in reciprocating compressors, after all, numerous technical adaptations would be necessary in a reciprocating compressor so that it comes to comprise, as a driving force element, an axial flux electric motor.

Another problem of the state of the art is the fact that, unlike what occurs in radial flux electric motors, in which the electromagnetic integration between stator and rotor generates rotating (torque) and radial magnetic forces in the rotor, axial flux electric motors are also subject, in addition to the rotating magnetic force (torque) on the rotor, to a magnetic attraction force, in axial direction, between the rotor and the stator. This means that a rotating shaft linked to the rotor of an axial flux electric motor also tends to undergo, in addition to the rotary movement, an axial displacement. Accordingly, because it comprises this other vector of displacement force between rotor and stator, axial flux electric motors are not applied in reciprocating compressors, after all, the traditional embodiments of reciprocating compressors do not include mechanical elements capable of forming the mounting axial clearances of the shaft and rotor subset in the block and stator subset and handle the axial movement of the rotary shaft under transport and compressor operation conditions.

An objective of the present invention is to provide reciprocating compressor with axial flux motor.

This objective is achieved by means of a reciprocating compressor, comprising:.

One of the advantages of the present invention is the fact that it provides a reciprocating compressor comprising an axial flux motor.

The reciprocating compressor according to the present invention consists of the fact that the stator is located between the crankcase and the rotor.

The reciprocating compressor according to the present invention also consists of the fact that the rotor is located between the crankcase and the stator.

In addition, the reciprocating compressor according to the present invention consists of the fact that the rotor is fixed to the rotating shaft by means of a first fixing arrangement.

Additionally, the reciprocating compressor according to the present invention consists of the fact that the stator is fixed to the crankcase by means of a second fixing arrangement.

The reciprocating compressor according to the present invention further comprises an axial bearing disposed between the lower region of the upper flange of the rotating shaft and the upper region of the crankcase.

In addition, the reciprocating compressor according to the present invention further comprises an axial bearing disposed between the rotor and the stator.

In addition, the reciprocating compressor according to the present invention consists of the fact that the stator further comprises a radial bearing arranged around the rotating shaft, wherein the radial bearing is defined by an annular structure which, projected from the stator, is arranged around a segment of the rotating shaft.

The reciprocating compressor according to the present invention further comprises a extended bearing hub.

Additionally, the reciprocating compressor according to the present invention comprises an axial bearing disposed between the rotor and the extended bearing hub.

It is also disclosed, a reciprocating compressor, which does not form part of the present invention, comprising:.

Conveniently, the reciprocating compressor consists of the fact that the rotor is fixed to the rotating shaft by means of a first fixing arrangement.

The reciprocating compressor also consists of the fact that the stator is fixed to the crankcase by means of a second fixing arrangement.

In addition, the reciprocating compressor further comprises a first hydrodynamic radial bearing formed in the space between the inner face of the first through hole and the rotating shaft first part.

Additionally, the reciprocating compressor further comprises a second hydrodynamic radial bearing formed in the space between the inner face of the second through hole and the rotating shaft second part.

Reciprocating compressor in which the stator further comprises an axial bearing disposed around the rotating shaft, wherein the axial bearing is defined by an annular structure which, protruding from the stator, is disposed around of a rotating shaft segment.

The reciprocating compressor further comprises an axial bearing disposed between the eccentric pin and the crankcase upper part.

Additionally, the reciprocating compressor according to the present invention further comprises an axial bearing disposed between the bearing hub and the rotor.

In addition, the reciprocating compressor also consists of the fact that the rotor is above the stator, and the rotor comprises a support structure in "Z" format for fixing to the rotating shaft.

In addition, the reciprocating compressor consists of the rotor and stator are separated by a first axial clearance, and the rotor and crankcase are separated by a second axial clearance.

Additionally, the reciprocating compressor consists of the first clearance is adjustable by using a bushing arranged between the stator and the crankcase or between the rotor and the rotating shaft.

Further, the reciprocating compressor consists of the fact that the second clearance is preferably adjustable by means of a bushing arranged between the rotor and the rotating shaft.

The reciprocating compressor according to the present invention also consists of the fact that the first clearance is formed by the displacement of the rotor or stator and the second clearance is generated through the displacement of a bushing or fixing arrangement.

Additionally, the reciprocating compressor according to the present invention further comprises an oil pump provided in the inner axial channel of the rotating shaft; or provided in the rotor.

In addition, the reciprocating compressor according to the present invention further comprises a fastening means that physically links the oil pump, the rotor and the rotating shaft.

An additional advantage of the method according to the present invention is to provide a simple and practical reciprocating compressor, of significantly reduced dimensions in relation to a radial engine reciprocating compressor, with adjustments of its axial clearances independently, allowing an easy industrial production and generating a robust configuration for transport and operation operations.

The objectives and advantages of the present invention will become clearer through the following detailed description of the examples and non-limiting drawings presented at the end of this document:.

<FIG>, not part of the invention, illustrates a first embodiment of the reciprocating compressor with axial flux motor according to the present invention.

According to <FIG>, the reciprocating compressor comprises a crankcase <NUM>, a rotating shaft <NUM>, an oil pump C and an electric motor with axial flux basically composed of a rotor <NUM> and a stator <NUM>.

The crankcase <NUM> comprises at least a first vertical projection 11a and at least a second vertical projection 11b for fixing the stator <NUM>. Additionally, the crankcase <NUM> comprises a through hole for receiving the rotating shaft <NUM>.

Said rotating shaft <NUM> comprises at least one inner axial channel <NUM> for circulating lubricating oil, said inner axial channel <NUM> extending from the lower end to the upper end of said rotating shaft <NUM>. Furthermore, the inner axial channel <NUM> is connected to at least one inner radial channel 22a, 22b for lubricating oil outlet, the inner axial channel <NUM> and the at least one inner radial channel 22a, 22b are fluidly connected to each other, so that the lubricating oil which enters the inner axial channel <NUM> exits through the inner radial channels 22a, 22b. In addition, the upper end of the rotating shaft <NUM> comprises a crankpin <NUM> associated with a connecting rod <NUM>, the connecting rod <NUM> also being associated with a movable piston <NUM> within a compression cylinder <NUM>.

The rotor <NUM> comprises magnets <NUM> and is fixed to the rotating shaft <NUM> by means of a first fixing arrangement <NUM>, said first fixing arrangement <NUM> may comprise any known fixation arrangement (by interference, welding, adhesive, screw, among others). The fixing arrangement <NUM> having the function of transmitting the movement of the rotor <NUM> to the rotating shaft <NUM>.

The stator <NUM> comprises electrical coils <NUM> and is fixed to the crankcase <NUM> by means of a second fixing arrangement <NUM>, said second fixing arrangement <NUM> comprising any known fixing arrangement (by interference, welding, adhesive, screw, among others). The fixing arrangement <NUM> having the function of keeping the positioning of the stator <NUM>, in relation to the crankcase <NUM>, static.

Also according to <FIG>, the rotor <NUM> is disposed above the stator <NUM>. In this condition, an axial bearing 50a is provided, used to limit the relative axial displacement between rotor <NUM> and stator <NUM> and, disposed between the lower region of the upper flange of the rotating shaft <NUM> and the upper region of the crankcase <NUM>. This axial bearing 50a (which may comprise, for example, a plain sliding bearing, bearing or bushings of materials with a low friction coefficient), in addition to assisting the rotation of the rotating shaft <NUM>, also prevents said rotating shaft <NUM> from undergoing axial displacements due to the magnetic attraction existing between the rotor <NUM> and the stator <NUM> when the motor is started.

According to <FIG>, the stator <NUM> is above the rotor <NUM>. In this condition, an axial bearing 50b is provided, used to limit the relative axial displacement between rotor <NUM> and stator <NUM>, and disposed between the rotor <NUM> and the stator <NUM> or between the rotor <NUM> and the annular structure <NUM>.

Additionally, this configuration also provides a radial bearing which, integrated with the stator <NUM>, is arranged around the rotating shaft <NUM>. Said radial bearing can comprise any type of bearing already known, such as, for example, a hydrodynamic bearing (bearing with some type of lubricant supply between the minimum clearance of parallel surfaces and, in this case, axially aligned) or a hydrostatic bearing (bearing with forced supply of some type of lubricant injected under pressure between two parallel surfaces and, in this case, axially aligned), or bushings of some low-friction or self-lubricating material.

According to this configuration, the general structure of the stator <NUM> is used to enable the formation of a radial bearing for said rotating shaft <NUM>, so that the rotating shaft <NUM> does not present problems of eccentricity and misalignment.

As shown in <FIG> and <FIG>, the radial bearing is defined by an annular structure <NUM> integrated with the stator <NUM> and arranged around the rotating shaft <NUM>. More particularly, the annular structure <NUM> is arranged around a segment of the rotating shaft <NUM> where the inner radial channel 22a is located.

Thus, the space formed between the annular structure <NUM> and the rotating axis <NUM> segment is adapted to retain a film of lubricating oil (from the inner radial channel 22a), forming a radial hydrodynamic bearing.

Thus, by taking advantage of the stator <NUM> structure itself to form a hydrodynamic radial bearing for the rotating shaft <NUM>, it is possible to build a simpler and more compact crankcase <NUM>.

Optionally, according to <FIG>, the crankcase <NUM> can comprise an extended bearing hub 11c. In this configuration, the stator <NUM> is arranged above the rotor <NUM>. Additionally, an axial bearing 50c is provided between the rotor <NUM> and the extended bearing hub 11c.

<FIG>, not part of the invention, illustrates a second embodiment of the reciprocating compressor with axial flux motor according to the present invention.

According to <FIG>, the reciprocating compressor comprises a crankcase <NUM>, with a crankcase upper part 100a and a crankcase lower part 100b, a rotating shaft <NUM>, with a rotating shaft first part 200a and a rotating shaft second part 200b, an oil pump C and an axial flux electric motor basically composed of a rotor <NUM> and a stator <NUM>.

The crankcase <NUM> comprises a first through hole 120a and a second through hole 120b for receiving the rotating shaft first part 200a and the rotating shaft second part 200b respectively.

The rotating shaft <NUM> comprises an eccentric pin <NUM> disposed between the first part 200a and the second part 200b, the eccentric pin <NUM> being associated with a connecting rod <NUM>, the connecting rod <NUM> also being associated with a movable piston <NUM> inside of a compression cylinder <NUM>.

The rotor <NUM> comprises magnets <NUM> and is fixed to the rotating shaft <NUM> by means of a first fixing arrangement <NUM>, said first fixing arrangement <NUM> can comprise any known fixation arrangement (welding, adhesive, screw, among others). The fixing arrangement <NUM> having the function of transmitting the movement of the rotor <NUM> to the rotating shaft <NUM>.

The stator <NUM> comprises electrical coils <NUM> and is fixed to the crankcase <NUM> by means of a second fixation arrangement <NUM>, said fixation arrangement <NUM> comprising any known fixation arrangement (welding, adhesive, screw, among others). The fixing arrangement <NUM> having as function to keep the positioning of the stator <NUM>, in relation to the crankcase <NUM>, static.

As can be seen in <FIG>, the space between the inner face of the first through hole 120a and the rotating shaft first part 200a receives a film of lubricating oil, forming a first hydrodynamic radial bearing 500a. Similarly, the space between the inner face of the second through hole 120b and the rotating shaft second part 200b also receives a film of lubricating oil, forming a second hydrodynamic radial bearing 500b. These bearings prevent premature wear of the rotating shaft <NUM> and of the first and second through holes 120a and 120b.

According to <FIG>, the second embodiment of the present invention provides an axial bearing <NUM> to keep the axial spacing between rotor <NUM> and stator <NUM> stable. Therefore, the axial bearing <NUM> can be mounted between the eccentric pin <NUM> and the crankcase upper part 100a.

Optionally, the axial bearing <NUM> could also be mounted between the bearing hub <NUM> and the rotor <NUM>.

Additionally, the second embodiment of the present invention also provides a radial bearing which, integrated with the stator <NUM>, is arranged around the rotating shaft <NUM>. Said radial bearing can comprise any type of bearing already known, such as, for example, a hydrodynamic bearing (bearing with some type of lubricant supply between the minimum clearance of parallel surfaces and, in this case, axially aligned) or a hydrostatic bearing (bearing with forced supply of some type of lubricant injected under pressure between two parallel surfaces and, in this case, axially aligned), or bushings of some low-friction or self-lubricating material.

According to the present invention, the general structure of the stator <NUM> is used to enable the formation of a radial bearing for said rotating shaft <NUM>, so that the rotating shaft <NUM> does not present problems of eccentricity and misalignment.

As shown in <FIG> and <FIG>, the radial bearing is defined by an annular structure <NUM>, no part of the invention, integrated with the stator <NUM> and arranged around the rotating shaft <NUM>. More particularly, the annular structure <NUM> is arranged around a segment of the rotating shaft <NUM> where the inner radial channel 222a is located.

Thus, the space formed between the annular structure <NUM> and the rotating shaft <NUM> segment is adapted to retain a film of lubricating oil (from the inner radial channel 222a), forming a radial hydrodynamic bearing.

<FIG>, not part of the invention, illustrates an optional configuration of the second embodiment. In this configuration, the motor is above the cylinder.

The present invention also provides configurations applicable to the first embodiment and to the second embodiment.

According to <FIG>, not part of the invention, in a configuration in which the rotor <NUM>, <NUM> is above the stator <NUM>, <NUM>, the rotor <NUM>, <NUM> comprises a support structure A in the form of "Z" for fixation to the rotating shaft <NUM>, <NUM>.

According to <FIG>, the rotor <NUM>, <NUM> and stator <NUM>, <NUM> can be separated by a first axial clearance F1, and the rotating shaft <NUM>, <NUM> and the crankcase <NUM>, <NUM> can be separated by a second axial clearance F2. The first F1 and the second F2 clearances are adjustable using a bushing B arranged between the rotor <NUM>, <NUM> and the rotating shaft <NUM>, <NUM>. Additionally, the first clearance F1 is formed by the displacement of rotor <NUM>, <NUM> over the bushing B or by the displacement of stator <NUM>, <NUM> over the crankcase <NUM>, <NUM>, while the second clearance F2 is formed by displacing the bushing B over the rotating axis <NUM>, <NUM>.

The bushing B is an annular (sliding) part disposed between rotor <NUM>, <NUM> and shaft <NUM>, <NUM>, allowing the second clearance F2 to be formed regardless of the formation of the first clearance F1.

The second clearance F2 defines a displacement field (for example, from <NUM> to <NUM>) for the axis, preventing it from getting stuck (if F2 = <NUM>) or with very high displacement, generating problems mainly during transport. Once the second clearance F2 is formed, the first clearance F1 (between rotor and stator) can be adjusted without changing F2.

According to <FIG>, an oil pump C of frustum-conical shape can be provided in the inner axial channel <NUM> of the rotating shaft <NUM>, <NUM> or can be provided in the rotor <NUM>, <NUM>. Thus, the oil intake is optimized. Additionally, the oil pump C also acts as an interface of physical contact between the rotor <NUM>, <NUM> and the rotating shaft <NUM>, <NUM>, ensuring the fixation of these elements and transmitting the movement of the rotor <NUM>, <NUM> to the rotating shaft <NUM>, <NUM>. The oil pump C can be fitted under interference on the rotating shaft <NUM>, <NUM>.

In addition to the embodiments presented above, the same inventive concept can be applied to other alternatives or possibilities of using the invention, such as, for example, in air compressors.

Claim 1:
Reciprocating compressor, comprising:
a crankcase (<NUM>);
a rotating shaft (<NUM>) comprising at least one inner axial channel (<NUM>), said inner axial channel (<NUM>) connected to at least one inner radial channel (22a, 22b) or to a crankpin (<NUM>);
the crankpin (<NUM>) is associated with a connecting rod (<NUM>), and the connecting rod (<NUM>) is associated with a movable piston (<NUM>) within a compression cylinder (<NUM>); and
an oil pump (C),
an axial flux electric motor comprising a rotor (<NUM>), with magnets (<NUM>), and a stator (<NUM>) with coils (<NUM>);
wherein the rotor (<NUM>) and the stator (<NUM>) are fixed to the shaft (<NUM>) and to the crankcase (<NUM>), respectively, by means of bearings or fixing arrangements;
wherein the stator (<NUM>) is located between the crankcase (<NUM>) and the rotor (<NUM>), and said rotor (<NUM>) and stator (<NUM>) are separated by a first axial clearance (F1);
wherein the shaft (<NUM>) and crankcase (<NUM>) are separated by a second lower axial clearance (F2);
characterized in that:
the first clearance (F1) and the second lower axial clearance (F2) are adjustable by displacing a bushing (B) disposed between the rotor (<NUM>) and the rotating shaft (<NUM>).